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Mechanochemical Stimulation of MCF7 Cells with Rod-Shaped Fe–Au Janus Particles Induces Cell Death Through Paradoxical Hyperactivation of ERK
Advanced Healthcare Materials
Abstract
Multifunctional nanoparticles that actively target-specific tissues are studied for cancer diagnosis and treatment. Magnetically and optically active particles are of particular interest because they enable multiple imaging modalities and physically modulated therapies, such as magnetic hyperthermia. Fe–Au nanorods are synthesized that have a long iron segment, coated with polyethylene glycol, and a short gold tip functionalized with heregulin (HRG), a known ligand of ErbB family of receptors. HRG–nanorods preferentially target MCF7 cells relative to MDA-MB-231 cells, as demonstrated in a novel microfluidics device. Targeting rates of these classical breast cancer cells correlate with their differential expression of ErbB2/3 receptors. HRG–nanorod binding stimulates the extracellular signal-regulated kinase 1/2 (ERK) phosphorylation in MCF7 cells. The increase in ERK phosphorylation is linked to “active zones,” dynamic regions in the cell periphery, which exhibit higher rates of particle binding than the rest of the cell. Periodically stretching cells using magnetic tweezers further activates ERK, which leads to cell death in cells co-treated with B-Raf inhibitors, through ERK hyperactivation. Although to a lesser extent, cell death is also achieved through magnetic hyperthermia. These results demonstrate nanoscale targeting and localized mechanochemical treatment of specific cancer cell lines based on their receptor expression using multifunctional nanoparticles.
Supplementary resource (1)
Data
October 2015
... According to the approach [13,83,98,100,101] used in our work, the mechanical action on transmembrane proteins (including integrin) changes their conformation, taking into account the contribution of ligand binding, can initiate cellular reactions. ...
... Mechanical activation of select signaling pathways may be combined with other (systemic) stimuli to induce cell death. In [100,101] it has recently been demonstrated that the activation of extracellular signal-regulated kinase pathway through periodic stretching specifically targeted ErbB3 receptors in MCF7 cells with 4 pN using micrometer-long iron rods with functionalized gold tips. ...
... As can be seen from this figure, at the field strength used in the experiments, the value of the force F n acting on the membrane is much lower than the threshold value (4 pN) [100] at Figure 11. (a)-maximum value of the vertical projection of the pulling force (Fn) acting on the membrane from the magnetite particle vs a magnetic field induction (B). ...
The paper discusses schemes for the implementation of magneto-mechanical anticancer therapy and the most probable scenarios of damaging mechanical effects on the membranes of malignant cells by targeted magnetic nanoparticles selectively bound to membrane mechanoreceptors employing aptamers. The conditions for selective triggering of the malignant cell apoptosis in a low-frequency non-heating alternating magnetic field, corresponding to the exceeding threshold value of the force acting on the membrane and its mechanoreceptors, are established using a nanoparticle dynamic simulation. The requirements for the functionality of magnetic nanoparticles and their suitability for biomedical applications are analysed. Attention is paid to the possibility of the formation of magnetite nanoparticle aggregates in an external magnetic field and their localization near tumor cell membranes. It is shown that the scenario involving the process of aggregation of magnetite nanoparticles provides a sufficient magneto-mechanical impact to achieve a therapeutic effect. A possible explanation for the experimentally established fact of successful application of magneto-mechanical therapy using magnetite nanoparticles is presented, in which complete suppression of the Ehrlich carcinoma in an alternating magnetic field as a response to a magnetome-chanical stimulus was demonstrated. This result confirmed the possibility of using the method for high efficiency treatment of malignant neoplasms. The paper is provided with an extensive review of key publications and the state of art in this area.
... To allow two types of functionalization on the same particle, nanowires with a gold end were synthesized. 34 These particles combining two different surface properties are called Janus particles. ...
... 22 Alternatively, the culture plate can be directly placed above a coil (Fig. 3(b)). 33,46,49,51 Kilinc et al. 34 used a Fe-Co-V tip wound with a copper coil to apply the magnetic eld (the amplitude is not indicated). 34 In the latter case, the magnetic eld was applied very locally (500 mm from the tip). ...
... 33,46,49,51 Kilinc et al. 34 used a Fe-Co-V tip wound with a copper coil to apply the magnetic eld (the amplitude is not indicated). 34 In the latter case, the magnetic eld was applied very locally (500 mm from the tip). Magnetic elds produced by these three methods are highly inhomogeneous and decrease sharply as a function of the distance from the eld source. ...
Cancer treatment by magneto-mechanical effect of particles (TMMEP) is a growing field of research. The principle of this technique is to apply a mechanical force on cancer cells in order to destroy them thanks to magnetic particles vibrations. For this purpose, magnetic particles are injected in the tumor or exposed to cancer cells and a low-frequency alternating magnetic field is applied. This therapeutic approach is quite new and a wide range of treatment parameters are explored to date, as described in the literature. This review explains the principle of the technique, summarizes the parameters used by the different groups and reports the main in vitro and in vivo results.
... magnetic particle to move in various ways, such as twisting [1], linear reciprocating vibration [3][4][5], rotation [6][7][8][9][10][11][12], and more complex motions [13][14][15][16][17][18][19]. ...
... Both nano- [4][5][6][7][8][10][11][12][13][14][15][16] and microscale [1,3,5,8,[17][18][19] magnetic particles have been investigated for damaging cancer cells via the magneto-mechanical force. Large or aggregated magnetic particles triggered by a dynamic magnetic field can easily damage cancer cells through generating large holes in the cell membrane owing to the large volume of particles. ...
Background
The magneto-mechanical force killing cancer cells is an interesting and important strategy for cancer therapy.
Results
Novel magnetic microspheres composed of a Fe 3 O 4 nanocore, a bovine serum albumin (BSA) matrix, and a rod-like SiO 2 nanoshell, which had flagellum-like surface for force-mediated cancer therapy were developed. One such magnetic microsphere (Fe 3 O 4 /BSA/rSiO 2 ) at a cancer cell (not leave the cell surface) under a low frequency vibrating magnetic field (VMF) could generate 6.17 pN force. Interestingly, this force could induce cancer cell to generate reactive oxygen species (ROS). The force and force-induced ROS could kill cancer cells. The cell killing efficiency of Fe 3 O 4 /BSA/rSiO 2 exposed to a VMF was enhanced with increasing silica nanorod length, and the microspheres with straight nanorods exhibited stronger cell killing ability than those with curled nanorods. Fe 3 O 4 /BSA/rSiO 2 triggered by a VMF could efficiently inhibit mouse tumor growth, while these microspheres without a VMF had no significant effect on the cell cycle distribution, cell viability, tumor growth, and mouse health .
Conclusions
These microspheres with unique morphological characteristics under VMF have great potential that can provide a new platform for treating solid tumors at superficial positions whether with hypoxia regions or multidrug resistance.
... Firstly, a low frequency dynamic or alternating magnetic field is very easy to build and has little effect on the human body. Secondly, magnetic IONPs could display movement, oscillate or rotate behaviour under low-frequency vibrating magnetic fields and generate mechanical force to stimulate cancer cells to induce cell apoptosis or death [44][45][46][47]. Lastly, compared with NIR, the magnetic field could penetrate deeper tissues and affect magnetic particles' behaviour inside tissues, stimulating deeper into tumour and destroying it. ...
... The advantages of magneto-mechanic force and low frequency vibrating magnetic field included: (1) Low frequency dynamic or alternating magnetic field is very easy to build and has little effect on the human body. (2) Magnetic IONPs could display movement, oscillate or rotate under low-frequency vibrating magnetic fields and generate mechanical force to stimulate cancer cells to induce cell apoptosis or death [44][45][46][47]. (3) Compared with NIR, the magnetic field could penetrate deeper into tissues and affect magnetic particles' behaviour inside tissues, which could stimulate deeper into the tumour for destroying it. ...
Background
Magnetic materials mediated by mechanical forces to combat cancer cells are currently attracting attention. Firstly, the magnetic force penetrates deeper into tissues than the NIR laser alone to destroy tumours. Secondly, the synergistic effect of nano-magnetic-material characteristics results in a viable option for the targeted killing of cancer cells. Therefore, mechanical force (MF) produced by magnetic nanomaterials under low frequency dynamic magnetic field combined with laser technology is the most effective, safe and efficient tool for killing cancer cells and tumour growth.
Results
In this study, we synthesized novel urchin-like hollow magnetic microspheres (UHMMs) composed of superparamagnetic Fe 3 O 4 . We demonstrated the excellent performance of UHMMs for killing laryngocarcinoma cancer cells through mechanical force and photothermal effects under a vibrating magnetic field and near-infrared laser, respectively. The killing efficiency was further improved after loading the synthesised UHMMs with Chlorin e6 relative to unloaded UHMMs. Additionally, in animal experiments, laryngocarcinoma solid tumour growth was effectively inhibited by UHMMs@Ce6 through magneto-mechanic force, photothermal and photodynamic therapy.
Conclusions
The biocompatibility and high efficiency of multimodal integrated therapy with the UHMMs prepared in this work provide new insights for developing novel nano therapy and drug loading platforms for tumour treatment. In vivo experiments further demonstrated that UHMMs/Ce6 are excellent tools for strongly inhibiting tumour growth through the above-mentioned characteristic effects.
Graphical Abstract
... Dans certaines études, des comptages au microscope optique du nombre de cellules ont été réalisés pour quantifier le nombre de cellules vivantes, en comparant avec un contrôle non traité. Des marqueurs peuvent être utilisés sur les noyaux et ainsi différencier les cellules saines des cellules affectées, caractérisées par un marquage nucléaire dense et une forme atypique (Kilinc et al. 2015). Une quantification de l'intensité lumineuse émise par les cellules exprimant la Luciférase, enzyme catalysant la réaction de bioluminescence, a aussi été utilisée pour quantifier le nombre de cellules (Muroski et al. 2016 ...
... suite à l'application du champ magnétique en présence de particules a été étudiée (Kilinc et al. 2015). ...
Le glioblastome est un cancer du cerveau très agressif dont les thérapies actuelles n’augmentent que très peu la durée de vie. Dans cette thèse, nous étudions un nouveau traitement par effet magnéto-mécanique de particules (TEMMP). Un champ magnétique rotatif à faible fréquence (20 Hz) est appliqué pour faire vibrer des particules magnétiques en contact avec les cellules cancéreuses. Les particules développées sont produites par une approche top-down en salle blanche. Les disques de permalloy utilisés présentent une configuration en vortex avec une faible rémanence et une bonne dispersion en suspension. Des particules multicouches de Co/Pt avec une anisotropie perpendiculaire et des vortex de permalloy en forme d’ellipses sont aussi étudiés. L’efficacité du TEMMP est évaluée in-vitro sur des cellules de glioblastome et les différents paramètres sont optimisés. Une forte diminution du nombre de cellules après traitement est alors observée et le comportement des cellules restantes est affecté. Le TEMMP est ensuite adapté pour une étude in-vivo dans un modèle orthotopique de glioblastome chez la souris nude. L’injection des particules en intra-tumoral est mise au point. Les tissus sont peu affectés par le TEMMP comparé à une injection de particules, et une faible augmentation de la survie est observée. Pour mimer les propriétés mécaniques du cerveau de manière plus pertinente, un modèle in-vitro 3D est alors développé et validé. Conçu avec des sphéroïdes de cellules pris dans un gel d’agarose, ce modèle apporte des pistes d’optimisation.
... This explains the increased ROS production typically observed in tumor cells after mechanochemical actuation ( Figure 2a) (Murad et al., 2019). Fe-Au MNCs + EMF promoted ERK1/2 signaling pathway in MCF7 cells through activation of human epidermal growth factor receptor 3 (HER3) at 4-12 pN ( Figure 2b) (Kilinc et al., 2015). Similarly, MNCs combined with CMF and EMF generated magnetic forces and ROS to activate the nonselective transient receptor potential (TRP) channels ( Figure 2c) (Brier et al., 2020). ...
Magnetic nanoparticles (MNs) are typically used as contrast agents for magnetic resonance imaging or as drug carriers with a remotely controlled delivery to the tumor. However, they can also potentiate the action of anticancer drugs under the influence of applied constant magnetic (CMFs) and electromagnetic fields (EMFs). This review demonstrates the role of magneto‐mechanochemical effects produced by MNs alone and loaded with anticancer agents (MNCs) in response to CMFs and EMFs for modulation of tumor redox state. The combined treatment is suggested to act by two mechanisms: spin‐dependent electron transport propagates free radical chain reactions, while magnetomechanical interactions cause conformational changes in drug molecules loaded onto MNs and generate reactive oxygen species (ROS). By adjusting the parameters of CMFs and EMFs during the magneto‐mechanochemical synthesis and subsequent treatment, it is possible to modulate ROS production and switch redox signaling involved in ERK1/2 and NF‐κB pathways from initiation of tumor growth to inhibition. Observations of tumor volume in different animal models and treatment combinations reported a 6%–70% reduction as compared with conventional drugs. Despite these results, there is a general lack of research in magnetic nanotheranostics that link redox changes across multiple levels of organization in the tumor‐bearing host. Further multidisciplinary studies with more focus on the relationship between the electron transport processes in biomolecules and their effects on the tumor‐host interaction should accelerate the clinical translation of magnetic nanotheranostics.
This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease
Therapeutic Approaches and Drug Discovery > Emerging Technologies
Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
... Besides magnetic QD systems, plasmonic tadpole-like JPs with enhanced cellular internalization have been used as plasmonic probes for near infrared (NIR) cell imaging [68]. Matchstick-shaped Au/ZnO/SiO 2 Janus nanorods, allowing multimodal dark-field, two-photon, and fluorescence imaging [69], Janus polymer nanospheres [70], and Fe-Au nanorods [71] have also demonstrated potential in cell imaging. ...
Janus particles are a unique type of materials combining two different functionalities in a single unit. This allows the combination of different analytical properties leading to new analytical capabilities, i.e., enhanced fluid mixing to increase sensitivity with targeting capturing abilities and unique advantages in terms of multi-functionality and versatility of modification, use, and operation both in static and dynamic modes. The aim of this conceptual review is to cover recent (over the last 5 years) advances in the use of Janus microparticles and micromotors in (bio)-sensing. First, the role of different materials and synthetic routes in the performance of Janus particles are described. In a second main section, electrochemical and optical biosensing based on Janus particles and motors are covered, including in vivo and in vitro methodologies as the next biosensing generation. Current challenges and future perspectives are provided in the conclusions section.
Graphical abstract
... Using the same principle, MNPs have been used to label circulating tumour cells so that they can be concentrated and detected for an early diagnosis of metastasis risk [82,83]. More recently, the magnetic guiding of immune cells loaded with MNPs has been proposed as an advanced solution to reduced vascular accessibility [84], and as a means to activate mechanosensitive membrane receptors that inhibit cancer proliferation [85]. ...
Hyperthermia has emerged as a promising alternative to conventional cancer therapies and in fact, traditional hyperthermia is now commonly used in combination with chemotherapy or surgery during cancer treatment. Nevertheless, non-specific application of hyperthermia generates various undesirable side-effects, such that nano-magnetic hyperthermia has arisen a possible solution to this problem. This technique to induce hyperthermia is based on the intrinsic capacity of magnetic nanoparticles to accumulate in a given target area and to respond to alternating magnetic fields (AMFs) by releasing heat, based on different principles of physics. Unfortunately, the clinical implementation of nano-magnetic hyperthermia has not been fluid and few clinical trials have been carried out. In this review, we want to demonstrate the need for more systematic and basic research in this area, as many of the sub-cellular and molecular mechanisms associated with this approach remain unclear. As such, we shall consider here the biological effects that occur and why this theoretically well-designed nano-system fails in physiological conditions. Moreover, we will offer some guidelines that may help establish successful strategies through the rational design of magnetic nanoparticles for magnetic hyperthermia.
... 41 Several studies have demonstrated that heregulinloaded magnetic nanorods selectively interact with ErbB3 receptors in MCF7 cells, initiating the activation of the extracellular signal-regulated kinase with 4 pN mechanical stretching under EFs. 42 Although some receptor clusters do not directly interact with the binding sites in MCs, they display tensional changes similar to those of bound ones. 43 Figure 1 shows that the distribution of mechanical stress from the site of exertion across the cell induces phosphorylation of the kinase. ...
Although nanotechnology advances have been exploited for a myriad of purposes, including cancer diagnostics and treatment, still there is little discussion about the mechanisms of remote control. Our main aim here is to explain the possibility of a magnetic field control over magnetic nanocomplexes to improve their delivery, controlled release and antitumor activity. In doing so we considered the nonlinear dynamics of magnetomechanical and magnetochemical effects based on free radical mechanisms in cancer development for future pre-clinical studies.
... Cell membrane is abundant with mechanical-sensitive receptors and ion channels, such as integrin receptor, 85 cadherin adhesion molecule, 88 ErbB receptor, 89 frizzled receptor, 90 notch receptor, 88 TREK-1 channel, 91 TRPV4 channel, 85 etc. Taken as an example, integrin is a mechanosensitive protein transmitting forces from the extracellular matrix to the cytoskeleton. ...
From single pole magnetic tweezers to robotic magnetic field generation systems, the development of magnetic micromanipulation systems, using electromagnets or permanent magnets, has enabled a multitude of applications for cellular and intracellular measurement and stimulation. Controlled by different configurations of magnetic field generation systems, magnetic particles have been actuated by an external magnetic field to exert forces/torques and perform mechanical measurements on the cell membrane, cytoplasm, cytoskeleton, nucleus, intracellular motors, etc. The particles have also been controlled to generate aggregations to trigger cell signaling pathways and produce heat to cause cancer cell apoptosis for hyperthermia treatment. Magnetic micromanipulation has become an important tool in the repertoire of toolsets for cell measurement and stimulation and will continue to be used widely for further explorations of cellular/intracellular structures and their functions. Existing review papers in the literature focus on fabrication and position control of magnetic particles/structures (often termed micro-nanorobots) and the synthesis and functionalization of magnetic particles. Differently, this paper reviews the principles and systems of magnetic micromanipulation specifically for cellular and intracellular measurement and stimulation. Discoveries enabled by magnetic measurement and stimulation of cellular and intracellular structures are also summarized. This paper ends with discussions on future opportunities and challenges of magnetic micromanipulation in the exploration of cellular biophysics, mechanotransduction, and disease therapeutics.
... Kilinc et al. synthesized Fe-Au nanorods for combined cell targeting, therapy and imaging able to specifically target breast cancer cells. In this design, the Au block was modified with heregulin, a ligand of HER family of receptors, whereas the magnetic response of the Fe block was used for mechanical perturbation and MRI [65]. A very nice work reported by Zhang et al. describes a method for the synthesis of uniform multifunctional Au/Fe 3 O 4 @C Janus nanoparticles. ...
Magnetic Janus particles bring together the ability of Janus particles to perform two different functions at the same time in a single particle with magnetic properties enabling their remote manipulation, which allows headed movement and orientation. This article reviews the preparation procedures and applications in the (bio)sensing field of static and self-propelled magnetic Janus particles. The main progress in the fabrication procedures and the applicability of these particles are critically discussed, also giving some clues on challenges to be dealt with and future prospects. The promising characteristics of magnetic Janus particles in the (bio)sensing field, providing increased kinetics and sensitivity and decreased times of analysis derived from the use of external magnetic fields in their manipulation, allows foreseeing their great and exciting potential in the medical and environmental remediation fields.
... 39 Kilinc et al. reported that heregulin-functionalized nanorods binding to HER2 receptor could stimulate ERK phosphorylation in MCF7 breast cancer cells. 40 The increase in ERK phosphorylation was associated with the existence of "active zones", i.e., dynamic regions in the cell periphery, exhibiting higher rates of nanoparticle binding compared to the rest of the cell, suggesting, therefore, a localized receptor activation. ...
Gold nanocages (AuNCs) have been shown to be a useful tool for harnessing imaging and hyperthermia therapy of cancer, thanks to their unique optical properties, low toxicity and facile surface functionalization. Herein, we use AuNCs for selective targeting of prostate cancer cells (PC3) via specific interaction between neuropeptide Y (NPY) receptor and three different NPY analogs conjugated to AuNCs. Localized surface plasmon band of the nanoconjugates was set around 800 nm, which is appropriate for in vivo applications. Long-term stability of nanoconjugates in different media was confirmed by UV-vis and DLS studies. Active NPY receptor targeting was observed by confocal microscopy showing time-dependent AuNCs cellular uptake. Activation of ERK1/2 pathway was evaluated by Western blot to confirm the receptor-mediated specific interaction with PC3. Cellular uptake kinetics were compared as a function of peptide structure. Cytotoxicity of nanoconjugates was evaluated by MTS and Annexin V assays, confirming their safety within the concentration range explored. Hyperthermia studies were carried out irradiating the cells, previously incubated with AuNCs, with a pulsed laser at 800 nm wavelength, showing a heating enhancement ranging from 6 to 35 °C above the culture temperature dependent on the irradiation power (between 1.6 and 12.7 W/cm2). Only cells treated with AuNCs underwent morphological alterations in the cytoskeleton structure upon laser irradiation, leading to membrane blebbing and loss of microvilli associated to cell migration. This effect is promising in view of possible inhibition of proliferation and invasion of cancer cells. In summary, our Au-peptide NCs proved to be an efficient theranostic nanosystem for targeted detection and activatable killing of prostate cancer cells.
... The Au/Fe-integrated theranostic particles exhibited a strong magnetic property suitable for their successful application as a contrast agent for magnetic resonance (MR) and x-ray CT imaging and high NIR absorbance leading to efficient photothermal ablation of cancer. Another dual-metal system, Fe-Au nanoparticles were developed, where Fe-Au nanorods were synthesized with a long iron segment and a short gold tip [65]. Magnetically and optically active nanoparticles are of great interest as they offer multiple imaging modalities along with physically regulatable therapy such as magnetic hyperthermia. ...
Photothermal therapy, also referred to as optical hyperthermia or photothermal ablation, is an emerging strategy for treating solid tumours. Colloidal gold converts the absorbed light into localized heat via a non-radiative mechanism, surface plasmon resonance, which ablates the solid tumours. Several plasmon resonating nanostructures, including gold nanoparticles (AuNPs), gold nanorods (AuNRs), gold nanoshells, gold nanocages, copper sulphide and carbon nanotubes, have shown potential for photo-activated cancer therapy. Generally, spherical AuNPs display absorption maxima between 500-550 nm, making them inefficient due to low tissue penetration. On the other hand, AuNRs absorb light in the near-infrared (NIR) region that penetrates deeper with higher spatial precision, and causes no damage to the surrounding healthy tissues due to the low energy absorption of NIR light by normal tissue. Moreover, the absorption range of light can be fine-tuned to the NIR region by adjusting the aspect ratios of AuNRs. However, large-scale synthesis and stability of this colloidal system still poses challenges for clinical translation. In this review, we discuss various strategies applied up to now for the synthesis of AuNRs. Current trends in the pre-clinical development of multifunctional AuNRs with emphasis on preparation and application strategies in cancer therapy have been delineated.
Any single cancer treatment technique has its associated disadvantages, which lead to low therapeutic efficiency or even therapeutic failure. The growth of a large-sized tumor is hard to completely inhibit through magnetic iron oxide nanoparticle-mediated photothermal therapy (PTT) alone. Therefore, magnetic iron oxide nanoparticle-mediated dual or multimodal therapies have been widely investigated. Numerous unique geometry nanostructures, such as hollow structures, core-shell structures, and yolk-shell structures, have been developed for drug loading via physical action or chemical reaction. Chemotherapeutic drugs and photosensitizers are commonly selected to fabricate the drug-loaded magnetic nanocomposites. They help improve cancer therapy through the synergistic effect between the photothermal and photodynamic effects or chemotherapy. In this chapter, the typical nanostructures of magnetic nanocomposites for drug loading in photothermal-chemotherapy, photothermal-photodynamic therapy, and “photothermal-photodynamic therapy + chemotherapy” have been discussed. Also, it includes the possible options to improve the therapy efficiency further.
Janus nanoparticles refer to a kind of asymmetric-structured nanoparticles composed of two or more distinct sides with differences in chemical nature and/or polarity on each side and thus can integrate two or more properties in one single particle. Due to their unique structure and surface properties, Janus nanoparticles have shown broad application potentials in optics, nuclear magnetic resonance, multi-mode imaging, and other fields. Unlike traditional contrast agents used in biological imaging, Janus nanoparticles are asymmetrically and directionally oriented to ensure stable partitioning of individual nanoparticles while integrating more functions. Much advancement have been carried out in the past few years, with some studies partially covering bioimaging applications. However, to our best knowledge, there are still no review papers specifically dedicated to the bioimaging applications with Janus nanoparticles. Bearing this in mind and taking the current challenges in this field into consideration, herein, we discuss representative approaches orchestrated for bioimaging applications, with the focus on the improvement of imaging quality brought by Janus nanoparticles and the development of multifunctional nanoplatforms in biological imaging fields, such as theranostics and therapies. Finally, based on the research experience of our group in this field, prospects for future research trends are put forward to provide new ideas for designing new Janus nanoparticles for clinical bioimaging.
The clinical translation of new cancer theranostic has been delayed by inherent cancer's heterogeneity. Additionally, this delay has been enhanced by the lack of an appropriate in vitro model, capable to produce accurate data. Nanoparticles and microfluidic devices have been used to obtain new and more efficient strategies to tackle cancer challenges. On one hand, nanoparticles-based therapeutics can be modified to target specific cells, and/or molecules, and/or modified with drugs, releasing them over time. On the other hand, microfluidic devices allow the exhibition of physiologically complex systems, incorporation of controlled flow, and control of the chemical environment. Herein, we review the use of nanoparticles and microfluidic devices to address different cancer challenges, such as detection of CTCs and biomarkers, point-of-care devices for early diagnosis and improvement of therapies. The future perspectives of cancer challenges are also addressed herein.
Conventional therapeutic interventions, which range from drug treatment to learning and training regimens, are often given at a fixed dose/intensity. This often leads to sub‐optimal responses, or even none at all. Similarly, fixed intensity training can lead to plateaus in learning trajectories and training outcomes. This barrier will impact the field of digital therapeutics, where drug‐based therapies may be complemented or replaced by learning and training platforms. A potential solution is to optimize training by identifying N‐of‐1 (single subject) training profiles that can then enhance learning trajectories through individualized training regimens. In this study, CURATE.AI, a mechanism‐independent and indication‐agnostic artificial intelligence (AI) platform, is used to identify N‐of‐1 learning trajectory profiles for healthy volunteers trained on the Multi‐Attribute Task Battery (MATB), a flight deck simulator developed by the National Aeronautics and Space Administration and United States Air Force. By leveraging modulated MATB training intensity in a prospective study, CURATE.AI successfully develops N‐of‐1 learning trajectory profiles that may actionably mediate training optimization on the single‐subject level, by dynamically identifying training inputs that drive the best possible scoring outcome. Therefore, CURATE.AI‐guided training may serve as a powerful optimization platform for digital therapy, student learning, cognitive decline prevention, and other indications.
Using magnetomechanical force to kill cancer cells has attracted great attention recently. This study presents novel hedgehog‐like microspheres composed of needle‐like magnetic nanoparticles with carbon and gold double shells. Using a novel low‐frequency vibrating magnetic field (VMF), these microspheres with sharp surfaces can seriously damage cancer cells and strongly inhibit mouse tumor growth through mechanical force. The cell killing efficiency depends on VMF exposure time, frequency, strength, and microsphere concentration. The maximum mechanical force generated by one microsphere acting on a cancer cell under a VMF is about 35.79 pN. The microspheres also induce photothermal ablation after being triggered by near‐infrared laser irradiation. Mouse tumors could not be detected after treatment with the synergistic stimuli of mechanical force and photothermal ablation. These results reveal a simple and highly efficient strategy using magnetic microspheres for local treatment of solid tumors in a remote and noninvasive manner. We developed hedgehog‐like gold‐coated magnetic microspheres (HGMMs) and a low‐frequency vibrating magnetic field. We demonstrated the growth of mouse tumors with an initial size of several millimeters could be inhibited by HGMM‐mediated magnetomechanical force, and the tumors disappeared upon treatment with both the mechanical force and photothermal effect generated by the HGMMs.
The biomimetic anisotropic particles have different physicochemical properties on the opposite two sides, enabling diverse applications in emulsion, photonic display, and diagnosis. However, the traditional anisotropic particles have a very small size, ranging from sub-microns to a few microns. The design and fabrication of anisotropic macron-sized particles with new structures and properties is still challenging. In this study, anisotropic polycaprolactone (PCL) microparticles well separated with each other were prepared by crystallization from the dilute PCL solution in a porous 3D gelatin template. They had fuzzy and smooth surfaces on each side, and a size as large as 70 μm. The fuzzy surface of the particle adsorbed significantly larger amount of proteins, and were more cell-attractive regardless of the cell types. The particles showed stronger affinity to fibroblasts over hepatocytes, which paved a new way for cell isolation merely based on the surface morphology. After a successive seeding process, Janus cell microparticles with fibroblasts and endothelial cells (ECs) on each side were designed and obtained by making use of the anisotropic surface morphology, which showed significant difference in ECs functions in terms of prostacyclin (PGl2) secretion, demonstrating the unique and appealing functions of this type of anisotropic microspheres.
In order to provide insight into how anisotropic nano-objects interact with living cell membranes, and possibly self-assemble, magnetic nanorods with an average size of around 100 nm × 1 µm are designed by assembling iron oxide nanocubes within a polymeric matrix under a magnetic field. The nano-bio interface at the cell membrane under the influence of a rotating magnetic field is then explored. A complex structuration of the nanorods intertwined with the membranes is observed. Unexpectedly, after a magnetic rotating stimulation, the resulting macrorods are able to rotate freely for multiple rotations, revealing the creation of a biomagnetic torsion pendulum.
Janus particles have two distinct surfaces or compartments. This enables novel applications that are impossible with homogeneous particles, ranging from the engineering of active colloidal metastructures to creating multimodal therapeutic materials. Recent years have witnessed a rapid development of novel Janus structures and exploration of their applications, particularly in the biomedical arena. It, therefore, becomes crucial to understand how Janus particles with surface or structural anisotropy might interact with biological systems and how such interactions may be exploited to manipulate biological responses. This perspective highlights recent studies that have employed Janus particles as novel toolsets to manipulate, measure, and understand cellular functions. Janus particles have been shown to have biological interactions different from uniform particles. Their surface anisotropy has been used to control the cell entry of synthetic particles, to spatially organize stimuli for the activation of immune cells, and to enable direct visualization and measurement of rotational dynamics of particles in living systems. The work included in this perspective showcases the significance of understanding the biological interactions of Janus particles and the tremendous potential of harnessing such interactions to advance the development of Janus structure-based biomaterials.
One of the most significant challenges in the diagnosis of brain cancer is efficient in vivo imaging using nontoxic nanoprobes. Herein, core-shell gold nanorod@MIL-88(Fe) nanostars are successfully constructed as triple-modality imaging (computed tomography/magnetic-resonance imaging/photoacoustic imaging) nanoprobes that show low cytotoxicity, high contrast, high penetration depth, and high spatial resolution for accurate and noninvasive imaging and diagnosis of gliomas.
We report a strategy for using magnetic Janus microparticles to control the stimulation of T cell signaling with single-cell precision. To achieve this, we designed Janus particles that are magnetically responsive on one hemisphere and stimulatory to T cells on the other side. By manipulating the rotation and locomotion of Janus particles under an external magnetic field, we could control the orientation of the particle–cell recognition and thereby the initiation of T cell activation. This study demonstrates a step towards employing anisotropic material properties of Janus particles to control single-cell activities without the need of complex magnetic manipulation devices.
We report a strategy for using magnetic Janus microparticles to control the stimulation of T cell signaling with single-cell precision. To achieve this, we designed Janus particles that are magnetically responsive on one hemisphere and stimulatory to T cells on the other side. By manipulating the rotation and locomotion of Janus particles under an external magnetic field, we could control the orientation of the particle-cell recognition and thereby the initiation of T cell activation. This study demonstrates a step towards employing anisotropic material properties of Janus particles to control single-cell activities without the need of complex magnetic manipulation devices.
Gold nanocages (AuNCs) have been shown to be a useful tool both for imaging and hyperthermia therapy of cancer, thanks to their outstanding optical properties, low toxicity and facile functionalization with targeting molecules, including peptides and antibodies. In particular, hyperthermia is a minimally invasive therapy which takes advantage of the peculiar properties of gold nanoparticles to efficiently convert the absorbed light into heat. Here, we use AuNCs for the selective targeting and imaging of prostate cancer cells. Moreover, we report the hyperthermic effect characterization of the AuNCs both in solution and internalized in cells. Prostate cancer cells were irradiated at different exposure times, with a pulsed near infrared laser, and the cellular viability was evaluated by confocal microscopy.
Janus particles, named after the two-faced Roman god Janus, have different surface makeups, structures or compartments on two sides. This review highlights recent advances in employing Janus particles as novel analytical tools for live cell imaging and biosensing. Unlike conventional particles used in analytical science, two-faced Janus particles provide asymmetry and directionality, and can combine different or even incompatible properties within a single particle. The broken symmetry enables imaging and quantification of rotational dynamics, revealing information beyond what traditional measurements offer. The spatial segregation of molecules on the surface of a single particle also allows analytical functions that would otherwise interfere with each other to be decoupled, opening up opportunities for novel multimodal analytical methods. We summarize here the development of Janus particles, a few general methods for their fabrication and, more importantly, the emerging and novel applications of Janus particles as multi-functional imaging probes and sensors.
Magnetic nanoparticles are promising new tools for therapeutic applications, such as magnetic nanoparticle hyperthermia therapy and targeted drug delivery. Recent in vitro studies have demonstrated that a force application with magnetic tweezers can also affect cell fate, suggesting a therapeutic potential for magnetically modulated mechanical stimulation. The magnetic properties of nanoparticles that induce physical responses and the subtle responses that result from mechanically induced membrane damage and/or intracellular signaling are evaluated. Magnetic particles with various physical, geometric, and magnetic properties and specific functionalization can now be used to apply mechanical force to specific regions of cells, which permit the modulation of cellular behavior through the use of spatially and time controlled magnetic fields. On one hand, mechanochemical stimulation has been used to direct the outgrowth on neuronal growth cones, indicating a therapeutic potential for neural repair. On the other hand, it has been used to kill cancer cells that preferentially express specific receptors. Advances made in the synthesis and characterization of magnetic nanomaterials and a better understanding of cellular mechanotransduction mechanisms may support the translation of mechanochemical stimulation into the clinic as an emerging therapeutic approach.
Carbon nanotubes (CNTs) are one of the most promising nanomaterials to be used in biomedicine for drug/gene delivery as well as biomedical imaging. This study develops radio-labeled, iron oxide-decorated multiwalled CNTs (MWNTs) as dual magnetic resonance (MR) and single photon emission computed tomography (SPECT) contrast agents. Hybrids containing different amounts of iron oxide are synthesized by in situ generation. Physicochemical characterisations reveal the presence of superparamagnetic iron oxide nanoparticles (SPION) granted the magnetic properties of the hybrids. Further comprehensive examinations including high resolution transmission electron microscopy (HRTEM), fast Fourier transform simulations, X-ray diffraction, and X-ray photoelectron spectroscopy assure the conformation of prepared SPION as γ-Fe2O3. High r2 relaxivities are obtained in both phantom and in vivo MRI compared to the clinically approved SPION Endorem. The hybrids are successfully radio labeled with technetium-99m through a functionalized bisphosphonate and enable SPECT/CT imaging and γ-scintigraphy to quantitatively analyze the biodistribution in mice. No abnormality is found by histological examination and the presence of SPION and MWNT are identified by Perls stain and Neutral Red stain, respectively. TEM images of liver and spleen tissues show the co-localization of SPION and MWNTs within the same intracellular vesicles, indicating the in vivo stability of the hybrids after intravenous injection. The results demonstrate the capability of the present SPION–MWNT hybrids as dual MRI and SPECT contrast agents for in vivo use.
Recent advances in nano-technology have made a whole zoo of particles of different shapes available for applications, but their interaction with biological cells and their toxicity is often not well understood. Experiments have shown that particle uptake by cells is determined by an intricate interplay between physico-chemical particle properties like shape, size, and surface functionalization, but also by membrane properties and particle orientation. Our work provides systematic understanding, based on a mechanical description, for membrane wrapping of nanoparticles, viruses, and bacterial forms. For rod-like particles, we find stable endocytic states with small and high wrapping fraction; an increased aspect ratio is unfavourable for complete wrapping. For high aspect ratios and round tips, the particles enter via a submarine-mode, side-first with their long edge parallel to the membrane. For small aspect ratios and flat tips, the particles enter tip-first via a rocket-mode.
Abstract In this review article we present basic principles of magnetically induced heat generation of magnetic nanoparticles for application in magnetic particle hyperthermia. After explanation of heating mechanisms, the role of particle-particle as well as particle-tissue interactions is discussed with respect to achievable heating power of the particles inside the tumour. On the basis of heat transfer theory at the micro-scale, the balance between generated and dissipated heat inside the tumour and the resulting damaging effects for biological tissue is examined. The heating behaviour as a function of tumour size is examined in combination with feasible field strength and frequency. Numerical calculations and experimental investigations are used to show the lower tumour size limit for tumour heating to therapeutically suitable temperatures. In summary, this article illuminates practical aspects, limitations, and the state of the art for the application of magnetic heating in magnetic particle hyperthermia as thermal treatment of small tumours.
The physical principles underlying some current biomedical applications of magnetic nanoparticles are reviewed. Starting from well-known basic concepts, and drawing on examples from biology and biomedicine, the relevant physics of magnetic materials and their responses to applied magnetic fields are surveyed. The way these properties are controlled and used is illustrated with reference to (i) magnetic separation of labelled cells and other biological entities; (ii) therapeutic drug, gene and radionuclide delivery; (iii) radio frequency methods for the catabolism of tumours via hyperthermia; and (iv) contrast enhancement agents for magnetic resonance imaging applications. Future prospects are also discussed.
Commercial nanoparticles supplied by Chemicell, Micromod and Bayer-Schering were characterised with regard to their nanocrystalline diameter, hydrodynamic diameter, total iron content and relative ferrous iron content. Additionally, calorimetric measurements were taken using a 900 kHz AC magnetic field of amplitude 5.66 kA/m. It was found that those samples containing relatively high (> 18%) ferrous content generated a substantially smaller (12% on average) intrinsic loss power (ILP) than those samples with a lower ferrous content. Two nominally identical Chemicell samples that differed only in their production date showed significantly different ILPs, attributed to a variation in batch-to-batch crystallite sizes. The highest ILP values in the cohort, ca. 3.1 nHm(2)/kg, were achieved for particles with hydrodynamic diameters of ca. 70nm and nanocrystalline diameters of ca. 12 nm. These compare favourably with most samples prepared in academic laboratories, although they are not as high as the ca. 23.4nHm(2)/kg reported for naturally occurring bacterial magnetosomes. (c) 2009 Elsevier B.V. All rights reserved.
Heregulin (HRG) belongs to the family of EGFs and activates the receptor proteins ErbB3 and ErbB4 in a variety of cell types to regulate cell fate. The interactions between HRG and ErbB3/B4 are important to the pathological mechanisms underlying schizophrenia and some cancers. Here, we observed the reaction kinetics between fluorescently labeled single HRG molecules and ErbB3/B4 on the surfaces of MCF-7 human breast cancer cells. The equilibrium association and the dissociation from equilibrium were also measured using single-molecule imaging techniques. The unitary association processes mirrored the EGF and ErbB1 interactions in HeLa cells [Teramura Y, et al. (2006) EMBO J 25:4215-4222], suggesting that the predimerization of the receptors, followed by intermediate formation (between the first and second ligand-binding events to a receptor dimer), accelerated the formation of doubly liganded signaling dimers of the receptor molecules. However, the dissociation analysis suggested that the first HRG dissociation from the doubly liganded dimer was rapid, but the second dissociation from the singly liganded dimer was slow. The dissociation rate constant from the liganded monomer was intermediate. The dynamic changes in the association and dissociation kinetics in relation to the dimerization of ErbB displayed negative cooperativity, which resulted in apparent low- and high-affinity sites of HRG association on the cell surface.
Cell surface receptors play ubiquitous roles in cell signaling and communication and their expression levels are important biomarkers for many diseases. Expression levels are, however, only one factor that determines the physiological activity of a receptor. For some surface receptors, their distribution on the cell surface, especially their clustering, provides additional mechanisms for regulation. To access this spatial information robust assays are required that provide detailed insight into the organization of cell surface receptors on nanometer length scales. In this manuscript, we demonstrate through combination of scattering spectroscopy, electron microscopy, and generalized multiple particle Mie theory (GMT) simulations that the density- and morphology-dependent spectral response of Au nanoparticle (NP) immunolabels bound to the epidermal growth factor receptors ErbB1 and ErbB2 encodes quantitative information of both the cell surface expression and spatial clustering of the two receptors in different unliganded in vitro cancer cell lines (SKBR3, MCF7, A431). A systematic characterization of the collective spectral responses of NPs targeted at ErbB1 and ErbB2 at various NP concentrations indicates differences in the large-scale organization of ErbB1 and ErbB2 in cell lines that overexpress these receptors. Validation experiments in the scanning electron microscope (SEM) confirm that NPs targeted at ErbB1 on A431 are more strongly clustered than NPs bound to ErbB2 on SKBR3 or MCF7 at overall comparable NP surface densities. This finding is consistent with the existence of larger receptor clusters for ErbB1 than for ErbB2 in the plasma membranes of the respective cells.
The magnetic nanoparticle has emerged as a potential multifunctional clinical tool that can provide cancer cell detection by magnetic resonance imaging (MRI) contrast enhancement as well as targeted cancer cell therapy. A major barrier in the use of nanotechnology for brain tumor applications is the difficulty in delivering nanoparticles to intracranial tumors. Iron oxide nanoparticles (IONP; 10 nm in core size) conjugated to a purified antibody that selectively binds to the epidermal growth factor receptor (EGFR) deletion mutant (EGFRvIII) present on human glioblastoma multiforme (GBM) cells were used for therapeutic targeting and MRI contrast enhancement of experimental glioblastoma, both in vitro and in vivo, after convection-enhanced delivery (CED). A significant decrease in glioblastoma cell survival was observed after nanoparticle treatment and no toxicity was observed with treatment of human astrocytes (P < 0.001). Lower EGFR phosphorylation was found in glioblastoma cells after EGFRvIIIAb-IONP treatment. Apoptosis was determined to be the mode of cell death after treatment of GBM cells and glioblastoma stem cell-containing neurospheres with EGFRvIIIAb-IONPs. MRI-guided CED of EGFRvIIIAb-IONPs allowed for the initial distribution of magnetic nanoparticles within or adjacent to intracranial human xenograft tumors and continued dispersion days later. A significant increase in animal survival was found after CED of magnetic nanoparticles (P < 0.01) in mice implanted with highly tumorigenic glioblastoma xenografts (U87DeltaEGFRvIII). IONPs conjugated to an antibody specific to the EGFRvIII deletion mutant constitutively expressed by human glioblastoma tumors can provide selective MRI contrast enhancement of tumor cells and targeted therapy of infiltrative glioblastoma cells after CED.
Recently, optical stimulation has begun to unravel the neuronal processing that controls certain animal behaviours. However, optical approaches are limited by the inability of visible light to penetrate deep into tissues. Here, we show an approach based on radio-frequency magnetic-field heating of nanoparticles to remotely activate temperature-sensitive cation channels in cells. Superparamagnetic ferrite nanoparticles were targeted to specific proteins on the plasma membrane of cells expressing TRPV1, and heated by a radio-frequency magnetic field. Using fluorophores as molecular thermometers, we show that the induced temperature increase is highly localized. Thermal activation of the channels triggers action potentials in cultured neurons without observable toxic effects. This approach can be adapted to stimulate other cell types and, moreover, may be used to remotely manipulate other cellular machinery for novel therapeutics.
NF-kappaB transcription factor is a critical regulator of the expression of genes involved in tumor formation and progression. Successful RNA interference (RNAi) therapeutics targeting NF-kappaB is challenged by small interfering RNA (siRNA) delivery systems, which can render targeted in vivo delivery, efficient endolysosomal escape, and dynamic control over activation of RNAi. Here, we report near-IR (NIR) light-inducible NF-kappaB downregulation through folate receptor-targeted hollow gold nanospheres carrying siRNA recognizing NF-kappaB p65 subunit. Using micro-positron emission tomography/computed tomography imaging, the targeted nanoconstructs exhibited significantly higher tumor uptake in nude mice bearing HeLa cervical cancer xenografts than nontargeted nanoparticles following i.v. administration. Mediated by hollow gold nanospheres, controllable cytoplasmic delivery of siRNA was obtained on NIR light irradiation through photothermal effect. Efficient downregulation of NF-kappaB p65 was achieved only in tumors irradiated with NIR light but not in nonirradiated tumors grown in the same mice. Liver, spleen, kidney, and lung were not affected by the treatments, in spite of significant uptake of the siRNA nanoparticles in these organs. We term this mode of action "photothermal transfection." Combined treatments with p65 siRNA photothermal transfection and irinotecan caused substantially enhanced tumor apoptosis and significant tumor growth delay compared with other treatment regimens. Therefore, photothermal transfection of NF-kappaB p65 siRNA could effectively sensitize the tumor to chemotherapeutic agents. Because NIR light can penetrate the skin and be delivered with high spatiotemporal control, therapeutic RNAi may benefit from this novel transfection strategy while avoiding unwanted side effect.
Degeneration of central axons may occur following injury or due to various diseases and it involves complex molecular mechanisms that need to be elucidated. Existing in vitro axotomy models are difficult to perform, and they provide limited information on the localization of events along the axon. We present here a novel experimental model system, based on microfluidic isolation, which consists of three distinct compartments, interconnected by parallel microchannels allowing axon outgrowth. Neurons cultured in one compartment successfully elongated their axons to cross a short central compartment and invade the outermost compartment. This design provides an interesting model system for studying axonal degeneration and death mechanisms, with a previously impossible spatial and temporal control on specific molecular pathways. We provide a proof-of-concept of the system by reporting its application to a well-characterized experimental paradigm, axotomy-induced Wallerian degeneration in primary central neurons. Using this model, we applied localized central axotomy by a brief, isolated flux of detergent. We report that mouse embryonic cortical neurons exhibit rapid Wallerian-like distal degeneration but no somatic death following central axotomy. Distal axons show progressive degeneration leading to axonal beading and cytoskeletal fragmentation within a few hours after axotomy. Degeneration is asynchronous, reminiscent of in vivo Wallerian degeneration. Axonal cytoskeletal fragmentation is significantly delayed with nicotinamide adenine dinucleotide pretreatment, but it does not change when distal calpain or caspase activity is inhibited. These findings, consistent with previous experiments in vivo, confirm the power and biological relevance of this microfluidic architecture.
Electronic supplementary material
The online version of this article (doi:10.1007/s12640-010-9152-8) contains supplementary material, which is available to authorized users.
We synthesized multimetal microrods intrinsically encoded with submicrometer stripes. Complex striping patterns are readily
prepared by sequential electrochemical deposition of metal ions into templates with uniformly sized pores. The differential
reflectivity of adjacent stripes enables identification of the striping patterns by conventional light microscopy. This readout
mechanism does not interfere with the use of fluorescence for detection of analytes bound to particles by affinity capture,
as demonstrated by DNA and protein bioassays.
Heat-induced therapeutic gene expression is highly desired for gene therapy to minimize side effects. Furthermore, if the gene expression is triggered by heat stress, combined therapeutic effects of hyperthermia and gene therapy may be possible. We combined TNF-alpha gene therapy driven by the stress-inducible promoter, gadd 153, with hyperthermia using magnetite cationic liposomes (MCLs). In nude mice, MCLs induced cell death throughout much of the tumor area on heating under an alternating magnetic field. This heat stress also resulted in a 3-fold increase in TNF-alpha gene expression driven by the gadd 153 promoter as compared with that of nonheated tumor. TNF-alpha gene expression was also observed in the peripheral area where the hyperthermic effect was not enough to cause cell death. The combined treatment strongly arrested tumor growth in nude mice over a 30-day period, suggesting potential for cancer treatment.
Increased growth factor receptor signaling is implicated in antiestrogen-resistant breast tumors suggesting that abrogation of such signaling could restore or prolong sensitivity to antihormonal agents. Activation of the mitogen-activated protein/extracellular regulated kinase kinase (MEK)-extracellular regulated kinase (ERK)1/2 cascade is a common component of such pathways. We investigated the ability of the MEK activation inhibitor U0126 to block the increased growth of estrogen receptor-positive MCF-7 breast cancer cells caused by fibroblast growth factor 1 (FGF-1), heregulin beta1 (HRGbeta1), and epidermal growth factor (EGF) in the presence of the pure antiestrogen ICI 182780 (Faslodex; fulvestrant). We found that either FGF-1 or HRGbeta1 but not EGF substantially reduced the inhibitory effects of U0126 on growth and ERK1/2 activation, including the combined inhibitory effects of U0126 and ICI 182780. FGF-1 and HRGbeta1 also reduced the inhibition of ERK1/2 phosphorylation by the MEK inhibitors PD98059 and PD184161. Interestingly, a transiently transfected dominant-negative MEK1 completely abrogated activation of a coexpressed green fluorescent protein-ERK2 reporter by all three of the factors. Despite a short-lived activation of Ras and Raf-1 by all three of the growth factors, both FGF-1 and HRGbeta1, unlike EGF, induced a prolonged activation of MEK and ERK1/2 in these cells. Thus, activation of FGF-1- and HRGbeta1-specific signaling causes MEK-dependent prolonged activation of ERK1/2, which is incompletely susceptible to known MEK inhibitors. We also demonstrate that the cytosolic phospholipase A2 inhibitor arachidonyl trifluoro methyl ketone and the pan PKC inhibitor bisindolymaleimide abrogated U0126-resistant phosphorylation of ERK1/2 induced by HRGbeta1 but not by FGF-1. Phosphorylation of ERK5 by all three of the factors was also resistant to U0126 suggesting that its activation is not sufficient to overturn growth inhibition due to diminished ERK1/2 activation. Therefore, therapy combining antiestrogens and MEK inhibitors may be ineffective in some antiestrogen-resistant estrogen receptor-positive breast cancers.
The Ras-Raf-MEK-extracellular signal-regulated kinase (ERK) pathway participates in the control of many fundamental cellular processes including proliferation, survival, and differentiation. The pathway is deregulated in up to 30% of human cancers, often due to mutations in Ras and the B-Raf isoform. Raf-1 and B-Raf can form heterodimers, and this may be important for cellular transformation. Here, we have analyzed the biochemical and biological properties of Raf-1/B-Raf heterodimers. Isolated Raf-1/B-Raf heterodimers possessed a highly increased kinase activity compared to the respective homodimers or monomers. Heterodimers between wild-type Raf-1 and B-Raf mutants with low or no kinase activity still displayed elevated kinase activity, as did heterodimers between wild-type B-Raf and kinase-negative Raf-1. In contrast, heterodimers containing both kinase-negative Raf-1 and kinase-negative B-Raf were completely inactive, suggesting that the kinase activity of the heterodimer specifically originates from Raf and that either kinase-competent Raf isoform is sufficient to confer high catalytic activity to the heterodimer. In cell lines, Raf-1/B-Raf heterodimers were found at low levels. Heterodimerization was enhanced by 14-3-3 proteins and by mitogens independently of ERK. However, ERK-induced phosphorylation of B-Raf on T753 promoted the disassembly of Raf heterodimers, and the mutation of T753 prolonged growth factor-induced heterodimerization. The B-Raf T753A mutant enhanced differentiation of PC12 cells, which was previously shown to be dependent on sustained ERK signaling. Fine mapping of the interaction sites by peptide arrays suggested a complex mode of interaction involving multiple contact sites with a main Raf-1 binding site in B-Raf encompassing T753. In summary, our data suggest that Raf-1/B-Raf heterodimerization occurs as part of the physiological activation process and that the heterodimer has distinct biochemical properties that may be important for the regulation of some biological processes.
We aimed to evaluate the feasibility and tolerability of the newly developed thermotherapy using magnetic nanoparticles on recurrent glioblastoma multiforme. Fourteen patients received 3-dimensional image guided intratumoral injection of aminosilane coated iron oxide nanoparticles. The patients were then exposed to an alternating magnetic field to induce particle heating. The amount of fluid and the spatial distribution of the depots were planned in advance by means of a specially developed treatment planning software following magnetic resonance imaging (MRI). The actually achieved magnetic fluid distribution was measured by computed tomography (CT), which after matching to pre-operative MRI data enables the calculation of the expected heat distribution within the tumor in dependence of the magnetic field strength. Patients received 4-10 (median: 6) thermotherapy treatments following instillation of 0.1-0.7 ml (median: 0.2) of magnetic fluid per ml tumor volume and single fractions (2 Gy) of a radiotherapy series of 16-70 Gy (median: 30). Thermotherapy using magnetic nanoparticles was tolerated well by all patients with minor or no side effects. Median maximum intratumoral temperatures of 44.6 degrees C (42.4-49.5 degrees C) were measured and signs of local tumor control were observed. In conclusion, deep cranial thermotherapy using magnetic nanoparticles can be safely applied on glioblastoma multiforme patients.
Progress in the prediction and optimization of the heating of magnetic
nanoparticles in an alternating magnetic fi eld is highly desirable for their
application in magnetic hyperthermia. Here, a model system consisting of
metallic iron nanoparticles with a size ranging from 5.5 to 28 nm is extensively
studied. Their properties depend strongly on their size: behaviors
typical of single-domain particles in the superparamagnetic regime, in the
ferromagnetic regime, and of multi-domain particles are observed. Ferromagnetic
single-domain nanoparticles are the best candidates and display
the highest specifi c losses reported in the literature so far (11.2 ± 1 mJ g − 1 ).
Measurements are analysed using recently demonstrated analytical formulas
and numerical simulations of the hysteresis loops. Several features expected
theoretically are observed for the fi rst time experimentally: i) the correlation
between the nanoparticle diameter and their coercive fi eld, ii) the correlation
between the amplitude of the coercive fi eld and the losses, and iii) the
variation of the optimal size with the amplitude of the magnetic fi eld. None
of these features are predicted by the linear response theory – generally used
to interpret hyperthermia experiments – but are a natural consequence of
theories deriving from the Stoner–Wohlfarth model; they also appear clearly
in numerical simulations. These results open the path to a more accurate
description, prediction, and analysis of magnetic hyperthermia.
Some of the advancements in the field of non-centrosymmetric Janus particles (JP) along with the synthesis, self-assembly behavior, physical properties, and applications, are discussed. Researchers focus on describing biological, biobased, and bioinspired JPs, access routes based on classical organic synthesis, along with macromolecular engineering and self-assembly of polymers, symmetry breaking at interfaces, selective growth of second compartments, and symmetry-breaking in confined volumes. The researchers also discuss related techniques using the break-up or patterning of side-by-side flown liquids, and miscellaneous techniques. They inform that significant progress has been made in diversifying synthetic strategies for the preparation of JPs over a period of time with the aim to include diverse functionalities, target inorganic or organic hybrid materials, along with finding ways toward a scale-up.
With the aim to design addressable magnetically-active carbon nanotubes (CNTs) for cancer treatment, the use of Fe-filled CNTs (Fe@MWCNTs) as multifunctional scaffolds is reported for exohedrally anchoring a monoclonal antibody (mAb) known to bind a plasma membrane receptor over-expressed in several cancer cells (EGFR). Comprehensive microscopic (transmission electron microscopy, atomic force microscopy, and scanning electron microscopy) and spectroscopic (Raman, 57Fe Mossbauer, energy dispersive spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction) characterizations reveal the efficient confinement of magnetically-active Fe phases (α-Fe and Fe3C), while compositional evaluations through XPS, thermogravimetric analysis and gel electrophoresis confirm that mAb immobilization onto Fe@MWCNTs occurs. Enzyme-linked immunosorbent assay (ELISA), confocal microscopy imaging and western blotting confirm the targeting action toward EGFR-overexpressing cell lines (EGFR+). In vitro magnetic filtration experiments demonstrate that a selective removal of EGFR+ cells from a mixed population of healthy cell lines could be obtained in very short times (≈10 min). Cytotoxicity evaluations by classic cell staining procedures after application of an electromagnetic radiation inducing magnetic fluid hyperthermia (MFH), show a selective suppression of the EGFR+ cell line. Molecular dynamics and docking simulations of the hybrid mAb/Fe@MWCNTs conjugates nicely show how the presence of the CNT framework does not sterically affect the conformational properties of the two antigen binding regions, further supporting the biochemical findings.
The potential of highly ordered array structures in sensing applications is well recognized, particularly with the ability to accurately define the structural composition and arrangement of the individual nanorods. The use of heterogeneous nano¬structures as sub-units generates an additional degree of freedom, which can be used to tailor the optical response of such arrays. In this communication, we report on the fabrication and characterization of well-defined Fe-Au bisegmented nanorod arrays in a repeating hexagonal arrangement. Through a delicate asymmetric etching method, free-standing Fe-Au nanorod arrays on a gold coated substrate are achieved with an inter-rod spacing of 26 nm. This separation distance renders the array capable of sustaining resonant electromagnetic wave coupling between individual rods. Owing to this coupling, the sub-wavelength arrangement and the structural heterogeneity, the nanorod arrays exhibit unique plasmonic responses in the near-infrared (NIR) range. Enhanced sensitivity in this spectral region has previously remained unidentified by gold-only nanorods of equivalent dimensions. This response offers substantial confirmation of the potential of these highly ordered, high-density arrays for biomedical relevant applications such as subcutaneous spectroscopy and biosensing.
There are four members of the EGFR family: EGFR, erbB2, erbB3 and erbB4. These receptors form ligand-activated oligomers which regulate intracellular processes via an oligomeric tyrosine kinase scaffold. The receptors are activated when the extracellular domain undergoes a conformational change which facilitates either homo- or hetero-oligomerization with other family members. The absence of one EGFR family member leads to embryonic or early post-natal death due to implantation, central nervous system or cardiac defects. Many mouse models of defective or deficient EGFR family members are available for studying physiology and/or pathology of EGFR family members. Sophisticated antibody and kinase inhibitors which target different family members have been designed, produced. EGFR and erbB2 are frequently activated, over expressed or mutated in many common cancers and the antagonists and/or inhibitors of EGFR and/or erbB2 signalling have already been shown to have therapeutic benefits for cancer patients.
Cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) play a crucial role in cell-cell interactions during nervous system development and function. The Aplysia CAM (apCAM), an invertebrate IgCAM, shares structural and functional similarities with vertebrate NCAM and therefore has been considered as the Aplysia homolog of NCAM. Despite these similarities, the binding properties of apCAM have not been investigated thus far. Using magnetic tweezers, we applied physiologically relevant, constant forces to apCAM-coated magnetic particles interacting with apCAM-coated model surfaces and characterized the kinetics of bond rupture. The average bond lifetime decreased with increasing external force, as predicted by theoretical considerations. Mathematical simulations suggest that the apCAM homophilic interaction is mediated by two distinct bonds, one involving all five immunoglobulin (Ig)-like domains in an antiparallel alignment and the other involving only two Ig domains. In summary, this study provides biophysical evidence that apCAM undergoes homophilic interactions, and that magnetic tweezers-based, force-clamp measurements provide a rapid and reliable method for characterizing relatively weak CAM interactions.
Resistive pulse sensing is used to monitor individual and aggregated rod-shaped nanoparticles as they move through tunable pores in elastomeric membranes. By comparing particles of similar dimensions, it is demonstrated that the resistive pulse signal of a rod is fundamentally different from that of a sphere. Rods can be distinguished using two measurements: the blockade event magnitude (Δi(p) ), which reveals the particle's size, and the full width at half maximum (FWHM) duration, which relates to the particle's speed and length. While the observed Δi(p) values agree well with simulations, the measured FWHM times are much larger than expected. This increase in dwell time, caused by rods moving through the pore in various orientations, is not observed for spherical particles. These differences are exploited in a new agglutination assay using rod-shaped particles. By controlling the surface chemistry and location of the capture ligand, rods are made to form either long "end-on-end" or wide "side-on" aggregates upon the addition of an analyte. This observation will facilitate multiplexed detection in agglutination assays, as particles with a particular aspect ratio can be distinguished by two measurements. This is first demonstrated with a biotinylated target and avidin capture probe, followed by the detection of platelet-derived growth factor (PDGF-BB) using an aptamer capture probe, with limits of detection down to femtomolar levels.
Ternary FePt-Au nanorods are synthesized as magnetic-plasmonic 1D nanostructures. Besides their widely tunable magnetic properties, their unique plasmonic response to the illumination polarization provides a powerful tool to optically image these sub-wavelength single nanorods. These nanoparticles also show the potential as a novel nano-bioprobe based on the demonstration of simultaneous magnetic manipulation and optical imaging of single particles inside live cells.
Near-infrared (NIR) hyperthermia agents are of current interest because they hold great promise as highly efficacious tools for cancer photothermal therapy. Although various agents have been reported, a practical NIR hyperthermia agent is yet unavailable. Here, we present the first demonstration that silicon nanomaterials-based NIR hyperthermia agent, that is, gold nanoparticles-decorated silicon nanowires (AuNPs@SiNWs), is capable of high-efficiency destruction of cancer cells. AuNPs@SiNWs are found to possess strong optical absorbance in the NIR spectral window, producing sufficient heat under NIR irradiation. AuNPs@SiNWs are explored as novel NIR hyperthermia agents for photothermal ablation of tumor cells. In particular, three different cancer cells treated with AuNPs@SiNWs were completely destructed within 3 min of NIR irradiation, demonstrating the exciting potential of AuNPs@SiNWs for NIR hyperthermia agents.
The EGFR/Erb-B receptor tyrosine kinases each play distinct and complementary roles in normal breast development. The four receptors form both homodimers and heterodimers in response to binding by ligands which show selectivity for one or more of the receptors (except Erb-B2). Together with the additional flexibility generated by the formation of different dimer pairs, these signalling networks play key roles in directing a variety of both autocrine and paracrine cellular responses. Complex two-way interactions between mammary epithelial cells and the surrounding stroma direct proliferation, duct formation, branching and terminal differentiation during puberty, pregnancy and lactation, with each receptor and ligand fulfilling distinct roles. Caricatures of the normal role of EGFR/Erb-B signalling resulting in aberrant cellular responses are seen in breast cancers, where over-expression and/or (less commonly) mutation of one or more of the receptors results in enhanced cell proliferation, motility, release of proteases and angiogenic factors. Given their importance in tumour progression, compared with most normal adult tissues and their links with resistance to chemotherapy and anti-endocrine therapy, Erb-B receptors (most notably Erb-B2) have been exploited as therapeutic targets. Monoclonal antibodies (e.g. trastuzumab, pertuzumab) and small molecule tyrosine kinase inhibitors (e.g. lapatinib, afatinib) have shown significant clinical responses in some breast cancer subtypes. Additional approaches include targeted toxins or drugs, peptide vaccines, immunRNase and chaperone inhibitors to deplete Erb-B2 protein levels. Greater understanding of the full spectrum of Erb-B-mediated signalling pathways and their misregulation in breast cancer will provide additional strategies to control malignant progression.
Superparamagnetic microbeads play an important role in a number of scientific and biotechnology applications including single-molecule force measurements, affinity separation, and in vivo and in vitro diagnostics. Magneto-optically active nanorods composed of single-crystalline Au and polycrystalline Fe segments were synthesized with diameters of 60 or 295 nm using templated electrodeposition. The Fe section was magnetically soft and had a saturation magnetization of approximately 200 emu/g, resulting in a 10-fold increase in magnetization relative to that iron oxide nanoparticles. The strong plasmonic response of the Au segment of the rod in both the longitudinal and transverse directions made it possible to detect the orientation of a single rod in a polarized light microscope with nanometer resolution. These nanorods provide significantly improved physical properties over iron oxide superparamagnetic beads, making it possible to simultaneously manipulate and monitor the orientation of biomolecules with well-defined forces at the nanometer scale.
HER-2 is in the EGF tyrosine kinase receptor family, overexpressed by many human cancers and minimally expressed by normal adult tissues. HER-2 expression in human cancers is correlated with reduced survival, increased metastasis, reduced apoptosis and increased proliferation. Herceptin is a humanised mouse antibody that targets and inactivates HER-2. In the present study, Herceptin was used to deliver ferric oxide-enriched nanoparticles to HER-2(+) cancer cells. If exposed to alternating magnetic field (AMF), the nanoparticles heat. We tested the ability of AMF-activated Herceptin-directed nanoparticles to selectively kill HER-2(+) human cancer cells.
Herceptin-conjugated nanoparticles were incubated with normal human mammary epithelial cells (HMEC)(HER-2(-)) or malignant human mammary epithelial cells (SK-BR-3)(HER-2(+)). Cells were stained to detect Herceptin or iron and the kinetics of binding quantified. Once conditions were optimised for binding, cells were exposed to either antibody-directed or non-antibody-conjugated nanoparticles, washed and sham-treated or exposed to AMF and cell death quantified.
SK-BR-3 cells bound Herceptin-directed nanoparticles in increasing amounts over 3 h but did not retain non-antibody conjugated nanoparticles. HMECs did not retain either nanoparticles. SK-BR-3 cells with bound Herceptin-directed-nanoparticles, exposed to AMF, died by apoptosis, quantifiable by Live/Dead and nuclear morphology assays and released LDH. Sham-treated SK-BR-3 cells with Herceptin-directed nanoparticles, HMECs with either nanoparticles, with or without AMF treatment, exhibited no increase in toxicity above baseline cell death using these three assays.
These studies demonstrate Herceptin-directed nanoparticles can selectively kill HER-2(+) cancer cells via hyperthermia after AMF activation.
Superparamagnetic iron oxide nanoparticles (SPIONs) have proven to be highly effective contrast agents for the magnetic resonance imaging diagnosis of solid tumors. This review examines the various techniques that are available to selectively target SPIONs toward a wide variety of cancerous tissues, with specific attention given to how the surface properties imparted by various targeting ligands affect the particles tissue distribution and pharmacokinetics. An in-depth examination of the various human cell lines utilized to test the assorted targeting methods is also presented, as well as an overview of the various types of cancer against which each targeting method has been utilized for both in vivo and in vitro studies. From the Clinical Editor: Functionalized superparamagnetic iron oxide nanoparticles (SPIONs) are very potent negative contrast materials for magnetic resonance imaging-based diagnosis. This comprehensive review examines techniques that selectively target SPIONs toward a wide variety of malignancies.
Nanomaterials that interact with light provide a unique opportunity for applications in biophotonic nanomedicine. Image-guided therapies could be designed based on multifunctional nanoparticles (NPs). Such NPs have a strong and tunable surface plasmon resonance absorption in the near-infrared region and can be detected using multiple imaging modalities (magnetic resonance imaging, nuclear imaging, and photoacoustic imaging). These novel nanostructures, once introduced, are expected to home in on solid tumors either via a passive targeting mechanism (i.e., the enhanced permeability and retention effect) or via an active targeting mechanism facilitated by ligands bound to their surfaces. Once the NPs reach their target tissue, their activity can then be turned on using an external stimulus. For example, photothermal conducting NPs primarily act by converting light energy into heat. As a result, the temperature in the treatment volume is elevated above the thermal damage threshold, which kills the cells. This process, termed photothermal ablation therapy (PTA), is effective, but it is also unlikely to kill all tumor cells when used alone. In addition to PTA, photothermal conducting NPs can also efficiently trigger the release of drugs and activate RNA interference. A multimodal approach, which permits simultaneous PTA therapy, chemotherapy, and therapeutic RNA interference, has the potential to completely eradicate residual diseased cells. In this Account, we provide an up-to-date review of the synthesis and characterization, functionalization, and in vitro and in vivo evaluation of NIR lightactivatable multifunctional nanostructures used for imaging and therapy. We emphasize research on hollow gold nanospheres, magnetic core-shell gold nanoshells, and semiconductor copper monosulfide NPs. We discuss three types of novel drug delivery systems in which hollow gold nanospheres are used to mediate controlled drug release.
Cancer nanotheranostics aims to combine imaging and therapy of cancer through use of nanotechnology. The ability to engineer nanomaterials to interact with cancer cells at the molecular level can significantly improve the effectiveness and specificity of therapy to cancers that are currently difficult to treat. In particular, metastatic cancers, drug-resistant cancers, and cancer stem cells impose the greatest therapeutic challenge for targeted therapy. Targeted therapy can be achieved with appropriately designed drug delivery vehicles such as nanoparticles, adult stem cells, or T cells in immunotherapy. In this article, we first review the different types of nanotheranostic particles and their use in imaging, followed by the biological barriers they must bypass to reach the target cancer cells, including the blood, liver, kidneys, spleen, and particularly the blood-brain barrier. We then review how nanotheranostics can be used to improve targeted delivery and treatment of cancer cells. Finally, we discuss development of nanoparticles to overcome current limitations in cancer therapy.
It is currently believed that magnetic nanoparticle heaters (MNHs) can kill cancer cells only when the temperature is raised above 43 °C due to energy dissipation in an alternating magnetic field. On the other hand, simple heat conduction arguments indicate that in small tumors or single cells the relative rates of energy dissipation and heat conduction result in a negligible temperature rise, thus limiting the potential of MNHs in treating small tumors and metastatic cancer. Here we demonstrate that internalized MNHs conjugated to epidermal growth factor (EGF) and which target the epidermal growth factor receptor (EGFR) do result in a significant (up to 99.9%) reduction in cell viability and clonogenic survival in a thermal heat dose dependent manner, without the need for a perceptible temperature rise. The effect appears to be cell type specific and indicates that magnetic nanoparticles in alternating magnetic fields may effectively kill cancer cells under conditions previously considered as not possible.
The first microfluidic synthesis of ionomer-based bifunctional Janus supraballs possessing two distinct magnetic-nanoparticle-dropped and quantum dot polymer hemispheres within an anisotropic structure is reported. Based on such Janus supraballs with stable fluorescence and superparamagnetism, a magneto-responsive fluorescent switch is developed to realize free-writing under a magnetic field. This is a promising, simple way to fabricate novel flexible bead displays.
The application of nanomaterials (NMs) in biomedicine is increasing rapidly and offers excellent prospects for the development of new non-invasive strategies for the diagnosis and treatment of cancer. In this review, we provide a brief description of cancer pathology and the characteristics that are important for tumor-targeted NM design, followed by an overview of the different types of NMs explored to date, covering synthetic aspects and approaches explored for their application in unimodal and multimodal imaging, diagnosis and therapy. Significant synthetic advances now allow for the preparation of NMs with highly controlled geometry, surface charge, physicochemical properties, and the decoration of their surfaces with polymers and bioactive molecules in order to improve biocompatibility and to achieve active targeting. This is stimulating the development of a diverse range of nanometer-sized objects that can recognize cancer tissue, enabling visualization of tumors, delivery of anti-cancer drugs and/or the destruction of tumors by different therapeutic techniques.
We report a facile synthesis of body centered cubic (bcc) Fe nanoparticles (NPs) via the thermal decomposition of iron pentacarbonyl, Fe(CO)(5), in the presence of hexadecylammonium chloride. These bcc-Fe NPs exhibit a drastically increased stability and magnetic moment (M(s) = 164 A·m(2)·kg(-1)(Fe)) even in physiological solutions, and have much enhanced magnetic imaging contrast (r(2) = 220 s(-1)·mM(-1)) and heating (SAR = 140 W·g(-1)(Fe)) effects. They may serve as robust probes for imaging and therapeutic applications.
Epidermal growth factor receptor (EGFR) is a type I receptor tyrosine kinase, the deregulation of which has been implicated in a variety of human carcinomas. EGFR signalling is preceded by receptor dimerization, typically thought to result from a ligand-induced conformational change in the ectodomain that exposes a loop (dimerization arm) required for receptor association. Ligand binding may also trigger allosteric changes in the cytoplasmic domain of the receptor that is crucial for signalling. Despite these insights, ensemble-averaging approaches have not determined the precise mechanism of receptor activation in situ. Using quantum-dot-based optical tracking of single molecules combined with a novel time-dependent diffusivity analysis, here we present the dimerization dynamics of individual EGFRs on living cells. Before ligand addition, EGFRs spontaneously formed finite-lifetime dimers kinetically stabilized by their dimerization arms. The dimers were primed both for ligand binding and for signalling, such that after EGF addition they rapidly showed a very slow diffusivity state that correlated with activation. Although the kinetic stability of unliganded dimers was in principle sufficient for EGF-independent activation, ligand binding was still required for signalling. Interestingly, dimers were enriched in the cell periphery in an actin- and receptor-expression-dependent fashion, resulting in a peripheral enhancement of EGF-induced signalling that may enable polarized responses to growth factors.
Part 1 - A tale of mude and dust Biology Physics Bacteria Atoms molecules Multicellular Soft Matter organisms Part 2 - A tale of mude and dust Biology PhysicsBacteria Atoms molecules Multicellular Soft Matter organisms
We report dual-functional hollow gold nanospheres (HAuNS, approximately 40-nm diameter) capable of mediating both photothermal ablation of cancer cells and drug release upon near-infrared (NIR) light irradiation. As high as 63% DOX by weight ( approximately 1.7 microg DOX/microg Au) could be loaded to polyethylene glycol (PEG)-coated HAuNS since DOX was coated to both the outer and the inner surfaces of HAuNS. Irradiation with NIR laser induced photothermal conversion, which triggered rapid DOX release from DOX-loaded HAuNS. The release of DOX was also pH-dependent, with more DOX released in aqueous solution at lower pH. Significantly greater cell killing was observed when MDA-MB-231 cells incubated with DOX-loaded HAuNS were irradiated with NIR light, attributable to both HAuNS-mediated photothermal ablation and cytotoxicity of released free DOX.
A previously developed cell labelling methodology has been evaluated to assess its potential to precisely control the degree of magnetic labelling. The two-step method provides a quick way of labelling cells by first biotinylating the cell membrane proteins and then binding streptavidin paramagnetic particles onto the biotinylated proteins. Characterisation studies on biotinylated HeLa cells have revealed that the biotin concentration on the cell surface can be varied by changing the biotinylating reagent concentration. At the optimal concentration (750 microm), a substantial surface biotin density (approximately 10(8) biotin per cell) could be achieved within 30 min. The degree of magnetic labelling could be altered by adjusting the concentration of paramagnetic particles added to the cells and the binding of the particles onto the cell surface was not considerably affected by the biotin density on the cell surface. The magnetic moment of the labelled cells was measured and correlated well with the degree of magnetic labelling. Cell viability studies indicated that the magnetic labelling was not cytotoxic. Magnetically labelled cells were then successfully targeted and manipulated by magnetic fields to form three dimensional multicellular structures.
Nanoparticles--particles in the size range 1-100 nm--are emerging as a class of therapeutics for cancer. Early clinical results suggest that nanoparticle therapeutics can show enhanced efficacy, while simultaneously reducing side effects, owing to properties such as more targeted localization in tumours and active cellular uptake. Here, we highlight the features of nanoparticle therapeutics that distinguish them from previous anticancer therapies, and describe how these features provide the potential for therapeutic effects that are not achievable with other modalities. While large numbers of preclinical studies have been published, the emphasis here is placed on preclinical and clinical studies that are likely to affect clinical investigations and their implications for advancing the treatment of patients with cancer.
The synthesis and characterization of bis-carboxyl-terminated PEG-coated FeNPs with magnetization greater than that of iron oxide nanoparticles (IONP) with comparable particle size was reported. Using concentrated reagents and the reaction kinetics afforded by the simultaneous introduction of reagents in the junction, a highly uniform particle size distribution is obtained. The higher magnetization and soft ferromagnetic nature shown by the novel FeNPs is evident from the magnetization curves. Increased magnetization afforded by the FeNPs allows for heat dissipation at frequencies in the safe range, while for IONP much higher frequencies are required to facilitate the same thermal dose. It is also shown that local hyperthermia is achievable with the FeNPs while IONPs require a dose in excess of 20-fold or greater to achieve the same temperature range.
We previously found that a polymer conjugated to the anticancer protein neocarzinostatin, named smancs, accumulated more in tumor tissues than did neocarzinostatin. To determine the general mechanism of this tumoritropic accumulation of smancs and other proteins, we used radioactive (51Cr-labeled) proteins of various molecular sizes (Mr 12,000 to 160,000) and other properties. In addition, we used dye-complexed serum albumin to visualize the accumulation in tumors of tumor-bearing mice. Many proteins progressively accumulated in the tumor tissues of these mice, and a ratio of the protein concentration in the tumor to that in the blood of 5 was obtained within 19 to 72 h. A large protein like immunoglobulin G required a longer time to reach this value of 5. The protein concentration ratio in the tumor to that in the blood of neither 1 nor 5 was achieved with neocarzinostatin, a representative of a small protein (Mr 12,000) in all time. We speculate that the tumoritropic accumulation of these proteins resulted because of the hypervasculature, an enhanced permeability to even macromolecules, and little recovery through either blood vessels or lymphatic vessels. This accumulation of macromolecules in the tumor was also found after i.v. injection of an albumin-dye complex (Mr 69,000), as well as after injection into normal and tumor tissues. The complex was retained only by tumor tissue for prolonged periods. There was little lymphatic recovery of macromolecules from tumor tissue. The present finding is of potential value in macromolecular tumor therapeutics and diagnosis.
When epidermal growth factor and its relatives bind the ErbB family of
receptors, they trigger a rich network of signalling pathways, culminating
in responses ranging from cell division to death, motility to adhesion. The
network is often dysregulated in cancer and lends credence to the mantra that
molecular understanding yields clinical benefit: over 25,000 women with breast
cancer have now been treated with trastuzumab (Herceptin®), a recombinant
antibody designed to block the receptor ErbB2. Likewise, small-molecule enzyme
inhibitors and monoclonal antibodies to ErbB1 are in advanced phases of clinical
testing. What can this pathway teach us about translating basic science into
clinical use?
Activation of the epidermal growth receptor (ErbB1) occurs within minutes of a radiation exposure. Immediate downstream consequences of this activation are currently indistinguishable from those obtained with growth factors (GF), e.g. stimulation of the pro-proliferative mitogen-activated protein kinase (MAPK). To identify potential differences, the effects of GFs and radiation on other members of the ErbB family have been compared in mammary carcinoma cell lines differing in their ErbB expression profiles. Treatment of cells with EGF (ErbB1-specific) or heregulin (ErbB4-specific) resulted in a hierarchic transactivations of ErbB2 and ErbB3 dependent on GF binding specificity. In contrast, radiation indiscriminately activated all ErbB species with the activation profile reflecting that cell's ErbB expression profile. Downstream consequences of these ErbB interactions were examined with MAPK after specifically inhibiting ErbB1 (or 4) with tyrphostin AG1478 or ErbB2 with tyrphostin AG825. MAPK activation by GFs or radiation was completely inhibited by AG1478 indicating total dependance on ErbB1 (or 4) depending on which ErbB is expressed. Inhibiting ErbB2 caused an enhanced MAPK response simulating an amplified ErbB1 (or 4) response. Thus ErbB2 is a modulator of ErbB1 (or 4) function leading to different MAPK response profiles to GF or radiation exposure.
MR molecular imaging is an exciting new frontier in the biomedical applications of MR. One of the clinically relevant targets is the tyrosine kinase Her-2/neu receptor, which has a significant role in staging and treating breast cancer. In this study Her-2/neu receptors were imaged in a panel of breast cancer cells expressing different numbers of the receptors on the cell membrane. Commercially available streptavidin-conjugated superparamagnetic nanoparticles were used as targeted MR contrast agent. The nanoparticles were directed to receptors prelabeled with a biotinylated monoclonal antibody and generated strong T(2) MR contrast in Her-2/neu-expressing cells. The contrast observed in MR images was proportional to the expression level of Her-2/neu receptors determined independently with FACS analysis. In these experiments, iron oxide nanoparticles were attached to the cell surface and were not internalized into the cells, which is a major advantage for in vivo applications of the method.
New folate-conjugated superparamagnetic maghemite nanoparticles have been synthesized for the intracellular hyperthermia treatment of solid tumors. These ultradispersed nanosystems have been characterized for their physicochemical properties and tumor cell targeting ability, facilitated by surface modification with folic acid. Preliminary experiments of nanoparticles heating under the influence of an alternating magnetic field at 108 kHz have been also performed. The nanoparticle size, surface charge, and colloidal stability have been assessed in various conditions of ionic strength and pH. The ability of these folate "decorated" maghemite nanoparticles to recognize the folate receptor has been investigated both by surface plasmon resonance and in folate receptor expressing cell lines, using radiolabeled folic acid in competitive binding experiments. The specificity of nanoparticle cellular uptake has been further investigated by transmission electron microscopy after incubation of these nanoparticles in the presence of three cell lines with differing folate receptor expression levels. Qualitative and quantitative determinations of both folate nanoparticles and nontargeted control nanoparticles demonstrated a specific cell internalization of the folate superparamagnetic nanoparticles.
Targeting cancer: Multifunctional magnetic gold nanoshells (Mag-GNS) are prepared by coating silica spheres with gold nanoshells embedded with Fe 3O4 nanoparticles. The Fe3O4 nanoparticles allow magnetic resonance imaging (MRI) for diagnosis, and the gold nanoshells enable photothermal therapy. By attaching an antibody to the Mag-GNS by a poly(ethylene glycol) (PEG) linker, cancer cells can be targeted. (Figure Presented).