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Feasibility Study of Dual-targeting Paclitaxel-loaded Magnetic Liposomes using Electromagnetic Actuation and Macrophages
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September 2016
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September 2016
... Efficient cargo loading can be achieved by using porous materials, such as biological hydrogels, or empty vesicles, such as liposomes or cell ghosts. Loading of drug molecules, genes, photosensitizers, and antibiotics, including paclitaxel (79,80), docetaxel (81), doxorubicin (82)(83)(84), mRNAs (85), indocyanine green (84), and ciprofloxacin (86), into a variety of artificial substrates, including nano-and microliposomes (79,80), poly(lactic-co-glycolic) acid (PLGA) particles (81), mesoporous silica nanoparticles (83) and microtubes (86), red blood cell (RBC) ghosts (84), and polyelectrolyte multilayers (82), has been shown in microrobotic applications. While the propulsion of drug-loaded biohybrid microrobots was demonstrated for short periods, further investigations are needed to confirm the noninvasiveness of any potential drug toward the biological unit. ...
... Efficient cargo loading can be achieved by using porous materials, such as biological hydrogels, or empty vesicles, such as liposomes or cell ghosts. Loading of drug molecules, genes, photosensitizers, and antibiotics, including paclitaxel (79,80), docetaxel (81), doxorubicin (82)(83)(84), mRNAs (85), indocyanine green (84), and ciprofloxacin (86), into a variety of artificial substrates, including nano-and microliposomes (79,80), poly(lactic-co-glycolic) acid (PLGA) particles (81), mesoporous silica nanoparticles (83) and microtubes (86), red blood cell (RBC) ghosts (84), and polyelectrolyte multilayers (82), has been shown in microrobotic applications. While the propulsion of drug-loaded biohybrid microrobots was demonstrated for short periods, further investigations are needed to confirm the noninvasiveness of any potential drug toward the biological unit. ...
... An attractive aspect of chemical control is the availability of a wide variety of chemical signals released locally by targeted cells or tissues, which can induce taxis behavior in different microorganisms. For example, biohybrid microrobots driven by neutrophils and macrophages were able to migrate toward chemoattractants generated by E. coli (83) and tumor cell lysate (80), respectively. Similarly, Park et al. (134) demonstrated the chemotactic motility of S. typhimurium-driven microrobots toward tumor cell lysates and spheroids in a microfluidic setup, as well as the accumulation of microrobots in tumors in a CT-26 tumor mouse model. ...
Biohybrid microrobots, composed of a living organism integrated with an artificial carrier, offer great advantages for the miniaturization of devices with onboard actuation, sensing, and control functionalities and can perform multiple tasks, including manipulation, cargo delivery, and targeting, at nano- and microscales. Over the past decade, various microorganisms and artificial carriers have been integrated to develop unique biohybrid microrobots that can swim or crawl inside the body, in order to overcome the challenges encountered by the current cargo delivery systems. Here, we first focus on the locomotion mechanisms of microorganisms at the microscale, crucial criteria for the selection of biohybrid microrobot components, and the integration of the selected artificial and biological components using various physical and chemical techniques. We then critically review biohybrid microrobots that have been designed and used to perform specific tasks in vivo. Finally, we discuss key challenges, including fabrication efficiency, swarm manipulation, in vivo imaging, and immunogenicity, that should be overcome before biohybrid microrobots transition to clinical use. Expected final online publication date for the Annual Review of Control, Robotics, and Autonomous Systems Volume 2 is May 3, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... Recent studies have shown that TAMs are recruited to the tumors and can form up to 70% of tumor mass [15]. The characteristic enables macrophages to be valuable biocarriers that can ferry therapeutic agents deep into the tumors [16]. Currently, many research groups have adopted macrophages as transporters to deliver therapeutic agents and proved the effectiveness of these systems in animal models. ...
... Relied on the intrinsic ability of macrophages to effectively cross the blood barrier and penetrate deeply to tumor tissues, which are main limitations that traditional nanoparticles-based drug delivery systems are facing with, many cell-mediated delivery systems have recently been prepared and have confirmed the efficiency of the immune cells as active biocarriers to ferry therapeutics deep into tumors [15,17,18,[28][29][30]. It has been shown that, as a payload of the vehicle, free drug was not applicable for the drug to be directly encapsulated into the cells because it will cause severe toxicity to the cells, thereby killing them, before they approach to the targeted area even at low concentrations [16,31]. Therefore, we used liposomes, because with their ability to control the drug liberation rate, they could prevent premature drug release to defend the macrophages. ...
... We aim to our final goal of adopting immune cells derived from a cancer patient, encapsulating with drug containing NPs, and sending back the engineered cells to the same patient to reduce the immune response, thus augmenting the efficacy and bringing our cell-based platform closer to clinical trials. In addition, as extended from our previously published works [16,33], in this report, we have focused on analyzing the NIR-light sensitivity of the magnetic liposomes (therapeutic agents) and the microrobots in terms of enhancing drug release behaviors upon exposure to the laser irradiation, thus providing a better perspective for practical applications of our cell-based system. ...
In the present work, we prepare and evaluate a cell-based microrobot for active drug delivery to tumors. The microrobots are fabricated using the engulfment activity of immune macrophages with drug-loaded magnetic liposomes (MNP-DLs) via phagocytosis. The synthesized MNP-DLs and the microrobots have high energy absorbance to NIR light with increased drug release rate after laser irradiation. The tumor killing ability of the prepared microrobots is validated on a colorectal cancer cell line. In addition, the active tumor targeting function by an external electromagnetic actuating (EMA) system and chemotaxis is verified. Experiment results show that a single microrobot can be manipulated by the EMA system to obtain the average velocity of approximately 11 μm/s, and the robots can cross the membranes mimicking the blood barrier to tumor chemo-attractants with the infiltration rate up to 74%. Consequently, this study proposes and analyzes an innovative aspect of the developed therapeutic cellular micro-platform for active tumor targeting and externally triggered drug delivery.
... Next, the MLVs were homogenized using ultra-sonication (VC750, Sonics & Materials, Newtown, CT, USA) at 50 • C for 10 min to obtain nano-sized liposomes. The liposomal solution was centrifuged at 1000 rpm for 15 min to separate un-encapsulated MNPs, and the supernatant was retained [33]. To collect the liposomes and remove free DTX, the solution was then centrifuged at 10,000 rpm for 10 min. ...
... Next, the cells were washed twice with cold PBS and the nuclei were stained with DAPI (1 g/mL) for 10 min. Finally, the cells were rinsed three times with PBS and imaged using CLSM [33]. For quantitative study, confluent MCF-7 cells were inoculated into 96-well plates (1 × 10 4 viable cells/well). ...
... The cytotoxicity of blank and drug-loaded non-targeting and targeting liposomes was evaluated by MTT assay [33]. Briefly, 1 × 10 4 MCF-7 cells were seeded in DMEM in a 96-well plate (SPL Life Sciences). ...
The aim of this work is to prepare and evaluate a novel lipid-polymer hybrid liposomal nanoplatform (hyaluronic acid-magnetic nanoparticle-liposomes, HA-MNP-LPs) as a vehicle for targeted delivery and triggered release of an anticancer drug (docetaxel, DTX) in human breast cancer cells. We first synthesize an amphiphilic hyaluronic acid hexadecylamine polymer (HA-C16) to enhance the targeting ability of the hybrid liposome. Next, HA-MNP-LPs are constructed to achieve an average size of 189.93 ± 2.74 nm in diameter. In addition, citric acid-coated magnetic nanoparticles (MNPs) are prepared and embedded in the aqueous cores while DTX is encapsulated in the hydrophobic bilayers of the liposomes. Experiments with coumarin 6 loaded hybrid liposomes (C6/HA-MNP-LPs) show that the hybrid liposomes have superior cellular uptake in comparison with the conventional non-targeting liposomes (C6/MNP-LPs), and the result is further confirmed by Prussian blue staining. Under near-infrared laser irradiation (NIR, 808 nm), the HA-MNP-LPs aqueous solution can reach 46.7 °C in 10 min, and the hybrid liposomes released over 20% more drug than non-irradiated liposomes. Using a combination of photothermal irradiation and chemotherapy, the DTX-loaded hybrid liposomes (DTX/HA-MNP-LPs) significantly enhance therapeutic efficacy, with the IC50 value of 0.69 ± 0.10 μg/mL, which is much lower than the values for radiation monotherapy or DTX monotherapy. Consequently, the prepared hybrid nanoplatform may offer a promising drug delivery vehicle with selective targeting and enhanced drug release in treating CD44-overexpressing cancers.
... Nowadays, the researches on design strategies of micro/nanorobots focus on developing some micro/nanostructures inspired by natural microorganisms. Main types of micro/nanorobot designs such as helical [29][30][31][32][33][34], surface-assisted [35][36][37][38][39][40], ciliary [41,42], scaffold [43][44][45][46] and biohybrid designs [47][48][49][50][51][52][53][54][55][56][57] have been successfully developed to overcome flow resistance and perform tasks in a biocompatible manner. The research on fabrication techniques of magnetically actuated micro/nanorobots is an important direction in the micro/ nanorobots field. ...
... Based on phagocytosis of mouse macrophages, Nguyen et al developed an anticancer drug delivery system that was prepared by encapsulating the anticancer drugs with magnetic liposomes and mouse macrophages ( figure 5(B)). The average velocity of the macrophages carrying the anticancer drugs can reach 10.48±4.43 μm s −1 under an external magnetic field [48]. Sperm cells are capable of protecting hydrophilic drugs from dilution, immune response or biodegradation by tissue fluids in the body [117][118][119]. ...
Magnetically actuated micro/nanorobots are typical micro- and nanoscale artificial devices with favorable attributes of quick response, remote and contactless control, harmless human-machine interaction and high economic efficiency. Under external magnetic actuation strategies, they are capable of achieving elaborate manipulation and navigation in extreme biomedical environments. This review focuses on state-of-the-art progresses in design strategies, fabrication techniques and applications of magnetically actuated micro/nanorobots. Firstly, recent advances of various robot designs, including helical robots, surface walkers, ciliary robots, scaffold robots and biohybrid robots, are discussed separately. Secondly, the main progresses of common fabrication techniques are respectively introduced, and application achievements on these robots in targeted drug delivery, minimally invasive surgery and cell manipulation are also presented. Finally, a short summary is made, and the current challenges and future work for magnetically actuated micro/nanorobots are discussed.
... Several 7 Stem Cells International types of NPs that exhibited good biocompatibility, biodegradability, and capability to load hydrophilic/hydrophobic drugs were widely studied for drug carrying. Liposomes (including unilamellar and multilamellar) enhanced the maximum tolerated dose (MTD) 20-fold in MAs of PTX [71] and 50-200-fold for Dox [30,67]. It was also reported that poly(lactic-co-glycolic acid) (PLGA) NPs were able to enhance 5-fold higher for Dox MTD for MAs [64], yet no obvious change was observed for PTX MTD on MSCs [69]. ...
... RGD is a short peptide that targets αvβ 3 integrinpositive tumors, and modifying RBCs with RGD allowed an obvious attachment in tumors that native RBCs could not achieve [23,48] (iii) For magnetizing modification, cell carriers have internalized magnetic particles, such as Fe 3 O 4 , to follow guidance from electromagnetic fields. This method was widely studied as external assistance to control the cell path, and MA motion and speed were found to be enhanced 29 times that of normal cells [71]. Along with this, it may improve SMAP capability and make a concession to the premise of reducing early leakage risk Enhancing accumulation can reduce drug demands. ...
Achievement of high targeting efficiency for a drug delivery system remains a challenge of tumor diagnoses and nonsurgery therapies. Although nanoparticle-based drug delivery systems have made great progress in extending circulation time, improving durability, and controlling drug release, the targeting efficiency remains low. And the development is limited to reducing side effects since overall survival rates are mostly unchanged. Therefore, great efforts have been made to explore cell-driven drug delivery systems in the tumor area. Cells, particularly those in the blood circulatory system, meet most of the demands that the nanoparticle-based delivery systems do not. These cells possess extended circulation times and innate chemomigration ability and can activate an immune response that exerts therapeutic effects. However, new challenges have emerged, such as payloads, cell function change, cargo leakage, and in situ release. Generally, employing cells from the blood circulatory system as cargo carriers has achieved great benefits and paved the way for tumor diagnosis and therapy. This review specifically covers (a) the properties of red blood cells, monocytes, macrophages, neutrophils, natural killer cells, T lymphocytes, and mesenchymal stem cells; (b) the loading strategies to balance cargo amounts and cell function balance; (c) the cascade strategies to improve cell-driven targeting delivery efficiency; and (d) the features and applications of cell membranes, artificial cells, and extracellular vesicles in cancer treatment.
... 4−7 However, there are limitations associated with the use of bacteria: (1) bacteria are usually harmful and are quickly cleared from the bloodstream by the immune system; (2) the attachment of the bacteria to the micro/ nanostructures is challenging and ineffective, limiting the therapeutic potential; and (3) the actuation forces generated by the bacteria are quite small, leading to poor targeting of the microrobots to the target site. 8,9 Macrophages (MΦs) can offer an alternative and effective method of carrying payloads and therapeutic agents, serving as cellular microrobots. 10−12 These cells are already part of the immune system and, therefore, when administered into the body would not induce an immune response. ...
... We measured blood circulation time by intravenously injecting DiD labeled 5 × 10 6 MΦs or the microrobots into the mice (n = 3 per group). At each time point of 3 min, 1,2,4,8,24,36,48, and 96 h, 20 μL of blood was collected via capillary tubes with heparinized coatings (Kimble Chase Life Science and Research Products, Vineland, New Jersey, USA) and was immediately mixed with 20 μL of 0.2% ethylenediaminetetraacetic acid (GenDEPOT, Barker, TX, USA) at pH 7.4 for anticoagulation of the blood. After that, the DiD signal from the blood was detected using the IVIS system, from which the relative FI was quantified, as mentioned previously. ...
... These robots were able to be manipulated in vitro in a confined space, and in vivo in a mouse tumor model [48]. We used poly-(vinyl alcohol)-coated (PVA-coated) MNPs encapsulated in paclitaxel liposomes and engulfed by J774A.1 macrophages, enabling dual controllability of the macrophages through an external magnetic field and chemotaxis [49]. In addition, MNPs show responsiveness to near-infrared (NIR) light from a laser [50]. ...
Macrophages, which are part of the mononuclear phagocytic system, possess sensory receptors that enable them to target cancer cells. In addition, they are able to engulf large amounts of particles through phagocytosis, suggesting a potential “Trojan horse” drug delivery approach to tumors by facilitating the engulfment of drug-hidden particles by macrophages. Recent research has focused on the development of macrophage-based microrobots for anticancer therapy, showing promising results and potential for clinical applications. In this review, we summarize the recent development of macrophage-based microrobot research for anticancer therapy. First, we discuss the types of macrophage cells used in the development of these microrobots, the common payloads they carry, and various targeting strategies utilized to guide the microrobots to cancer sites, such as biological, chemical, acoustic, and magnetic actuations. Subsequently, we analyze the applications of these microrobots in different cancer treatment modalities, including photothermal therapy, chemotherapy, immunotherapy, and various synergistic combination therapies. Finally, we present future outlooks for the development of macrophage-based microrobots.
... Macrophages are immune cells that are capable of engulfing broken cells and pathogens. Macrophages are ideal drug carriers because of their phagocytic ability [124]. Hiep Xuan Cao [125] use a phasemodulation method to form an acoustic potential well at the focal point, and macrophages were manipulated to follow an arbitrary trajectory in a spherical three-dimensional space with a diameter of 4 mm. ...
Single-cell microrobots are new microartificial devices that use a combination of single cells and artificial devices, with the advantages of small size, easy degradation and ease of manufacture. With externally driven strategies such as light fields, sound fields and magnetic fields, microrobots are able to carry out precise micromanipulations and movements in complex microenvironments. Therefore, single-cell microrobots have received more and more attention and have been greatly developed in recent years. In this paper, we review the main classifications, control methods and recent advances in the field of single-cell microrobot applications. First, different types of robots, such as cell-based microrobots, bacteria-based microrobots, algae-based microrobots, etc., and their design strategies and fabrication processes are discussed separately. Next, three types of external field-driven technologies, optical, acoustic and magnetic, are presented and operations realized in vivo and in vitro by applying these three technologies are described. Subsequently, the results achieved by these robots in the fields of precise delivery, minimally invasive therapy are analyzed. Finally, a short summary is given and current challenges and future work on microbial-based robotics are discussed.
... A drug delivery system (DDS) is required not only to deliver drugs with high efficacy but also to deliver drugs with strong adverse reactions to desired tissues in order to avoid damaging other tissues. Various liposome-based drug delivery methods have been developed, including passive delivery methods with surface modification [6,7] and active delivery methods using magnetic nanoparticles [8]. ...
The role of liposomes as drug carriers has been investigated. Ultrasound-based drug release methods have been developed for on-demand drug delivery. However, the acoustic responses of current liposome carriers result in low drug release efficiency. In this study, CO2-loaded liposomes were synthesized under high pressure from supercritical CO2 and irradiated with ultrasound at 237 kHz to demonstrate their superior acoustic responsiveness. When liposomes containing fluorescent drug models were irradiated with ultrasound under acoustic pressure conditions that are safe for the human body, CO2-loaded liposomes synthesized using supercritical CO2 had 17.1 times higher release efficiency than liposomes synthesized using the conventional Bangham method. In particular, the release efficiency of CO2-loaded liposomes synthesized using supercritical CO2 and monoethanolamine was 19.8 times higher than liposomes synthesized using the conventional Bangham method. These findings on the release efficiency of acoustic-responsive liposomes suggest an alternative liposome synthesis strategy for on-demand release of drugs by ultrasound irradiation in future therapies.
... The washing process was conducted several times to completely remove the unphagocytosed SPIONs. The macrophages containing SPIONs, which were termed "microrobots" or Macbots, were harvested using a cell scraper [57]. ...
Targeted drug delivery using microrobots manipulated by an external actuator has significant potential to be a practical approach for wireless delivery of therapeutic agents to the targeted tumor. This work aimed to develop a novel acoustic manipulation system and macrophage-based microrobots (Macbots) for a study in targeted tumor therapy. The Macbots containing superparamagnetic iron oxide nanoparticles (SPIONs) can serve as drug carriers. Under an acoustic field, a microrobot cluster of the Macbots is manipulated by following a predefined trajectory and can reach the target with a different contact angle. As a fundamental validation, we investigated an in vitro experiment for targeted tumor therapy. The microrobot cluster could be manipulated to any point in the 4 × 4 × 4 mm region of interest with a position error of less than 300 μm. Furthermore, the microrobot could rotate in the O-XY plane with an angle step of 45 degrees without limitation of total angle. Finally, we verified that the Macbots could penetrate a 3D tumor spheroid that mimics an in vivo solid tumor. The outcome of this study suggests that the Macbots manipulated by acoustic actuators have potential applications for targeted tumor therapy.
... The macrophages are recruited to tumors due to electromagnetic fields and the chemoattract properties of macrophages for dual targeting. This dual targeting system is expected to be developed into a potential cancer treatment strategy [148]. ...
Nanoparticle delivery systems have good application prospects in the treatment of various diseases, especially in cancer treatment. The effect of drug delivery is regulated by the properties of nanoparticles. There have been many studies focusing on optimizing the structure of nanoparticles in recent years, and a series of achievements have been made. This review summarizes the optimization strategies of nanoparticles from three aspects—improving biocompatibility, increasing the targeting efficiency of nanoparticles, and improving the drug loading rate of nanoparticles—aiming to provide some theoretical reference for the subsequent drug delivery of nanoparticles.
... 在外加磁场的作用下, 生物医用磁 性纳米材料在体内可以产生多种效应, 例如电磁效应、磁 热效应以及磁-机械力效应等等, 从而可以用来控制药物 释放、进行磁热治疗以及磁控制离子通道活化 [30] . 特殊设 计的磁场能够引导超顺磁氧化铁纳米颗粒标记的巨噬细 胞从血液进入肿瘤病灶, 达到抑制或治疗肿瘤的目的 [31] . 此外, 强磁场还可以引导磁性药物载体到达病灶部位浓聚, 达到多种治疗药物增敏及靶向治疗的作用, 也是近期肿瘤 化学治疗领域的新进展之一 [3] . ...
High magnetic fields are unique artificial physical environments. Since 1913, more than 10 Nobel prizes were given to novel findings related to high magnetic fields in the areas of high-temperature superconductivity, new materials, and life sciences. In recent years, progress in superconducting technologies has dramatically enhanced the application of high magnetic fields in scientific research, industry, and healthcare. Many countries have established national-level high magnetic research centers to strengthen scientific research in magnetic fields. The National High Magnetic Field Laboratory at Florida State University in the United States, the Grenoble High Magnetic Field Laboratory in France, the High Field Magnet Laboratory in Nijmegen in Netherlands, the Tsukuba Magnet Laboratory in Japan, and the High Magnetic Field Laboratory of the Chinese Academy of Sciences in China are the most recognized magnetic field research centers worldwide. Of these institutions, the High Magnetic Field Laboratory in China has a unique research team focused on magnetic field life science research. Current progress at Chinese institutions in high-level talent teams, scientific research, and industry applications is significant and has achieved considerable international influence. In April 2018, the 620th session of the Xiangshan Science Conference, "High Magnetic Field and Life Health: New Conditions, New Questions, New Opportunities", was held in Beijing. This conference attracted more than 40 participants from approximately 30 domestic and international institutions. The following central issues were discussed at the conference: (1) the theory and techniques of high magnetic equipment based on novel superconductive materials; (2) fundamental life science research under high magnetic fields; (3) magnetic nanoparticle medication and iron metabolism; and (4) applications of dynamic magnetic fields in human health care and medicine. The present paper offers a comprehensive summary of the opinions, views, and visions collected during this conference. In addition, this paper reviews recent progress in the interdisciplinary field of high magnetic fields and life science and healthcare. For each central issue discussed in the 620th session of the Xiangshan Science Conference, this review gives a brief summary of the current advancements and challenging problems in research. The key scientific questions and application techniques in this field and the strategic thinking and landscape planning of the scientific research are promoted. Several unknown questions and future directions of innovative and featured research are identified in this paper. First, the scientific questions in the field need to be refined. Moreover, it is necessary to consider how to achieve scientific breakthroughs and high-level scientific research results with the scientific and technical advantages that currently exist in China. Second, the translation-oriented interdisciplinary scientific research in this field needs to be one of the primary research directions to produce innovative principles, methods, and technologies for healthcare and medical treatments. Third, the cooperation of the research groups in China needs to be enhanced to advance the fundamental and application research of life sciences, health, and medical care with respect to high magnetic fields.
... Recent studies reported that TAMs are recruited to the tumors and can form up to 70% of tumor mass. The characteristic enables macrophages to become valuable biocarriers that can ferry therapeutic agents deep into the tumors [17]. Recently, many research groups have adopted macrophages as transporters to deliver therapeutic agents and proved the effectiveness of these systems in animal models. ...
In this study, we prepare and evaluate a novel cellbased micro-platform (microrobot) for active tumor therapy. The microrobots are fabricated utilizing the engulfment activity of immune cells (macrophages) with drug-loaded magnetic liposomes via phagocytosis. First, we synthesize magnetic nanoparticles (MNP) with superparamagnetic properties and high energy absorbance to near-infrared (NIR) light, and load the MNPs to liposomes (MNP-DLs). Then, we prepare the microrobots by incubating the MNP-DLs with the macrophages. After that, we characterize the tumor targeting ability of the microrobots using electromagnetic actuating (EMA) system and a transwell chemotactic assay. Experiment results show that the microrobots can be controlled by an external magnetic field to reach the average velocity of approximately 11 μm/second, and they can cross the membranes mimicking the blood barrier to tumor chemo-attractants with the infiltration rate up to 74%. Therefore, the study proposes an innovative approach for active tumor targeting and NIR light triggered drug delivery using the developed cellular microrobots.
... In a recent study, they refined this approach by employing macrophages filled with liposomes of roughly 150 nm diameter filled with Fe 3 O 4 NPs and PTX instead of DTX. 244 The dual-targeting by magnetic and chemotactic (tumortropic) stimuli, as well as chemotherapeutic activity toward breast and colorectal cancer, was assessed in an in vitro model. As discussed earlier, the biocamouflage effect of blood cells is induced by their endogenous nature that allows them to act as "Trojan horses" within the patient's immune system. ...
Micromotors are devices that operate at the microscale and convert energy to motion. Many micromotors are microswimmers, i.e., devices that can move freely in a liquid at a low Reynolds number, where viscous drag dominates over inertia. Hybrid biomicromotors are microswimmers that consist of both biological and artificial components, i.e., one or several living microorganisms combined with one or many synthetic attachments. Initially, living microbes were used as motor units to transport synthetic cargo at the microscale, but this simple allocation has been altered and extended gradually, especially considering hybrid biomicromotors for biomedical in vivo applications, i.e., for non-invasive microscale operations in the body. This review focuses on these applications, where other properties of the microbial component, for example, the capability of chemotaxis, biosensing, and cell-cell interactions, have been exploited in order to realize tasks like localized diagnosis, drug delivery, or assisted fertilization in vivo. In the biohybrid approach, biological and artificially imposed functionalities act jointly through a microrobotic device that can be controlled or supervised externally. We review the development and state-of-the-art of such systems and discuss the mastery of current and future challenges in order to evolve hybrid biomicromotors from apt swimmers to adapted in vivo operators.
Magnetically driven swimming microrobot is a typical one in the family of microrobots and they can achieve navigation and manipulation in low Reynolds number biomedical environments with an external magnetic drive strategy. This study reviews recent advances in material selection, structure design, fabrication techniques, drive control method, and applications for magnetically driven swimming microrobots. First, the materials used in magnetically driven swimming microrobots were introduced and the effect of material selection on performance was discussed. Second, structure design of swimming microrobots and manufacturing techniques are reviewed, followed by a discussion on the main advances in effective motion control, path planning, and path tracking. Then, the multi-applications of magnetically driven swimming microrobots including targeted drug delivery, cell manipulation, and minimally invasive surgery are summarized. Finally, the current challenges and future directions of the work on magnetically driven swimming microrobots are discussed.
Based on the biological safety considerations for biomedical micro‐ and nanorobots, the substrates of biomedical micro‐ and nanorobots in the past two decades have mostly been DNA, flexible organic polymer materials, mesoporous silica particles, and so on, while the combination of nuts and screws should still belong to the micromation of steel macrorobots. Metal micro‐ and nanomaterials are one of the main substrates for preparing biomedical micro‐ and nanorobots. Inorganic nanoparticles have unique photothermal, electromagnetic, and other properties, so they have become excellent substrates for micro‐ and nanorobots. The inorganic material most commonly used as the substrate of micro‐ and nanorobots is mesoporous silica. This chapter describes the related research of biomedical micro‐ and nanorobots that can be used in the internal environment, which are constructed by three kinds of widely used driving systems: magnetic field, light, and ultrasonic field.
Micro-/nanorobots (MNRs) can be autonomously propelled on demand in complex biological environments and thus may bring revolutionary changes to biomedicines. Fluorescence has been widely used in real-time imaging, chemo-/biosensing, and photo-(chemo-) therapy. The integration of MNRs with fluorescence generates fluorescent MNRs with unique advantages of optical trackability, on-the-fly environmental sensitivity, and targeting chemo-/photon-induced cytotoxicity. This review provides an up-to-date overview of fluorescent MNRs. After the highlighted elucidation about MNRs of various propulsion mechanisms and the introductory information on fluorescence with emphasis on the fluorescent mechanisms and materials, we systematically illustrate the design and preparation strategies to integrate MNRs with fluorescent substances and their biomedical applications in imaging-guided drug delivery, intelligent on-the-fly sensing and photo-(chemo-) therapy. In the end, we summarize the main challenges and provide an outlook on the future directions of fluorescent MNRs. This work is expected to attract and inspire researchers from different communities to advance the creation and practical application of fluorescent MNRs on a broad horizon.
To address the issue that synthetic swimming nanorobots are susceptible to immune clearance and fouling in vivo, swimming hybrid cell‐based robots (cellbots) composed of living cells have been developed. Swimming cellbots use living cells such as sperm, bacteria, and algae as fabrication units to obtain the swimming capacity, which can be functionalized by adding different kinds of functional components and cargoes. Swimming cellbots not only inherit the biological functions of natural cells, but also can realize diverse locomotion modes under the action of their synthetic parts. This perspective highlights the fabrication, functionalization and multimode motion control of swimming cellbots, and possible medical application. As a representative example of swimming cellbots, dual‐responsive neutrobots have two driving modes: rotating magnetic field actuation and chemotactic locomotion, which can be utilized to cross the blood–brain barrier and target the glioblastoma in mice. The delivery efficiency of these drug‐loaded neutrobots can reach about 10% which is significantly higher than that of traditional nanocarriers. Such swimming cellbots may load different types of drugs and can be navigated through the combination of natural chemotaxis and externally physical fields such as magnetic, optical, and ultrasonic fields which may have potential in biomedical fields. Swimming cellbots with multifunction of motility and in vivo medical treatment means are presented, which are built by cells like sperm, bacteria, erythrocyte, and leukocyte, as well as synthetic materials like nanoparticles, drugs, and vesicles. The dual‐responsive neutrobots are highlighted as an advanced example of multimode locomotion ability and in vivo target delivery.
Neuron-specific enolase (NSE) is a cancer biomarker for diagnosing small cell lung carcinoma, carcinoids, islet cell tumors, and neuroblastomas. In this study, we developed an ultrasensitive electrochemiluminescence (ECL)-based immunoassay to determine NSE, consisting of the separation and sensing elements. First, superparamagnetic iron oxide (Fe3O4) nanoparticles were synthesized and attached to primary NSE monoclonal (Ab1-Fe3O4) to prepare a separating nanosystem. Then D-glucose-containing liposomes ([email protected]) were prepared and covalently attached to a second monoclonal antibody using Sulfo-SMCC ([email protected]2). Afterward, to develop a sensing electrode, gold nanoparticles (AuNPs) were electrochemically formed on a screen-printed electrode (SPE), and multi-walled carbon nanotubes (MW) were deposited on the SPE. Glucose oxidase (GOx) enzymes were conjugated with the carboxylic groups of MW on the sensing electrode. Finally, polyluminol (PLu) was electropolymerized on the electrode. Ab1-F3O4 and [email protected]2 were used to capture NSE ([email protected]2-(NSE)-Ab1-F3O4). ECL signals from polyluminol (PLU-GOx-MW-Au-SPE) and hydrogen peroxide, produced by oxidation of glucose by GOx reaction, were proportional to the concentration of captured NSE. Immunoassay's detection limit (LOD) and linear range (LDR) were found to be 12.8 fg.mL⁻¹ (at S/N = 3) and 100 fg.mL⁻¹ to 100 ng.mL⁻¹, respectively. This immunoassay resulted in acceptable accuracy with recoveries in the 98.2 – 102.6 % range and high reproducibility with RSD of less than 3.4%.
Reprogramming the immunosuppressive tumor microenvironment by modulating macrophages holds great promise in tumor immunotherapy. As a class of professional phagocytes and antigen‐presenting cells in the innate immune system, macrophages can not only directly engulf and clear tumor cells, but also play roles in presenting tumor‐specific antigen to initiate adaptive immunity. However, the tumor‐associated macrophages (TAMs) usually display tumor‐supportive M2 phenotype rather than anti‐tumor M1 phenotype. They can support tumor cells to escape immunological surveillance, aggravate tumor progression, and impede tumor‐specific T cell immunity. Although many TAMs‐modulating agents have shown great success in therapy of multiple tumors, they face enormous challenges including poor tumor accumulation and off‐target side effects. An alternative solution is the use of advanced nanostructures, which not only can deliver TAMs‐modulating agents to augment therapeutic efficacy, but also can directly serve as modulators of TAMs. Another important strategy is the exploitation of macrophages and macrophage‐derived components as tumor‐targeting delivery vehicles. Herein, we summarize the recent advances in targeting and engineering macrophages for tumor immunotherapy, including (1) direct and indirect effects of macrophages on the augmentation of immunotherapy and (2) strategies for engineering macrophage‐based drug carriers. The existing perspectives and challenges of macrophage‐based tumor immunotherapies are also highlighted. Modulating macrophages for tumor immunotherapy holds great promise to improve anti‐tumor efficacy. Inhibition of macrophage recruitment, depleting tumor‐associated macrophages (TAMs), repolarizing TAMs, and regulating macrophage‐mediated phagocytosis of tumor cells are the four major strategies for manipulating macrophage‐mediated tumor immunotherapy.
Thanks to millions of years of evolution, living beings have developed complex mechanisms for sensing, actuation, and adaptation to the surrounding environment. Biohybrid robots exploit these mechanisms by embedding living components and combining them with nonliving elements. This allows overcoming some of the issues affecting entirely artificial devices, such as difficult scalability to small scales, inability to self-heal, and possible immunogenicity. In this chapter, biohybrid microrobots based on bacteria or other single cells (e.g., sperm cells, erythrocytes, neutrophils) are described. The most relevant examples reported in the state-of-the-art are analyzed, focusing on their specific sensing and actuation mechanisms. Relying on the use of a complete and autonomous living organism, they must be considered examples of a top-down approach, which needs to find ways of adequately controlling them. Specific applications of these systems are also described, with a particular focus on clinical ones. Then, muscle-based multicellular robots are introduced. Such systems are based on a bottom-up approach, through which single contractile units (skeletal muscle cells, cardiomyocytes, or insect-derived cells) are assembled and integrated with materials supporting them, to achieve effective locomotion and other functions. The main applications and challenges related to multicellular biohybrid microrobots are described, mentioning among others, modeling issues and the need for implementing multiple degrees of freedom, yet keeping high controllability by an external user.
Due to the difficulty of targeting systemically delivered therapeutics for cancer, interest has grown in exploiting biological agents to enhance tumor accumulation and mediate localized drug delivery. Equipped with onboard sensing and active motility, some cells respond to specific cues of the tumor microenvironment, making them ideal candidates for smart cancer therapy. Herein, recent progress and developments are presented on the use of four of the most promising cell‐based systems for tumor targeting and drug delivery—immune cells, stem cells, platelets, and bacteria. Strategies to further enhance specificity at the tissue and cell level are discussed, including genetic engineering, chemical cell surface modification, and the use of external physical stimuli. With crucial ongoing efforts addressing the safety and efficacy of living intelligent therapeutics, a new era of cancer medicine is on the horizon. Immune cells, stem cells, platelets, and bacteria possess unique attributes making them ideal candidates for smart cancer therapy. Equipped with onboard sensing and active motility, these cells can home to tumors where they release therapeutic cargo. External stimuli, such as magnetic fields, as well as cell surface modifications and genetic engineering can further enhance their safety and efficacy.
Peripheral nerve injuries result in disrupted cellular communication between the central nervous system and somatic distal end targets. The peripheral nervous system is capable of independent and extensive regeneration; however, meaningful target muscle reinnervation and functional recovery remain limited and may result in chronic neuropathic pain and diminished quality of life. Macrophages, the primary innate immune cells of the body, are critical contributors to regeneration of the injured peripheral nervous system. However, in some clinical scenarios, macrophages may fail to provide adequate support with optimal timing, duration, and location. Here, we review the history of immunosuppressive and immunomodulatory strategies to treat nerve injuries. Thereafter, we enumerate the ways in which macrophages contribute to successful nerve regeneration. We argue that implementing macrophage-based immunomodulatory therapies is a promising treatment strategy for nerve injuries across a wide range of clinical presentations.
Therapeutic agents, such as drugs and cells, play an essential role in virtually every treatment of injury, illness, or disease. However, the conventional practices of drug delivery often result in undesirable side effects caused by drug overdose and off‐target delivery. In the case of cell delivery, the survival rate of the transplanted cells is extremely low and difficulties with the administration route of cells remain a problem. Recently, magnetically actuated microrobots have started offering unique opportunities in targeted therapeutic delivery due to their tiny size and ability to access hard‐to‐reach lesions in a minimally invasive manner; considerable advances in this regard have been made over the past decade. Here, recent progress in magnetically actuated microrobots, developed for targeted drug/cell delivery, is presented, with a focus on their design features and mechanisms for controlled therapeutic release. Additionally, the practical challenges faced by the microrobots, and future research directions toward the swift bench‐to‐bedside translation of the microrobots are addressed.
We described a magnetic chitosan microscaffold tailored for applications requiring high biocompatibility, biodegradability, and monitoring by real-time imaging. Such magnetic microscaffolds exhibit adjustable pores and sizes depending on the target application and provide various functions such as magnetic actuation and enhanced cell adhesion using biomaterial-based magnetic particles. Subsequently, we fabricated the magnetic chitosan microscaffolds with optimized shape and pore properties to specific target diseases. As a versatile tool, the capability of the developed microscaffold was demonstrated through in vitro laboratory tasks and in vivo therapeutic applications for liver cancer therapy and knee cartilage regeneration. We anticipate that the optimal design and fabrication of the presented microscaffold will advance the technology of biopolymer-based microscaffolds and micro/nanorobots.
Over the past decades, considerable attention has been dedicated to the exploitation of diverse immune cells as therapeutic and/or diagnostic cell‐based microrobots for hard‐to‐treat disorders. To date, a plethora of therapeutics based on alive immune cells, surface‐engineered immune cells, immunocytes’ cell membranes, leukocyte‐derived extracellular vesicles or exosomes, and artificial immune cells have been investigated and a few have been introduced into the market. These systems take advantage of the unique characteristics and functions of immune cells, including their presence in circulating blood and various tissues, complex crosstalk properties, high affinity to different self and foreign markers, unique potential of their on‐demand navigation and activity, production of a variety of chemokines/cytokines, as well as being cytotoxic in particular conditions. Here, the latest progress in the development of engineered therapeutics and diagnostics inspired by immune cells to ameliorate cancer, inflammatory conditions, autoimmune diseases, neurodegenerative disorders, cardiovascular complications, and infectious diseases is reviewed, and finally, the perspective for their clinical application is delineated. Synthetic biology is a rapidly growing technology that has an enormous potential for the development of novel therapeutics and imaging tools. This review focuses on the latest progress in the design of immune cell‐derived microrobots and biomimetic nanoparticles as engineered biocarriers to ameliorate hard‐to‐treat diseases.
Background
Paclitaxel (PTX) has been clinically used for several years due to its good therapeutic effect against cancers. Its poor water-solubility, non-selectivity, high cytotoxicity to normal tissue and worse pharmacokinetic property limit its clinical application.
Objective
To review the recent progress on the PTX delivery systems.
Methods
In recent years, the copolymeric nano-drug delivery systems for PTX are broadly studied. It mainly includes micelles, nanoparticles, liposomes, complexes, prodrugs and hydrogels, etc. They were developed or further modified with target molecules to investigate the release behavior, targeting to tissues, pharmacokinetic property, anticancer activities and bio-safety of PTX. In the review, we will describe and discuss the recent progress on the nano-drug delivery system for PTX since 2011.
Results
The water-solubility, selective delivery to cancers, tissue toxicity, controlled release and pharmacokinetic property of PTX are improved by way of its encapsulation into the nano-drug delivery systems. In addition, its activities against cancer are also comparable or high when compared with commercial formulation.
Conclusion
Encapsulating PTX into nano-drug carriers should be helpful to reduce its toxicity to human, keep or enhance its activity and improve its pharmacokinetic property.
Although great efforts have been undertaken to develop a nanoparticle-based drug delivery system (DDS) for the treatment of solid tumors, the therapeutic outcomes are still limited. Immune cells, which possess an intrinsic ability to phagocytose nanoparticles and are recruited by tumors, can be exploited to deliver nanotherapeutics deep inside the tumors. Photothermal therapy using near-infrared light is a promising non-invasive approach for solid tumor ablation, especially when combined with chemotherapy. In this study, we designed and evaluated a macrophage-based, multiple-nanotherapeutics DDS, involving the phagocytosis by macrophages of both small-sized gold nanorods and anticancer drug-containing nanoliposomes. The aim was to treat solid tumors, utilizing the tumor-infiltrating properties of macrophages with synergistic photothermal-chemotherapy. Using a 3D cancer spheroid solid tumor model, we show that tumor penetration and coverage by the nanoparticles were both markedly enhanced when the macrophages were used, compared to when using the nanoparticles only. In addition, in vivo experiments involving both local and systemic administrations in breast tumor-bearing mice demonstrate that the proposed DDS can effectively target and kill the tumors, especially when combined with chemo-photothermal therapy. Consequently, this immune cell-based theranostic strategy may represent a potentially important advancement in the treatment of solid tumors.
Monocyte-derived macrophages orchestrate tissue regeneration by homing to sites of injury, phagocytosing pathological debris, and stimulating other cell types to repair the tissue. Accordingly, monocytes have been investigated as a translational and potent source for cell therapy, but their utility has been hampered by their rapid acquisition of a pro-inflammatory phenotype in response to the inflammatory injury microenvironment. To overcome this problem, we designed a cell therapy strategy where monocytes are exogenously reprogrammed by intracellularly loading the cells with biodegradable microparticles containing an anti-inflammatory drug in order to modulate and maintain an anti-inflammatory phenotype over time. To test this concept, poly(lactic-co-glycolic) acid microparticles were loaded with the anti-inflammatory drug dexamethasone (Dex) and administered to primary human monocytes for four hours to facilitate phagocytic uptake. After removal of non-phagocytosed microparticles, microparticle-loaded monocytes differentiated into macrophages and stored the microparticles intracellularly for several weeks in vitro, releasing drug into the extracellular environment over time. Cells loaded with intracellular Dex microparticles showed decreased expression and secretion of inflammatory factors even in the presence of pro-inflammatory stimuli up to 7 days after microparticle uptake compared to untreated cells or cells loaded with blank microparticles, without interfering with phagocytosis of tissue debris. This study represents a new strategy for long-term maintenance of anti-inflammatory macrophage phenotype using a translational monocyte-based cell therapy strategy without the use of genetic modification. Because of the ubiquitous nature of monocyte-derived macrophage involvement in pathology and regeneration, this strategy holds potential as a treatment for a vast number of diseases and disorders.
Statement of significance
We report a unique and translational strategy to overcome the challenges associated with monocyte- and macrophage-based cell therapies, in which the cells rapidly take on inflammatory phenotypes when administered to sites of injury. By intracellularly loading monocytes with drug-loaded microparticles prior to administration via phagocytosis, we were able to inhibit inflammation while preserving functional behaviors of human primary macrophages derived from those monocytes up to seven days later. To our knowledge, this study represents the first report of reprogramming macrophages to an anti-inflammatory phenotype without the use of genetic modification.
Paclitaxel (PTX) is a potent drug for treating advanced solid carcinomas; however, its clinical utility is limited by its poor water solubility. Despite the promise of using nanoparticles to deliver hydrophobic PTX, achieving sufficient drug loading while maintaining small particle size and stability in biological media remains a challenge. Here, a PTX nanoparticle (NP) formulation with small size and great stability is presented that targets breast cancer cells and enables controlled release of PTX. This NP formulation (NP‐PTX‐FA) comprises a superparamagnetic iron oxide core coated with short‐ and long‐chain polyethylene glycol: the former for conjugation of hydrophobic PTX and folic acid (FA), and the latter as an outer layer for improved hydrophilicity. The NP‐PTX‐FA has a uniform size distribution (averaging 28.2 ± 0.64 nm) and high drug loading capacity of 22.8 wt% (vs <10 wt% normally). NP‐PTX‐FA releases the drug under conditions mimicking the acidic intracellular pH of breast cancer cells and the FA conjugation leads to higher NP uptake by target cells, enhancing the cytotoxicity to target cells compared to free PTX. This NP formulation holds great promise to improve breast cancer therapy and potential to deliver other hydrophobic drugs for treating various cancer types. A nanoparticle that exhibits small particle size, great stability, high drug loading, and enables the controlled release of paclitaxel (PTX) for targeted treatment of breast cancer cells is developed. This targeted magnetic nanoparticle, functionalized with pH‐cleavable paclitaxel, significantly enhances the cytotoxicity toward tumor cells as compared to free paclitaxel.
Recent advances in the versatility and sophistication of design, fabrication, and control methods of mobile microrobots could have a transforming impact on future healthcare technologies. Self‐propelled or remotely actuated, synthetic, or biohybrid microrobots can navigate to difficult‐to‐reach regions in the human body to deliver therapeutics for microscopically localized medical interventions. Here, recent progress in the design of microrobotic systems concerning therapeutic delivery of drugs, cells, and genetic materials is reported. This perspective prioritizes the design aspects of microrobots for medical cargo loading, navigation in biologically relevant environments, and controlled cargo release. In the final section, future prospects and a discussion on the critical shortcomings for the benchside‐to‐bedside translation of medical microrobots are provided.
Near-infrared persistent luminescence nanoparticles (NIR-PLNPs) are promising imaging agents due to deep tissue penetration, high signal-to-noise ratio, and repeatedly charging ability. Here, we report liposome-coated NIR-PLNPs (Lipo-PLNP) as a novel persistent luminescence imaging guided drug carrier for chemotherapy. The Lipo-PLNP nanocomposite shows the advantages of superior persistent luminescence and high drug loading efficiency, and enables autofluorescence-free and long-term tracking of drug delivery carriers with remarkable therapeutic effect.
The restriction of anti-cancer drugs entry to tumor sites in the brain is a major impediment to the development of new strategies for the treatment of glioma. Based on the finding that macrophages possess an intrinsic homing property enabling them to migrate to tumor sites across the endothelial barriers in response to the excretion of cytokines/chemokines in the diseased tissues, we exploited macrophages as 'Trojan horses' to carry drug-loading nanoparticles (NPs), pass through barriers, and offload them into brain tumor sites. Anticancer drugs were encapsulated in nanoparticles to avoid their damage to the cells. Drug loading NPs was then incubated with RAW264.7 cells in vitro to prepare macrophage-NPs (M-NPs). The release of NPs from M-NPs was very slow in medium of DMEM and 10% FBS and significantly accelerated when LPS and IFN-γ were added to mimic tumor inflammation microenvironment. The viability of macrophages was not affected when the concentration of doxorubicin lower than 25 μg/ml. The improvement of cellular uptake and penetration into the core of glioma spheroids of M-NPs compared with NPs was verified in in vitro studies. The tumor-targeting efficiency of NPs was also significantly enhanced after loading into macrophages in nude mice bearing intracranial U87 glioma. Our results provided great potential of macrophages as an active biocarrier to deliver anticancer drugs to the tumor sites in the brain and improve therapeutic effects of glioma.
Therapeutic nanoparticles (TNPs) aim to deliver drugs more safely and effectively to cancers, yet clinical results have been unpredictable owing to limited in vivo understanding. Here we use single-cell imaging of intratumoral TNP pharmacokinetics and pharmacodynamics to better comprehend their heterogeneous behaviour. Model TNPs comprising a fluorescent platinum(IV) pro-drug and a clinically tested polymer platform (PLGA-b-PEG) promote long drug circulation and alter accumulation by directing cellular uptake toward tumour-associated macrophages (TAMs). Simultaneous imaging of TNP vehicle, its drug payload and single-cell DNA damage response reveals that TAMs serve as a local drug depot that accumulates significant vehicle from which DNA-damaging Pt payload gradually releases to neighbouring tumour cells. Correspondingly, TAM depletion reduces intratumoral TNP accumulation and efficacy. Thus, nanotherapeutics co-opt TAMs for drug delivery, which has implications for TNP design and for selecting patients into trials.
In this study, we developed the cancer treatment through the combination of chemotherapy and thermotherapy using doxorubicin-loaded magnetic liposomes. The citric acid-coated magnetic nanoparticles (CAMNP, ca. 10 nm) and doxorubicin were encapsulated into the liposome (HSPC/DSPE/cholesterol = 12.5:1:8.25) by rotary evaporation and ultrasonication process. The resultant magnetic liposomes (ca. 90 to 130 nm) were subject to characterization including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), zeta potential, Fourier transform infrared (FTIR) spectrophotometer, and fluorescence microscope. In vitro cytotoxicity of the drug carrier platform was investigated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using L-929 cells, as the mammalian cell model. In vitro cytotoxicity and hyperthermia (inductive heating) studies were evaluated against colorectal cancer (CT-26 cells) with high-frequency magnetic field (HFMF) exposure. MTT assay revealed that these drug carriers exhibited no cytotoxicity against L-929 cells, suggesting excellent biocompatibility. When the magnetic liposomes with 1 μM doxorubicin was used to treat CT-26 cells in combination with HFMF exposure, approximately 56% cells were killed and found to be more effective than either hyperthermia or chemotherapy treatment individually. Therefore, these results show that the synergistic effects between chemotherapy (drug-controlled release) and hyperthermia increase the capability to kill cancer cells.
In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.
We propose a bacteria-based microrobot (bacteriobot) based on a new fusion paradigm for theranostic activities against solid tumors. We develop a bacteriobot using the strong attachment of bacteria to Cy5.5-coated polystyrene microbeads due to the high-affinity interaction between biotin and streptavidin. The chemotactic responses of the bacteria and the bacteriobots to the concentration gradients of lysates or spheroids of solid tumors can be detected as the migration of the bacteria and/or the bacteriobots out of the central region toward the side regions in a chemotactic microfluidic chamber. The bacteriobots showed higher migration velocity toward tumor cell lysates or spheroids than toward normal cells. In addition, when only the bacteriobots were injected to the CT-26 tumor mouse model, Cy5.5 signal was detected from the tumor site of the mouse model. In-vitro and in-vivo tests verified that the bacteriobots had chemotactic motility and tumor targeting ability. The new microrobot paradigm in which bacteria act as microactuators and microsensors to deliver microstructures to tumors can be considered a new theranostic methodology for targeting and treating solid tumors.
15-Deoxy-Δ(12,14)-prostaglandin J2 (15d-PGJ2) and activin are implicated in the control of apoptosis, cell proliferation, and inflammation in cells. We examined both the mechanism by which 15d-PGJ2 regulates the transcription of activin-induced activin receptors (ActR) and Smads in HepG2 cells and the involvement of the nuclear factor- κ B (NF- κ B) and mitogen-activated protein kinase (MAPK) pathways in this regulation. Activin A (25 ng/mL) inhibited HepG2 cell proliferation, whereas 15d-PGJ2 (2 μ M and 5 μ M) had no effect. Activin A and 15d-PGJ2 showed different regulatory effects on ActR and Smad expression, NF- κ B p65 activity and MEK/ERK phosphorylation, whereas they both decreased IL-6 production and increased IL-8 production. When co-stimulated with 15d-PGJ2 and activin, 15d-PGJ2 inhibited the activin-induced increases in ActR and Smad expression, and decreased activin-induced IL-6 production. However, it increased activin-induced IL-8 production. In addition, 15d-PGJ2 inhibited activin-induced NF- κ B p65 activity and activin-induced MEK/ERK phosphorylation. These results suggest that 15d-PGJ2 suppresses activin-induced ActR and Smad expression, down-regulates IL-6 production, and up-regulates IL-8 production via suppression of NF- κ B and MAPK signaling pathway in HepG2 cells. Regulation of ActR and Smad transcript expression and cytokine production involves NF- κ B and the MAPK pathway via interaction with 15d-PGJ2/activin/Smad signaling.
Magnetotactic bacteria (MTB) are capable of swimming along magnetic field lines. This unique feature renders them suitable in the development of magnetic-guided, auto-propelled microrobots to serve in target molecule separation and detection, drug delivery, or target cell screening in a microfluidic chip. The biotechnology to couple these bacteria with functional loads to form microrobots is the critical point in its application. Although an immunoreaction approach to attach functional loads to intact MTB was suggested, details on its realization were hardly mentioned. In the current paper, MTB-microrobots were constructed by attaching 2 μm diameter microbeads to marine magnetotactic ovoid MO-1 cells through immunoreactions. These microrobots were controlled using a special control and tracking system. Experimental results prove that the attachment efficiency can be improved to ∼30% via an immunoreaction. The motility of the bacteria attached with different number of loads was also assessed. The results show that MTB can transport one load at a velocity of ∼21 μm/s and still move and survive for over 30 min. The control and tracking system is fully capable of directing and monitoring the movement of the MTB-microrobots. The rotating magnetic fields can stop the microrobots by trapping them as they swim within a circular field with a controllable size. The system has potential use in chemical analyses and medical diagnoses using biochips as well as in nano/microscale transport.
Microrobots developed by the technological advances are useful for application in various fields. Nevertheless, they have limitations with respect to their actuator and motility. Our experiments aim to determine whether a bioactuator using the flagellated bacteria Serratia marcescens would enhance the motility of microrobots. In this study, we investigate that the flagellated bacteria Serratia marcescens could be utilized as actuators for SU-8 microstructures by bovine serum albumin-selective patterning. Firstly, we analyze the adherence of the bacteria to the SU-8 micro cube by selective patterning using 5% BSA. The results show that number of attached-bacteria in the uncoated side of the selectively- coated micro cube with BSA increased by 200% compared with that in all sides of the non treated micro cube. Secondly, the selectively BSA coated micro cube had 210% higher motility than the uncoated micro cube. The results revealed that the bacteria patterned to a specific site using 5% BSA significantly increase the motility of the bacteria actuated microstructure.
Lung cancer is the leading cause of cancer-related mortality worldwide. The lack of tumor specificity remains a major drawback for effective chemotherapies and results in dose-limiting toxicities. However, a ligand-mediated drug delivery system should be able to render chemotherapy more specific to tumor cells and less toxic to normal tissues. In this study, we isolated a novel peptide ligand from a phage-displayed peptide library that bound to non-small cell lung cancer (NSCLC) cell lines. The targeting phage bound to several NSCLC cell lines but not to normal cells. Both the targeting phage and the synthetic peptide recognized the surgical specimens of NSCLC with a positive rate of 75% (27 of 36 specimens). In severe combined immunodeficiency (SCID) mice bearing NSCLC xenografts, the targeting phage specifically bound to tumor masses. The tumor homing ability of the targeting phage was inhibited by the cognate synthetic peptide, but not by a control or a WTY-mutated peptide. When the targeting peptide was coupled to liposomes carrying doxorubicin or vinorelbine, the therapeutic index of the chemotherapeutic agents and the survival rates of mice with human lung cancer xenografts markedly increased. Furthermore, the targeting liposomes increased drug accumulation in tumor tissues by 5.7-fold compared with free drugs and enhanced cancer cell apoptosis resulting from a higher concentration of bioavailable doxorubicin. The current study suggests that this tumor-specific peptide may be used to create chemotherapies specifically targeting tumor cells in the treatment of NSCLC and to design targeted gene transfer vectors or it may be used one in the diagnosis of this malignancy.
Water-based magnetic fluids, generally intended for biomedical applications, often have various coating molecules that make them stable and compatible with biological liquids. Magnetic fluids containing iron oxide particles have been prepared by a co-precipitation method, using citric acid as stabilizer. The magnetic particles of the magnetic fluids were obtained by chemical precipitation from ferric (FeCl(3)) and ferrous salts (FeSO(4) or FeCl(2)) in alkali medium (ammonia hydroxide). Citric acid was used to stabilize the magnetic-particle suspension. Physical tests were performed in order to determine various microstructural and rheological features. Transmission electron microscopy was the main investigation method for assessing the magnetic-particle size. The dimensional distribution of the magnetic-particle physical diameter was analyzed using the box-plot statistical method while infrared absorption spectra were used to study the colloidal particle structure. The magnetic-fluid density (picnometric method), viscosity (capillary method) and surface tension (stalagmometric method) were measured using standard methods.
One of the challenges to adopt photothermal ablation clinically is optimization of the agent delivery in vivo. Herein, a cell-mediated delivery and therapy system by employing macrophage vehicles to transport 7 nm diameter Au nanorods (sAuNRs) is described. Owing to the small size, the sAuNRs exhibit much higher macrophage uptake and negligible cytotoxicity in comparison with commonly used 14 nm diameter AuNRs to achieve healthy BSA-coated sAuNRs-laden-macrophages. By delivering BSA-coated sAuNRs to the entire tumor after intratumoral injection, the BSA-coated sAuNRs-laden-macrophages show greatly improved photothermal conversion almost everywhere in the tumor, resulting in minimized tumor recurrence rates compared to free BSA-coated sAuNRs. Our findings not only provide a desirable approach to improve the photothermal therapy efficiency by optimizing the intratumoral distribution of the agents, but also expedite clinical application of nanotechnology to cancer treatment.
In this paper, we propose a new concept for a hybrid actuated microrobot for tumor-targeting therapy. For drug delivery in tumor therapy, various electromagnetic actuated microrobot systems have been studied. In addition, bacteria-based microrobot (so-called bacteriobot), which use tumor targeting and the therapeutic function of the bacteria, has also been proposed for solid tumor therapy. Compared with bacteriobot, electromagnetic actuated microrobot has larger driving force and locomotive controllability due to their position recognition and magnetic field control. However, because electromagnetic actuated microrobot does not have self-tumor targeting, they need to be controlled by an external magnetic field. In contrast, the bacteriobot uses tumor targeting and the bacteria's own motility, and can exhibit self-targeting performance at solid tumors. However, because the propulsion forces of the bacteria are too small, it is very difficult for bacteriobot to track a tumor in a vessel with a large bloodstream. Therefore, we propose a hybrid actuated microrobot combined with electromagnetic actuation in large blood vessels with a macro range and bacterial actuation in small vessels with a micro range. In addition, the proposed microrobot consists of biodegradable and biocompatible microbeads in which the drugs and magnetic particles can be encapsulated; the bacteria can be attached to the surface of the microbeads and propel the microrobot. We carried out macro-manipulation of the hybrid actuated microrobot along a desired path through electromagnetic field control and the micro-manipulation of the hybrid actuated microrobot toward a chemical attractant through the chemotaxis of the bacteria. For the validation of the hybrid actuation of the microrobot, we fabricated a hydrogel microfluidic channel that can generate a chemical gradient. Finally, we evaluated the motility performance of the hybrid actuated microrobot in the hydrogel microfluidic channel. We expect that the hybrid actuated microrobot will be utilized for tumor targeting and therapy in future. Biotechnol. Bioeng. 2015;9999: 1-9. © 2015 Wiley Periodicals, Inc.
© 2015 Wiley Periodicals, Inc.
The biomimetic delivery system (BDS) based on special type of endogenous cells like macrophages and T cells, has been emerging as a novel strategy for cancer therapy, due to its tumor homing property and biocompatibility. However, its development is impeded by complicated construction, low drug loading or negative effect on the cell bioactivity. The present report constructed a BDS by loading doxorubicin (DOX) into a mouse macrophage-like cell line (RAW264.7). It was found that therapeutically meaningful amount of DOX could be loaded into the RAW264.7 cells by simply incubation, without significantly affecting the viability of the cells. Drug could release from the BDS and maintain its activity. RAW264.7 cells exhibited obvious tumor-tropic capacity towards 4T1 mouse breast cancer cells both in vitro and in vivo, and drug loading did not alter this tendency. Importantly, the DOX loaded macrophage system showed promising anti-cancer efficacy in terms of tumor suppression, life span prolongation and metastasis inhibition, with reduced toxicity. In conclusion, it is demonstrated that the BDS developed here seems overcome some of the main issues related to a BDS. The DOX loaded macrophages might be a potential BDS for targeted cancer therapy.
Copyright © 2015. Published by Elsevier B.V.
Biocompatibility, sensing, and self-actuation are very important features for a therapeutic biomedical microrobot. As a new concept for tumor theragnosis, this paper proposes a monocyte-based microrobots, which are combining the phagocytosis and engulfment activities containing human acute monocytic leukemia cell line (THP-1) with various sized polystyrene microbeads are engulfed instead of a therapeutic drug. For the validation of the blood vessel barrier-penetrating activity of the monocyte-based microrobot, we fabricate a new cell migration assay with monolayer-cultured endothelial cell (HUVEC), similar with the blood vessels. We perform the penetrating chemotactic motility of the monocyte-based microrobot using various types of the chemo-attractants, such as monocyte chemotactic protein (MCP)-1, human breast cancer cell lines (MCF7)-cell lysates, and -contained alginate spheroids. The monocyte-based microrobot show chemotactic transmigrating motilities similar with what an actual monocyte does. This new paradigm of a monocyte-based microrobot having various useful properties such as biocompatibility, sensing, and self-actuation can become the basis of a biomedical microrobot using monocytes for diagnosis and therapy of various diseases. Biotechnol. Bioeng. © 2014 Wiley Periodicals, Inc.
Cellular hitchhiking leverages the use of circulatory cells to enhance the biological outcome of nanoparticle drug delivery systems, which often suffer from poor circulation time and limited targeting. Cellular hitchhiking utilizes the natural abilities of circulatory cells to: (i) navigate the vasculature while avoiding immune system clearance, (ii) remain relatively inert until needed and (iii) perform specific functions, including nutrient delivery to tissues, clearance of pathogens, and immune system surveillance. A variety of synthetic nanoparticles attempt to mimic these functional attributes of circulatory cells for drug delivery purposes. By combining the advantages of circulatory cells and synthetic nanoparticles, many advanced drug delivery systems have been developed that adopt the concept of cellular hitchhiking. Here, we review the development and specific applications of cellular hitchhiking-based drug delivery systems.
A bacteria-based microrobot (bacteriobot) was proposed and investigated as a new type of active drug delivery system because of its useful advantages, such as active tumor targeting, bacteria-mediated tumor diagnosis, and therapy. In this study, we fabricated a bacteriobot with enhanced motility by selective attachment of flagellar bacteria (Salmonella typhimurium). Through selective bovine serum albumin (BSA) pattering on hydrophobic polystyrene (PS) microbeads, many S. typhimurium could be selectively attached only on the unpatterned surface of PS microbead. For the evaluation of the chemotactic motility of the bacteriobot, we developed a microfluidic chamber which can generate a stable concentration gradient of bacterial chemotactic chemicals. Prior to the evaluation of the bacteriobot, we first evaluated the directional chemotactic motility of S. typhimurium using the proposed microfluidic chamber, which contained a bacterial chemo-attractant (L-aspartic acid) and a chemo-repellent (NiSO 4), respectively. Compared to density of the control group in the microfluidic chamber without any chemical gradient, S. typhimurium increased by about 16% in the L-aspartic acid gradient region and decreased by about 22% in the NiSO 4 gradient region. Second, we evaluated the bacteriobot's directional motility by using this microfluidic chamber. The chemotactic directional motility of the bacteriobot increased by 14% and decreased by 13% in the concentration gradients of L-aspartic acid and NiSO 4 , respectively. These results confirm that the bacteriobot with selectively patterned S. typhimurium shows chemotaxis motility very similar to that of S. typhimurium. Moreover, the directional motilities of the bacteria and bacteriobot could be demonstrated quantitatively through the proposed micro-fluidic chamber.
Many people proposed living things as actuators, for example microbes, cell and protein molecules. To address these problems for biomedical application, especially drug delivery system, a novel, miniature, and energy-efficient propulsion concept is proposed in this paper. Some bacteria have flagellar motor for swimming in water environment. The bacterial flagellar motor is a molecular machine that converts ion-motive force into mechanical force. Liposome is well known component for drug delivery. This vesicle can contain biologically active compounds. We proposed a new integration method of these two functions, bacteria motility and liposome carrier. Bacteria and liposome are combined through antibody binding technique and we have created a bacteria-driven liposome easily. Consequently, the effect of antibody when bacteria attached to liposome is studied experimentally. Furthermore, the stochastic nature of bacterial bio propulsion of liposome is investigated. It is shown that the mobility of liposome with bacteria was higher than that of liposome without bacteria and demonstrate potential for highly-functional drug delivery system.
We proposed a new bacteria patterning method on the restricted region of microbeads, using the submerged property of polystyrene microbeads on various concentrations of agarose gel. Moreover, we fabricated a bacterial microrobot using attenuated Salmonella typhimurium through the new patterning methods. We controlled the submerged degree of polystyrene microbeads through the regulation of the hardness of the agarose gel. The polystyrene microbeads on agarose gel were transferred onto a poly-dimethylsiloxane (PDMS) surface for easy manipulation of the microbeads. Then, we treated the polystyrene microbeads on the PDMS surface with antibacterial adherent factors, such as O2 plasma and bovine serum albumin (BSA). The Salmonella typhimurium was attached to the entire surface of the untreated polystyrene microbeads, whereas Salmonella typhimurium were only attached to the restricted surface region of the treated polystyrene microbeads through the proposed patterning method. The bacteria-attached microbeads gain motility by the propulsion of the attached bacteria, and the selective-bacteria-attached microbeads showed enhanced motility. Compared with whole-bacteria-attached polystyrene microbeads (1.74 ± 1.62 μm/s), the selective bacteria-attached polystyrene microbeads, using O2 plasma and BSA, showed 9.18 ± 1.88 μm/s and 14.65 ± 8.66 μm/s faster moving velocities, respectively. Through the results, we expected that the proposed patterning methodology of microbeads could contribute to the development of biomedical bacterial microrobots.
Drug targeting to tumors with limited toxicity and enhanced efficacy of drug is one of the important goals for cancer treatment pharmaceutics. Monocytes/macrophages are able to migrate to tumor sites across the blood barriers by acting as Trojan horses carrying drug cargoes. Taking this advantage, we have intended to develop an efficient administration system using a biologically active carrier of mouse peritoneal macrophage bearing liposomal doxorubicin (macrophage-LP-Dox). We expect that this system could improve the cancer therapeutic efficacy through deeper penetration into tumor even hypoxic region behind tumor blood vessel. We first confirmed that macrophages containing iron oxides could migrate and infiltrate into tumors effectively by MR imaging. Next, we showed that doxorubicin (Dox) encapsulated with liposomes (LP-Dox) was successfully loaded into macrophages, in which the biological activity of macrophage and cytotoxicity of Dox against tumor cells were well preserved. Delivery of Dox into tumor tissue by systemic administration of macrophage-LP-Dox was verified in both subcutaneous and metastasis xenograft tumor models. Importantly, the effective inhibition of in vivo tumor growth was proved with this system. Our results provide the feasibility of macrophages-LP-drug as an active biocarrier for the enhancement of therapeutic effects in cancer treatment and open new perspectives for the active delivery of drugs.
Nanobots - tiny robots that can be injected into the body to perform medical procedures - are the stuff of science fiction. Swimming microrobots propelled by artificial flagella bring that fantasy closer to reality.
The diffusion of univalent cations and anions out of spontaneously formed liquid crystals of lecithin is remarkably similar to the diffusion of such ions across biological membranes. If the unit structure of the liquid crystal is accepted as being that of a bimolecular leaflet, then these leaflets have been shown to be many orders of magnitude more permeable to anions than to cations. The diffusion rate for cations is very significantly controlled by the sign and magnitude of the surface charge at the water/lipid interface. There is a decrease of the diffusion rate for cations as the negative charge on the lipid structure decreases—which diminishes to zero for a positively charged membrane—the diffusion rate of anions remaining very high. The exchange diffusion rate of Cl− and I− was greater than that of F−, NO3−, SO42− and HPO42− but no significant differences were detectable for the cation series, Li+, Na+, K+, Rb+ and choline. The membranes are very permeable to water.Because the diffusion rate of cations is low, the phospholipid liquid crystalline structures appear to “bind” or “capture” cations. It is found that as the surface charge of the lipid lamellae is increased, the amount of cation per μmle of lipid increases. It is argued that if the cation is sequestered in aqueous compartments between the bimolecular leaflets, and if the thickness of the aqueous compartments is determined by the surface charge density of the lipid head groups and by the ionic strength of the aqueous phase in accordance with double-layer theory, the amount of cation trapped would also be expected to vary.
Antibody or ligand-mediated targeting of liposomal anticancer drugs to antigens expressed selectively or over-expressed on tumor cells is increasingly being recognized as an effective strategy for increasing the therapeutic indices of anticancer drugs. This review summarizes some recent advances in the field of ligand-targeted liposomes (LTLs) for the delivery of anticancer drugs. New approaches used in the design and optimization of LTLs is discussed and the advantages and potential problems associated with their therapeutic applications are described. New technologies are widening the spectrum of ligands available for targeting and are allowing choices to be made regarding affinity, internalization and size. The time is rapidly approaching where we will see translation of anticancer drugs entrapped in LTLs to the clinic.
A novel liposomal formulation of paclitaxel targeting the folate receptor (FR) was synthesized and characterized. This formulation was designed to overcome vehicle toxicity associated with the traditional Cremophor EL-based formulation and to provide the added advantages of prolonged systemic circulation time and selective targeting of the FR, which is frequently overexpressed on epithelial cancer cells. The formulation had the composition of dipalmitoyl phosphatidylcholine/dimyristoyl phosphatidylglycerol/monomethoxy-polyethylene glycol (PEG)2000-distearoyl phosphatidylethanolamine/folate-PEG3350-distearoyl phosphatidylethanolamine (DPPC/DMPG/mPEG-DSPE/folate-PEG-DSPE) at molar ratios of (85.5:9.5:4.5:0.5) and a drug-to-lipid molar ratio of 1:33. The liposomes were prepared by polycarbonate membrane extrusion. The mean particle size of the liposomes was 97.1 nm and remained stable for at least 72 h at 4 degrees C. FR-targeted liposomes of the same lipid composition entrapping calcein were shown to be efficiently taken up by KB oral carcinoma cells, which are highly FR+. FR-targeted liposomes containing paclitaxel showed 3.8-fold greater cytotoxicity compared to non-targeted control liposomes in KB cells. Plasma clearance profiles of paclitaxel in the liposomal formulations were then compared to paclitaxel in Cremophor EL formulation. The liposomal formulations showed much longer terminal half-lives (12.33 and 14.23 h for FR-targeted and non-targeted liposomes, respectively) than paclitaxel in Cremophor EL (1.78 h). In conclusion, the paclitaxel formulation described in this study has substantial stability and favorable pharmacokinetic properties. The FR-targeted paclitaxel formulation is potentially useful for treatment of FR+ tumors and warrants further investigation.
This paper describes the use of a simple microfluidic device for studying T cell chemotaxis. The microfluidic device is fabricated in poly(dimethylsiloxane) (PDMS) using soft-lithography and consists of a "Y" type fluidic channel. Solutions are infused into the device by syringe pumps and generate a concentration gradient in the channel by diffusion. We show that the experimentally measured gradient profiles agree nicely with theoretical predictions and the gradient is stable in the observation region for cell migration. Using this device, we demonstrate robust chemotaxis of human T cells in response to single and competing gradients of chemokine CCL19 and CXCL12. Because of the simplicity of the device, it can flexibly control gradient generation in space and time, and would allow generation of multiple gradient conditions in a single chip for highly parallel chemotaxis experimentation. Visualization of T cell chemotaxis has previously been limited to studies in 3D matrices or under agarose assays, which do not allow precise control or variation in conditions. Acknowledging the importance of lymphocyte homing in the adaptive immune response, the ability to study T cell chemotaxis in microfluidic devices offers a new approach for investigating lymphocyte migration and chemotaxis in vitro.
Destruction of hypoxic regions within tumors, virtually inaccessible to cancer therapies, may well prevent malignant progression. The tumor's recruitment of monocytes into these regions may be exploited for nanoparticle-based delivery. Monocytes containing therapeutic nanoparticles could serve as "Trojan Horses" for nanoparticle transport into these tumor regions. Here we report the demonstration of several key steps toward this therapeutic strategy: phagocytosis of Au nanoshells, and photoinduced cell death of monocytes/macrophages as isolates and within tumor spheroids.
- T Lin-Ai
- T Pi-Ju
- W Yu-Chao
- W Yu-Jing
- L Leu-Wei
- Y Chung-Shi
T. Lin-Ai, T. Pi-Ju, W. Yu-Chao, W. Yu-Jing, L. Leu-Wei, Y. Chung-Shi,
Thermosensitive liposomes entrapping iron oxide nanoparticles for
controllable drug release, Nanotechnology 20 (2009) 135101.
Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery
- B R Smith
- H Eid
- J A Rallapalli
- T Prescher
- L A Larson
- Herzenberg
B.R. Smith, B. GhosnEliver Eid, H. Rallapalli, J.A. Prescher, T. Larson, L.A.
Herzenberg, et al., Selective uptake of single-walled carbon nanotubes by
circulating monocytes for enhanced tumour delivery, Nat. Nano 9 (2014)
481-487.