Article

Constrained Synthesis of Cobalt Oxide Nanomaterials in the 12-Subunit Protein Cage from Listeria innocua

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Abstract

The protein cage of the 12-subunit ferritin-like protein from Listeria innocua has been utilized as a size and shape constrained reaction environment for the synthesis of two cobalt oxide minerals, Co(3)O(4) and Co(O)OH. Reaction of Co(II) with H(2)O(2) at pH 8.5 under either elevated temperature (65 degrees C) or ambient temperature (23 degrees C) resulted in the formation of cobalt oxide nanoparticles encapsulated within the protein cage. At elevated temperatures, Co(3)O(4) was formed while at lower temperature the oxyhydroxide Co(O)OH was found. Mineral particles, commensurate in size with the internal dimensions of the protein (5 nm), were imaged by transmission electron microscopy and shown to be surrounded by the intact protein cage. The minerals were investigated by electron diffraction and revealed a crystalline Co(3)O(4) phase and an amorphous Co(O)OH phase. Further investigation of these composite materials using size exclusion chromatography, gel electrophoresis, dynamic light scattering, and zeta potential measurements indicated that the mineral was encapsulated within the protein cage giving rise to properties of both the mineral and protein components.

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... 49 A protein cage comprising 12-subunit ferritin-like protein from Listeria innocua (a Gram-positive rod-shaped bacterium) was used as a size-and shape-constrained reaction environment for fabricating two cobalt oxide minerals, Co 3 O 4 (crystalline) and Co(O)OH (amorphous). 50 He has a visiting scientist's position at the Regional Centre of Advanced Technologies and Materials, Palacky University, Olomouc, Czech Republic. He has over 45 years of research experience in the management of multidisciplinary technical programs ranging from natural products chemistry to development of more environmentally friendly synthetic methods using microwaves, ultrasound, etc. Lately, he is focused on greener approaches to assembly of nanomaterials and sustainable applications of magnetically retrievable nanocatalysts in benign media. ...
... It was surmised that high degree of spatial compartmentalization was the consequence of various electrostatic interfaces that ensued at the interior and exterior of this protein cage and the electrostatic properties of the interior surface directing the mineralization of transition metal oxides and oxyhydroxides. 50 Possibly, this high local concentration at the protein-solution interface lowered the redox potential of Co(II) oxidation, thus enabling spatially selective oxidation. As in mammalian ferritin biomineralization, after nucleation, the primarily produced crystallite could act as a catalytic site for additional oxidative hydrolysis; the autocatalytic mineralization procedure within the protein cage for the mineral oxide afforded a remarkable level of control in the fabrication of size-constrained particles. ...
... As in mammalian ferritin biomineralization, after nucleation, the primarily produced crystallite could act as a catalytic site for additional oxidative hydrolysis; the autocatalytic mineralization procedure within the protein cage for the mineral oxide afforded a remarkable level of control in the fabrication of size-constrained particles. 50 2.1.2. Yeasts. ...
Article
Cobalt and cobalt oxide nanomaterials have diverse significant applications in areas, including energy storage, anode material in rechargeable Li-ion batteries, electrochromic sensors, solar cells and photocatalysis. Additionally, these nanoparticles display antimicrobial, anticancer, antioxidant, antifungal, and enzyme inhibition properties. Generally, various physicochemical approaches have been employed for the fabrication of cobalt and cobalt oxide nanoparticles, but because of their considerable disadvantages such as toxicity, and time consuming reactions, there is a demand for development of safer, greener, eco-friendly, and cost-effective synthetic methods; greener tactics can eliminate the arduousness and complications of physicochemical methods. In this critical review, noteworthy recent advancements pertaining to the catalytic and biomedical applications of green-synthesized cobalt and cobalt oxide nanoparticles are highlighted as well as their sustainable synthetic options.
... In this way, Dps−nanoparticle composites have been used in applications in ways similar to those of ferritin, for example, as catalyst for the growth of single-walled carbon nanotubes 94 or for the size constrained mineralization with ferrimagnetic iron oxid nanoparticles and cobalt oxyhydrite cores by Allen et al. 95,96 2. THE FERRITIN PROTEIN SHELL AS MULTIVALENT SCAFFOLD As a consequence of the regular assembly of the protein subunits, binding sites and reactive groups on the surface of the complexes are arranged in a geometrically well-defined manner. The distances of functional groups in dendrimers or multiple antigen peptides are basically defined by steric or electrostatic repulsion, but protein complexes provide a well-defined, rigid scaffold of which the structure can be known to atomic resolution. ...
... Further, Allen et al. synthesized two cobalt oxide minerals, Co 3 O 4 and Co(O)OH, inside the cavity. 96 The first product was produced at 65°C, while the latter formed at room temperature. In both cases, TEM shows the formation of electron dense particles in the FLP interior, but only the high temperature product showed diffraction patterns, indicating that the spinel phase of cobalt oxide Co 3 O 4 was formed. ...
... The particles had an average diameter of 4.34 ± 0.55 nm. 95,96 The magnetism of the antiferromagnetic Co 3 O 4 particles was investigated, and surface or finite-size effects may play a major role in the magnetic behavior, which was characterized by a low Neél temperature of 15 ± 2 K. 201 The magnetic properties of the maghemite (γ-Fe 2 O 3 ) formed in Listeria innocua Dps were also magnetically characterized. 202 The slow chemical reaction synthesis was applied for the synthesis of CdS-nanoparticles. ...
Article
Protein structures such as ferritin in combination with synthetic as well as genetic alterations has proven to be highly interesting for the production of new materials. Ferritin describes a family of iron storage proteins with ubiquitous distribution among all life forms, with the notable exception of yeast and they are the most abundant members of the ferritin-like superfamily and may have developed from a rubrerythrin-like ancestor protein with two homologous pairs of antiparallel helices as main structural feature. The protein shell of mammalian ferritin is usually heterogeneous and consists of a mixture of two subunits of about 21 kDa, termed H for heavy (predominant in heart) and of about 19 kDa, termed L for light chain (predominant in liver), with around 55% amino acid homology for human H- and Lferritin. Apoferritin can be readily disassembled and reassembled by reducing the pH to a value as low as pH 2 and increasing it above pH 7, respectively. Holo-ferritin exhibits a remarkable affinity for anions and some nonferrous metal ions. Direct demineralization of the iron core in ferritins can be induced with strong Fe(III) chelators.
... the same method, CdS NCs coated with Pt clusters were also synthesized as a mimic of the enzyme to enhance the photoinduced nitrate reduction activity, which benefits from the fact that the peptide-templated NC configuration eliminates the need for electron mediators and exogenous sacrificial electron donors, both of which must be considered if one uses enzyme for the nitrate reduction [113]. To take a step further, by incorporating the binding peptides into various protein structures, one has been able to create material assembly structures in larger scale in one, two, and three dimensions by employing the self-assembly nature of the biomolecules [32,[114][115][116][117][118][119][120][121][122][123]. Stable protein 1 (SP1) is a protein that can resist high temperature and assemble into a lateral organization of ultra-dense docking arrays. ...
... Wild-type SP1s can assemble into hexagonal patterns so they can also be potentially used for the two-dimensional (2D) assembly of Au NPs, as shown in Figs.8C,D [116]. Other proteins including ferritin-like protein cages, CCMV and CPMV, as well as chaperonin proteins have been used for the 2D assembly [118][119][120] . Another potential candidate for the 2D assembly is crystalline bacteria cell-surface layer (S-layer), which is the monomolecular array composed of a single protein or glycoprotein species and represents the simplest biological membrane. ...
Article
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Mimicking the evolution processes of Nature, the combinatorial approach to biomolecular recognition properties attracts much attention due to the potential as a generic scheme to achieving complex material structures and hierarchical assemblies with molecular precision from the bottom up. In this paper, some recent efforts in the biomimetic synthesis of inorganic materials are reviewed, with emphasis placed on in vitro material formation with the use of protein/peptide molecules found in natural organisms as well as those with specific affinities to inorganic materials selected through the molecular evolution process. The applications of material-specific peptides and proteins in sensing and guiding hierarchical material assembly are also briefly discussed at the end.
... Both proteins have an atomically homogeneous structure determined by the genetic code [19], and can biomineralize several kinds of nanoparticles within their cages. Many kinds of metal, metal oxides and semiconductor nanoparticles can also be artificially synthesized in the hollow cavity [20][21][22][23][24]. Since the growth of the nanoparticles is regulated by the protein shell, nanoparticles synthesized in the cavity are uniformly sized. ...
... Figure 4 is an XRD pattern of a cobalt oxide core from TLiD1. The crystal structure of the TLiD1 cobalt oxide is a spinel structure of Co 3 O 4 , consistent with Allen's report of the wild-type L. innocua Dps core [20]. This implies that the composition of the cobalt oxide is unaltered by minTBP-1. ...
Article
We report a nanodot (ND) floating gate memory (NFGM) with a high-density ND array formed by a biological nano process. We utilized two kinds of cage-shaped proteins displaying SiO2 binding peptide (minTBP-1) on their outer surfaces: ferritin and Dps, which accommodate cobalt oxide NDs in their cavities. The diameters of the cobalt NDs were regulated by the cavity sizes of the proteins. Because minTBP-1 is strongly adsorbed on the SiO2 surface, high-density cobalt oxide ND arrays were obtained by a simple spin coating process. The densities of cobalt oxide ND arrays based on ferritin and Dps were 6.8 × 10(11) dots cm(-2) and 1.2 × 10(12) dots cm(-2), respectively. After selective protein elimination and embedding in a metal-oxide-semiconductor (MOS) capacitor, the charge capacities of both ND arrays were evaluated by measuring their C-V characteristics. The MOS capacitor embedded with the Dps ND array showed a wider memory window than the device embedded with the ferritin ND array. Finally, we fabricated an NFGM with a high-density ND array based on Dps, and confirmed its competent writing/erasing characteristics and long retention time.
... 50,51) Similar to apoferritin, the Dps cavity has been used as a nanoscale chamber for NP formation. 25,52,53) The N-and C-termini, which are both positioned on its outer surface, have been used to introduce additional functionalities for device applications, 54) such as dye-sensitized solar cells. 55) 2.2 TMV TMV was one of the first isolated viruses and is one of the best-characterized plant viruses. ...
... Thus, the same strategies as for apoferritin have been employed, while the smaller size of LIDps should restrict NP diameters to less than 4.5 nm. For example, 53) CdS, 52) CdSe, 25) and Pt 110) NPs have been fabricated using this biotemplate. In the case of CdSe and CdS, Cd 2+ should be added before the Se or S precursor to form NPs with uniform size [Figs. ...
Article
Virus particles and proteins are excellent examples of naturally occurring structures with well-defined nanoscale architectures, for example, cages and tubes. These structures can be employed in a bottom-up assembly strategy to fabricate repetitive patterns of hybrid organic–inorganic materials. In this paper, we review methods of assembly that make use of protein and virus scaffolds to fabricate patterned nanostructures with very high spatial control. We chose (apo)ferritin and tobacco mosaic virus (TMV) as model examples that have already been applied successfully in nanobiotechnology. Their interior space and their exterior surfaces can be mineralized with inorganic layers or nanoparticles. Furthermore, their native assembly abilities can be exploited to generate periodic architectures for integration in electrical and magnetic devices. We introduce the state of the art and describe recent advances in biomineralization techniques, patterning and device production with (apo)ferritin and TMV.
... Approaches have been developed that utilize empty ferritin (apoferritin) to access alternative iron oxide polymorphs by changing the reaction conditions. Using these principles a wide variety of other nonnatural minerals have been successfully nucleated and grown within ferritin cages (Allen et al., 2003;Douglas and Stark, 2000;Klem et al., 2008;Meldrum et al., 1995;Uchida et al., 2010). ...
Chapter
Within biology, molecules are arranged in hierarchical structures that coordinate and control the many processes that allow for complex organisms to exist. Proteins and other functional macromolecules are often studied outside their natural nanostructural context because it remains difficult to create controlled arrangements of proteins at this size scale. Viruses are elegantly simple nanosystems that exist at the interface of living organisms and nonliving biological machines. Studied and viewed primarily as pathogens to be combatted, viruses have emerged as models of structural efficiency at the nanoscale and have spurred the development of biomimetic nanoparticle systems. Virus-like particles (VLPs) are noninfectious protein cages derived from viruses or other cage-forming systems. VLPs provide incredibly regular scaffolds for building at the nanoscale. Composed of self-assembling protein subunits, VLPs provide both a model for studying materials’ assembly at the nanoscale and useful building blocks for materials design. The robustness and degree of understanding of many VLP structures allow for the ready use of these systems as versatile nanoparticle platforms for the conjugation of active molecules or as scaffolds for the structural organization of chemical processes. Lastly the prevalence of viruses in all domains of life has led to unique activities of VLPs in biological systems most notably the immune system. Here we discuss recent efforts to apply VLPs in a wide variety of applications with the aim of highlighting how the common structural elements of VLPs have led to their emergence as paradigms for the understanding and design of biological nanomaterials.
... [34] Moreover, apo-ferritin protein is typically used for internal metal mineralization such as with cobalt oxide Co 3 O 4 and Co(O)OH. [35] Mann and colleagues showed the formation of Fe 3 O 4 (or -Fe 2 O 3 ) under conditions of elevated temperature and pH. ...
... [1][2][3] Biomolecules, such as proteins and DNA, provide various kinds of unique properties and exhibit nanoscale structures with various dimensions making them attractive candidates for constructing the nano-structured materials. As one of the conventional synthetic strategies by utilizing biomolecules, cage-shaped proteins [4][5][6][7][8][9][10][11][12] and spherical viruses [13] as bio-supramolecular templates have been utilized to prepare well-defined nanoparticles by biomineralization. ...
... Protein, as a classical biopolymer, has been widely used in the field of biomimetic synthesis. [17][18][19][20] Ferritin (Fn) is a hollow, nearly spherical 24 subunits protein with diameter about 12 nm and a hollow cavity of 8 nm. 21 It belongs to a group of proteins with different patterns that can be found in most living creatures. ...
Article
It is essential to control the size and morphology of nanoparticles strictly in nanomedicine. Protein cages offer significant potential for templated synthesis of inorganic nanoparticles. In this study, we successfully synthesized ultrasmall copper sulfide (CuS) nanoparticles inside the cavity of ferritin (Fn) nanocages by a biomimetic synthesis method. The uniform CuS-Fn nanocages (CuS-Fn NCs) showed strong near-infrared absorbance and high photothermal conversion efficiency. In quantitative ratiometric photoacoustic imaging (PAI), the CuS-Fn NCs exhibited superior photoacoustic tomography improvements for real-time in vivo PAI of entire tumors. With the incorporation of radionuclide 64Cu, 64CuS-Fn NCs also served as an excellent PET imaging agent with higher tumor accumulation compared to free copper. Following the guidance of PAI and PET, CuS-Fn NCs were applied in photothermal therapy to achieve superior cancer therapeutic efficiency with good biocompatibility both in vitro and in vivo. The results demonstrate that the bioinspired multi-functional CuS-Fn NCs have potential as clinically translatable cancer theranostics and could provide a noninvasive, highly sensitive, and quantitative in vivo guiding method for cancer photothermal therapies in experimental and clinical settings.
... These nanoparticles of transition metal oxide can exhibit unique physical and chemical properties because of their edge surface sites and their limited particle size [7]. Number of transition metal oxides has been synthesized by various researchers, for example zinc oxide (ZnO) [8], titanium dioxide (TiO 2 ) [9], ferric oxide (Fe 2 O 3 ) [10], nickel oxide (NiO) [11], cobalt oxide (Co 3 O 4 ) [12] and tin oxide (SnO 2 ) [13]. Among all of these nanoparticles of transition metals oxide, SnO 2 has gained much attention because of its n-type semiconductor behavior with 3.6 eV band gap at room temperature [14]. ...
Article
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Tin oxide nanocubes are synthesized by hydrothermal approach by using the stannic chloride as precursor salt and sodium hydroxide as precipitating agent in aqueous media. Synthesized product is analyzed by various techniques: X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM). Structural composition and parameters of the product are analyzed by (XRD). Morphology of the product is analyzed by (SEM). These synthesized nanocubes are used in two applications: (1) as a photocatalyst and (2) as a fuel additive. Synthesized nanoparticles are used as photocatalyst for the degradation of an organic dye (Congo red) in aqueous medium. Photocatalytic degradation kinetics of dye is monitored at different concentrations of hydrogen peroxide and catalyst in the presence of sunlight. The percentage conversion of dye is also calculated for different concentrations of hydrogen peroxide and catalyst. Efficiency of fuel is analyzed by studying various parameters: flash point, fire point, cloud point, pour point, kinematic viscosity, specific gravity and calorific value at different dosage of SnO2 (10, 20, 30 and 40 ppm). It is found that values of these parameters changes significantly by changing the dosage of catalyst.
... Cobalt oxides have drawn increasing attention due to their unique size, shape dependent properties [3] and diverse spectrum of applications such as, ethylene oxidation [1], energy storage and conversion, glucose detection, water spitting [4], catalytic oxidation [5], lithium ion batteries [6], as a contrasting agent for magnetic resonance, in biomedical sensors [3] and targeted drug delivery [3,4,7]. ...
Article
Full-text available
This paper focuses on a comparative analysis between the carboxylate precursors obtained through the redox reaction between cobalt nitrate and 1,2-propanediol, and cobalt nitrate with 1,3-propanediol, respectively. The formation of the lactate and malonate precursors was followed with thermal analysis, FTIR spectrometry and acido-basic analysis (conductometric/ potentiometric titrimetry). The decomposition of the carboxylate precursors and the formation rate of cobalt oxides were observed by X-ray diffractometry and FTIR spectrometry, following advanced thermal treatments at 500°C, 800°C and 1000°C, with a pretreatment at 300°C. The differences between the two positional diol isomers are comparatively discussed.
... Many studies have shown that a wide range of ionic and metallic nanoparticles, with no direct biological relevance, can be selectively grown inside the pre-formed protein cages derived from ferritin and related Dps proteins (Fig. 15A). 4,[188][189][190][191][192] The substrate flexibility in ferritins and Dps is largely due to the facile transport of cations across the capsid shell in response to an electrostatic gradient, and facilitated nucleation on the interior of the cage driven by ion accumulation at patches of high negative charge density on the interior protein interface. In addition, the protein cages themselves provide a well-defined volume and thus control and limit the size of the inorganic nanoparticles grown. ...
Article
Within the materials science community, proteins with cage-like architectures are being developed as versatile nanoscale platforms for use in protein nanotechnology. Much effort has been focused on the functionalization of protein cages with biological and non-biological moieties to bring about new properties of not only individual protein cages, but collective bulk-scale assemblies of protein cages. In this review, we report on the current understanding of protein cage assembly, both of the cages themselves from individual subunits, and the assembly of the individual protein cages into higher order structures. We start by discussing the key properties of natural protein cages (for example: size, shape and structure) followed by a review of some of the mechanisms of protein cage assembly and the factors that influence it. We then explore the current approaches for functionalizing protein cages, on the interior or exterior surfaces of the capsids. Lastly, we explore the emerging area of higher order assemblies created from individual protein cages and their potential for new and exciting collective properties.
... There are many chemical methods that can be chosen to prepare magnetic nanoparticles, including classical chemical coprecipitation (Cornell & Schwertmann, 2003;Sugimoto, 2003;Schwarzer & Peukert, 2004), sol-gel syntheses (Dai et al. 2005;Duraes et al. 2005;Fouad et al. 2006), hydrothermal and high temperature reactions (Hyeon et al. 2001;Sun et al. 2004), surfactant mediate/template syntheses (in constrained environments) (Inouye et al. 1982;Deng et al. 2003), sonochemical reactions (Shafi et al. 1997;Koltypin et al. 1996), hydrolysis and thermolysis of precursors (Kimata et al. 2003), flow injection syntheses (Salazar-Alvarez et al. 2006), microemulsions (Solans et al. 2005;Geng et al. 2006), biomimetic mineralization (Allen et al. 2003;Rice et al. 2004), aerosol/vapor methods (Morales et al. 2003;Alexandrescu et al. 2005), and electrospray syntheses (Fürstner, 2008;Pascal et al. 1999). Among these methods, the chemical coprecipitation synthesis is one of the simplest and most efficient way for the preparation of magnetite particles (Laurent et al. 2010). ...
Book
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Despite the fact that nanotechnology has been present for a few decades, there is a big gap between how nanotechnology is perceived and what nanotechnology can truly offer in all sectors of water. The question to be answered is 'what more can we expect from nanotechnology' in the water field? The rational nano-design starts with well-defined problem definitions, necessitates interdisciplinary approaches, involves 'think-outside-the-box', and represents the future growth point of environmental nanotechnology. However, it is still largely new to the educated public and even scientists and engineers in water fields. Therefore, it is the purpose of this book to promote the concept of rational nano-design and to demonstrate its creativity, innovation, and excitement. This book presents a series of carefully selected rationally designed nano- materials/devices/surfaces, which represent drastically different, ground-breaking, and eye-opening approaches to conventional problems to embody the concept of nano-design and to illustrate its remarkable potential to change the face of the research in water industry in the future. Each of the book contributors is world-renowned expert in the burgeoning field of rational nano-design for applications. Rational Design of Next-generation Nanomaterials and Nanodevices for Water Applications is intended for undergraduates, graduates, scientists and professionals in the fields of environmental science, material science, chemistry, and chemistry engineering. It provides coherent and good material for teaching, research, and professional reference. Contents: Introduction to rational nano-design for water applications; Design and Application of Magnetic-core Composite Nano/Micro Particles for Environmental Remediation; Rational Design of Functional Nanoporous Materials to Confine Water Pollutant in Controlled Nano-space; Hierarchical materials as a design concept for multifunctional membranes; Smart membrane materials for controllable oil-water separation; Design of the next-generation Forward Osmosis draw solution; Nanotechnology for Microbial Fuel Cells. https://www.iwapublishing.com/books/9781780406855/rational-design-next-generation-nanomaterials-and-nanodevices-water-applications
... The iron core of nature ferritin can be removed by reduction, and inorganic clusters or nanoparticles can be synthesized in the cavity by mineralization [28]. The mineral core, semiconductor core, and metal/metal alloy core were all introduced to the modification or reformation of ferritin, such as Mn 3 O 4 [29], Co 3 O 4 [30], CaCO 3 [31], CdSe [32], ZnSe [33], Au [34], and CoPt [29], which could be synthesized with a unified shape and size distribution. ...
Article
Full-text available
Ferritin is a spherical iron storage protein composed of 24 subunits and an iron core. Using biomimetic mineralization, magnetic iron oxide can be synthesized in the cavity of ferritin to form magnetoferritin (MFt). MFt, also known as a superparamagnetic protein, is a novel magnetic nanomaterial with good biocompatibility and flexibility for biomedical applications. Recently, it has been demonstrated that MFt had tumor targetability and a peroxidase-like catalytic activity. Thus, MFt, with its many unique properties, provides a powerful platform for tumor diagnosis and therapy. In this review, we discuss the biomimetic synthesis and biomedical applications of MFt.
... 26,27 The spherical dodecamer possesses robust shell with a hollow central cavity (the inner diameter is ~ 4 nm), and thus it has been widely used for sizeconstrained synthesis of multiple inorganic nanoparticles such as Co3O4, Co(O)OH, γ-Fe2O3, CdS, CdSe nanoparticles, Pt-clusters. 28,29 It also has exhibited great potential applications in catalysis, drug delivery and imaging, likewise ferritin proteins. 29 However, to the best of our knowledge, Dps has yet to be explored as building blocks for the construction of high ordered assemblies. ...
Article
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Fabrication of ordered assemblies with protein nanocages as building blocks has attracted great attention. Here, we re-engineered the exterior surface of the smallest natural nanocage, DNA-binding protein from starved cells...
... After room-temperature incubation, centrifugation, washing and drying, the cobalt oxide nanoparticles were finally prepared [39]. In addition, Allen et al. also found that Listeria could also be used to synthesize cobalt oxide nanomaterials, which could improve the properties of mineral and protein components [40]. Compared with chemical methods, this method is more environmentally friendly, but its process is lengthy and can easily cause pollution. ...
Article
Full-text available
Cobalt is essential to the metabolism of all animals due to its key role in cobalamin, also known as vitamin B12, the primary biological reservoir of cobalt as an ultra-trace element. Current cancer treatment strategies, including chemotherapy and radiotherapy, have been seriously restricted by their side effects and low efficiency for a long time, which urges us to develop new technologies for more effective and much safer anticancer therapies. Novel nanotechnologies, based on different kinds of functional nanomaterials, have been proved to act as effective and promising strategies for anticancer treatment. Based on the important biological roles of cobalt, cobalt oxide nanoparticles (NPs) have been widely developed for their attractive biomedical applications, especially their potential for anticancer treatments due to their selective inhibition of cancer cells. Thus, more and more attention has been attracted to the preparation, characterization and anticancer investigation of cobalt oxide nanoparticles in recent years, which is expected to introduce novel anticancer treatment strategies. In this review, we summarize the synthesis methods of cobalt oxide nanoparticles to discuss the advantages and restrictions for their preparation. Moreover, we emphatically discuss the anticancer functions of cobalt oxide nanoparticles as well as their underlying mechanisms to promote the development of cobalt oxide nanoparticles for anticancer treatments, which might finally benefit the current anticancer therapeutics based on functional cobalt oxide nanoparticles.
... For instance, The Dps from listeria innocua have been used in the formation of 4.5-6.0 nm Fe 3 O 4 [169] and 3.5 nm Co 3 O 4 particles [170]. The CCMV virus have used for the crystallization of polyoxometalate species like Vn, Mb and W [171]. ...
... These mutated Dps could assemble similar to WT proteins and form dodecamers, paving way for engineering proteins with novel functions (Swift et al. 2006). Dps can bind other metal ions in addition to iron and this property has been utilized to generate mineral cores of cobalt and oxygen in L. innocua Dps (Allen et al. 2003). ...
Chapter
DNA binding proteins under starvation (Dps) are proteins belonging to the ferritin family with the capacity for DNA binding, in addition to iron storage and ferroxidation. Present only in the prokaryotes, these multifaceted proteins have been assigned with a number of roles, from pathogenesis to nucleoid condensation and protection. They have a significant role in protecting the cells from free radical assaults, indirectly by sequestration of iron and by directly binding to the DNA. Due to their symmetry, stability and biomineralization capacity, these proteins have ever increasing potential applications in biotechnology and drug delivery. This chapter tries to bring together all these aspects of Dps in the view of current understanding and older perspectives by studies of our group as well as other experts in the field.
... For example, CCMV, CPMV, and many other VLP scaffolds have been used for the biomineralization of titanium dioxide, nickel, iron, platinum, cobalt, and other nanoparticles (Aljabali et al., 2010;Klem et al., 2008). Ferritins, as well as the smaller L. innocua ferritin-like Dps nanocage, are inherently suitable to synthesize iron oxides (including maghemite, magnetite, and hematite), but have also been used to mineralize metallic iron, iron-platinum, cobalt oxide, copper sulfide, cadmium selenide, palladium, silver, and cobalt, and many other nanomaterials (Allen et al., 2003;Hosein et al., 2004;Kang et al., 2011;Kasyutich et al., 2010;Kramer et al., 2004;Okuda et al., 2010;Parker et al., 2008;Uchida et al., 2006;Ueno et al., 2004;Usselman et al., 2010;Wang et al., 2016b). In addition, modified M. jannaschii sHSPs have served as reaction vessels for the mineralization of both iron oxide and cobalt platinum alloy nanoparticles (Flenniken et al., 2003;Klem et al., 2005) and T. maritima encapsulins have been used for synthesis of gold and silver nanoparticles (Giessen and Silver, 2016a;Künzle et al., 2018). ...
Article
Full-text available
Protein nanocompartments (PNCs) are self-assembling biological nanocages that can be harnessed as platforms for a wide range of nanobiotechnology applications. The most widely studied examples of PNCs include virus-like particles, bacterial microcompartments, encapsulin nanocompartments, enzyme-derived nanocages (such as lumazine synthase and the E2 component of the pyruvate dehydrogenase complex), ferritins and ferritin homologues, small heat shock proteins, and vault ribonucleoproteins. Structural PNC shell proteins are stable, biocompatible, and tolerant of both interior and exterior chemical or genetic functionalization for use as vaccines, therapeutic delivery vehicles, medical imaging aids, bioreactors, biological control agents, emulsion stabilizers, or scaffolds for biomimetic materials synthesis. This review provides an overview of the recent biomedical and bioengineering advances achieved with PNCs with a particular focus on recombinant PNC derivatives.
... 15,17,20) We also used recombinant Listeria apoferritin (Lis-apofer) molecules from Listeria innocua. [20][21][22] These proteins were overproduced with Escherichia coli and purified. Iron oxide cores were biomineralized in the ferritin cavity. ...
Article
Full-text available
High-density cage-shaped proteins with inorganic cores were selectively adsorbed as a monolayer onto a 3-aminopropyl-triethoxysilane (APTES) layer on a Si substrate. The electrostatic interaction between the protein and substrate surface was studied and it was proven that protein adsorption density depends on the quantitative balance of surface charge on the substrate and protein. The combination of a highly positive APTES layer and moderately negative ferritin. Fer-4, achieved an adsorption density of 7.6 x 10(11) cm(-2) and the combination of the APTES layer and Listeria ferritin (Lis-fer) reached an adsorption density of 1.3 x 10(12) cm(-2). The adsorption process including the reduced charge of Lis-fer due to denaturation further enhanced the adsorption density up to 1.5 x 10(12) mm(-2), whereas no Lis-fer was adsorbed onto the SiO2 surface under the same conditions. This new technique makes it possible to produce a nanodot monolayer with a density higher than 1 x 10(12) cm(-2), which can be applied to floating nanodot gate memories.
Article
Nanoscale materials could potentially form the basis of a new generation of environmental remediation technologies that provide solutions to some of the challenging environmental cleanup problems. In this study, we report on the preparation of a series of supported iron and cobalt oxyhydroxide nanoparticle model surfaces and also investigated their reactivities toward a SO2 /O2 mixture. Horse spleen ferritin was used to prepare 3 nm and 5 nm supported ferrihydrite nanoparticles and a ferritin like protein from Listeria innocua was used to prepare 3-4 nm cobalt oxide nanoparticles. Atomic Force Microscopy (AFM) was used to characterize the particles. Attenuated total reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) was used to study the in-situ oxidation of SO2 on the nanoparticles.
Magnetic nanophases nucleated within horse spleen apoferritin nanotemplates under in vivo physiological conditions and in vitro reconstitution were characterized by Mössbauer spectroscopy in lyophilized form. Mössbauer spectra recorded at 80 K indicate that for the in vivo produced ferritin the presence of phosphates within the ferritin biomineral core results in larger quadrupole splittings, both at interior and surface sites, 0.62 mm/s and 1.06 mm/s, respectively, as compared to 0.56 mm/s and 0.75 mm/s for the reconstituted ferritin. Data collected at lower temperatures give blocking temperatures of 55 and 40 K for in vitro and in vivo samples. At 4.2 K, both samples give similar saturation hyperfine field values for the interior (495 kOe) and surface (450 kOe) iron sites. The temperature dependence of the reduced hyperfine magnetic fields at the interior iron sites is consistent with the collective magnetic excitations model, due to the particle's magnetization precession about the anisotropy axis. In contrast, a marked decrease in the reduced hyperfine field at surface sites with increasing temperature indicates a more complex spin excitation energy landscape at the surface.
Chapter
This chapter highlights the recent advanced research in the field of nanostructure preparation based on various peptides and proteins. It focuses on several important templates, including peptides, type I collagen, lysozyme, and protein cages. The introduction of peptide and protein templates obviously optimizes the materials' biological and physical properties and greatly expands the application areas of the obtained nanomaterials. There are several reviews about the applications in electronics, reactors, and sensors, so a prospect of preparation of peptide- and protein-based nanomaterials, more than applications, is presented here.
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The possibility of developing hydrogen gas as an environmentally friendly alternative fuel has received considerable attention1-6. However, the majority of hydrogen produced for energy yielding applications is generated by the process of reforming methane or fossil fuels7 , 8. Thus, we are not in a position to develop a hydrogen energy economy that is independent of nonrenewable fossils fuels. A renewable source for the production of hydrogen is needed for the development of hydrogen as an alternative fuel.
Chapter
Protein cages are used as templates to synthesize nanoparticles (NPs) for nanotechnology, especially nanoelectronic devices. The biomineralization capability has been extended and NPs of materials needed for the nanotechnology and nanoelectronic devices, such as metal, metal oxide compound, semiconductor, oxide semiconductor, magnetic material, were artificially synthesized in the cavity and used in the devices. In the first section of the chapter, NP synthesis, NP placement, and electronic device fabrications are described. The second section talks about site-directed placement of NPs, where NPs synthesized themselves have specific and attractive characteristics. The third section of the chapter discusses fabrication of nanodevices by the NP and protein conjugates. Floating nanodot gate memory (FNGM) and single-electron transistor (SETs) are also described in detail in this chapter.
Article
The protein capsids of viruses represent a fascinating class of regular geometric objects formed through efficient self-assembly processes. By capitalizing on the ability of these multivalent structures to arrange large numbers of synthetic functional groups, viral capsids have now found use in three major areas of materials science: (1) as templates for the growth and/or positioning of inorganic nanoparticles; (2) as carriers for use in biomedical imaging and drug delivery; and (3) as scaffolds for photoactive and chemically catalytic groups. This chapter surveys the recent progress in these fields and examines the various chemical techniques that have been used to add new chemical functionality to these structures.
Article
Iron oxide magnetic nanoparticles with biocompatibility and functional coatings via appropriate surface chemistry approaches have been used for immobilization of cells, proteins, enzymes, antibodies, oligonucleotides and drugs through covalent bonding or adsorption. The surface-modified magnetic nanoparticles have been widely used in biological and biomedical areas such as immobilization of biomolecules; separation of metal ions, cells, proteins, DNA; immunoassay, biochemical analysis and magnetic resonance imaging (MRI) probes. In this paper, preparation methods, surface modification approaches and analytical applications of iron oxide-based magnetic nanoparticles are reviewed.
Chapter
The synthesis of nanoparticles with controlled composition, size and shape has long been of scientific and technological interest. Despite efforts invested to this problem, selective preparation of tailor made particles by conventional methods constitutes a considerable challenge. In contrast, highly selective fabrication of monodisperse functional nanosized particles occurs continuously in every living cell. The process of building of inorganic and hybrid organic–inorganic architectures on templates of biopolymers through biomineralization is also very common in biological systems and provides the level of control that has not been closely achieved in conventional technology. Any biomineralization is achieved through controlled nucleation of metal cations by functional groups in amino acid constituting proteins. Study of the biomineralization in the last two decades and attempts to mimic the process have been highly successful although details are far from being completely understood
Article
While biomineralization in apoferritin has effectively synthesized highly monodispersed nanoparticles of various metal oxides and hydroxides, the detailed kinetics and mechanisms of Mn(III) (hydr)oxide formation inside apoferritin cavities have not been reported. To address this knowledge gap, we first identified the phase of solid Mn(III) formed inside apoferritin cavities as -MnOOH. To analyze the oxidation and nucleation mechanism of -MnOOH inside apoferritin by quantifying oxidized Mn, we used a colorimetric method with leucoberbelin blue (LBB) solution. In this method, LBB dissembled apoferritin by inducing an acidic pH environment, and reduced -MnOOH nanoparticles. The LBB-enabled kinetic analyses of -MnOOH nanoparticle formation suggested that the orders of reaction with respect to Mn2+ and OH- are 2 and 4, respectively, and -MnOOH formation follows two-step pathways: First, soluble Mn2+ undergoes apoferritin catalyzed oxidation at the ferroxidase dinuclear center, Mn(III)-protein complex, P-[Mn2O2(OH)2]. Second, the oxidized Mn(III) dissociates from the protein binding sites and are subsequently nucleated to form -MnOOH nanoparticles in the apoferritin cavities. This study reveals key kinetics and mechanistic information of the Mn-apoferritin systems and the results facilitate applications of apoferritin as a means of nanomaterial synthesis.
Chapter
This chapter discusses the ferritin superfamily of iron storage proteins, mineral core deposited within the protein shell, and product of ferritin aggregation and degradation and haemosiderin. The crystal structure of insect ferritin also shows a tetrahedral symmetry consisting of 12 heavy chain and 12 light chain subunits, in contrast to that of mammalian ferritin. The chapter focusses on the mechanisms involved in iron uptake into ferritin, and shows how storage iron might be mobilised from the storage proteins. It explains the mechanism of iron deposition in Dps proteins. The bis-Met-coordinated haems in Escherichia coli haem-containing bacterioferritin (BFR) play an important role iniron release from the mineral core, with the electron transfer of electrons into the inner cavity being the rate-limiting step of the release reaction. The chapter finally provides usage of the apoferritin protein shell in a nanoreactor for the formation of a variety of non-native, unusual, mineralised nanoparticles.
Article
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Compartmentalization is a hallmark of living systems. Through compartmentalization, ubiquitous protein nanocages such as viral capsids, ferritin, small heat shock proteins, and DNA-binding proteins from starved cells fulfill a variety of functions, while their shell-like structures hold great promise for various applications in the field of nanomedicine and nanotechnology. However, the number and structure of natural protein nanocages are limited, and these natural protein nanocages may not be suited for a given application, which might impede their further application as nanovehicles, biotemplates or building blocks. To overcome these shortcomings, different strategies have been developed by scientists to construct artificial protein nanocages, and 1D, 2D and 3D protein arrays with protein nanocages as building blocks through genetic and chemical modification to rival the size and functionality of natural protein nanocages. This review outlines the recent advances in the field of the design and construction of artificial protein nanocages and their assemblies with higher order, summarizes the strategies for creating the assembly of protein nanocages from zero-dimension to three dimensions, and introduces their corresponding applications in the preparation of nanomaterials, electrochemistry, and drug delivery. The review will highlight the roles of both the inter-subunit/intermolecular interactions at the key interface and the protein symmetry in constructing and controlling protein nanocage assemblies with different dimensions.
Article
An emerging strategy for synthesizing nanoclusters and nanoparticles involves the confinement of particle precursors within small volumes and the subsequent reduction and aggregation of those precursors into discrete particles. These spatially isolated volumes are termed nanoreactors, and they impose barriers that not only restrict the movement of metal atoms and other reactants but also provide reaction conditions that are distinct from those of the surrounding environment. Nanoreactors for particle syntheses can be prepared by various strategies, which fall generally into two categories: solution-based and substrate-confined. Solution-based nanoreactors are broadly defined as 3D capsules that can be manipulated in solution, whereas substrate-confined nanoreactors are isolated volumes on a macroscopic substrate or surface. Here, we survey and analyse the merits of different nanoreactor techniques used to synthesize clusters and nanoparticles that cannot easily be made using traditional methods. We look at how the focus in this field has expanded beyond pure synthesis to making massive and complex libraries of materials and enabling exploration of the materials genome through high-throughput screening techniques.
Article
The subject of this review article was first reported approximately three decades ago upon the discovery of a starvation-inducible protein found tightly bound to chromosomal DNA in 3-day-old starved cultures of Escherichia coli. As a result, they were named “DNA-binding protein from starved cells” or Dps. Recognized by their homology to ferritins, these proteins were classified as a new branch of the Ferritin-like proteins superfamily and designated as miniferritins. These proteins present a cage-like structure built by twelve identical four-helix bundle monomers. They are capable of performing fast oxidation of ferrous ions using hydrogen peroxide, while still retaining the possibility of using molecular oxygen as co-substrate, and subsequently accumulating ferric ions in its cavity in a ferric mineral form. This complex catalytic activity is designed to protect cells from oxidative stress conditions, reducing the risk of harmful oxygen radical species being formed in particular physiological conditions. They are also capable of binding to and compacting DNA, becoming the most abundant nucleoid protein in the stationary phase, adding physical protection to the chemical protection attained by the ferroxidation reaction. Miniferritins are almost ubiquitous to Bacteria and Archaea, with protein characterization reported for over 60 microorganisms and several thousands of homologous genes annotated in current genomic databases, which demonstrates the importance of these proteins in Prokarya. In this manuscript we offer an extensive, yet concise, description of the state of the art on miniferritins, including their regulation, the global structural features, metal center characterization, diverse functional properties and the current stage of multifaceted biotechnological applications.
Article
Due to its unique structure, recent years have witnessed the use of apo-ferritin to accumulate various non-natural metal ions as a scaffold for nanomaterial synthesis. However, the transport mechanism of metal ions into the cavity of apo-ferritin is still unclear, limiting the rational design and controllable preparation of nanomaterials. Here, we conducted all-atom classical molecular dynamics (MD) simulations combined with Markov state models (MSMs) to explore the transportation behavior of Au(iii) ions. We exhibited the complete transportation paths of Au(iii) from solution into the apo-ferritin cage at the atomic level. We also revealed that the transportation of Au(iii) ions is accompanied by coupled protein structural changes. It is shown that the 3-fold axis channel serves as the only entrance with the longest residence time of Au(iii) ions. Besides, there are eight binding clusters and five 3-fold structural metastable states, which are important during Au(iii) transportation. The conformational changes of His118, Asp127, and Glu130, acting as doors, were observed to highly correlate with the Au(iii) ion's position. The MSM analysis and Potential Mean Force (PMF) calculation suggest a remarkable energy barrier near Glu130, making it the rate-limiting step of the whole process. The dominant transportation pathway is from cluster 3 in the 3-fold channel to the inner cavity to cluster 5 on the inner surface, and then to cluster 6. These findings provide inspiration and theoretical guidance for the further rational design and preparation of new nanomaterials using apo-ferritin.
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The main challenge in the development of artificial bionanoreactors is controllable immobilization of multiple catalytic components within a single scaffold composed of protein assemblies. In this chapter, we describe catalytic systems constructed in interior nanospaces of porous protein crystals and protein cages. Immobilization of multiple molecules or nanoparticles in the interior nanospaces enables complex reactions such as electron transfer reactions, photocatalytic reactions and tandem reactions. These reactions are promoted by precise coimmobilization of the catalytic components with specifically arranged molecular interactions in the internal nanospaces of protein assemblies.
Chapter
In using thermoelectric generators (TEGs) as energy harvesters for wearable electronics, comfortableness would be the first priority and practical efficiency of power generation the next. Therefore, mechanical flexibility, lightness, and low thermal conductivity are major issues. Because natural air cooling is assumed for such applications, very low thermal conductivity and millimeter thicknesses are required to obtain sufficient temperature difference between front (cold) and back (hot) sides of TEG. To satisfy these requirements while maintaining mechanical flexibility, total design from materials to device structures is important. In this chapter, a novel device structure and fabrication method using CNT (carbon nanotube) yarn with p/n-striped doping and fabric substrate is introduced as an example of such approach. Thickness-controllable and thermally insulating thermoelectric (TE) fabric has been realized without interconnecting many p- and n-blocks by electrodes. It is also highly durable against bending or stretching because of the mechanical isolation of TE components from the substrate. Another material design suppressing the thermal conductivity in a condensed phase of CNTs using core-shell-type biomolecule is also demonstrated. Thermal conductivity is dramatically suppressed by phonon scattering at the biomolecular junction.
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Thermal properties of strongly coupled complex dusty plasmas (SCCDPs) are calculated by using improved method of homogeneous nonequilibrium molecular dynamics (HNEMD) simulations, expressed by Yukawa potential, in the canonical ensemble (NVT). The nonlinear effects, under the action of variable external force field strengths, are computed for three-dimensional (3D) SCCDPs. New results for thermal conductivity λ0 with appropriate normalization (Einstein’s frequency ωE) are measured for a wide range of plasma coupling (1 ≤ Γ ≤ 300) and screening strength (1 ≤ κ ≤ 4). Our results of normalized thermal conductivity depend on both Coulomb coupling Γ and screening κ parameters and it is demonstrated that the minimum value of λmin shifts toward higher Γ by an increase in κ, as expected and confirmed in an earlier work. The present results obtained through HNEMD technique are compared with the earlier 3D nonequilibrium molecular dynamics (NEMD), equilibrium molecular dynamics (EMD), inhomogeneous NEMD results, and theoretical predictions. The presented results of thermal conductivity and nonlinear behavior of SCCDPs have a satisfactory agreement with the earlier used results. Lattice correlation (Ψ) and energies for varying plasma parameters (Γ, κ) have confirmed the three phases as nonideal gaseous-like, liquid-like, and strongly coupled (crystalline structure) complex plasmas.
Article
Quantum dots (QDs) are studied intensively nowadays as fluorescent probes for biomedical applications due to their high emission quantum yield, excellent resistance to photo-bleaching, photo-stability and large Stokes shift, when contrasted with commonly utilized organic fluorescent dyes. This study introduces a protein engineering approach to incorporate metal coor-dination sites for the sustainable synthesis and stabilization of biocompatible CdS QDs in proteins. The resulting protein-stabilized CdS QDs (Prot-QDs), generated by a green aqueous route at 37 ºC, are highly photo-luminescent and photo-stable, have a long shelf-life and high stability under physiological conditions. The Prot-QDs showed effective internalization and high fluorescence in cells, even at low doses, and biocompatibility. This work focuses on CdS QDs, since this composition has been extensively studied, however this approach could be easily translated to QDs with other metal composition. Here, protein design emerges as promising approach to generate protein-nanomaterial hybrids as broadly applicable tools in different applications such as light-emitting devices, metal ion detection, and biomedical applications.
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This chapter highlights some unique modification strategies and chemistries that can be applied to virus-based scaffolds to turn them into useful materials with a wide range of applicability. It discusses recent efforts focused on the utilization of virus-based materials for applications in energy-relevant materials, such as battery electrodes and storage devices, and medically-relevant materials, including sensing devices, drug and gene delivery systems, and contrast agents. The chapter then outlines manufacturing protocols, as well as some of the basic engineering protocols and procedures that can be applied to modify and functionalize viral structures for their desired applications. A viral nanoparticle (VNP) is referred when the complete virion is used as a template for functionalization. Finally, the chapter discusses some of the benefits and drawbacks to using VNP and viruslike particle (VLP) platforms in terms of their safety and practicality for use in translational medicine.
Thesis
L’avènement des nanotechnologies engendre une exposition accrue de l’homme aux nanomatériaux, représentant un risque d’un genre nouveau. A cet égard un grand nombre de recherches porte sur l’étude de leur toxicité. Néanmoins, les questions de dégradation et transformation des nanoparticules dans l’organisme sont encore peu abordées. Des études effectuées au laboratoire ont montré qu’après injection de nanoparticules d’oxyde de fer in vivo, celles-ci sont confinées dans les lysosomes où elles sont dégradées. Une partie de mes travaux de thèse se sont concentrés sur une voie possible de métabolisation des produits de dégradation issus de nanoparticules d’oxydes de fer par l’intermédiaire d’une protéine intervenant dans le métabolisme du fer, la ferritine. Nous avons élaboré plusieurs stratégies afin de détecter et de suivre le transfert de métaux vers la ferritine. Ces travaux ont permis de mettre en évidence un processus de prise en charge des produits de dégradation des nanoparticules d’oxyde de fer à l’échelle moléculaire. Une seconde partie de mes travaux ont été consacré au suivi des produits issus de la dégradation des nanoparticules d’oxyde de fer à l’échelle de l’organisme. La haute concentration endogène en fer rendant impossible ce suivi, une stratégie consistant à marquer les nanoparticules de fer avec un isotope du fer, le 57Fe, a permis de suivre les dynamiques de circulation des produits de dégradation in vivo sur une période de six mois. Nous avons également effectué un double marquage des nanoparticules, du cœur inorganique ainsi que de leur enrobage afin de caractériser leur intégrité in vivo
Article
Iron storage in biology is carried out by cage-shaped proteins of the ferritin superfamily, one of which is the dodecameric protein Dps. In Dps, four distinct steps lead to the formation of metal nanoparticles: attraction of ion-aquo complexes to the protein matrix, passage of these complexes through translocation pores, oxidation of these complexes at ferroxidase centers, and, ultimately, nanoparticle formation. In this study, we investigated Dps from Listeria innocua to structurally characterize these steps for Co2+, Zn2+, and La3+ ions. The structures reveal that differences in their ion coordination chemistry determine alternative metal ion-binding sites on the areas of the surface surrounding the translocation pore that captures nine La3+, three Co2+, or three Zn2+ ions as aquo clusters and passes them on for translocation. Inside these pores, ion-selective conformational changes at key residues occur before a gating residue to actively move ions through the constriction zone. Ions upstream of the Asp130 gate residue are typically hydrated, while ions downstream directly interact with the protein matrix. Inside the cavity, ions move along negatively charged residues to the ferroxidase center, where seven main residues adapt to the three different ions by dynamically changing their conformations. In total, we observed more than 20 metal-binding sites per Dps monomer, which clearly highlights the metal-binding capacity of this protein family. Collectively, our results provide a detailed structural description of the preparative steps for amino acid-assisted biomineralization in Dps proteins, demonstrating unexpected protein matrix plasticity.
Chapter
Fabrication of nanostructures by biomolecules, termed the “bio nano process (BNP),” has been proposed, and the process utilizes the biotemplated biomineralization of inorganic materials and self-assembly. NP synthesis by genetically modified cage-shaped proteins, ferritin, and DNA-binding protein from starved cells, Dps, is the most basic part of the BNP. The BNP can produce homogenous NPs inside cage-shaped protein. NP growth is limited by the protein shell and the same size NP can be produced. The surrounding protein shells deliver/array the accommodated NPs at designated positions through the interaction of the protein and inorganic material surface. Even a single NP placement to a nanodisk on a substrate is possible. In such placement and arraying, aptamer and electrostatic interactions play the important roles. Obtained NP arrays are proved to be able to fabricate key components of nanoelectronic devices through the integration of top-down and bottom-up technology. The BNP can also produce three-dimensional bioconjugate of cage-shaped proteins and CNTs. This new material has a quantum effect and high thermal insulation by the protein shell. The measurement of thermoelectric properties confirmed that this bioconjugate is a new type of thermoelectric materials.
Chapter
Fabrication of magnetic materials with a high level of control down to the nanoscale is a current synthetic challenge. Nature is able to achieve this level of precision under ambient conditions and in aqueous solutions, by using specific biomineralisation proteins to produce highly monodisperse magnetic nanoparticles within the magnetosome organelles of magnetotactic bacteria. This chapter explores the use of such proteins outside the magnetosome, in synthetic magnetite formation reactions, where their ability to control and affect the nanoparticle products in terms of size, morphology and material purity is demonstrated. Understanding how these proteins function to achieve their activity is of particular interest, and we bring together the current literature to assess the roles of sequence and self-assembly in this process. In addition to the magnetosome-derived proteins, researchers are expanding the biological toolkit of available magnetic material mineralising proteins by using and adapting others. We investigate a number of these proteins including ferritin, heat shock protein cages and even small peptides. These can be used without modification, or they can be engineered to contain artificial binding sequences, selected via processes such as phage display. Developing new mineralising sequences allows proteins to be used with materials which are not naturally occurring, such as the platinum alloys of cobalt and iron, which have industrially desirable magnetic characteristics. The proteins/peptides covered in this chapter have the potential to aid future production of precise magnetic nanoparticles for diverse applications in the biomedical and data storage fields.
Article
Stable and catalytically active nano particles with small sizes are of paramount importance in catalysis, but the preparation of such particles has been a great challenge due to their propensity to aggregate into large and less active particles. Herein, we would like to report the formation of ultra-small and uncommon RhO2 particles within an organic cage in the homogeneous solution, and the soluble assembly showed both better durability and high activity towards ammonia borane methanolysis to generate hydrogen gas. A volcanic plot of the turnover frequencies (TOFs) over the molar amount of Rh per cage was demonstrated, and RhO2[email protected] showed a TOF of around 286 min⁻¹ at room temperature. Our assembly also showed better durability during the catalysis in contrast to NPs made from pure rhodium acetate, and there was no aggregation formed after five runs. We further demonstrated the Michaelis-Menten model through the kinetic study, an indication that the catalytic reaction happened within the organic cage. The actual active sites of the catalyst was zero-valent metal Rh. Interestingly the installation of azobenzene groups at the opening of the cage led to gated activity through the trans-cis conformation interchange, due to the different steric hindrances affecting the diffusion rates of reactants.
Chapter
This chapter focuses on the following metal oxide nanoparticles, including magnesium oxide nanoparticles, alumina nanoparticles, antimony oxide, cobalt oxide nanoparticles, cerium oxide nanoparticles, indium oxide nanoparticles, iron oxide nanoparticles, lanthanum oxide nanoparticles, neodynium oxide nanoparticles, nickel oxide nanoparticles, samarium oxide nanoparticles, silica nanoparticles, and titanium dioxide nanoparticles. Synthesis of hollow alumina nanoparticles was described by Smovzh, where nanostructured carbon-aluminum material was prepared by conducting composite electrode sputtering in an electric arc, followed by annealing in oxygen. The chapter tabulates some representative methods for the synthesis of cerium oxide nanoparticles. Gao has discussed a forced hydrolysis protocol for the preparation of samarium oxide nanoparticles. In this method, samarium oxide, urea, and nitric acid were used as starting materials. Silica nanoparticles have active silanol groups, which makes the surface modification very easy. A relatively simple synthesis procedure and wide availability of silicon compounds that can be purchased commercially allow a wide range of applications of silica nanoparticles.
Article
Proteins hold great promise in forming complex nanoscale structures which could be used in the development of new nanomaterials, devices, biosensors, electronics and pharmaceuticals. The potential to produce nanomaterials from proteins is well supported by the numerous examples of self-assembling proteins found in nature. We have explored self-assembling proteins for use as supramolecular building blocks, or tectons, specifically the N-terminal domain of Lsr2, Nterm-Lsr2. A key feature of this protein is that it undergoes self-assembly via proteolytic cleavage, thereby allowing us to generate supramolecular assemblies in response to a specific trigger. Herein, we report the effects of pH and protein concentration on the oligomerisation of Nterm-Lsr2. Furthermore, via protein engineering, we have introduced a new trigger for oligomerisation via enteropeptidase cleavage. The new construct of Nterm-Lsr2 can be activated and assembled in a controlled fashion and provides some ability to alter the ratio of higher ordered structures formed. This article is protected by copyright. All rights reserved.
Article
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The polypeptide chain that assembles into the unusual dodecameric shell of Listeria innocua apoferritin lacks the ferroxidase centre characteristic of H-type mammalian chains, but is able to catalyse both Fe(II) oxidation and nucleation of the iron core. A cluster of five carboxylate residues, which correspond in part to the site of iron core nucleation typical of L-type mammalian ferritins, has been proposed to be involved in both functions. The features of the iron uptake kinetics and of Fe(II) autoxidation in the presence of citrate followed spectrophotometrically confirm this assignment. In Listeria the kinetics of iron uptake is hyperbolic at low Fe(II)-to-dodecamer ratios and becomes sigmoidal when iron exceeds 150 Fe(II) atoms per dodecamer, namely when a fast crystal growth phase follows a slow initial nucleation step. Iron autoxidation in the presence of citrate displays a similar behaviour. Thus the time course is sigmoidal at low citrate-to-Fe ratios at which Fe(III) polymerization is predominant, but is hyperbolic at ligand concentrations high enough to prevent polymerization. The marked inhibitory effect of Tb(III) on the kinetics of iron incorporation confirms that carboxylates provide the iron ligands in L. innocua apoferritin. Iron uptake followed in steady-state fluorescence experiments allows one to distinguish Fe(II) binding and oxidation from the subsequent movement of Fe(III) into the apoferritin cavity as in mammalian ferritins despite the different localization of the tryptophan residues.
Article
Oxidation of CO over Co3O4 at ambient temperature was studied with flow reactor experiments, and in-situ spectroscopic and structural methods. The catalyst deactivates during the reaction. The rate of deactivation increased with increasing CO or CO2 gas-phase concentration but decreased with increased O2 concentration or increased temperature. Regeneration of the catalyst in 10% O2/Ar was more efficient than regeneration in Ar alone. The presence of carbonates and surface carbon on the deactivated catalyst was concluded from TPO experiments. None of these species could, however, be correlated with the deactivation of the catalyst. In-situ FTIR showed the presence of surface carbonates, carbonyl, and oxygen species. The change in structure and oxidation state of the catalyst was studied by in-situ XRD, in-situ XANES, XPS, and flow reactor experiments. One possible explanation for the deactivation of the catalyst is a surface reconstruction hindering the redox cycle of the reaction.
Article
Research News: Virus protein rages, capsids, which display a wide range of sizes and shapes, can be used for constrained materials synthesis. The authors briefly review recent work involving capsids, including the use of spherical viruses for inorganic mineralization and organic polymer encapsulation and the mineralization of anisotropic structures such as the tobacco mosaic virus, which can lead to mineralized fibers of iron oxide or silica with very high aspect ratios. The topic of gating-which enables the selective entrapment and release of materials from within the central cavity-is briefly touched upon.
Article
Oxidation of CO over Co3O4 at ambient temperature was studied with flow reactor experiments, and in-situ spectroscopic and structural methods. The catalyst deactivates during the reaction. The rate of deactivation increased with increasing CO or CO2 gas-phase concentration but decreased with increased O2 concentration or increased temperature. Regeneration of the catalyst in 10% O2/Ar was more efficient than regeneration in Ar alone. The presence of carbonates and surface carbon on the deactivated catalyst was concluded from TPO experiments. None of these species could, however, be correlated with the deactivation of the catalyst. In-situ FTIR showed the presence of surface carbonates, carbonyl, and oxygen species. The change in structure and oxidation state of the catalyst was studied by in-situ XRD, in-situ XANES, XPS, and flow reactor experiments. One possible explanation for the deactivation of the catalyst is a surface reconstruction hindering the redox cycle of the reaction.
Article
We describe the primitive model of an electrochemical interface by using a free energy functional of the Landau type. The relevant variables are assumed to be the charge and total ion density and the Coulomb interaction is explicitly taken into account. Explicit results are obtained in a mean field approach which is derived by writing the equations for the extrema of the free energy. The model reduces to Gouy-Chapman theory for some values of the parameters of the model, but for other parameter sets, in which the positive and negative ions are not behaving symmetrically, we find a regime different from that predicted by Gouy-Chapman theory. In particular, the charge and total ion density may exhibit an oscillatory behaviour as a function of distance from the electrode. We briefly discuss other possible applications of this general approach to electrochemical problems.
Article
Co3O4 has been prepared by thermal decomposition of basic CoCO3 in the temperature range 200 to 800 °C. The pzc has been measured by potentiometric titration and has been found to coincide with the iep determined by microelectrophoresis. The pzc is constant at ca. 7.3 between 200 and 450 °C. The GCSG model of the electrical double layer has been applied to the experimental data to derive the real surface area of the oxide and the inner layer capacitance. The electrochemical surface area coincides with BET data. The results of this work have been compared with those obtained previously with Co3O4 prepared by thermal decomposition of the nitrate.
Article
The light-activated degradation kinetics of quinoline were studied in detail on Hg lamp and Suntest solar-simulated irradiation. Fenton-photoassisted mineralization in homogeneous solution with a peroxide to quinoline ratio of approximately 50 (quinoline, approximately 1 mM) was complete in about 30 min on Hg lamp irradiation. Reactions activated by a solar simulator led to 80% mineralization of the same quinoline solutions within the same time period due to a lack of a strong UV component. Heterogeneous photocatalytic TiO2-mediated degradation proceeded at a slower rate than the homogeneous reaction. The influence of a number of factors, such as the substrate concentration, solution pH, gas atmosphere and dynamics of H2O2 addition, was investigated. The stoichiometry of the mineralization reaction was analysed as a function of the gas atmosphere used. Quinoline degradation was possible via dark and light-activated reactions. Quinoline did not affect the H2O2 consumption rate in the presence of Fe3+ ions. This suggests that, during degradation, the reaction of Fe3+ ions with H2O2 is the rate-determining step. Quinoline did not complex with Fe3+ ions in the dark. However, complex formation occurred during photodegradation with Fenton-like reagents, such as Cr6+ or Cu2+ ions and combinations of Cu2+ +Fe3+ ions, in the presence of H2O2. The latter systems were compared with the classical Fenton reagent leading to quinoline mineralization.
Article
The protein cage constrained synthesis of ferrimagnetic iron oxide nanoparticles was presented. The ferritin-like protein (FLP) from the bacteria Listeria innocua was cloned into an inducible E. coli heterologous expression system and was analyzed by size exclusion chromatography (SEC), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The Fe mineralization in the FLP cage under the non-physiological conditions of elevated temperature, pH and controlled oxidation was also investigated.
Article
The application of quasi-elastic light scattering for the determination of particle size distributions is reviewed. The basic principles and assumptions on which the method relies are presented on an introductory level. The practical performances are illustrated by different results including results obtained by round-robin comparative studies. Finally, new developments for on-line or in situ characterization of concentratedand opaque dispersions are briefly presented.
Article
Cage architectures based on the cowpea chlorotic mottle virus (see Figure) have been employed to achieve a synthetic mimic of the iron storage protein ferritin. The electrostatic nature of the inner protein surface could be changed by up to 3240 units of charge, while still maintaining a stable cage structure. The spatial isolation within the protein cage prevents bulk aggregation of the mineral particles and results in a stable, mono-disperse colloid.
Article
Self-assembled cage structures of nanometre dimensions can be used as constrained environments for the preparation of nanostructured materials, and the encapsulation of guest molecules, with potential applications in drug delivery and catalysis. In synthetic systems the number of subunits contributing to cage structures is typically rather small,. But the protein coats of viruses (virions) commonly comprise hundreds of subunits that self-assemble into a cage for transporting viral nucleic acids. Many virions, moreover, can undergo reversible structural changes that open or close gated pores to allow switchable access to their interior. Here we show that such a virion - that of the cowpea chlorotic mottle virus - can be used as a host for the synthesis of materials. We report the mineralization of two polyoxometalate species (paratungstate and decavanadate) and the encapsulation of an anionic polymer inside this virion, controlled by pH-dependent gating of the virion's pores. The diversity in size and shape of such virus particles make this a versatile strategy for materials synthesis and molecular entrapment.
Article
The chelate is quantitatively formed only in the pH range 6.5-7.5. Despite the large stability constant, a large excess of reagent is required to suppress interferences. The most suitable wavelength for the photometric measurement is 500 nm, where the molar absorptivity is 1.607 x 10(4) 1.mole(-1). cm(-1). The procedure given allows determination of 8 x 10(-4)% Co in a l-g sample. The standard deviation for cobalt is 2.1 mug/100 ml (f = 19). Applications to analysis of iron and steel, nickel, copper, ores and silicates are given.
Article
A multimeric protein that behaves functionally as an authentic ferritin has been isolated from the Gram-positive bacterium Listeria innocua The purified protein has a molecular mass of about 240,000 Da and is composed of a single type of subunit (18,000 Da). L. innocua ferritin is able to oxidize and sequester about 500 iron atoms inside the protein cage. The primary structure reveals a high similarity to the DNA-binding proteins designated Dps. Among the proven ferritins, the most similar sequences are those of mammalian L chains that appear to share with L. innocua ferritin the negatively charged amino acids corresponding to the iron nucleation site. In L. innocua ferritin, an additional aspartyl residue may provide a strong complexing capacity that renders the iron oxidation and incorporation processes extremely efficient. This study provides the first experimental evidence for the existence of a non-heme bacterial ferritin that is related to Dps proteins, a finding that lends support to the recent suggestion of a common evolutionary origin of these two protein families.
Article
Ferritin is characterized by a highly conserved architecture that comprises 24 subunits assembled into a spherical cage with 432 symmetry. The only known exception is the dodecameric ferritin from Listeria innocua. The structure of Listeria ferritin has been determined to a resolution of 2.35 A by molecular replacement, using as a search model the structure of Dps from Escherichia coli. The Listeria 12-mer is endowed with 23 symmetry and displays the functionally relevant structural features of the ferritin 24-mer, namely the negatively charged channels along the three-fold symmetry axes that serve for iron entry into the cavity and a negatively charged internal cavity for iron deposition. The electron density map shows 12 iron ions on the inner surface of the hollow core, at the interface between monomers related by two-fold axes. Analysis of the nature and stereochemistry of the iron-binding ligands reveals strong similarities with known ferroxidase sites. The L. innocua ferritin site, however, is the first described so far that has ligands belonging to two different subunits and is not contained within a four-helix bundle.
Article
The empty protein cage of ferritin has been used to synthesize and entrap nanoscale particles of a green cobalt oxide via oxidative hydrolysis of Co(II) by H 2O 2. The resulting composite material retains the properties of the protein while incorporating the characteristics of the encapsulated mineral. The visible absorption spectrum has a broad band at 350 nm and the IR spectrum shows a band at 587 cm -1 characteristic of the cobalt oxyhydroxide Co(O)OH.
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Interest in magnetic nanoparticles has increased in the past few years by virtue of their potential for applications in fields such as ultrahigh-density recording and medicine. Most applications rely on the magnetic order of the nanoparticles being stable with time. However, with decreasing particle size the magnetic anisotropy energy per particle responsible for holding the magnetic moment along certain directions becomes comparable to the thermal energy. When this happens, the thermal fluctuations induce random flipping of the magnetic moment with time, and the nanoparticles lose their stable magnetic order and become superparamagnetic. Thus, the demand for further miniaturization comes into conflict with the superparamagnetism caused by the reduction of the anisotropy energy per particle: this constitutes the so-called 'superparamagnetic limit' in recording media. Here we show that magnetic exchange coupling induced at the interface between ferromagnetic and antiferromagnetic systems can provide an extra source of anisotropy, leading to magnetization stability. We demonstrate this principle for ferromagnetic cobalt nanoparticles of about 4 nm in diameter that are embedded in either a paramagnetic or an antiferromagnetic matrix. Whereas the cobalt cores lose their magnetic moment at 10 K in the first system, they remain ferromagnetic up to about 290 K in the second. This behaviour is ascribed to the specific way ferromagnetic nanoparticles couple to an antiferromagnetic matrix.
Article
A new instrument, based on the principle of phase analysis light scattering (PALS) for the measurement of electrophoretic mobilities, has been produced. Such measurements are particularly useful in the study of dispersions in nonpolar and highly conducting media. The current PALS configuration can be used to measure mobilities up to 3 orders of magnitude lower than with the conventional Doppler mode. The device has a number of new features; in particular, all the signal processing is digital and the optical system features a reference beam configuration. Data are presented to show that on suitable samples both the PALS technique and conventional laser Doppler electrophoresis can be performed on the same instrument and the techniques are in good agreement.
  • Douglas T.
  • Stefanini S.