Showing papers in "Small in 2011"
TL;DR: The synthesis, characterization, properties, and applications of graphene-based materials are discussed and the promising properties together with the ease of processibility and functionalization make graphene- based materials ideal candidates for incorporation into a variety of functional materials.
Abstract: Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.
2,246 citations
TL;DR: The identification of single- and few- layer boron nitride is described, its optical contrast is much smaller than that of graphene but even monolayers are discernable by optimizing viewing conditions.
Abstract: Properties of few-nanometer-thick boron nitride sheets (often referred to as few-layer BN) have been attracting steady interest over the last several years. [ 1 ] Although individual atomic planes of BN were also isolated [ 2 ] and investigated by transmission electron microscopy (TEM) [ 3–5 ] and atomic force microscopy (AFM) [ 6 ] , interest in BN monolayers has been rather limited, especially when compared to the interest generated by its ‘sister’ material, graphene. [ 7 ]
1,030 citations
TL;DR: This article focusses on the cellular uptake, location and translocation, and any biological consequences, such as cytotoxicity, of the most widely studied and used nanoparticles,such as carbon-based nanoparticle, metallic nanoparticles and quantum dots.
Abstract: The interactions of nanoparticles with the soft surfaces of biological systems like cells play key roles in executing their biomedical functions and in toxicity. The discovery or design of new biomedical functions, or the prediction of the toxicological consequences of nanoparticles in vivo, first require knowledge of the interplay processes of the nanoparticles with the target cells. This article focusses on the cellular uptake, location and translocation, and any biological consequences, such as cytotoxicity, of the most widely studied and used nanoparticles, such as carbon-based nanoparticles, metallic nanoparticles, and quantum dots. The relevance of the size and shape, composition, charge, and surface chemistry of the nanoparticles in cells is considered. The intracellular uptake pathways of the nanoparticles and the cellular responses, with potential signaling pathways activated by nanoparticle interactions, are also discussed.
1,000 citations
TL;DR: Recently, nanocomposites made by graphene and transition metal oxides have attracted wide attention in the field of supercapacitors due to their synergetic effect, arising from the combination of the redox reaction of metal oxide with the high surface area/conductivity of graphene, to improve the electrochemical performance.
Abstract: The supercapacitor is considered as a promising candidate for energy storage due to its high power performance, long life cycle, and low maintenance cost. [ 3 ] Pseudocapacitive materials, such as transition metal oxides, are being explored for use in supercapacitors with a large specifi c capacitance and high energy density. [ 4 ] However, pseudocapacitors often suffer from the low rate capability and poor stability, because the active materials are usually insulating or semiconducting, which hinders the fast electron transport required for high charge/discharge rates. As an ideal matrix, graphene is commonly used for growth of functional nanomaterials. [ 1a , 2c , 5 ] Recently, nanocomposites made by graphene and transition metal oxides have attracted wide attention in the fi eld of supercapacitors due to their synergetic effect, arising from the combination of the redox reaction of metal oxides with the high surface area/conductivity of graphene, to improve the electrochemical performance. [ 6 ]
986 citations
TL;DR: The rapidly evolving field of gold nanoparticle thermal therapy is reviewed, highlighting recent literature and describing current challenges to clinical translation of the technology.
Abstract: Nanotechnology-based cancer treatment approaches potentially provide localized, targeted therapies that aim to enhance efficacy, reduce side effects, and improve patient quality of life. Gold-nanoparticle-mediated hyperthermia shows particular promise in animal studies, and early clinical testing is currently underway. In this article, the rapidly evolving field of gold nanoparticle thermal therapy is reviewed, highlighting recent literature and describing current challenges to clinical translation of the technology.
816 citations
TL;DR: The covalent functionalization of graphene oxide (GO) with chitosan (CS) is successfully accomplished via a facile amidation process, and the resulting GO-CS/pDNA nanoparticles exhibit reasonable transfection efficiency in HeLa cells at certain nitrogen/phosphate ratios.
Abstract: The covalent functionalization of graphene oxide (GO) with chitosan (CS) is successfully accomplished via a facile amidation process. The CS-grafted GO (GO-CS) sheets consist of about 64 wt.% CS, which imparts them with a good aqueous solubility and biocompatibility. Additionally, the physicochemical properties of GO-CS are studied. As a novel nanocarrier, GO-CS is applied to load a water-insoluble anticancer drug, camptothecin (CPT), via π-π stacking and hydrophobic interactions. It is demonstrated that GO-CS possesses a superior loading capacity for CPT, and the GO-CS-CPT complexes show remarkably high cytotoxicity in HepG2 and HeLa cell lines compared to the pure drug. At the same time, GO-CS is also able to condense plasmid DNA into stable, nanosized complexes, and the resulting GO-CS/pDNA nanoparticles exhibit reasonable transfection efficiency in HeLa cells at certain nitrogen/phosphate ratios. Therefore, the GO-CS nanocarrier is able to load and deliver both anticancer drugs and genes.
793 citations
TL;DR: The first part briefly reviews various general methods developed for producing magnetic nanoparticles (NPs) and presents and categorizes the synthesis of magnetic nanocomposites with mesoporous structures.
Abstract: Magnetic nanocomposites with well-defined mesoporous structures, shapes, and tailored properties are of immense scientific and technological interest. This review article is devoted to the progress in the synthesis and applications of magnetic mesoporous materials. The first part briefly reviews various general methods developed for producing magnetic nanoparticles (NPs). The second presents and categorizes the synthesis of magnetic nanocomposites with mesoporous structures. These nanocomposites are broadly categorized into four types: monodisperse magnetic nanocrystals embedded in mesoporous nanospheres, microspheres encapsulating magnetic cores into perpendicularly aligned mesoporous shells, ordered mesoporous materials loaded with magnetic NPs inside the porous channels or cages, and rattle-type magnetic nanocomposites. The third section reviews the potential applications of the magnetic nanocomposites with mesoporous structures in the areas of heath care, catalysis, and environmental separation. The final section offers a summary and future perspectives on the state-of-the art in this area.
667 citations
TL;DR: The results indicate that both MSNs and PEGylated MSNs of different particle sizes (80-360 nm) distribute mainly in the liver and spleen, a minority of them in the lungs, and a few in the kidney and heart.
Abstract: The in vivo biodistribution and urinary excretion of spherical mesoporous silica nanoparticles (MSNs) are evaluated by tail-vein injection in ICR mice, and the effects of the particle size and PEGylation are investigated. The results indicate that both MSNs and PEGylated MSNs of different particle sizes (80-360 nm) distribute mainly in the liver and spleen, a minority of them in the lungs, and a few in the kidney and heart. The PEGylated MSNs of smaller particle size escape more easily from capture by liver, spleen, and lung tissues, possess longer blood-circulation lifetime, and are more slowly biodegraded and correspondingly have a lower excreted amount of degradation products in the urine. Neither MSNs nor PEGylated MSNs cause tissue toxicity after 1 month in vivo.
542 citations
TL;DR: It is demonstrated that the PEI-GO is an excellent nanocarrier for effective delivery of siRNA and chemical drugs, and that sequential delivery of the siRNAs and the anticancer drug doxorubicin by PEi-GO into cancer cells exhibits a synergistic effect, which leads to a signifi cantly enhanced chemotherapy effi cacy.
Abstract: PEI GO The RNA interference (RNAi) technique, an effective method to inhibit protein expression by targeted cleavage of messenger RNA (mRNA), has made substantial progress since the fi rst demonstration of gene knockdown in mammalian cells. [ 1 ] Short interfering RNA (siRNA) induces specifi c silencing of targeted protein, thus offering signifi cant potential in overcoming multiple drug resistance (MDR) of cancer cells. [ 2 ] For example, Bcl-2 protein, one of the main antiapoptotic defense proteins, is closely related to the MDR of cancer cells. [ 3 ] Knockdown of the Bcl-2 protein expression level in cancer cells by Bcl-2-targeted siRNA would effectively overcome the MDR of cancer cells and sensitize cancer cells to anticancer drugs. [ 3 d, 4 ] Herein, we report sequential delivery of Bcl-2-targeted siRNA and the anticancer drug doxorubicin (DOX) using polyethylenimine (PEI)-functionalized graphene oxide (PEI-GO). We demonstrate that the PEI-GO is an excellent nanocarrier for effective delivery of siRNA and chemical drugs, and that sequential delivery of the siRNA and DOX by PEI-GO into cancer cells exhibits a synergistic effect, which leads to a signifi cantly enhanced chemotherapy effi cacy. To the best of our knowledge, this is the fi rst report on applications of GO-based nanovectors for delivery of siRNA, and sequential delivery of siRNA and anticancer drugs into cancer cells. Graphene, a newly discovered 2D nanomaterial, has been studied extensively due to its fundamental importance and potential applications, [ 5 ] while exploration of its biomedical applications has just started. [ 6 ] Noncovalent adsorption through π – π stacking, electrostatic, and other molecular interactions has proven to be effective for immobilizing chemical drugs, single-stranded DNA, and RNA onto GO sheets. [ 6 a–e]
530 citations
TL;DR: Mechanistic studies on how uniform nanocrystals are obtained in hot-injection and heat-up methods are reviewed and theoretical explanations are provided in the current review.
Abstract: Synthesis of uniform nanocrystals is very important because the size uniformity of an ensemble of nanocrystals is directly related to the homogeneity of their chemical and physical properties. Classical theory suggests that burst nucleation and diffusion-controlled growth are the most important factors for the control of the size distribution in colloidal synthesis. In the last two decades, the numerous reports on the synthesis of uniform nanocrystals have popularized two major synthetic methods, namely, hot-injection and heat-up, to obtain uniform nanocrystals of various materials including metals, semiconductors, and oxides. Mechanistic studies on how such uniform nanocrystals are obtained in those two methods are reviewed and theoretical explanations are provided in the current review.
483 citations
TL;DR: A wide range of promising laboratory and consumer biotechnological applications from microscale genetic and proteomic analysis kits, cell culture and manipulation platforms, biosensors, and pathogen detection systems to point-of-care diagnostic devices, high-throughput combinatorial drug screening platforms, schemes for targeted drug delivery and advanced therapeutics, and novel biomaterials synthesis for tissue engineering are reviewed.
Abstract: Harnessing the ability to precisely and reproducibly actuate fluids and manipulate bioparticles such as DNA, cells, and molecules at the microscale, microfluidics is a powerful tool that is currently revolutionizing chemical and biological analysis by replicating laboratory bench-top technology on a miniature chip-scale device, thus allowing assays to be carried out at a fraction of the time and cost while affording portability and field-use capability. Emerging from a decade of research and development in microfluidic technology are a wide range of promising laboratory and consumer biotechnological applications from microscale genetic and proteomic analysis kits, cell culture and manipulation platforms, biosensors, and pathogen detection systems to point-of-care diagnostic devices, high-throughput combinatorial drug screening platforms, schemes for targeted drug delivery and advanced therapeutics, and novel biomaterials synthesis for tissue engineering. The developments associated with these technological advances along with their respective applications to date are reviewed from a broad perspective and possible future directions that could arise from the current state of the art are discussed.
TL;DR: This review covers recent major advancement in the nanomedicine field and also highlights studies using the PRINT technology, which focuses on both nanoparticles and microparticles.
Abstract: Nanomedicine is an emerging field that applies concepts in nanotechnology to the development of novel diagnostics and therapeutics. Physical and chemical properties of particles, including size, shape, modulus, surface charge and surface chemistry, play important roles in the efficacy of nanomedicines. This review focuses on the effect of particle physical and chemical properties on their interactions with cells in vitro and their pharmacokinetics and biodistribution in vivo.
TL;DR: Cellulose nanocrystals have emerged as a new class of nanomaterials for polymer reinforcement and nanocomposite formulation owing to their exceptionally high mechanical strength, low density, chemical tunability, environmental sustainability, and anticipated low cost.
Abstract: Cellulose nanocrystals (CNCs) have emerged as a new class of nanomaterials for polymer reinforcement and nanocomposite formulation owing to their exceptionally high mechanical strength (modulus of 100–140 GPa), low density (1.6 g cm − 3 ), chemical tunability, environmental sustainability, and anticipated low cost. [ 1 ] CNCs have also been fostered for a myriad of applications including enzyme immobilization, [ 2 ]
TL;DR: Nickel cobalt nanowire is prepared by hydrothermal and thermal decomposition processes, with mesoporous characteristics and nanocrystal structure that results from the coexistence of nickel and cobalt ions.
Abstract: Excellent electrochemical performance results from the coexistence of nickel and cobalt ions, with mesoporous characteristics and nanocrystal structure. Nickel cobalt nanowire is prepared by hydrothermal and thermal decomposition processes. High capacitance of 722 F g(-1) can be obtained at 1 A g(-1) in 6 M KOH, with a capacitance retention ratio of ca. 79% at 20 A g(-1) .
TL;DR: Graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices as mentioned in this paper, which shows high transmittance and display good heating performance.
Abstract: High-performance and novel graphene-based electrothermal films are fabricated through a simple yet versatile solution process. Their electrothermal performances are studied in terms of applied voltage, heating rate, and input power density. The electrothermal films annealed at high temperature show high transmittance and display good heating performance. For example, the graphene-based film annealed at 800 °C, which shows transmittance of over 80% at 550 nm, can reach a saturated temperature of up to 42 °C when 60 V is applied for 2 min. Graphene-based films annealed at 900 and 1000 °C can exhibit high steady-state temperatures of 150 and 206 °C under an applied voltage of 60 V with a maximum heating rate of over 7 °C s(-1) . For flexible heating films patterned on polyimide, a steady-state temperature of 72 °C could be reached in less than 10 s with a maximum heating rate exceeding 16 °C s(-1) at 60 V. These excellent results, combined with the high chemical stability and mechanical flexibility of graphene, indicate that graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices.
TL;DR: The design and synthesis of graphene–metal nanohybrid assemblies are of great interest for the exploration of their applications and involve highly toxic chemicals, such as hydrazine hydrate, high temperature and, moreover, multiple steps are required that are time or labor consuming.
Abstract: Graphene, a 2D sp 2 -hybridized carbon sheet, has recently attracted great attention due to its unique electrical, optical, and mechanical properties as well as its potential use in various fi elds, such as electronics, supercapacitors, sensors, and composite materials. [ 1 ] Many methods have been proposed for graphene production, among which the chemical reduction of graphene oxide (GO) obtained from ultrasonic exfoliation of oxidized graphite is the most convenient way to yield large quantities of graphene sheets. [ 2 ] However, the practical applications of graphene are challenged by its irreversible agglomeration both in the drying state and in common solvents, which signifi cantly reduces its effectiveness. Introducing metal nanoparticles (NPs) was initially proposed in order to separate graphene sheets. [ 3 ] Nowadays, it is well realized that the dispersion of metal NPs on graphene sheets also potentially provides a new way to develop novel catalytic, magnetic, and optoelectronic materials. [ 4 ] The design and synthesis of graphene–metal nanohybrid assemblies are therefore of great interest for the exploration of their applications. Graphene–metal nanocomposites have typically been prepared by chemical or thermal reduction of mixtures of graphene (or GO) and metallic precursors. [ 3 , 5 ] Obviously, these methods involve highly toxic chemicals, such as hydrazine hydrate, or high temperature and, moreover, multiple steps are required that are time or labor consuming. Recently, electrochemical reduction of GO has been developed. [ 6 ] It is attractive for graphene-fi lm synthesis due to its simple, fast, and green nature. Typically, the electrochemical synthesis of graphene is carried out via two steps, namely, GO being fi rst assembled on the electrodes by dip-coating, drop-casting, or spray-coating methods and then being subjected to electrochemical reduction. Shortly thereafter, an approach, using GO-coated electrodes being immersed in a metallic precursor solution to perform one-step coelectrochemical reduction, was proposed to fabricate graphene– metal nanocomposite fi lms. [ 7 ] However, the above-mentioned
TL;DR: A facile strategy to synthesize water-soluble fluorescent gold nanoclusters (Au NCs) stabilized with the bidentate ligand dihydrolipoic acid (DHLA) is reported, making them promising imaging agents for biomedical and cellular imaging applications.
Abstract: A facile strategy to synthesize water-soluble fluorescent gold nanoclusters (Au NCs) stabilized with the bidentate ligand dihydrolipoic acid (DHLA) is reported. The DHLA-capped Au NCs are characterized by UV-vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The Au NCs possess many attractive features including ultrasmall size, bright near-infrared luminescence, high colloidal stability, and good biocompatibility, making them promising imaging agents for biomedical and cellular imaging applications. Moreover, their long fluorescence lifetime (>100 ns) makes them attractive as labels in fluorescence lifetime imaging (FLIM) applications. As an example, the internalization of Au NCs by live HeLa cells is visualized using the FLIM technique.
TL;DR: A method to produce scalable, low-resistance, high-transparency, percolating networks of silver nanowires by spray coating is presented and the critical processing parameter is shown to be the spraying pressure.
Abstract: A method to produce scalable, low-resistance, high-transparency, percolating networks of silver nanowires by spray coating is presented. By optimizing the spraying parameters, networks with a sheet resistance of R(s) ≈ 50 Ω □(-1) at a transparency of T = 90% can be produced. The critical processing parameter is shown to be the spraying pressure. Optimizing the pressure reduces the droplet size resulting in more uniform networks. High uniformity leads to a low percolation exponent, which is essential for low-resistance, high-transparency films.
TL;DR: This review provides an overview of various macroscopic CNT assemblies, with a focus on their preparation and mechanical properties as well as their potential applications in practical fields.
Abstract: As classical 1D nanoscale structures, carbon nanotubes (CNTs) possess remarkable mechanical, electrical, thermal, and optical properties. In the past several years, considerable attention has been paid to the use of CNTs as building blocks for novel high-performance materials. In this way, the production of macroscopic architectures based on assembled CNTs with controlled orientation and configurations is an important step towards their application. So far, various forms of macroscale CNT assemblies have been produced, such as 1D CNT fibers, 2D CNT films/sheets, and 3D aligned CNT arrays or foams. These macroarchitectures, depending on the manner in which they are assembled, display a variety of fascinating features that cannot be achieved using conventional materials. This review provides an overview of various macroscopic CNT assemblies, with a focus on their preparation and mechanical properties as well as their potential applications in practical fields.
TL;DR: The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials.
Abstract: Ordered mesoporous carbide-derived carbon (OM-CDC) materials produced by nanocasting of ordered mesoporous silica templates are characterized by a bimodal pore size distribution with a high ratio of micropores. The micropores result in outstanding adsorption capacities and the well-defined mesopores facilitate enhanced kinetics in adsorption processes. Here, for the first time, a systematic study is presented, in which the effects of synthesis temperature on the electrochemical performance of these materials in supercapacitors based on a 1 M aqueous solution of sulfuric acid and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid are reported. Cyclic voltammetry shows the specific capacitance of the OM-CDC materials exceeds 200 F g(-1) in the aqueous electrolyte and 185 F g(-1) in the ionic liquid, when measured in a symmetric configuration in voltage ranges of up to 0.6 and 2 V, respectively. The ordered mesoporous channels in the produced OM-CDC materials serve as ion-highways and allow for very fast ionic transport into the bulk of the OM-CDC particles. At room temperature the enhanced ion transport leads to 75% and 90% of the capacitance retention at current densities in excess of ∼10 A g(-1) in ionic liquid and aqueous electrolytes, respectively. The supercapacitors based on 250-300 μm OM-CDC electrodes demonstrate an operating frequency of up to 7 Hz in aqueous electrolyte. The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials.
TL;DR: It is shown that the properties of analyte-sensitive fluorophores can be tuned by using interactions with the underlying nanoparticles, and their use for intracellular pH-sensing demonstrated.
Abstract: Water solubilization of nanoparticles is a fundamental prerequisite for many biological applications. To date, no single method has emerged as ideal, and several different approaches have been successfully utilized. These 'phase-transfer' strategies are reviewed, indicating key advantages and disadvantages, and a discussion of conjugation strategies is presented. Coating of hydrophobic nanoparticles with amphiphilic polymers provides a generic pathway for the phase transfer of semiconductor, magnetic, metallic, and upconverting nanoparticles from nonpolar to polar environments. Amphiphilic polymers that include maleimide groups can be readily functionalized with chemical groups for specific applications. In the second, experimental part, some of the new chemical features of such polymer-capped nanoparticles are demonstrated. In particular, nanoparticles to which a pH sensitive fluorophore has been attached are described, and their use for intracellular pH-sensing demonstrated. It is shown that the properties of analyte-sensitive fluorophores can be tuned by using interactions with the underlying nanoparticles.
TL;DR: From simple to complex, from spherical to nonspherical, from polymerization and reaction crystallization to self-assembly, this review aims to help readers be aware of the many aspects of this field.
Abstract: Recent advances in the fabrication of complex particles and particle-based materials assisted by droplet-based microfluidics are reviewed. Monodisperse particles with expected internal structures, morphologies, and sizes in the range of nanometers to hundreds of micrometers have received a good deal of attention in recent years. Due to the capability of generating monodisperse emulsions and of executing precise control and operations on the suspended droplets inside the microchannels, droplet-based microfluidic devices have become powerful tools for fabricating complex particles with desired properties. Emulsions and multiple-emulsions generated in the microfluidic devices can be composed of a variety of materials including aqueous solutions, gels, polymers and solutions containing functional nanoparticles. They are ideal microreactors or fine templates for synthesizing advanced particles, such as polymer particles, microcapsules, nanocrystals, and photonic crystal clusters or beads by further chemical or physical operations. These particles are promising materials that may be applicable for many fields, such as photonic materials, drug delivery systems, and bio-analysis. From simple to complex, from spherical to nonspherical, from polymerization and reaction crystallization to self-assembly, this review aims to help readers be aware of the many aspects of this field.
TL;DR: The current review critically explores the recent progress on the chemical preparation of graphene-based nanomaterials and their applications in sensors.
Abstract: Graphene is a flat monolayer of carbon atoms packed tightly into a 2D honeycomb lattice that shows many intriguing properties meeting the key requirements for the implementation of highly excellent sensors, and all kinds of proof-of-concept sensors have been devised. To realize the potential sensor applications, the key is to synthesize graphene in a controlled way to achieve enhanced solution-processing capabilities, and at the same time to maintain or even improve the intrinsic properties of graphene. Several production techniques for graphene-based nanomaterials have been developed, ranging from the mechanical cleavage and chemical exfoliation of high-quality graphene to direct growth onto different substrates and the chemical routes using graphite oxide as a precusor to the newly developed bottom-up approach at the molecular level. The current review critically explores the recent progress on the chemical preparation of graphene-based nanomaterials and their applications in sensors.
TL;DR: It is suggested that a dissolving microneedle patch can deliver hGH and other biopharmaceuticals in a manner suitable for self-administration without sharp biohazardous waste.
Abstract: The clinical impact of biotechnology has been constrained by the limitations of traditional hypodermic injection of biopharmaceuticals. Microneedle patches have been proposed as a minimally invasive alternative. In this study, the translation of a dissolving microneedle patch designed for simple, painless self-administration of biopharmacetucials that generates no sharp biohazardous waste is assessed. To study the pharmacokinetics and safety of this approach, human growth hormone (hGH) was encapsulated in 600 μm-long dissolving microneedles composed of carboxymethylcellulose and trehalose using an aqueous, moderate-temperature process that maintained complete hGH activity after encapsulation and retained most activity after storage for up to 15 months at room temperature and humidity. After manual insertion into the skin of hairless rats, hGH pharmacokinetics were similar to conventional subcutaneous injection. After patch removal, the microneedles had almost completely dissolved, leaving behind only blunt stubs. The dissolving microneedle patch was well tolerated, causing only slight, transient erythema. This study suggests that a dissolving microneedle patch can deliver hGH and other biopharmaceuticals in a manner suitable for self-administration without sharp biohazardous waste.
TL;DR: The results suggest that (nano)particle uptake might not follow commonly defined size limits for uptake processes, and highlight the variability of uptake kinetics for the same material in different cell types, having important implications for the assessment of the safety of nanomaterials and for the potential biomedical applications of nanoparticles.
Abstract: The mechanism(s) of nanoparticle-cell interactions are still not understood. At present there is little knowledge of the relevant length- and timescales for nanoparticle intracellular entry and localization within cells, or the cell-specificity of nanoparticle uptake and localisation. Here, the effect of particle size on the in-vitro intracellular uptake of model fluorescent carboxyl-modified polystyrene nanoparticles is investigated in various cell lines. A range of micro- and nanoparticles of defined sizes (40 nm to 2 μm) are incubated with a series of cell types, including HeLa and A549 epithelial cells, 1321N1 astrocytes, HCMEC D3 endothelial cells, and murine RAW 264.7 macrophages. Techniques such as confocal microscopy and flow cytometry are used to study particle uptake and subcellular localisation, making significant efforts to ensure reproducibility in a semiquantitative approach. The results indicate that internalization of (nano)particles is highly size-dependent for all cell lines studied, and the kinetics of uptake for the same type of nanoparticle varies in the different cell types. Interestingly, even cells not specialized for phagocytosis are able to internalize the larger nanoparticles. Intracellular uptake of all sizes of particles is observed to be highest in RAW 264.7 cells (a specialized phagocytic cell line) and the lowest in the HeLa cells. These results suggest that (nano)particle uptake might not follow commonly defined size limits for uptake processes, and highlight the variability of uptake kinetics for the same material in different cell types. These conclusions have important implications for the assessment of the safety of nanomaterials and for the potential biomedical applications of nanoparticles.
TL;DR: The first high-performance ZnO hollow-sphere nanofilm-based photodetector is constructed by 'water-oil interfacial self-assembly' of polystyrene (PS)/ZnO core/shell nanospheres and subsequent thermal treatment.
Abstract: The first high-performance ZnO hollow-sphere nanofilm-based photodetector is constructed by 'water-oil interfacial self-assembly' of polystyrene (PS)/ZnO core/shell nanospheres and subsequent thermal treatment. The versatile growth substrate, general fabrication strategy, and high performance including excellent sensitivity, high spectral selectivity, and fast response times show the current work to be a new paradigm in the preparation of hollow-sphere nanofilm-based photodetectors.
TL;DR: This work has shown that, at this small scale, qualitative changes in physicochemical properties such as surface plasmon resonance in metal nanoparticles, quantum confi nement in semiconductor particles, and superparamagnetism in magnetic nanomaterials, are connected to the number of atoms or molecules forming the material.
Abstract: Nanomaterials, understood as the study of materials having at least one dimension on the nanometer scale, has been a fruitful area of research during the past few years. [ 1 ] The main reason for this increasing interest is that, at this small scale, qualitative changes in physicochemical properties such as surface plasmon resonance in metal nanoparticles, quantum confi nement in semiconductor particles, and superparamagnetism in magnetic nanomaterials, are connected to the number of atoms or molecules forming the material. [ 2 ]
TL;DR: These results demonstrate successful biomolecular-targeted hydrophobic drug delivery carriers that selectively target specific cancer cells and result in enhanced drug delivery and cell mortality.
Abstract: Synthetic methodologies integrating hydrophobic drug delivery and biomolecular targeting with mesoporous silica nanoparticles are described. Transferrin and cyclic-RGD peptides are covalently attached to the nanoparticles utilizing different techniques and provide selectivity between primary and metastatic cancer cells. The increase in cellular uptake of the targeted particles is examined using fluorescence microscopy and flow cytometry. Transferrin-modified silica nanoparticles display enhancement in particle uptake by Panc-1 cancer cells over that of normal HFF cells. The endocytotic pathway for these particles is further investigated through plasmid transfection of the transferrin receptor into the normal HFF cell line, which results in an increase in particle endocytosis as compared to unmodified HFF cells. By designing and attaching a synthetic cyclic-RGD, selectivity between primary cancer cells (BT-549) and metastatic cancer cells (MDA-MB 435) is achieved with enhanced particle uptake by the metastatic cancer cell line. Incorporation of the hydrophobic drug Camptothecin into these two types of biomolecular-targeted nanoparticles causes an increase in mortality of the targeted cancer cells compared to that caused by both the free drug and nontargeted particles. These results demonstrate successful biomolecular-targeted hydrophobic drug delivery carriers that selectively target specific cancer cells and result in enhanced drug delivery and cell mortality.
TL;DR: The ability of diamond nanoparticles to deliver small interfering RNA (siRNA) into Ewing sarcoma cells is investigated with a view to the possibility of in-vivo anticancer nucleic-acid drug delivery.
Abstract: The ability of diamond nanoparticles (nanodiamonds, NDs) to deliver small interfering RNA (siRNA) into Ewing sarcoma cells is investigated with a view to the possibility of in-vivo anticancer nucleic-acid drug delivery. siRNA is adsorbed onto NDs that are coated with cationic polymer. Cell uptake of NDs is demonstrated by taking advantage of the NDs' intrinsic fluorescence from embedded color-center defects. Cell toxicity of these coated NDs is shown to be low. Consistent with the internalization efficacy, a specific inhibition of EWS/Fli-1 gene expression is shown at the mRNA and protein level by the ND-vectorized siRNA in a serum-containing medium.