Showing papers on "Nanocages published in 2012"
TL;DR: Compared to Pt-based catalysts, metal-free catalysts have several noteable advantages, in that they do not suffer CO poisoning or crossover effects, have long-term operational stability, and are relatively cost-effective.
Abstract: The oxygen reduction reaction (ORR) is one of the most crucial factors limiting the performance of proton exchange membrane fuel cells due to its slow kinetics. [ 1 , 2 ] The development of effi cient ORR electrocatalysts is thus of great signifi cance. Today, platinum is usually used as the electrocatalyst for ORR; however, the large-scale application of fuel cells is hampered by the its scarcity and high cost. [ 3 ] In addition, Pt-based catalyst is sensitive to deactivation in the presence of CO, methanol and also susceptible to time-dependent drift. [ 1 ] Hence, great efforts have been devoted to exploring the advanced ORR catalysts to rival the commercial Pt/C catalyst in activity and durability with reduced Pt loading, [ 1 , 4–6 ] or nonprecious metals, [ 7–10 ] or even metalfree species. [ 11–16 ] Compared to Pt-based catalysts, metal-free catalysts have several noteable advantages, in that they do not suffer CO poisoning or crossover effects, have long-term operational stability, and are relatively cost-effective. Following the breakthrough in discovering the metal-free catalyst of PEDOT for ORR, [ 11 ] heteroatom-doped carbon nanotubes (CNTs) were demonstrated to be a new kind of promising metal-free electrocatalyst. Doping with either electron-rich nitrogen [ 12 ] or electrodefi cient boron [ 13 ] can transform CNTs into superb metal-free ORR catalysts, and the co-doping can provide further space for performance optimization, [ 14 ] which forms a scientifi cally interesting and technologically important subject today. However, there are still some key issues to address. First, enhancing the catalytic activity by increasing the specifi c surface area is an important challenge. This has proven to be diffi cult for doped CNTs, [ 17 , 18 ] although undoped CNTs have been prepared with high specifi c surface areas ( > 1200 m 2 g − 1 ) in the case of singlewalled CNTs. [ 19 ] In addition, the origin of the ORR activity for doped CNTs is still a matter of controversy and need to be further clarifi ed. [ 10 , 12 , 20–22 ] Since the metal impurities with ORR activity, i.e., the residue from the catalyst used in the growth of
684 citations
TL;DR: This study reports the synthesis, characterization, and electrochemical evaluation of cubic intermetallic PtCu(3) nanocages, which possess a more accessible surface area and a unique hollow structure that contribute to improved electrocatalytic activity in the methanol oxidation reaction.
Abstract: Noble metals such as platinum (Pt) are widely used as catalysts in fuel cells and other heterogeneous catalytic processes. However, there is an urgent need to develop substitutes for pure Pt catalysts to reduce the overall use of precious Pt and at the same time to enhance poisoning resistance. A promising strategy is to design Pt based bi- or trimetallic nanostructures because their unique structures and compositions would enhance their catalytic performance. In this study, we report the synthesis, characterization, and electrochemical evaluation of cubic intermetallic PtCu(3) nanocages. The influential effects of several important experimental parameters on the final products have been explored through systematic studies on the growth of PtCu(3) nanocages. Relative to the current commercial Pt electrocatalyst, these PtCu(3) nanocages possess a more accessible surface area and a unique hollow structure, which contribute to improved electrocatalytic activity in the methanol oxidation reaction.
549 citations
TL;DR: Carbon nanocages are conveniently produced by an in situ MgO template method and demonstrate high specific capacitance over a wide range of charging-discharging rates with high stability, superior to the most carbonaceous supercapacitor electrode materials to date.
Abstract: Supercapacitor electrode materials: Carbon nanocages are conveniently produced by an in situ MgO template method and demonstrate high specific capacitance over a wide range of charging-discharging rates with high stability, superior to the most carbonaceous supercapacitor electrode materials to date. The large specific surface area, good mesoporosity, and regular structure are responsible for the excellent performance.
496 citations
TL;DR: In this article, the thermal decomposition of Co3O4 nanoparticles of cobalt-based Prussian blue analogues at different temperatures was used to obtain high discharge capacity of 800, 970, 828, 854, and 651 mAhg.
Abstract: Co3O4 nanoparticles have been prepared by a facile strategy, which involves the thermal decomposition of nanoparticles of cobalt-based Prussian blue analogues at different temperatures. The nanoparticles prepared at 450, 550, 650, 750, and 850 °C exhibited a high discharge capacity of 800, 970, 828, 854, and 651 mAhg–1, respectively, after 30 cycles at a current density of 50 mAg–1. The nanocages produced at 550 °C show the highest lithium storage capacity. It is found that the nanocages display nanosize grains, hollow structure, a porous shell, and large specific surface area. At the temperature higher than 650 °C, the samples with larger grains, better crystallinity, and lower specific surface area can be obtained. It is found that the size, crystallinity, and morphology of nanoparticles have different effects on electrochemical performance. Better crystallinity is able to enhance the initial discharge capacity, while porous structure can reduce the irreversible loss. Therefore, the optimal size, crysta...
400 citations
TL;DR: It is expected that the present work will provide a promising strategy for the development of efficient oxygen reduction electrocatalysts and can also be extended to the preparation of other hybrid or hetero-nanostructures with desirable morphologies and functions.
Abstract: Pd–Pt alloy nanocrystals (NCs) with hollow structures such as nanocages with porous walls and dendritic hollow structures and Pd@Pt core–shell dendritic NCs could be selectively synthesized by a ga...
338 citations
TL;DR: Fluorescence and electronic spin resonance results show that the gold nanocage in the bioconjugate nanostructure can dramatically quench the photosensitizer and inhibit the production of singlet oxygen, which is supposed to alleviate the photosenitizers' unwanted side effects originating from their nontargeted distribution.
Abstract: A new bioconjugate nanostructure was constructed by using photosensitizer-incorporated mixed lipid-coated gold nanocages for two-photon photothermal/photodynamic cancer therapy in vitro with high efficiency. Scanning electron microscopic and transmission electron microscopic images reveal that the precursors and bioconjugate nanostructure as-prepared are narrowly dispersed and possess uniform morphologies. The relevant energy dispersion X-ray analysis and UV–vis spectra indicate that the bioconjugate nanostructure above was assembled successfully and has a strong absorption in the near-infrared region. Fluorescence and electronic spin resonance results show that the gold nanocage in the bioconjugate nanostructure can dramatically quench the photosensitizer and inhibit the production of singlet oxygen, which is supposed to alleviate the photosensitizers’ unwanted side effects originating from their nontargeted distribution. We have demonstrated that as the nanocomplex is internalized by cancer cells, under...
300 citations
TL;DR: Hollow structures of TiO 2 are of great interest and stringent control of the synthesis conditions and addition of polyelectrolytes are almost indispensable in these methods to control the hydrol-like properties of nanomaterials.
Abstract: Specifi cally, anisotropic nanocages with non-spherical shapes and regular interiors are of particular interests for their unique advantages that are diffi cult to achieve through conventional structures with round shape. [ 2 , 3 ] For instance, they are essential building blocks of complex hierarchical architectures with multiple functionalities. [ 3–5 ] The benefi ts of anisotropic carriers for targeted drug delivery are also well demonstrated. [ 3 , 6 ] Different from usual hollow spheres, it is in principle much more diffi cult to synthesize anisotropic nanocages. Even with templating strategies, there are not many good examples of anisotropic nanocages reported possibly due to extra technological diffi culties involved including less controllable coating around high-curvature surfaces, the defi ciency of dispersed anisotropic templates available and poor preservation of the shape with high residual stresses. [ 1 ] Recently, some novel approaches have been developed for the preparation of anisotropic nanocages of various materials such as noble metals and semiconductor compounds based on different principles such as the Kirkendall effect, galvanic replacement, chemical etching, solid-state decomposition, quasi-templating process and self-organization of crystallites. [ 7–18 ] Notwithstanding these advances, the design and synthesis of high-quality anisotropic nanocages of many functional materials, e.g., anatase TiO 2 , still remain as a signifi cant challenge until now. Titanium dioxide (TiO 2 ) is one of most investigated materials for its unique properties and great importance in many areas. [ 19–21 ] For many of these applications, it is crucial to manipulate their morphology, crystalline texture and surface characteristics of nanomaterials for better control of the properties. In particular, hollow structures of TiO 2 are of great interest. So far, enormous effort has been devoted to the synthesis and structural tailoring of diverse TiO 2 hollow nanostructures by either templating against colloids of various materials or template-free methods. [ 22–32 ] However, stringent control of the synthesis conditions and addition of polyelectrolytes are almost indispensable in these methods to control the hydrol-
244 citations
TL;DR: A novel facile strategy based on the Kirkendall effect for the fabrication of Co(3)O(4) porous nanocages with porous shells and containing nanoparticles that is potentially competitive for scaling-up industrial production.
Abstract: Herein we report a novel facile strategy for the fabrication of Co(3)O(4) porous nanocages based on the Kirkendall effect, which involves the thermal decomposition of Prussian blue analogue (PBA) Co(3)[Co(CN)(6)](2) truncated nanocubes at 400 °C. Owing to the volume loss and release of internally generated CO(2) and N(x) O(y) in the process of interdiffusion, Co(3)O(4) nanocages with porous shells and containing nanoparticles were finally obtained. When evaluated as electrode materials for lithium-ion batteries, the as-prepared Co(3)O(4) porous nanocages displayed superior battery performance. Most importantly, capacities of up to 1465 mA h g(-1) are attained after 50 cycles at a current density of 300 mA g(-1). Moreover, this simple synthetic strategy is potentially competitive for scaling-up industrial production.
221 citations
TL;DR: A novel material of gold nanoshells on drug-loaded silica nanorattles which can combine the hyperthermia with chemotherapy to optimize cancer therapy whose synergistic effects are greater than the two individual treatments alone.
Abstract: One of the current challenges in biomedicine is to develop safe and effective nanomedicines for selective tumor therapy.[1] Recently, near-infrared (NIR) light absorbing plasmonic nanomaterials have attracted intensive attention for their hyperthemia therapy to kill tumorigenic cells without damaging normal cells, such as gold nanorods,[2] gold nanocages,[3] AuxAg1-x dendrites,[4] gold nanoshells on polystyrene spheres,[5] assembled gold nanoparticles[6] and many multifunctional nanocomposites.[7] Our previous study reported a novel material of gold nanoshells on drug-loaded silica nanorattles which can combine the hyperthermia with chemotherapy to optimize cancer therapy whose synergistic effects are greater than the two individual treatments alone.[8] Despite the successful application of many gold-based NIR absorbing materials in cancer therapy, most studies of them rely on the passive targeting effect (the so-called enhanced permeability and retention, EPR effect) to direct nanocarriers at tumor sites through the enhanced permeability of tumor vasculature and the decreased draining efficacy of tumor lymphatics.[9,10] The lack of cell specific interactions may decrease the therapeutic efficacy and thus need a relatively long NIR light irradiation time (30 min in vitro, e.g.),[11] a high NIR laser light irradiation intensity (35 W cm-2 in vitro, e.g.),[12] or repeated injections and NIR laser light irradiations[8] as the previous reports. Furthermore, not all tumors exhibit EPR effect which can enhance the preferential accumulation of nanoparticles in the tumor.[13,14] For clinical applications, a more effective drug delivery strategy should be developed to promote the binding and internalization of nanocarrier through their specific interactions with the receptors expressed on the cell surface of interest.[15]
171 citations
TL;DR: The ability to directly and quickly image the distribution of Au nanocages in vivo allows us to further optimize their physicochemical properties for a range of theranostic applications.
Abstract: Gold nanocages have recently emerged as a novel class of photothermal transducers and drug carriers for cancer treatment. However, their pharmacokinetics and tumor targeting capability remain largely unexplored due to the lack of an imaging modality for quick and reliable mapping of their distributions in vivo. Herein, Au nanocages were prepared with controlled physicochemical properties and radiolabeled with 64Cu in high specific activities for in vivo evaluation using positron emission tomography (PET). Our pharmacokinetic studies with femtomolar administrations suggest that 30 nm nanocages had a greatly improved biodistribution profile than 55 nm nanocages, together with higher blood retention and lower hepatic and splenic uptakes. In a murine EMT-6 breast cancer model, the small cages also showed a significantly higher level of tumor uptake and a greater tumor-to-muscle ratio than the large cages. Quantitative PET imaging confirmed rapid accumulation and retention of Au nanocages inside the tumors. Th...
148 citations
TL;DR: In this paper, a CoO octahedral nanocage was successfully fabricated by a simple method and the coordination etching agents played key roles in the formation of these non-spherical hollow structures.
TL;DR: Truncated rhombic dodecahedral zeolitic imidazolate framework-8 (Zif-8) nanocrystals are fabricated with acetate as a modulating ligand and ZnS hollow polyhedra with uniform morphology are obtained using the ZIF-8 templates.
TL;DR: Several theranostic agents and their impact on the development of more effective photothermal therapies for the treatment of cancer are discussed, including hollow gold nanoshells, gold gold-sulfide nanoparticles, gold nanocages, carbon and titanium nanotubes, photothermal-based nanobubbles, polymeric nanoparticles and copper-based nanoparticles.
Abstract: The theranostic potential of several nanostructures has been discussed in the context of photothermal therapies and imaging In the last several decades, the burden of cancer has grown rapidly, making the need for new theranostic approaches vital Lasers have emerged as promising tools in cancer treatment, especially with the advent of photothermal therapies wherein light absorbing dyes or plasmonic gold nanoparticles are used to generate heat and achieve tumor damage Recently, photoabsorbing nanostructures have materialized that can be employed in conjunction with lasers in the near-infrared region in order to enhance both imaging and photothermal effects The incorporation of tunable nanostructures has resulted in improved specificity in cancer treatment Silica-cored gold nanoshells and gold nanorods currently serve as the chief plasmonic structures for photothermal therapy Although gold nanorods and silica-cored gold nanoshells have shown promise as therapeutic agents, over the past few years new nanostructures have emerged that offer comparable and even superior theranostic properties In the present review, several theranostic agents and their impact on the development of more effective photothermal therapies for the treatment of cancer are discussed These agents include hollow gold nanoshells, gold gold-sulfide nanoparticles, gold nanocages, carbon and titanium nanotubes, photothermal-based nanobubbles, polymeric nanoparticles and copper-based nanocrystals
TL;DR: A smart therapeutic nanoplatform based on Fe(3)O(4)@CaP capped gold nanocages, which integrates magnetic targeting, photothermal therapy and chemotherapy for killing cancer cells, results in a synergistic effect in cancer treatment.
TL;DR: Here the galvanic replacement technique is used to prepare nanocages made of gold, platinum, and palladium to study the effect of the dielectric properties of the other metals on the plasmonic properties ofThe gold nanoshell in these mixed nanoparticles.
Abstract: Hollow metallic nanoparticles have been attracting the attention of many researchers in the past five years due to their new properties and potential applications. The unique structure of the hollow nanoparticles; presence of two surfaces (internal and external), and the presence of both cavities and pores in the wall surfaces of these nanoparticles are responsible for their unique properties and applications. Here the galvanic replacement technique is used to prepare nanocages made of gold, platinum, and palladium. In addition, hollow double shell nanoparticles are made of two metal shells like Au–Pt, Pt–Au, Au–Pd, Pd–Au, Pd–Pt, and Pt–Pd. Silver nanocubes are used as templates during the synthesis of hollow nanoparticles with single metal shell or double shell nanocages. Most of the problems that could affect the synthesis of solid Silver nanocubes used as template as well as the double shell nanocages and their possible solutions are discussed in a detail. The sizes and shapes of the single-shell and d...
TL;DR: Although the shish kabob of nanocages has exactly the same chemical composition and even the same Archimedean-solid structure as those of its discrete analogue, its gas-adsorption capacity is remarkably improved because assembly of a chain exposes the internal surface of an individual cage.
Abstract: Using a ligand bearing a bulky hydrophobic group, a “shish kabob” of nanocages, has been assembled through either a one-fell-swoop or a step-by-step procedure by varying the dielectric constant of the assembly mixture. A hydrophobic solvent breaks down the chain to discrete nanocages, while a hydrophilic solvent reverses the procedure. Although the shish kabob of nanocages has exactly the same chemical composition and even the same Archimedean-solid structure as those of its discrete analogue, its gas-adsorption capacity is remarkably improved because assembly of a chain exposes the internal surface of an individual cage. This dimension-augmentation strategy may have general implications in the preparation of porous materials.
TL;DR: The rational design of shell-crosslinked knedel-like nanoparticles is elaborated for therapeutic packaging and delivery, with emphasis on the polymer chemistry aspects to accomplish the synthesis of such nanoparticulate systems.
Abstract: Polymeric nanoparticles are promising delivery platforms for various biomedical applications. One of the main challenges toward the development of therapeutic nanoparticles is the premature disassembly and release of the encapsulated drug. Among the different strategies to enhance the kinetic stability of polymeric nanoparticles, shell- and core-crosslinking have been shown to provide robust character, while creating a suitable environment for encapsulation of a wide range of therapeutics, including hydrophilic, hydrophobic, metallic, and small and large biomolecules, with gating of their release as well. The versatility of shell- and core-crosslinked nanoparticles is driven from the ease by which the structures of the shell- and core-forming polymers and crosslinkers can be modified. In addition, postmodification with cell-recognition moieties, grafting of antibiofouling polymers, or chemical degradation of the core to yield nanocages allow the use of these robust nanostructures as “smart” nanocarriers. The building principles of these multifunctional nanoparticles borrow analogy from the synthesis, supramolecular assembly, stabilization, and dynamic activity of the naturally driven biological nanoparticles such as proteins, lipoproteins, and viruses. In this review, the chemistry involved during the buildup from small molecules to polymers to covalently stabilized nanoscopic objects is detailed, with contrast of the strategies of the supramolecular assembly of polymer building blocks followed by intramicellar stabilization into shell-, core-, or core–shell-crosslinked knedel-like nanoparticles versus polymerization of polymers into nanoscopic molecular brushes followed by further intramolecular covalent stabilization events. The rational design of shell-crosslinked knedel-like nanoparticles is then elaborated for therapeutic packaging and delivery, with emphasis on the polymer chemistry aspects to accomplish the synthesis of such nanoparticulate systems.
TL;DR: In this article, the authors investigated the role of water and reaction time in the growth of Zn-doped In2O3 nanostructures and hollow spindle-like HSNs.
Abstract: Novel Zn-doped In2O3 nanocages and hollow spindle-like nanostructures (HSNs) have been prepared by calcining precursors obtained via a facile template-free hydrothermal method. The change in morphology, size, and phase compositions in a controlled synthesis of the Zn-doped In2O3 nanostructures are achieved by simple adjustments of the amount of water. The result of this formation mechanism investigation reveals that the amount of water and the reaction time make significant contributions to the growth of Zn-doped In2O3 nanostructures. The driving forces for the formation of the nanostructures are the precipitation–dissolution–renucleation–growth and Ostwald ripening processes based on time-dependent experimental results. The gas-sensing properties of Zn-doped In2O3 nanocages and HSNs have shown high sensitivity toward formaldehyde (HCHO) vapor at a relatively low operating temperature. Note that the gas sensor fabricated with Zn-doped In2O3 HSNs exhibit a higher and faster response than those fabricated with Zn-doped In2O3 nanocages due to the larger surface area and the decreasing size of the particle.
TL;DR: Au nanoparticles with different sizes were introduced into the nanocages of a mesoporous material SBA-16 with the aid of chemical modification, leading to new Au-supported catalysts Au/SBA16.
Abstract: Au nanoparticles with different sizes were introduced into the nanocages of a mesoporous material SBA-16 with the aid of chemical modification, leading to new Au-supported catalysts Au/SBA-16. These catalysts were characterized with Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microspectroscopy (TEM), N2 sorption, and X-ray photoelectron microspectroscopy (XPS). These results revealed that uniform Au nanoparticles with sizes of a few nanometers were successfully positioned inside the nanocages of SBA-16. Such catalysts were catalytically active in the oxidative esterification of various alcohols even including less reactive straight-chain alcohols. It was found that the activity of this catalyst strongly depended on the Au loading, and the Au loading of 5 wt % (corresponding to Au particles of 2–3 nm in sizes) led to the highest activity. Its activity was much higher than those of the analogous catalysts prepared from commercial silica gel as well as SBA-...
TL;DR: In this article, the performance of carbon nanocages (CNCs) with diameters of about 200∼500 nm has been evaluated by discharge/charge measurement and electrochemical impedance spectroscopy, which showed that the CNCs displayed excellent cycling performance and good rate capability with no noticeable capacity fading up to 50 cycles at current densities of 100, 300 and 500 mA g−1.
Abstract: Carbon nanocages (CNCs) with diameters of about 200∼500 nm have been synthesized by a simple method. The electrochemical properties of the CNCs as anode materials were evaluated by discharge/charge measurement and electrochemical impedance spectroscopy. Results showed that the CNCs displayed excellent cycling performance and good rate capability with no noticeable capacity fading up to 50 cycles at current densities of 100, 300 and 500 mA g−1. Their electrochemical properties were significantly improved after annealing treatment of the CNCs at 600 °C. For example, the CNCs(2)-annealed exhibited much better electrochemical performance with a high reversible capacity of 520 mAh g−1 after 50 cycles at current density of 100 mA g−1. A discharge capacity of 380 mAh g−1 can be obtained after 50 cycles at high current density of 500 mA g−1. The results of the Raman, thermal gravimetric and electrochemical impedance analysis indicated that the graphitization degree, electronic conductivity and charge-transfer rate of the CNCs have been improved after annealing treatment.
TL;DR: This paper describes the synthesis of Pd@M(x)Cu(1-x) (M = Au, Pd, and Pt) nanocages with a yolk-shell structure through galvanic replacement reactions that involve PD@Cu core-shell nanocubes as sacrificial templates and ethylene glycol as the solvent.
Abstract: NSF [DMR-1215034]; Georgia Institute of Technology; China Scholarship Council (CSC); U.S. Department of Energy, Basic Energy Sciences, by the Materials Sciences and Engineering Division [DE-AC02-98CH10886]
TL;DR: In this paper, a polyhedral hollow structure (PHS) with hollow interior and high geometrical symmetry is successfully prepared via a novel in situ oxidative etching method at room temperature.
Abstract: Well-defined polyhedral hollow structures (PHSs) Cu 2 O with hollow interior and high geometrical symmetry are successfully prepared via a novel in situ oxidative etching method at room temperature. X-ray power diffraction (XRD), field-emission scanning electron microscope (FESEM), and high-resolution transmission electron microscopy (HRTEM) techniques were employed to elaborately characterize the structure and morphology of the as-prepared samples. These PHSs Cu 2 O with hollow interiors and open “window” show effective-applied and good-diffusion structure for the gas-sensing application, which will exhibit short good response, response/recovery times and good reproducibility to ethanol. It is found that type-I nanocages Cu 2 O have a response of 8.6–50 ppm ethanol at the optimal operating temperature of 210 °C and the response time is within 23.7 s.
TL;DR: This work demonstrates successful cross-linking by click chemistry of stabilizers around paclitaxel NCs to form polymeric "nanocages", which retained the particulate drug through a combination of physical entrapment and physisorption.
Abstract: Many potent drugs are difficult to administer intravenously due to poor aqueous solubility. One validated approach for addressing this issue is to process them into colloidal dispersions known as “nanocrystals” (NCs). However, NCs possess high-energy surfaces that must be stabilized with surfactants to prevent aggregation. In addition, the stabilizer provides a means of anchoring targeting moieties to the NCs for achieving deposition or uptake at specified locations. Nevertheless, a critical challenge is that the surfactant (and consequently the targeting agents) can be shed upon high dilution. This work demonstrates successful cross-linking by click chemistry of stabilizers around paclitaxel NCs to form polymeric “nanocages”. Cross-linking does not cause aggregation, as evidenced by transmission electron microscopy, and the nanocages retained the particulate drug through a combination of physical entrapment and physisorption. Size measurements by dynamic light scattering showed that nanocages act as ster...
TL;DR: In this paper, single-crystalline TiOF 2 nanocubes with edge length of around 200-300nm have been synthesized under hydrothermal conditions using titanium (IV) isopropoxide (TIP) as titanium source, HF as etchant.
TL;DR: In this article, a microwave hydrothermal method was used to synthesize hollow microspheres composed of hundreds of nanorods, and the evolution process of BiVO4 with different microstructures indicated that the amount of EDTA added played a crucial role in determining the shape of the samples.
TL;DR: It is reported that the water oxidation activity can be significantly increased by confining ruthenium molecular catalysts, such as RuII(bda)(pic)2, in the nanocage of SBA-16, which provides a new strategy for the preparation of highly efficient solid-hosted catalysts for water oxidation.
Abstract: Here, we report that the water oxidation activity can be significantly increased by confining ruthenium molecular catalysts, such as RuII(bda)(pic)2, in the nanocage of SBA-16. The TOF of RuII(bda)(pic)2 confined in the nanocage increased from 1.2 to 8.7 s−1 by simply increasing the number of RuII(bda)(pic)2 molecules from one to seven in each nanocage, which is direct evidence for the “cooperative activation” mechanism involved in a binuclear reaction pathway for water oxidation reactions. The TOF of RuII(bda)(pic)2 confined in the nanocage can be as high as two times that of the homogeneous RuII(bda)(pic)2 due to the enhanced “cooperative activation” in the limited space of nanocages. Moreover, preliminary kinetic studies suggest that the stability of the molecular catalysts can be greatly improved after confinement in the nanocage. This strategy not only provides a new strategy for the preparation of highly efficient solid-hosted catalysts for water oxidation, but also gives direct evidence for the oxygen evolution mechanism.
TL;DR: This work describes a novel strategy for the fabrication of plasmonic nanopowders (dried gold nanoparticles) by using wet chemical nanoparticle synthesis, PEG-SH functionalization, and a standard freeze-drying technique, which results in redispersed gold nanorods, attractive candidates for plAsmonic photothermal therapy in clinical settings.
Abstract: We describe a novel strategy for the fabrication of plasmonic nanopowders (dried gold nanoparticles) by using wet chemical nanoparticle synthesis, PEG-SH functionalization, and a standard freeze-drying technique. Our strategy is illustrated by successful fabrication of different plasmonic nanopowders, including gold nanorods, gold-silver nanocages, and gold nanospheres. Importantly, the dried nanoparticles can be stored for a long time under usual conditions and then can easily be dissolved in water at a desired concentration without such hard manipulations as sonication or heating. Redispersed samples maintain the plasmonic properties of parent colloids and do not form aggregates. These properties make pegylated freeze-dried gold nanoparticles attractive candidates for plasmonic photothermal therapy in clinical settings. In this work, redispersed gold nanorods were intravenously administered to mice bearing Ehrlich carcinoma tumors at doses of 2 and 8 mg (Au)/kg (animal). Particle biodistribution was measured by atomic absorption spectroscopy, and tumor hyperthermia effects were studied under laser NIR irradiation. Significant tumor damage was observed only at the higher dose of the nanorods.
TL;DR: The surface of gold nanocages are functionalized with SV119, a synthetic small molecule specific to sigma-2 receptors, and the capability of this new class of conjugates for targeting cancer cells is demonstrated.
Abstract: We have functionalized the surface of gold nanocages with SV119, a synthetic small molecule specific to sigma-2 receptors, and then demonstrated the capability of this new class of conjugates for targeting cancer cells.
TL;DR: In this paper, both luminescent carbon nanoparticles (CNPs) and carbon nanocages (CNCs) were simultaneously synthesized using laser ablation of carbon black suspension in poly(ethylene glycol) using the open Z-scan technique at the laser wavelength of 532 nm.
Abstract: Both luminescent carbon nanoparticles (CNPs) and carbon nanocages (CNCs) were simultaneously synthesized using laser ablation of carbon black suspension in poly(ethylene glycol) The formation of luminescent CNPs and CNCs depends on the size of carbon black and the laser power density The optical limiting (OL) measurements of luminescent CNPs, CNCs and their mixture were performed using the open Z-scan technique at the laser wavelength of 532 nm The mixture of luminescent CNPs and CNCs shows much stronger OL response than carbon black, luminescent CNPs and CNCs in the PEG500N solution The luminescent CNPs can help to enhance the OL effects of CNC suspensions
TL;DR: The first application of Ag nanocubes, Au/ Ag alloy nanoparticles, and Au/Ag nanocages in a multiplexed dot immunoassay is reported, based on the staining of analyte drops on a nitrocellulose membrane strip by using multicolor nanoparticles conjugated with biospecific probing molecules.
Abstract: We report the first application of Ag nanocubes, Au/Ag alloy nanoparticles, and Au/Ag nanocages in a multiplexed dot immunoassay. The assay principle is based on the staining of analyte drops on a nitrocellulose membrane strip by using multicolor nanoparticles conjugated with biospecific probing molecules. Nanoparticles were prepared by a galvanic replacement reaction between the Ag atoms of silver nanocubes and Au ions of tetrachloroauric acid. Depending on the Ag/Au conversion ratio, the particle plasmon resonance was tuned from 450 to 700 nm and the suspension color changed from yellow to blue. The particles of yellow, red, and blue suspensions were functionalized with chicken, rat, and mouse immuno gamma globulin (IgG) molecular probes, respectively. The multiplex capability of the assay was illustrated by a proof-of-concept experiment involving simultaneous one-step determination of target molecules (rabbit anti-chicken, anti-rat, and anti-mouse antibodies) with a mixture of fabricated conjugates. Under naked eye examination, no cross-colored spots or nonspecific bioconjugate adsorption were observed, and the low detection limit was about 20 fmol.