Nano

Gold nanorods (AuNRs) have been considered as suitable materials for diverse biomedical applications in controlling cell behaviors. The nanoisland system with well-dispersed silica coated Au nanorods (Si-AuNRs) was used to demonstrate the enhanced cell growth of normal and cancer cells (MDA-MB-231 mammalian breast cancer cells) from the induced expressions of the heat shock proteins (HSPs). The over-expressions of HSP could help in protein folding in cell proliferations and growths of both the normal and cancer cells. In the current study, interesting mechanisms of cancer cell growth with Si-AuNRs than the conventional systems, such as incubator, would be presented. We believe that the growth of cancer cells in near infrared (NIR) region using Si-AuNRs induced the activities of HSPs, which could help the protein folding in cell growth and survival in comparison to the cells grown in the incubator only. The cell growth enhancing technology could be expanded in diverse applications in cell culture systems.

The green synthesis of gold nanoparticles (Au NPs) for catalytic and biological applications has been drawing great attention. To compare with plant extracts, the polysaccharides may be good reducing and stabilizing agents. In this work, we describe the preparation of longan polysaccharide stabilized gold nanoparticles (Au_n-LP NPs) by reduction of gold ions using a green synthetic method. The formation of gold nanoparticles (Au NPs) was confirmed by UV-Vis spectra. TEM showed that Au NPs had a small size (7.8–15.6nm) and were highly dispersed without any aggregation. XPS confirmed that the surface elemental composition of Au_n-LP NPs was C, O, and Au. DLS demonstrated that Au_n-LP NPs had good stability and negative zeta potential. In addition, Au_n-LP NPs had high catalytic activity for the reduction of 4-nitrophenol. More importantly, Au_n-LP NPs had ignorable cytotoxicity towards HeLa cells and showed good antioxidant activity. Taken together, the results indicated that longan polysaccharide can be used as reducing agents and stabilizers for the preparation of metallic nanoparticles, and the product had wide applications.

The olivine LiFePO₄ with various morphologies and different growth lattice planes was prepared by a controllable hydrothermal method with changing precursor concentration and using phytic acid as phosphorus source. The microstructure, crystal orientation and electrochemical performance of the prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and charge–discharge tests. The results show that the morphologies of all samples change from spindle-like to hierarchical plate-like and then to long plate-like shape, and the main exposed facets transform from (100) to (001). This indicates that the precursor concentration and phytic acid play important roles in exposing facets and controlling the morphology of LiFePO₄. In order to illustrate these phenomena, a reasonable assembly process is provided and the formation is explained. Li ion diffusion coefficient along [100] and [001] directions was calculated by using electrochemical impedance spectroscopy (EIS). The results show that the diffusion coefficient of (100) facet is higher than that of (001) facet, indicating a good electrochemical performance for (100) facet. In addition, the capacity test is carried out, which also confirms the above results. With the precursor concentration of 0.5M, the obtained LiFePO₄ with self-assembled hierarchical structure, smaller size and (100) facet shows the best electrochemical performance: 162.1mAh/g at 0.1C and 112.4mAh/g at 10C. Using phytic acid as phosphorus source and controlling precursor concentration to prepare high performance LiFePO₄ open up a new prospect for the production of cathode materials for lithium ion batteries.

Aggravating environmental problems have driven the unprecedented development of sustainable materials. Treatments of environmental pollutants with biomass-based sustainable materials are catching attention of more researchers. In the present work, a biomass-based strategy was developed to prepare sustainable molecularly imprinted nanocomposite membranes (S-MINMs). Based on this strategy, biomass-activated carbon nanoparticles (ACNPs) as the porous filler were integrated into the porous cellulose acetate (CA)/chitosan (CS) hybrid membranes to synthesize renewable and easy degradable basal membranes. The specific recognition sites were fabricated from simple free radical polymerization method, and using methacrylic acid (MAA) and acrylamide (Am) as functional monomers, we obtain improved adsorption capacity on tetracycline (TC, template molecule). Performance of S-MINMs was evaluated by adsorption isotherm, adsorption kinetics, perm-selectivity, reusability and biodegradability. Results indicated that the as-prepared S-MINMs not only exhibited desirable biodegradability, but also possess superior adsorption and separation performance toward TC (15.99mg g${}^{-1}$ for adsorption capacity and 4.91 for perms-selectivity factor). The method developed here shows great potential for development of sustainable membranes for selective separation of various pollutants.

In this present study, graphene oxide (GO) was used as a secondary chain extender and a functional modification assistant to fabricate a three-dimensional nanocomposite (GO-WPU) with waterborne polyurethane (WPU) through the prepolymer dispersion. The tensile strength and elastic modulus of GO-WPU with 0.2wt.% GO content, compared with those of pure WPU, increase by 170.38% and 50.9%, respectively. Even with a small amount of GO content added, the ultraviolet absorption rate significantly increased, whereas the ultraviolet transmittance decreased significantly. Other properties such as thermal stability and so on were also much enhanced. These results suggested that the functional nanocomposite GO-WPU prepared through the prepolymer dispersion will be an effective fabrication approach and have a wider scope of applications in functional coating materials and film materials.

Graphitic carbon nitride with nitrogen vacancies was successfully synthesized by the three-step method for the calcination of melamine, following urea-assisted hydrothermal and jacjoin calcination approach. The structural, surface, optical and electric properties were characterized by XRD, FT-IR, SEM, TEM, UV–Vis DRS, PL, N₂ physical adsorption/desorption and electrochemical methods, which proved that this strategy of modifying g-C₃N₄ by nitrogen vacancies not only increased the specific surface area, exposed more active sites, but also inhibited the recombination of photogenerated carriers on the surface of photocatalysts, resulting in the enhancement of photocatalytic and electrocatalytic performances. The photocatalytic activities were measured under visible light irradiation ($\lambda >420$nm), and their degradation efficiencies could be achieved for 99.8%, 55%, 100% and 99.7% corresponding to that of rhodamine B, acid orange II, methyl orange and methylene blue, respectively. The trapping experiments demonstrated that $•{\mathrm{\text{O}}}_2^{-}$ played an important role in the degradation process. In addition, being an active electrocatalyst, nitrogen-deficient g-C₃N₄ showed a lower Tafel slope, smaller overpotential and the more effective electrochemical surface area compared with that of bare g-C₃N₄ in neutral media. This work underlines the importance of defect engineering to promote catalytic performance, which can provide a simple and efficient way for modifying g-C₃N₄ and other N-based catalysts.

Cantilever-based piezoelectric has been the most preferred technique for energy harvesting and sensing application due to its simple design. The energy conversion efficiency has been continuously improved by exploring alternative cantilever geometries by increasing the stress distribution on the beam surface. In this paper, we have introduced half elliptical and full elliptical profile modification in the cantilever structure to improve and uniformly distribute the stress at the beam surface. Stress distribution characteristics of the modified cantilever beams were investigated and compared using finite element analysis. Based on the theoretical and finite element analysis, cantilever beams were fabricated using 3D print technology. Fabricated cantilever beams were then used to investigate the piezoelectric performances of polyvinylidene fluoride (PVDF) in composite of barium titanate (BaTiO₃) nanoparticles in the form of electrospun composite nanofibers. FTIR analysis shows successful conversion of alpha phase to beta phase of PVDF and PVDF/BaTiO₃ nanocomposites. During 6Hz cyclic actuating experiment, maximum voltage output of 0.15V and 1.5nA current output were observed. The concept was proposed to replace MEMS-based sensor in hand tremor quantification to assist Parkinson disease management.

The interaction between colloidal gold nanoparticles (AuNPs) and lysozyme (Lyz) has been studied through spectroscopic and microscopic measurements, molecular docking simulation and colorimetric measurements to investigate corona formation and the mechanism, affinity, number of sites and stoichiometry of binding. Molecular docking simulation endorses that, at physiological pH, the interaction between basic NH₂ group of arginine and citrate ions is predominant than the interaction between citrate ions and the positive surface charge of the bare AuNPs that result in the desorption of citrate ions from Au surfaces and finally, electrostatic interaction between $-{\mathrm{\text{COO}}}^{-}$ group of arginine and positive charge surface of AuNPs results in the adsorption of Lyz on Au surfaces. As observed from Benesi–Hildebrand and fluorescence analyses, the ground state complex formation between Lyz and AuNPs requires several minutes, which is approximately 11 min in the present work to attain stoichiometric ratio 1:1. CD spectra indicate insignificant or no conformational change in the secondary structure of Lyz in the presence of AuNPs. The time variation of LSPR peak position and peak height in the presence of Lyz have been studied extensively through spectroscopic and microscopic measurements. Detailed discussion on the probable time-specific roles of change in local dielectric constant, plasmon coupling and electrostatic interaction on these variations has been presented. Colorimetric change of the AuNPs-Lyz system with time has been analyzed by measuring the red, blue and green color fractions as well as its correlation with the process of corona formation and aggregation has been investigated to propose a novel naked eye colorimetric approach of studying these processes in AuNPs-Lyz system.

In view of the importance of convenient and rapid H₂O₂ detection for biological analysis, we herein propose Ag nanoparticle (NP)-decorated silica microspheres as a probe for instant and non-enzymatic on-site colorimetric detection of H₂O₂. The surface hydroxyl groups of silica microspheres were reacted with (3-mercaptopropyl)trimethoxysilane to afford thiolated microspheres that subsequently bind Ag NPs. The oxidation of residual –SH groups on the silica surface to –S–S– moieties in the presence of H₂O₂ induces the aggregation of decorated microspheres and is accompanied by a color change. Sensor response is found to be proportional to H₂O₂ concentration in the range from 100nM to 1mM, with UV–Vis and colorimetric detection limits determined as 10${}^{-8}$M and 10${}^{-5}$M, respectively. The developed platform is successfully used to detect H₂O₂ in simulated human urine and is, therefore, concluded to be sufficiently stable and selective for practical applications.

LaFeO₃/NiO modified g-C₃N₄ nanosheets (L-N/CNS) were synthesized by a two-step method. HRTEM results showed that an intimate contact between LaFeO₃, NiO and N-CNS was successfully established. Ninety percent of phenol was degraded within 120min, and the hydrogen evolution rate of 171.2$\mu$molh${}^{-1}$g${}^{-1}$ was obtained over the L-N/CNS heterojunctions under the visible-light irradiation. It was higher than that of g-C₃N₄ nanosheets, NiO modified g-C₃N₄ and LaFeO₃/g-C₃N₄. The$\cdot$O${}_2^{-}$ radicals acted the crucial role in the photocatalytic degradation reaction. EIS, PL and time-resolved fluorescence spectra demonstrated that L-N/CNS possessed the highest charge separation efficiency. The intimate contact between LaFeO₃, NiO and g-C₃N₄ nanosheets promoted the separation and transfer of photo-induced electron–hole pairs and consequently prolonged the exciton lifetime, and implied more photo-induced electrons could be probably involved in the photocatalytic reactions on the surface of photocatalysts. Thus, the visible-light driven photocatalytic performances of L-N/CNS were effective. This work provided a feasible method to design and construct heterostructures for the exploitation of solar energy.

In this work, the 3D porous hierarchical MoS₂ nanostructures were prepared via a simple hydrothermal deposition method only utilizing titanium (Ti) mesh as a substrate. The as-synthesized uniform MoS₂ flower-like nanostructures were assembled by nanosheets composed of several stacking layers. The curved and rough surface of cylindrical Ti wire was beneficial to assembly of MoS₂ nanosheets into hierarchical architectures. Moreover, the electrochemical performance of the as-prepared MoS₂ nanostructured electrodes for capacitors was also investigated. The structural advantages lead to a remarkably improved pseudocapacitive property including high capacitance and durable cycling ability.

Cu-N-C electrocatalyst was successfully prepared with Cu-BTC and polyacrylonitrile as templates by electrospinning and in-situ growth method. The effect of various $N$-doped content on the electrochemical performance of the catalyst were investigated and the Cu-N-C-0.25 exhibited the best OER/ORR catalytic activities. When it was applied to the cathode of the zinc-air batteries, the power density of Cu-N-C-0.25 was 209.1mWcm${}^{-2}$, which exceeded that of the commercial Pt/C$+$IrO₂ hybrid catalyst (157mWcm${}^{-2}$). The excellent electrochemical performance may be attributed to large number of active sites and high specific surface area on Cu-N-C electrocatalyst. It will be a promising alternative to precious metal catalysts containing Pt, Ir or Ru and their oxides.

Photochromic materials aroused enormous interest due to their potential application for rewritable paper, smart labeling and sensor devices. In this paper, we proposed to dissolve spiropyran (SP, photochromic material) and polyacrylonitrile (PAN, polymer matrix) in dimethyl fumarate (DMF) to prepare photochromic nanofibers by electrospinning. The target SP compounds were featured by FTIR, ultraviolet (UV) and ¹HNMR, and the nanofibers were characterized by FTIR, UV-vis spectra, scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and contact angle (CA). The test results demonstrated that photochromic SP was synthesized successfully, and the nanofiber membrane possesses extraordinary color-converting properties including obvious color change from white to purple, reversible fast switching between two colors when exposed to UV light and achieve maximum color change in 1min, and switchable hydrophilic and hydrophobic properties as well as excellent photo-fatigue resistance over 20 cycles. In addition, it has good thermal stability allowing it to be used under harsh conditions. In view of the above characteristics, we believe that the as-prepared nanofiber film will be a promising reusable writing substrate.

Self-regulating temperature hyperthermia based on magnetic fluid with low Curie temperature is a moderately effective method for cancer treatment. The improvement of the properties of magnetic fluids is the key for application of this method. In this paper, Bi-doped LSMO magnetic nanoparticles were synthesized using a simple sol–gel method and coated by hyaluronic acid through high energy ball milling for their possible application in self-regulating temperature hyperthermia. The crystal structure, morphology, basic magnetic properties and heating properties of these nanoparticles in a high frequency magnetic field were investigated. It was found that the hyaluronic acid-coated La${}_{0.7}$Sr${}_{0.2}$Bi${}_{0.1}$MnO₃ magnetic nanoparticles, with an average particle diameter of $\sim$100nm and a Curie temperature of 48^∘C, possess outstanding induction heating properties. The saturation heating temperature, specific absorption rate and effective specific absorption rate are 48^∘C, 117W/g and 0.27W/g$•$kHz$•$(kA/m²), respectively.