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Electrostatically Directed Assembly of Nanostructured Composites for Enhanced Photocatalysis
摘要： It is well established that the activity of photocatalysts can be improved by deposition of redox catalysts, which can effectively extract the photogenerated charge carriers, enhance the rate of interfacial reactions, and thus suppress undesired recombination processes. For optimum performance, a high degree of control over the loading, size, and surface catalytic properties of redox catalyst particles is desirable. Herein, a novel, highly controllable, and versatile method for preparation of TiO2 catalyst composites is reported. It starts with the generation of “naked” (ligand-free) nanoparticles of CuOx or FeOx by pulsed laser ablation of metal oxide targets in water. In the next step, a nearly quantitative colloidal deposition of CuOx and FeOx nanoparticles onto anatase TiO2 substrate is achieved by adjusting the pH in order to establish electrostatic attraction between the colloids and the substrate. The resulting TiO2–CuOx and TiO2–FeOx assemblies with optimum catalyst amount (≈0.5 wt%) exhibit photocatalytic rates in degradation of 2,4-dichlorophenoxyacetic acid enhanced by a factor of ≈1.5 as compared to pristine TiO2 under simulated solar irradiation. The electrostatically directed assembly of TiO2 with ligand-free catalyst nanoparticles generated by pulsed laser ablation is thus demonstrated as a viable tool for preparation of composites with enhanced photocatalytic performance.
关键词： photocatalysis,titanium dioxide,laser ablation,colloidal deposition,nanoparticles
更新于2025-09-23 15:23:52
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Dual-emission color-controllable nanoparticle based molecular imprinting ratiometric fluorescence sensor for the visual detection of Brilliant Blue
摘要： Single-component dual-emission nanoparticles were synthesized by chelating the organic ligand 8-hydroxyquinoline (HQ) to the surface of CdTe/ZnS quantum dots, namely CdTe/ZnQ2, and were used to construct a novel mesoporous structured molecular imprinting ratiometric fluorescence sensor by facile one-pot sol-gel polymerization for the visual detection of Brilliant Blue. The CdTe/ZnQ2 had bimodal fluorescence belonging to CdTe and ZnQ2 segments, respectively; significantly, the emission wavelength of CdTe was optimized to be 630 nm for the largest overlap with the absorption spectrum of Brilliant Blue. Consequently, fluorescence resonance energy transfer (FRET) efficiency was greatly enhanced, resulting in ideal determination. A favorable linearity toward Brilliant Blue was obtained within 0–1.0 μmol?L-1 along with profuse color evolution from orange to yellowish orange to yellowish green to green, and a high detectability of 8.8 nmol?L-1 was offered. Excellent recognition selectivity for Brilliant Blue over possibly coexistent food colorants was demonstrated, with a high imprinting factor of 7.1. Furthermore, endogenous Brilliant Blue was detected ranging from 0.21–41.03 mg/kg in six typical food samples with relative standard deviations lower than 3.5%, and the results agreed well with that afforded by conventional methods. Using Brilliant Blue as a model, this dual-emission color-controllable nanoparticle based imprinting ratiometric fluorescence sensor provided promising perspectives for the highly selective and sensitive, rapid, visual detection of colored substances in complicated matrices.
关键词： Molecular imprinting,Brilliant Blue,Dual-emission nanoparticles,Ratiometric fluorescence,Visual detection
更新于2025-09-23 15:23:52
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Highly selective and sensitive detection of catecholamines using NaLuGdF4:Yb3+/Er3+ upconversion nanoparticles decorated with metal ions
摘要： We developed a novel optical sensor for sensitive and selective detection of catecholamines based on upconversion nanoparticles (UCNPs) decorated with different metal ions (UCNP-Men+). 1,2-ethanedithiol was chosen as a surface additive to synthesize the NaLuGdF4:Yb3+/Er3+ UCNPs by one-step at 200 °C. The as-prepared UCNPs exhibited a strong emission under the continuous excitation at 980 nm. It was found that catecholamines could be more effectively detected in the presence of UCNP-Fe3+, whereas, dopamine and epinephrine were detected selectively using UCNP-Li+ and UCNP-Cu2+ sensors, respectively. Under the optimum conditions, the limit of detections (LODs) for catecholamines, dopamine, and epinephrine are 2.8, 2.5, and 2.4 nM, respectively, with good linearity in the range of 5–320 nM for total catecholamines and 5–30 nM for dopamine and epinephrine. The developed method has been successfully applied to detect dopamine and epinephrine in human urine samples with good accuracy and satisfactory recovery.
关键词： Upconversion nanoparticles,Human urine,Metal ion decorated,Catecholamines,1,2-ethanedithiol
更新于2025-09-23 15:23:52
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Magnetic metamorphosis of structurally enriched sol-gel derived SnO2 nanoparticles
摘要： Pure SnO2 and aliovalent substituted polycrystalline Sn0.98?xLa0.02ZnxO2 (x = 0.02, 0.04 and 0.06) samples have been synthesized via sol-gel technique. Rietveld re?nement of X-ray di?raction (XRD) patterns con?rm the single phase tetragonal rutile-type (P mnm 42/) crystalline structure for all the synthesized samples. Crystallite size from XRD analysis is found to decrease from 14 nm to 11 nm as x increases from 0 to 0.06 in Sn0.98?xLa0.02ZnxO2 matrix. Transmission Electron Microscopy further reveals the decrease in average crystallite size from 7 nm for pure SnO2 to 5 nm with increase in Zn2+ concentration in system. Morphological study through Field Emission Scanning Electron Microscopy reveals the agglomeration of nanoparticles on increasing the Zn concentration. The room temperature photoluminescence (PL) measurements mark the change in peak intensity centered around 300–450 nm upon La and Zn co-doping into SnO2 lattice. Deconvolution of PL peak unveil the presence of defects/vacancies and local disorders in (La, Zn) co-doped SnO2 matrix. Further, the magnetic properties have been studied using Vibrating Sample Magnetometer, which envisage the room temperature ferromagnetism (RTFM) in nonmagnetic La3+ and Zn2+ ion modi?ed SnO2. The observed RTFM in (La, Zn) co-doped SnO2 is mainly due to oxygen vacancies which is also supported by PL results.
关键词： Rietveld re?nement,RTFM,SnO2 nanoparticles,Defect states
更新于2025-09-23 15:23:52
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Improvement of Cancer Therapy by TAT Peptide Conjugated Gold Nanoparticles
摘要： Gold nanoparticles (AuNPs) are potent anticancer agent that controls drug delivery to tumors. Here, we describe the identification of TAT-Cell Penetrating Peptide (TAT-CPP) conjugated AuNPs, as a novel delivery system to the cancerous regions. TAT-peptide was modified to BSA-AuNPs [Bovine Serum Albumin (BSA) coated AuNPs] electrostatically. The binding efficiency of TAT-AuNPs was tested using Dynamic Light Scattering, UV–Vis spectrophotometer and Zeta potential. The nano-complex (BSA-AuNPs; with and without TAT-CPP) was applied against Rhabdomyosarcoma and Murine fibroblast (L20B) cancer lines, in vitro. Cytotoxicity effect was evaluated by MTT assay at 0.125, 0.25, 0.5 and 1 mg/ml concentration for 24 and 48 h incubation time. Results demonstrated that TAT-(BSA-AuNPs) exhibits significant toxicity for both cancer cell lines. TAT-CPP has improved cancer cell reduction, where cytotoxicity more than 80% has been achieved. This study was conducted to achieve the simplicity and facility in cancer therapy, where the small-sized TAT-AuNPs acts as a simple therapeutic agent in the specific delivery and targeting the deep, irregular, and complicated cancer regions in the human body. Therefore, it could replace other cancer treatment techniques, even dispense the laser irradiation in the phototherml therapy.
关键词： BSA,CPP,Small sized gold nanoparticles,Cancer treatment,TAT
更新于2025-09-23 15:23:52
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Nanomechanical, Mechanical Responses and Characterization of Piezoelectric Nanoparticle-Modified Electrospun PVDF Nanofibrous Films
摘要： Limitless implementations of nanofibrous membrane show the importance of understanding the nanomechanical responses for water purification and piezoelectric nanogenerator applications. Here, the polyvinylidene fluoride (PVDF) electrospun nanofibrous films doped by 0.01, 0.05 and 0.1 wt% of ZnO nanoparticles were prepared in the method of electrospinning. Characterizations of PVDF nanocomposite fibrous films were inspected using field emission scanning electron microscope, thermogravimetric analysis, water contact angle, uniaxial tensile test and nanoindentation technique. The influence of minimal concentration of piezoelectric nanoparticles on the morphological, water contact angle, dynamic water contact angle, piezoelectric, thermal and mechanical stabilities of nanocomposite fibrous films was examined. The nanoscale mechanical properties of the PVDF/ZnO nanofibrous films were performed by nanoindentation technique at different spots of nanofibrous mat to examine the elastic–plastic behavior of membranes. The eventual ZnO nanoparticle-modified nanofibrous membranes have been shown nano-level fibers, considerable hydrophilicity and preferable thermal, mechanical and piezoelectric properties. The doping of polymer by 0.1 wt% of ZnO nanoparticles exposed significant enhancement of thermal, mechanical and nanomechanical responses of the melting temperature 2% (170–173 °C), tensile strength 20% (2.418 MPa), elastic modulus 18% (2.418 GPa) and hardness 60% (235 MPa) and piezoelectric coefficient 13.42 pC/N of the nanofibrous films. These understandings of nanoscale properties are highly promising in the development of sensor and actuators, biomedical, energy harvesting and water filtration devices.
关键词： Thin films,Nanomechanical responses,Nanofibers,PVDF,Piezoelectric nanoparticles,Electrospinning
更新于2025-09-23 15:23:52
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Improvement of nickel nanocomposite coatings by combining zinc-doped TiO2 nanoparticles
摘要： Pure nickel and compound of nickel coatings (Ni-TiO2 and Ni-Zn/TiO2) were coated on the steel material using Watts bath with the electrodeposition conditions. Effect of the nanoparticle type and current density on the coating structure, surface morphology of the coating, hardness of the coating, and the corrosion properties of the coatings are presented. Phase and elemental analysis of the coatings were carried out by XRD and EDS techniques, respectively. SEM was used to investigate the surface morphology of the coatings, and Vickers microhardness values were measured to determine the hardness variation of the coatings. NaCl solution (3.5 wt%) was used to evaluate the corrosion properties of the coatings by the potentiodynamic polarization tests. Corrosion current density of 2.890 μA/cm2 for pure nickel coating was improved to 0.379 μA/cm2 by the coating of Zn-doped TiO2 nanoparticles at the 7A/dm2 current density. Microhardness of the Zn-doped TiO2 coating was improved compared to the pure Ni coating.
关键词： Sol-gel processes,Metal matrix composites,Nanoparticles,Composite coatings
更新于2025-09-23 15:23:52
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Colorimetric detection of normetanephrine, a pheochromocytoma biomarker, using bifunctionalised gold nanoparticles
摘要： A simple and effective colorimetric method for the detection of normetanephrine (NMN), an O-methylated metabolite of norepinephrine, using functionalised gold nanoparticles is described. This metabolite is an important biomarker in the diagnosis of adrenal tumours such as pheocromocytoma or paraganglioma. The colorimetric probe consists of spherical gold nanoparticles (AuNPs) functionalised with two different ligands, which specifically recognize different functional groups in normetanephrine. Thus, a benzaldehyde-terminated ligand was used for the recognition of the amino alcohol moiety in NMN, by forming the corresponding oxazolidine. On the other hand, N-acetyl-cysteine was chosen for the recognition of the phenolic hydroxyl group through the formation of hydrogen bonds. The selective double molecular recognition between the probe and the hydroxyl and the amino-alcohol moieties of normetanephrine led to interparticle-crosslinking aggregation resulting in a change in the color of the solution, from red to blue, which could be observed by naked eye. The probe was highly selective towards normetanephrine and no color changes were observed in the presence of other neurotransmitter metabolites such as homovanillic acid (HVA) (dopamine metabolite), 5-hydroxyindoleacetic acid (5-HIAA) (serotonin metabolite), or other biomolecules present in urine such as glucose (Glc), uric acid (U.A), and urea. Finally, the probe was evaluated in synthetic urine with constituents that mimic human urine, where a limit of detection of 0.5 mM was achieved.
关键词： Gold nanoparticles,Aggregation,Pheocromocytoma,Normetanephrine,Colorimetric detection
更新于2025-09-23 15:23:52
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Ultrasmall Au-Ag Alloy Nanoparticles: Protein-directed Synthesis, Biocompatibility and X-ray Computed Tomography Imaging ?
摘要： The ultrasmall sizes of nanoparticles have attracted significant attention for potential application in the fields of catalysis and nanomedicine. Herein, we reported on the green preparation and X-ray computed tomography (CT) imaging of ultrasmall bimetallic bovine serum albumin-directed gold-silver (Au-Ag@BSA) nanoparticles (2–4 nm) using BSA as a stabilizing and template-directed agent. Further, the effects of synthesis condition were systematically explored to prepare products by adjusting the different molar ratios of Au/Ag. The resulting Au-Ag@BSA nanoparticles exhibited the spherical shape, well-dispersed ability, as well as long-term room-temperature stability. The cytotoxicity effects of Au-Ag@BSA nanoparticles on A549 and MCF-7 cells were compared with those of individual Ag nanoparticles, and the results indicated lower cytotoxicity effect by Au-Ag@BSA nanoparticles. Furthermore, the in vivo toxicity of Au-Ag@BSA nanoparticles was investigated in the early-stage zebrafish embryos. The results indicate that there are not any obvious changes of survival and hatching percentages at multiple growth stages (4-120 hpf) even a high level of Au-Ag@BSA nanoparticles (up to 80 mM), revealing the good biocompatibility. Interestingly, a rational design of Au/Ag molar ratio (3:2) surprisingly possessed the enhanced CT performances compared to the Au nanoparticles and iohexol. Accordingly, this study highlights a new prospect in the green preparation of ultrasmall alloy nanomaterials with good biocompatibility and will be of great interest in developing CT contrast agent, catalyst as well as drug delivery carrier.
关键词： green synthesis,Au-Ag@BSA nanoparticles,biocompatibility,zebrafish embryos,enhanced CT imaging
更新于2025-09-23 15:23:52
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Cholesterol Functionalization of Gold Nanoparticles Enhances Photo-Activation of Neural Activity
摘要： Gold nanoparticles (AuNPs) attached to the extracellular leaflet of the plasma membrane of neurons can enable the generation of action potentials (APs) in response to brief pulses of light. Recently described techniques to stably bind AuNP bioconjugates directly to membrane proteins (ion channels) in neurons enable robust AP generation mediated by the photoexcited conjugate. However, a strategy that binds the AuNP to the plasma membrane in a non-protein-specific manner could represent a simple, single-step means of establishing light-responsiveness in multiple types of excitable neurons contained in the same tissue. Based on the ability of cholesterol to insert into the plasma membrane, here we test whether AuNP functionalization with linear dihydrolipoic acid-poly(ethylene) glycol (DHLA-PEG) chains that are distally terminated with cholesterol (AuNP-PEG-Chol) can enable light-induced AP generation in neurons. Dorsal root ganglion (DRG) neurons of rat were labelled with 20 nm diameter spherical AuNP-PEG-Chol conjugates wherein ~30% of the surface ligands (DHLA-PEG-COOH) were conjugated to PEG-Chol. Voltage recordings under current-clamp conditions showed that DRG neurons labeled in this manner exhibited a capacity for AP generation in response to microsecond and millisecond pulses of 532 nm light, a property attributable to the close tethering of AuNP-PEG-Chol conjugates to the plasma membrane facilitated by the cholesterol moiety. Light-induced AP and subthreshold depolarizing responses of the DRG neurons were similar to those previously described for AuNP conjugates targeted to channel proteins using large, multicomponent immunoconjugates. This likely reflected the AuNP-PEG-Chol’s ability, upon plasmonic light absorption and resultant slight and rapid heating of the plasma membrane, to induce a concomitant transmembrane depolarizing capacitive current. Notably, AuNP-PEG-Chol delivered to DRG neurons by inclusion in the buffer contained in the recording pipette/electrode enabled similar light-responsiveness, consistent with the activity of AuNP-PEG-Chol bound to the inner (cytofacial) leaflet of the plasma membrane. Our results demonstrate the ability of AuNP-PEG-Chol conjugates to confer timely stable and direct responsiveness to light in neurons. Further, this strategy represents a general approach for establishing excitable cell photosensitivity that could be of substantial advantage for exploring a given tissue’s suitability for AuNP-mediated photo-control of neural activity.
关键词： nanoparticle functionalization,cholesterol,action potential,neural photo-activation,optocapacitance,gold nanoparticles,photosensitivity,dorsal root ganglion cell
更新于2025-09-23 15:23:52