Preparation, Electrochemical Property and Application in Bulk-modified Electrode of Dawson-type Phosphomolybdate-doped Polypyrrole Composite Nanoparticles

IntroductionPolyoxometalates(POMs)have attracted much at-tention in catalysis,medicine,bioanalysis and materialsciences due to their chemical,structural and electro-nic versatility in recent years[1—3].One of the most im-portant properties of POMs is the…     

Polyaniline／Prussian Blue Composite Film Electrochemical Biosensors for Cholesterol Detection

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Gold Nanoparticles/Biphenol–biphenoquinone for Ultra-trace Voltammetric Determination of Captopril

This study aims to synthesize gold nanoparticles/biphenol–biphenoquinone (AuNPs−BOH−BQ) and to study its application as a novel heterogeneous electron transfer mediator to modify carbon paste electrode (CPE/Au NPs−BOH−BQ) for ultra-trace determination of captopril (CP). Characterization results show well dispersed Au NPs with sizes in the range of 8.0–10.5 nm. Under optimized conditions, the calibration plot was linear from 1 to 5×10⁴ nM (two segments, 1–150 nM and 0.15–50.0 μM) and the detection limit was calculated to be 0.4 nM (S/N=3). Finally, the suggested sensor showed stable and reliable responses to CP in CP pharmaceutical tablet and urine samples.     

Gold Nanoparticles Monolayer Doping PEDOT : PSS Janus Film for Hydrogen Sulfide Sensor

AuNPs monolayer doping Poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT : PSS) film on interdigitated electrode had been fabricated into AuNPs/PEDOT : PSS Janus film sensor to detect hydrogen sulfide (H₂S). The results show that the Janus film sensors have a wide measurement range of H₂S concentration. The sensitivity of PEDOT : PSS/AuNPs sensor grows up with the thickness of Janus film increases. The resistance response of AuNPs Janus film was affected little by the rough surface states of PEDOT : PSS film. In addition, the PEDOT : PSS/AuNPs film sensor had been used again to detect H₂S. This work presents a platform to inspire a novel high sensitive chemiresistive sensor via nanoparticles monolayer.     

Preparation and Characterization of Heparin‐Stabilized Gold Nanoparticles

A simple method for preparing gold nanoparticles in aqueous solution has been developed by using glycosaminoglycan‐heparin as reducing and stabilizing agent and HAuCl₄ as precursor. The obtained gold nanoparticles were characterized by UV‐vis spectroscopy, resonance light scattering spectroscopy (RLS), transmission electron microscopy (TEM) and electrophoresis technology. The influence of reactant concentration for the preparation of gold nanoparticles was investigated. The results indicated that the gold nanoparticles carried negative charges in the aqueous solution and the size and shape of the gold nanoparticles could be controlled by changing the concentration of the heparin. Moreover, the gold nanoparticles obtained with relatively high concentration of heparin were very stable and had relative narrow size distribution.     

Electroactive Composite Pd–Polypyrrole and Its Catalytic Properties in the Reaction of Styryl Bromide Cyanation

A composite material in the form of powder is synthesized by a redox reaction in mixed aqueous solution of Pd(NH₃)₄Cl₂ + pyrrole. The composite consists of polypyrrole globules with palladium nanoparticles uniformly distributed inside the latter. Being applied as a film on the electrode surface, both components of this material exhibit redox activity. Palladium particles inside the composite exhibit catalytic properties in cyanation of styryl bromides, a reaction widely used in fine organic synthesis.     

Janus Gold Nanostars–Mesoporous Silica Nanoparticles for NIR-Light-Triggered Drug Delivery

Janus gold nanostar–mesoporous silica nanoparticle ( AuNSt–MSNP ) nanodevices able to release an entrapped payload upon irradiation with near infrared (NIR) light were prepared and characterized. The AuNSt surface was functionalized with a thiolated photolabile molecule ( 5 ), whereas the mesoporous silica face was loaded with a model drug (doxorubicin) and capped with proton-responsive benzimidazole-β-cyclodextrin supramolecular gatekeepers ( N 1 ). Upon irradiation with NIR-light, the photolabile compound 5 photodissociated, resulting in the formation of succinic acid, which induced the opening of the gatekeeper and cargo delivery. In the overall mechanism, the gold surface acts as a photochemical transducer capable of transforming the NIR-light input into a chemical messenger (succinic acid) that opens the supramolecular nanovalve. The prepared hybrid nanoparticles were non-cytotoxic to HeLa cells, until they were irradiated with a NIR laser, which led to intracellular doxorubicin release and hyperthermia. This induced a remarkable reduction in HeLa cells viability.     

Quick and Sensitive Determination of Fluoroquinolones by Capillary Electrophoresis–Potential Gradient Detection

Abstract

A rapid, capillary electrophoresis–potential gradient detection method was developed for determining three fluoroquinolones: rufloxacin, enoxacin, and moxifloxacin. The fluoroquinolones were baseline separated within 3.5 min with background electrolyte composed of 50 mM acetic acid and 6 mM potassium hydroxide at pH 3.7. For the first time, electrokinetic injection was applied in capillary electrophoretic separation of fluoroquinolones, and an average of ca. 10-fold improvement in detection limits was observed. The method was applied to a fortified chicken tissue sample with detection limits (S/N = 3) of 22–24 ng g^?1, suggesting the potential of the method for determining fluoroquinolone residues in real samples.     

Box–Behnken Experimental Design for the Synthesis of Magnetite–Polypyrrole Composite for the Magnetic Solid Phase Extraction of Non-steroidal Anti-inflammatory Drug Residues

A magnetite–polypyrrole composite adsorbent was synthesized and applied for the magnetic solid phase extraction of three non-steroidal anti-inflammatory drugs in aqueous solution and systematically investigated using Box–Behnken design. The synthesized composite adsorbent was characterized using Fourier-transform infrared spectroscopy, transmission electron microscopy, the Brunauer–Emmett–Teller method, vibrating sample magnetometry, and X-ray diffraction. The material was successfully modeled by Box–Behnken design (R²?=?0.94–0.98, p value: <0.001%) by monitoring the extraction efficiencies of naproxen, diclofenac sodium, and mefenamic acid. The analytes were determined using high-performance liquid chromatography with ultraviolet detection. The polymerization time was found to be the most significant factor, followed by amount of oxidant and monomer in the synthesis of the composite with a fixed Fe₃O₄ mass. Box–Behnken design was employed for the optimization of four parameters affecting the magnetic solid phase extraction: sample pH, salt addition, adsorption, and desorption time (R²?=?0.88–0.94). The optimized conditions for the procedure were validated, providing low detection limits (0.9–3.5?µg?L^?1) with good reproducibility (<7.16% relative standard deviation) and excellent recoveries (97.87–100.49%) for tap, river, and wastewater samples. The synthesized adsorbent demonstrated good adsorption efficiency for the simultaneous determination of the non-steroidal anti-inflammatory drug residues.     

Synthesis and Electrocatalytic Activity of 3Au?1Pd Alloy Nanoparticles/Graphene Composite for Bisphenol A Detection

In this study, a 3Au? 1Pd alloy nanoparticles/graphene composite (3Au? 1Pd alloy NPs/GN) with carboxyl groups and hydroxyl groups was prepared facilely by co‐reduction of graphene oxide (GO), HAuCl₄, K₂PdCl₄, with an Au? Pd alloy molar ratio of 3 : 1. The composite modified glass carbon electrode (GCE) showed a good performance for detecting bisphenol A (BPA) due to the enhanced electron transfer kinetics and large active surface area. The effective enrichment of BPA is attributed to the carboxyl groups and hydroxyl groups on the composite. According to the results of differential pulse voltammetry (DPV), the BPA oxidation current is linear to its concentration in the range of 10 nM–5.0 µM (R=0.998), and the detection limit is found to be 4.0 nM (S/N=3).     

Electrochemical Behavior and Application of Pirarubicin at Gold Nanoparticles–Modified Indium Tin Oxide Electrode

Abstract

A new type of gold nanoparticles–attached indium tin oxide electrode was made. By SEM and EDS, the as‐prepared gold nanoparticles–modified ITO electrode was characterized. This modified electrode has been used for the determination of pirarubicin (THP) in urine by cyclic voltammetry. Compared to a bare ITO electrode, the modified electrode exhibited a marked enhancement in the current response. Liner calibration curves are obtained in the range 5×10^?9mol/L～1.5×10^?6 mol/L with a detection limit of 1×10^?9 mol/L. The percentage of the recoveries ranged from 99.3% to 106.3%. The practical analytic utility of the method is illustrated by quantitative determination of THP in urine.     

Electrodeposition of Silver Nanoparticles on MWCNT Film Electrodes for Hydrogen Peroxide Sensing

Silver （Ag） nanoparticles were directly electrodeposited on multi-walled carbon nanotubes （MWCNT） in AgNO3/LiNO3 containing EDTA （ethylenediaminetetraacetic acid）. The structure and nature of the resulting Ag/MWNT composite were characterized by field emission scanning electron microscopy （FE-SEM）, transmission electron microscopy （TEM） and X-ray diffraction （XRD）, and the distribution shape of Ag nanoparticles was found to be dependent on the presence of EDTA. The modified electrode showed excellent electrocatalytic activity to redox reaction of hydrogen peroxide and the mechanism of hydrogen peroxide was partly reversible procession with oxidation and reduction peaks at 0.77 and -0.83 V, respectively. The oxidation and reduction peak currents were linearly related to hydrogen peroxide concentration in the range of 1×10^-6-3×10^-4 and 1 ×10^-8-7× 10^-4 mol·L^-1 with correlation coefficients of 0.996 and 0.986, and 3s-detection limit of 9 × 10^-7 and 7 × 10^-9 mol·L^-1.     

Preparation and Characterization of Gold Thin Film Electrode Modified by Microbe

Goldelectrodeisincommonuseinelectro-analysisbecauseofitsstabilityandcorrosionresisting.Herewereportanovelmethodforpreparationofgoldthinfilmelectrodemodifiedbymicrobe.Previousworksontheuseofmicrobetoadsorbthecompoundsofgoldandothermetalsweremainlyfocusedonrecoveryofnoblemetalsandtreatmentofwastedwater"=.Thebacteriamodifiedelectrodeshavebeenreportedindetectionofenzyme'andBOD'.Nowwereportthemethodofapplyingmicrobetopreparethegoldthinfilmelectrode.Thepreparationmethodissimpleandthegoldthinfilmel…     

γ-Glutamylcysteine- and Cysteinylglycine-Directed Growth of Chiral Gold Nanoparticles and their Crystallographic Analysis

Chiral optical metamaterials with delicate structures are in high demand in various fields because of their strong light–matter interactions. Recently, a scalable strategy for the synthesis of chiral plasmonic nanoparticles (NPs) using amino acids and peptides has been reported. Reported herein, 3D chiral gold NPs were synthesized using dipeptide γ-Glu-Cys and Cys-Gly and analyzed crystallographically. The γ-Glu-Cys-directed NPs present a cube-like outline with a protruding chiral wing. In comparison, the NPs synthesized with Cys-Gly exhibited a rhombic dodecahedron-like outline with curved edges and elliptical cavities on each face. Morphology analysis of intermediates indicated that γ-Glu-Cys generated an intermediate concave hexoctahedron morphology, while Cys-Gly formed a concave rhombic dodecahedron. NPs synthesized with Cys-Gly are named 432 helicoid V because of their unique morphology and growth pathway.     

Fluorinated PLGA Nanoparticles for Enhanced Drug Encapsulation and 19F NMR Detection

In the continuous search for multimodal systems with combined diagnostic and therapeutic functions, several efforts have been made to develop multifunctional drug delivery systems. In this work, through a covalent approach, a new class of fluorinated poly(lactic-co-glycolic acid) co-polymers (F-PLGA) were designed that contain an increasing number of magnetically equivalent fluorine atoms. In particular, two novel compounds, F₃-PLGA and F₉-PLGA, were synthesized and their chemical structure and thermal stability were analyzed by solution NMR, DSC, and TGA. The obtained F-PLGA compounds were proven to form in aqueous solution colloidal stable nanoparticles (NPs) displaying a strong ¹⁹F NMR signal. The fluorinated NPs also showed an enhanced ability to load hydrophobic drugs containing fluorine atoms compared to analogous pristine PLGA NPs. Preliminary in vitro studies showed high cell viability and the NP ability to intracellularly deliver and release a functioning drug.     

Characterization of a Novel Agarose–Nickel Composite Matrix for Protein Nanoparticles Affinity Chromatography in Expanded Bed

The novel agarose–nickel (Ag–Ni) expanded bed matrix was investigated with regard to suitability for practical recovery of nano-bioproducts (NBPs) such as protein nanoparticles as drug delivery carriers. The matrix was immobilized by Reactive Green 19 (RG19) dye–ligand and was subjected to biochemical evaluation through batch adsorption studies (isotherm and kinetic studies) and column chromatography of bovine serum albumin nanoparticles (BSA NPs) with average size of 85–95 nm as a model system. Based on adsorption isotherm investigations, the adsorption phenomenon appeared to follow the Langmuir isotherm model with maximum binding capacity of 24.9 mg/ml adsorbent. Subsequently adsorption data were modeled using the pseudo-first-order and pseudo-second-order kinetics equation. The results demonstrated that the adsorption process kinetics followed the pseudo-first-order kinetic model. The dynamic binding capacity (DBC) for BSA NP adsorption was calculated at various flow velocities which showed favorable column efficiency at relatively high flow rates. BSA NPs recovery was studied in the expanded bed column which resulted in 74 % recovery. The results indicated that the novel resin is a promising chromatographic medium for protein nanoparticle separation with high adsorption capacity and column efficiency at reasonably high flow rates. The generic application of such dye–ligand immobilized composite matrix for the adsorption and purification of BSA NPs as a nanoparticulate bioproduct was discussed.     

Self‐Organized Nanocomposite of Gold Nanoparticles and π‐Electron Organic Molecules

Aggregates of gold nanoparticles were formed by simple addition of a dithiafulvene derivative (DF) to an acetonitrile solution containing gold ions. The discrete gold nanoparticles in the aggregates were separated by monolayers of oxidized DF. No aggregation was observed with the addition of poly(vinylpyrrolidone) (PVP), which acted as a strong stabilizer and inhibited self‐assembly of the gold nanoparticles. DF acted as a reducing agent for gold ions, a stabilizer, and a tether for the resulting gold nanoparticles. Intermolecular S···S interaction and Au–S bonds might be the driving force for the self‐assembly of the gold nanoparticles.     

Immobilization of Horseradish Peroxidase on a Biocompatible Titania Layer–Modified Gold Electrode for the Detection of Hydrogen Peroxide

Abstract

A procedure for fabricating an enzyme electrode has been described based on the effective immobilization of horseradish peroxidase to an ultrathin titania layer–modified self‐assembled gold electrode. The resulting electrode exhibits excellent electrocatalytical activity to hydrogen peroxide in the presence of hydroquinone as a mediator. The analytical conditions were studied in detail by using an amperometric method. Under the optimized conditions, a detection limit of 7.1×10^?7 mol l^?1 and a linear response to hydrogen peroxide that ranged from 1×10^?6 mol l^?1 to 7.6×10^?4 mol l^?1 were obtained. The reproducibility and stability were examined with satisfactory results.     

Blend Composites Based on Polystyrene–CdSe Quantum Dots and Polystyrene–Gold Nanoparticles Hybrid Systems

Polystyrenes of different molecular masses are synthesized by controlled radical polymerization via the reversible addition fragmentation chain transfer mechanism. The resulting polymers are used for designing nanocomposites based on cadmium selenide quantum dots and gold nanoparticles. It is demonstrated that the photoluminescence of quantum dots in the sol grows appreciably during continuous irradiation for 5–6 h but is reduced during the “light switching off–switching on” process. It is shown that, upon the addition of gold nanoparticles, the photoluminescence of quantum dots in the sols changes insignificantly.