Zhiying Miao

A novel nonenzymatic hydrogen peroxide sensor based on multi-wall carbon nanotube/silver nanoparticle nanohybrids modified gold electrode

A novel strategy to fabricate hydrogen peroxide (H(2)O(2)) sensor was developed based on multi-wall carbon nanotube/silver nanoparticle nanohybrids (MWCNT/Ag nanohybrids) modified gold electrode. The process to synthesize MWCNT/Ag nanohybrids was facile and efficient. In the presence of carboxyl groups functionalized multi-wall carbon nanotubes (MWCNTs), silver nanoparticles (Ag NPs) were in situ generated from AgNO(3) aqueous solution and readily attached to the MWCNTs convex surfaces at room temperature, without any additional reducing reagent or irradiation treatment. The formation of MWCNT/Ag nanohybrids product was observed by transmission electron microscope (TEM), and the electrochemical properties of MWCNT/Ag nanohybrids modified gold electrode were characterized by electrochemical measurements. The results showed that this sensor had a favorable catalytic ability for the reduction of H(2)O(2). The resulted sensor could detect H(2)O(2) in a linear range of 0.05-17 mM with a detection limit of 5x10(-7)M at a signal-to-noise ratio of 3. The sensitivity was calculated as 1.42 microA/mM at a potential of -0.2 V. Additionally, it exhibited good reproducibility, long-term stability and negligible interference of ascorbic acid (AA), uric acid (UA), and acetaminophen (AP).

A novel glucose biosensor based on the immobilization of glucose oxidase onto gold nanoparticles-modified Pb nanowires

A novel glucose biosensor was developed, based on the immobilization of glucose oxidase (GOD) with cross-linking in the matrix of bovine serum albumin (BSA) on a Pt electrode, which was modified with gold nanoparticles decorated Pb nanowires (GNPs-Pb NWs). Pb nanowires (Pb NWs) were synthesized by an L-cysteine-assisted self-assembly route, and then gold nanoparticles (GNPs) were attached onto the nanowire surface through -SH-Au specific interaction. The morphological characterization of GNPs-Pb NWs was examined by transmission electron microscopy (TEM). Cyclic voltammetry and chronoamperometry were used to study and to optimize the electrochemical performance of the resulting biosensor. The synergistic effect of Pb NWs and GNPs made the biosensor exhibit excellent electrocatalytic activity and good response performance to glucose. The effects of pH and applied potential on the amperometric response of the biosensor have been systemically studied. In pH 7.0, the biosensor showed the sensitivity of 135.5 microA mM(-1) cm(-2), the detection limit of 2 microM (S/N=3), and the response time <5 s with a linear range of 5-2200 microM. Furthermore, the biosensor exhibits good reproducibility, long-term stability and relative good anti-interference.

Preparation of dendritic nanostructures of silver and their characterization for electroreduction.

Silver nanostructures of different morphologies including well-defined dendrites were synthesized on an Au substrate by a simple surfactant-free method without using any template. The morphology of the material was investigated by field-emission transmission electron microscopy and scanning electron microscopy. The crystal nature of the dendritic nanostructure was revealed from their X-ray diffraction and electron diffraction patterns. Effects of applied potential, electrolysis time, and the solution concentration were studied. The possible formation mechanism of the dendritic morphology was discussed from the aspects of kinetics and thermodynamics based on the experiment results. The H(2)O(2) electroreduction ability of the dendritic materials was characterized. Use of silver dendrite-modified electrode as H(2)O(2) sensor was also demonstrated.

Non-enzymatic Hydrogen Peroxide Sensors Based on Multi-wall Carbon Nanotube/Pt Nanoparticle Nanohybrids

A novel strategy to fabricate a hydrogen peroxide (H2O2) sensor was developed by using platinum (Pt) electrodes modified with multi-wall carbon nanotube-platinum nanoparticle nanohybrids (MWCNTs/Pt nanohybrids). The process to synthesize MWCNTs/Pt nanohybrids was simple and effective. Pt nanoparticles (Pt NPs) were generated in situ in a potassium chloroplatinate aqueous solution in the presence of multi-wall carbon nanotubes (MWCNTs), and readily attached to the MWCNTs convex surfaces without any additional reducing reagents or irradiation treatment. The MWCNT/Pt nanohybrids were characterized by transmission electron microscope (TEM), and the redox properties of MWCNTs/Pt nanohybrids-modified Pt electrode were studied by electrochemical measurements. The MWCNTs/Pt-modified electrodes exhibited a favorable catalytic ability in the reduction of H2O2. The modified electrodes can be used to detect H2O2 in the range of 0.01–2 mM with a lower detection limit of 0.3 μM at a signal-to-noise ratio of 3. The sensitivity of the electrode to H2O2 was calculated to be 205.80 μA mM−1 cm−2 at working potential of 0 mV. In addition, the electrodes exhibited an excellent reusability and long-term stability as well as negligible interference from ascorbic acid, uric acid, and acetaminophen.

Synthesis of silver nanowires and their applications in the electrochemical detection of halide

A silver nanowires modified platinum (Ag NWs/Pt) electrode was developed for simultaneous and selective determination of chloride, bromide and iodide ions by cyclic voltammetry in aqueous solutions. Silver nanowires were synthesized by an l-cysteine-assisted poly (vinyl pyrrolidone) (PVP)-mediated polyol route. X-ray diffraction (XRD) and scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) were employed to investigate the prepared nanowires. The intrinsic high surface area and the fast electron transfer rate ascribed from the nanowire structure could further improve halide detection performance. The determination was based on measurement of the well-separated oxidation peak currents of respective silver halides formed on the surface of silver during an anodic potential sweep. The concentration range was linear from 50 μM to 20.2mM for bromide and iodide and 200 μM to 20.2mM for chloride, and the sensitivity was 0.059 μA/mM, 0.042 μA/mM and 0.032 μA/mM for chloride, bromide and iodide, respectively. The correlation coefficient was 0.999 in each case. The Ag NWs/Pt electrode offered a useful platform for the development of a highly sensitive halide sensor.

A novel non-enzyme hydrogen peroxide sensor based on catalytic reduction property of silver nanowires.

A novel strategy to fabricate a hydrogen peroxide (H2O2) sensor was developed based on silver nanowires modified Pt electrode. The sensor was fabricated by simple casting of silver nanowires (Ag NWs) aqueous solution on a Pt electrode. Silver nanowires were synthesized by an l-cysteine-assisted poly (vinyl pyrrolidone) (PVP)-mediated polyol route. UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to investigate the prepared nanowires. The electrochemical properties of H2O2 sensor were evaluated by cyclic voltammetry (CV) and chronoamperometry. The as-obtained silver nanowires exhibited favorable electroreduction activity toward H2O2, and results indicated that the Ag NWs modified Pt (Ag NWs/Pt) electrode might be gifted from CV scanning with higher surface area and more active sites that afford more effective surface exposure in the electrode-electrolyte interface and consequently improved electrochemical properties. At the applied potential of -0.2V vs. Ag/AgCl, the Ag NWs/Pt electrode as an enzyme-free sensor exhibited a wide linear range of 0.5μM-30mM to H2O2, with a remarkable sensitivity of 9.45μA/mM, a detection limit of 0.2μM estimated at a signal-to-noise ratio of 3 and fast response time (within 5s). Moreover, it showed good reproducibility, anti-interferant ability and long-term stability. The excellent performance of the sensor might be attributed to the well-defined silver nanowires with special catalytic activity.

Noncovalently functionalized multi-wall carbon nanotubes in aqueous solution using the hydrophobin HFBI and their electroanalytical application

A novel noncovalent approach was developed for the functionalization of multi-wall carbon nanotubes (MWNTs) using the hydrophobin, HFBI. Owing to the amphipathic nature, HFBI can be adopted onto the surface of MWNTs to form HFBI-MWNTs nanocomposite with good dispersion in water. The HFBI-MWNTs nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle measurements (WCA). Furthermore, a glucose biosensor was developed based on HFBI-MWNTs by a one-step casting method. The resulting biosensor displayed high sensitivity, wider linear range, low detection limit, and fast response for glucose detection, which implicated that the HFBI-MWNTs nanocomposite film holds great promise in the design of electrochemical devices, such as sensors and biosensors.

Highly-ordered perpendicularly immobilized FWCNTs on the thionine monolayer-modified electrode for hydrogen peroxide and glucose sensors

In this paper, we innovatively immobilized few-walled carbon nanotubes (FWCNTs) perpendicularly on Au surface through conductive thionine instead of aminoalkanethiols so as to improve electrochemical properties. Because FWCNTs own smaller aggregates, stronger chemical corrosion resistant, and higher conductivity than single-walled carbon nanotubes (SWCNTs), and thionine is a good electron transfer mediator can provide amino and sulfhydryl groups playing the same function as insulating aminoalkanethiols. The strategy for obtaining perpendicularly aligned FWCNTs (p-FWCNTs) is electrostatically assembled thionine and 11-amino-n-undecanethiol (AUT) on Au surface via Au-S bond to provide amino groups for covalently combining terminus-carboxylated FWCNTs, we confirmed and compared the results by AFM, Raman spectroscopy and electrochemical methods. In order to prove the constructed basement has excellent electrochemical properties can provide a good platform for sensors fabrication, we developed a novel non-enzymatic hydrogen peroxide (H2O2) sensor by electrodepositing Pt nanoparticles (PtNPs) on p-FWCNTs/Thionine/Au electrode surface, and verified the result by TEM, EDX and electrochemical techniques. Furthermore, polyallylamine (PAA) and poly(vinyl sulfate) (PVS) permselective layer, poly(diallyldimethylammonium) (PDDA) and glucose oxidase (GOx) multilayer films were layer-by-layer self-assembled on p-FWCNTs/Thionine/Au surface to fabricate a glucose biosensor. Either the non-enzymatic H2O2 sensor or the enzyme-based glucose biosensor showed good sensitivity, selectivity, reproducibility and stability, both them had been applied for biological sample analysis with satisfactory results. The results show that the p-FWCNTs/Thionine/Au electrode can work as an ideal platform for the development of highly sensitive sensors, coupled with p-FWCNTs are rich in functional groups could be used for fabricating diverse sensors.

Facile synthesis of β-lactoglobulin-functionalized multi-wall carbon nanotubes and gold nanoparticles on glassy carbon electrode for electrochemical sensing.

A facile approach was developed for the preparation of nanocomposite based on β-lactoglobulin (BLG)-functionalized multi-wall carbon nanotubes (MWCNTs) and gold nanoparticles (GNPs) for the first time. Owing to the amphipathic nature, BLG can be adopted onto the surface of MWCNTs to form BLG-MWCNTs with uniform dispersion in water. Taking advantage of sulfhydryl groups on BLG-MWCNTs, GNPs were decorated on the BLG-MWCNTs-modified glassy carbon electrode (GCE) by electrodeposition. The nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy and X-ray spectroscopy analysis. Cyclic voltammetry and chronoamperometric method were used to evaluate the electrocatalytic ability of the nanocomposite. Furthermore, a glucose biosensor was developed based on the immobilization of glucose oxidase with cross-linking in the matrix of bovine serum albumin (BSA) on the nanocomposite modified GCE. The resulting biosensor exhibited high sensitivity (3.98 μA mM(-1)), wider linear range (0.025-5.5 mM), low detection limit (1.1 μM at the signal-to-noise ratio of 3) and fast response time (within 7s) for glucose detection.

One step electrodeposition of dendritic gold nanostructures on β-lactoglobulin-functionalized reduced graphene oxide for glucose sensing.

Dendritic gold nanostructures (AuNDs) were successfully synthesized by one step electrodeposition on reduced graphene oxide (rGO) functionalized by a globular protein, β-lactoglobulin (BLG), for the first time. Owing to its sulfhydryl groups, water-soluble BLG-rGO provided a superb platform for the growth of AuNDs. Scanning electron microscopy, Raman spectroscopy and X-ray spectroscopy analysis were used to investigate the as prepared BLG-rGO-AuNDs nanocomposite. Electrocatalytic ability of the nanocomposite was evaluated by cyclic voltammetry and chronoamperometric method. In order to prove the superiority of BLG-rGO-AuNDs, we developed a novel glucose biosensor on the nanocomposite modified glassy carbon electrode (GCE) through a cross-linking method. The biosensor exhibited a remarkable sensitivity of 46.2 μA mM(-1) cm(-2), a wide linear range of 0.05-6 mM glucose, a low detection limit of 22.9 µM (S/N=3), and a rapid response time (within 6 s). The prepared biosensor also used to detect glucose in human serum and statistical analysis in the respect of reproducibility was done.