Baorong Hou

Highly efficient photocatalytic performance of graphene-ZnO quasi-shell-core composite material.

In the present paper, the graphene-ZnO composite with quasi-shell-core structure was successfully prepared using a one-step wet chemical method. The photocatalytic Rhodamine B degradation property and the photoelectrochemical performance of the graphene-ZnO quasi-shell-core composite are dependent on the amount of graphene oxide that is added. When the amount of graphene oxide added is 10 mg, the graphene-ZnO quasi-shell-core composite possesses the optimal photocatalytic degradation efficiency and the best photoelectrochemical performance. An efficient interfacial electric field is established on the interface between the graphene and ZnO, which significantly improves the separation efficiency of the photogenerated electron-hole pairs and thus dramatically increases its photoelectrochemical performance. In addition to the excellent photocatalytic and photoelectrochemical properties, the electron migration ability of the grephene-ZnO quasi-shell-core composite is significantly enhanced due to the graphene coating on ZnO surface; therefore, this material has great potential for application as a substrate material to accept electrons in dye solar cell and in narrow bandgap semiconductor quantum dot sensitized solar cells.

Impedimetric immunosensor doped with reduced graphene sheets fabricated by controllable electrodeposition for the non-labelled detection of bacteria

A facile, sensitive and reliable impedimetric immunosensor doped with reduced graphene sheets (RGSs) and combined with a controllable electrodeposition technique was developed for the selective detection of marine pathogenic sulphate-reducing bacteria (SRB). The morphology of RGSs and the electrochemical properties of RGSs-doped chitosan (CS) nanocomposite film were investigated by atomic force microscopy, Fourier transform infrared spectroscopy, and cyclic voltammetry (CV). Electrochemical impedance spectroscopy and CV were used to verify the stepwise assembly of the sensor system. Faradic impedance spectroscopy for charge transfer for the redox probe Fe(CN)(6)(3-/4-) was done to determine SRB concentrations. The diameter of the Nyquist diagram that is equal to the charge-transfer resistance (R(ct)) increased with increasing SRB concentration. A linear relationship between R(ct) and SRB concentration was obtained in the SRB concentration range of 1.8×10(1) to 1.8×10(7) cfu/ml. The impedimetric biosensor gave a distinct response to SRB, but had no obvious response to Vibrio angillarum. It showed a high selectivity for the detection of the pathogen. Based on a combination of the biocompatibility of CS and good electrical conductivity of RGSs, a nanocomposite film with novel architecture was used to immobilize biological and chemical targets and to develop a new type of biosensor.

Direct immobilisation of antibodies on a bioinspired architecture as a sensing platform

A sensitive and selective immunosensor for the nonlabeled detection of sulfate-reducing bacteria (SRB) is constructed using a self-polymerised polydopamine film as the immobilisation platform. Self-polymerisation of dopamine is used as a powerful approach for applying multifunctional coatings onto the surface of a gold electrode. The polydopamine film is used not only as the immobilisation platform, but also as a cross-linker reagent for the immobilisation of the anti-SRB antibody. The polydopamine film is loaded with a high density of anti-SRB antibodies linked to the substrate to obtain high response signals. The formation and fabrication of the biosensor and the quantification of antibody anchoring are monitored, and SRB detection is performed by either quartz crystal microbalance (QCM) or electrochemical impedance spectroscopy (EIS). After modeling the impedance Nyquist plots of the SRB/anti-SRB/polydopamine/gold electrode for increasing concentrations of SRB, the electron transfer resistance (R(ct)) is used as a measure of immunocomplex binding. The R(ct) is correlated with the concentration of bacterial cells in the range of 1.8×10(2) to 1.8×10(6) CFU mL(-1); the detection limit is 50 CFU mL(-1). This work demonstrates a new immobilisation platform for the development of a sensitive and label-less impedimetric and piezoelectric immunosensor. This immunosensor may be broadly applied in clinical diagnoses and the monitoring of water environmental pollution. The method proposed is distinct in its ease of application, use of a simple protocol, and mild reaction conditions. These allow it to be applied to a wide variety of materials.

Vancomycin-functionalised Ag@TiO2 phototoxicity for bacteria.

This study reports on the synthesis of vancomycin (Van)-functionalised Ag@TiO(2) nanoparticles and their enhanced bactericidal activities. Van-Ag@TiO(2) nanoparticles were prepared by nanoparticle deposition and chemical cross-linking reactions. The catalysts showed high efficiency for the degradation of methylene blue under ultraviolet (UV) illumination. The photocatalytic inactivation of the sulphate-reducing bacteria, Desulfotomaculum, was also studied under UV light irradiation and in the dark using aqueous mixtures of Ag, Ag@SiO(2), Ag@TiO(2), and Van-Ag@TiO(2). The Van-Ag@TiO(2) nanoparticles showed a capacity to target Van-sensitive bacteria. They also effectively prevented bacterial cell growth through the functionalised nanoparticles under UV irradiation for 1h. To investigate the specificity of the catalyst phototoxicity, a Van-resistant bacteria, Vibrio anguillarum, was used as the negative control. The results indicated that Van-Ag@TiO(2) nanoparticles had a higher selective phototoxicity for Van-sensitive bacteria. Therefore, the antibiotic molecule-functionalised core-shell nanoparticles allow for selective photokilling of pathogenic bacteria.

Monitoring microbial populations of sulfate-reducing bacteria using an impedimetric immunosensor based on agglutination assay

An impedimetric immunosensor was fabricated for rapid and non-labeled detection of sulfate-reducing bacteria, Desulforibrio caledoiensis (SRB) by immobilizing lectin-Concanavalin A using an agglutination assay. The immobilization of lectin was conducted using amine coupling on the surface of a gold (Au) electrode assembled with 11-Mercaptoundecanoic acid. Electrochemical impedance spectroscopy (EIS) was used to verify the stepwise assembly of the sensor system. The work conditions of the impedimetric immunosensor, such as pH of the buffer solutions and the incubation time of lectin, were optimized. Faradic impedance spectra for charge transfer for the redox probe Fe(CN)(6)(3-/4-)were measured to determine SRB concentrations. The diameter of the Nyquist diagram that is equal to the charge-transfer resistance (R(ct)) increased with increasing SRB concentration. A linear relationship between R(ct) and SRB concentration was obtained in SRB concentration range of 1.8 to 1.8 x 10(7)cfu/ml. The variation of the SRB population during the growth process was also monitored using the impedimetric immunosensor. This approach has great potential for simple, low-cost, and time-saving monitoring of microbial populations.

Determination of sulphate-reducing bacteria based on vancomycin-functionalised magnetic nanoparticles using a modification-free quartz crystal microbalance

A fast, sensitive and reliable quartz crystal microbalance (QCM) biosensor is described for the selective detection of the marine pathogenic sulphate-reducing bacterium (SRB), D. desulfotomaculum. Based on the amplification of the response of vancomycin-functionalized magnetic nanoparticles (Van-mNPs), under an external magnetic field, the bacteria-mNPs conjugates attach to the surface of an Au electrode. The QCM biosensor gave a distinct response to the vancomycin-sensitive, D. desulfotomaculum, but had no obvious response to the vancomycin-resistant bacterium, Vibrio anguillarum. The effects of the optimization conditions such as the incubation time and pH on the detection were also investigated, respectively. Optimised assays showed that the biosensor could obtain the best response with a 30 min incubation of the bacteria with the Van-mNPs. A linear relationship between the QCM response and the logarithm of the bacterial concentration was observed in the range of 1.8 x 10(4) to 1.8 x 10(7)cfu/ml. The sensor system has a potential for further applications and provides a facile and sample method for detection of pathogenic bacteria.

Fabrication of durable anticorrosion superhydrophobic surfaces on aluminum substrates via a facile one-step electrodeposition approach

With unique water-repellent and self-cleaning properties, engineering metallic materials with superhydrophobicity endows them with greatly enhanced corrosion resistance. Herein, a facile and controllable one-step electrodeposition approach was employed to fabricate a superhydrophobic surface (SHPS) on an aluminum (Al) substrate as a barrier against corrosion media. The wettability, morphology, and chemical composition of the consequent SHPS were characterized by contact angle (CA), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDS), respectively. The anti-contamination and anticorrosion behaviors of the resultant SHPS were investigated by self-cleaning test, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The electrochemical results indicate that the resultant SHPS possessed greatly enhanced corrosion resistance, and were able to reduce the corrosion of a bare Al surface, with an inhibition efficiency of 99.96%. Furthermore, the as-fabricated SHPS maintained excellent durability and stability after air exposure, deionized water immersion, and 3.5 wt% NaCl solution immersion. We believe that SHPS fabricated by a versatile one-step electrodeposition approach would make it possible to develop engineering materials with durable self-cleaning and anticorrosion properties for use in rugged environments.

One-step electrodeposition fabrication of a superhydrophobic surface on an aluminum substrate with enhanced self-cleaning and anticorrosion properties

This paper presents a facile, low-cost, one-step approach to fabricate a superhydrophobic surface via electrodepositing aluminum in an ethanol solution containing cerium nitrate hexahydrate and myristic acid. The wettability, morphology and chemical composition of the as-prepared surfaces were characterized by water contact angle (WCA), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and Fourier transform infrared spectroscopy (FTIR). The highest WCA of the as-prepared surface after the one-step electrodeposition process reaches 162.1 degrees. Water droplet adhesion force, water stream reflecting, water droplet bouncing, and self-cleaning properties were investigated respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests demonstrated that the as-prepared superhydrophobic surface greatly improved the corrosion resistance of the aluminum substrate. The corrosion current density (I-corr) of the as-prepared superhydrophobic surface is smaller by more than 3 orders of magnitude. The presented method is facile, low-cost, and relatively environmentally friendly, and has promising applications in anticorrosion and anticontamination fields.

Electron transfer process from marine biofilms to graphite electrodes in seawater.

It is known that electron transfer processes exist between microorganisms and electrodes. Many anaerobic bacteria, which can transfer electrons to solid electrodes, had been identified. However, little attention has been paid to the interactions between aerobic biofilms and electrodes. In this study, marine biofilms formation on graphite electrodes was characterized by open circuit potential and field emission scanning electron microscopy. Electron transfer between marine aerobic biofilms and graphite electrodes was investigated primarily by cyclic voltammograms and electrochemical impedance spectroscopy techniques. Herein, we suggest that marine biofilms are a kind of conductive biofilms that can transfer electrons to graphite electrodes under anaerobic and aerobic conditions. Some cytochrome species in bacterial biofilms may play a key role in the electron transfer process.

Inhibiting Effect of Ciprofloxacin, Norfloxacin and Ofloxacin on Corrosion of Mild Steel in Hydrochloric Acid

The inhibiting effect of ciprofloxacin, norfloxacin and ofloxacin on the corrosion of mild steel in 1 mol.L(-1) HCl and the mechanism were studied at different temperatures using mass loss measurement, electrochemical method, and X-ray photoelectron spectroscopy (XPS). Effective inhibition was shown by mass loss, potentiodynamic polarization and impedance spectroscopy measurement. The corrosion rate of the metal in the mass loss measurement, and the corrosion reaction on cathode and anode in the electrochemical measurement were accelerated when temperature was increased. XPS results showed that the inhibitors adsorbed effectively on the metal surface.