Hailin Fang

A sensitive and label-free photoelectrochemical aptasensor using Co-doped ZnO diluted magnetic semiconductor nanoparticles

Co-doped ZnO diluted magnetic semiconductor as a novel photoelectric beacon was first constructed for photoelectrochemical (PEC) aptasensor of acetamiprid. The fabricated PEC sensing is based on the specific binding of acetamiprid and its aptamer, which induces the decreasement of enhanced photocurrent produced by the electron donor of quercetin. Co(2+) doping has a beneficial effect in extending the band width of light absorption of ZnO into the visible region and to promote the separation of the photoinduced carriers due to the sp-d exchange interactions existing between the band electrons and the localized d electrons of Co(2+). The fabricated aptasensor was linear with the concentration of acetamiprid in the range of 0.5-800 nmolL(-1) with the detection limit of 0.18 nmolL(-1). The presence of same concentration of other conventional pesticides did not interfere in the detection of acetamiprid and the recovery is between 96.2% and 103.7%. This novel PEC aptasensor has good performances with high sensitivity, good selectivity, low cost and portable features. The strategy of Co-doped ZnO diluted magnetic semiconductor paves a new way to improve the performances of PEC aptasensor.

Reduced graphene oxide-Hemin-Au nanohybrids: Facile one-pot synthesis and enhanced electrocatalytic activity towards the reduction of hydrogen peroxide

A facile and effective strategy is demonstrated for the synthesis of ternary reduced graphene oxide-Hemin-Au (rGO-H-Au) nanohybrids. The nanohybrids were synthesized through a one-pot in situ reduction of GO and HAuCl4 under alkaline conditions using GO, Hemin and HAuCl4 as the starting materials. The synthesis process can be finished within 1h in a solution phase, without adding any additional surfactant, stabilizing agent and toxic or harsh chemical reducing agents. The resulting nanohybrids were characterized by UV-vis spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and so on. Electrochemical measurements showed that the rGO-H-Au nanohybrids exhibited good electrocatalytic activity for the reduction of hydrogen peroxide (H2O2). Based on this property, a simple and highly sensitive amperometric biosensor for H2O2 had been developed. The linear relationships were obtained from 0.1 µM to 40 µM and the detection limit was estimated to be 30 nM. The simple and sensitive sensing platform showed great promising applications in the pharmaceutical, clinical and industrial detection of H2O2.

A label-free photoelectrochemical aptasensor for bisphenol A based on surface plasmon resonance of gold nanoparticle-sensitized ZnO nanopencils.

A simple and novel photoelectrochemical (PEC) aptasensor for selective detection of bisphenol A (BPA) was developed using surface plasmon resonance of Au nanoparticles activated ZnO nanopencils. With the irradiation of simulated light, the increased photocurrent of nano-Au/ZnO than that of pure ZnO nanopencil is induced by the hot electrons from excited Au nanoparticles. The perfect selectivity is attributed to the specific binding of BPA to its aptamer. With the addition of BPA, the conformation of aptamer changed to a G-quadruplex structure, which resulted in the blockages of photogenerated electron-transfer channels. Based on the above mechanisms and the optimized conditions, the assembled PEC aptasensor was linear with the concentration of BPA in the range of 1-1000nmolL(-1) with a detection limit of 0.5nmolL(-1). The presence of the same concentration and similar structure of other organics did not interfere in the detection of BPA and the recovery was between 96.2% and 108.4%. It has been successfully applied to the detection of BPA in drinking water and liquid milk samples. This PEC aptasensor has good performances in novelty, selectivity, sensitivity and low cost, and it provides an alternative approach to the detection of BPA.

Direct electrolytic exfoliation of graphite with hemin and single-walled carbon nanotube: Creating functional hybrid nanomaterial for hydrogen peroxide detection

We present a new, facile and efficient method to prepare functional graphene (GN) hybrid nanomaterials using direct electrolytic exfoliation of graphite robs in hemin (HN) and single-walled carbon nanotube (SWCNT) solution. During the exfoliation process, HN and SWCNT were simultaneously adsorbed on the surface of GN nanosheets through noncovalent π-π interaction, and then 3D GN-HN-SWCNT hybrid nanomaterials were formed. Due to the synergic effect among GN, HN, and SWCNT, these hybrid nanomaterials possessed excellent electrocatalysis properties and were used to construct novel electrochemical biosensor for H2O2 determination. The results displayed a wide linear range of 0.2 μM-0.4 mM and a low detection limit of 0.05 μM. Moreover, the developed sensor was successfully applied for real samples, such as beverages, and showed great promise in routine sensing applications.

DETERMINATION OF TRACE LEAD AND CADMIUM USING STRIPPING VOLTAMMETRY IN FLUIDIC MICROCHIP INTEGRATED WITH SCREEN-PRINTED CARBON ELECTRODES

A homemade fluidic microchip integrated with screen-printed carbon electrodes (SPCE) for direct detection of trace Pb(II) and Cd(II) has been designed. Analytes are accumulated and determined in a flow system with stripping voltammetry, and the methods of standardization are applied for self-calibration. The portable device produces a well-defined and reproducible electrochemical signal for monitoring Cd(II) and Pb(II), and limits of detection are low to 2.0 ppb and 3.0 ppb, respectively. Meanwhile, Pb(II) and Cd(II) in aqueous solutions are also qualitative measured with calibration both by internal standard and standard addition method. The proposed methodology possesses the advantages of simple, fast, high sensitivity, and stability. It has potential applications in the fields of environmental monitoring and biomedical science for real-time and online measurements.