Ultrasensitive Electrochemical Sensor Based On Graphene Oxide Composites For Food Additives Analysis

In this paper, we used the graphene oxide as aubatrate, and then modified them with functional materials to prepare new composite materials. Composite materials have the advantages of graphene oxide combined with other materials, such as big adsorption, high electrical conductivity. The composite materials were modified on electrode, then the high selectivity and high sensitivity electrochemical sensor was prepared. The sensor was used in the detection of food additives. The paper includes four sections.An imprinted electrochemical sensor based on glassy carbon electrode (GCE) for ultrasensitive detection of chrysoidine was fabricated. A GCE was modified by magnetic graphene oxide/?-cyclodextrin/gold nanoparticles composites (MGO/?-CD@AuNPs). The sensing surface area and electronic transmission rate were increased, which was benefited from the distribution property of MGO/?-CD@AuNPs. The MGO/?-CD@AuNPs composite improved electrochemical response and sensitivity of the sensor. The molecularly imprinted electrochemical sensor was prepared by electropolymerization on modified electrode. Chrysoidine and pyrrole were used as template molecule and functional monomer, respectively. Under the optimization experimental conditions, the electrochemical sensor exhibited excellent analytical performance:the detection of chrysoidine ranged from 5.0×10-8 mol/L to 5.0×10-6 mol/L with the detection limit of 1.68×10-8 mol/L. The sensor was applied to determine chrysoidine in spiked water samples and showed high selectivity, good sensitivity and acceptable reproducibility. The proposed method provides a promising platform for trace amount detection of other food additives.An imprinted electrochemical sensor based on graphene oxide/carboxylated multiwalled carbon nanotube/ionic liquid/gold nanoparticles/molecularly imprinted polymers (GO/CCNTs/IL/AuNPs/MIPs) has proved high ultrasensitive and selective in analysis of vanillin in spiked water sample. The GO/CCNTs/IL/AuNPs composite was utilized to improve electrochemical response and sensitivity of the sensor. The molecularly imprinted polymer membrane was prepared by electropolymerization and could specific determine vanillin. Under the optimized conditions, the prepared molecular imprinting electrode material showed a fast rebinding dynamics, which was successfully applied to vanillin detection with a wide linearity range from 1.00×10-8 to 2.50×10-6 mol/L and a detection limit of 6.23×10-10 mol/L. The proposed the imprinted electrochemical sensor also exhibited high repeatability (relative standard deviation of 3.16%) and stability (3.8%) for the analysis of real samples.A highly selective and sensitive electrochemical sensor for detection of L-cysteine based on a graphene oxide/carboxylated multiwalled carbon nanotube/manganese dioxide/gold nanoparticles composite (GO/CCNTs/AuNPs@MnO2) was developed. The property of the glassy carbon electrode which was modified by GO/CCNTs/AuNPs@MnO2 contributed to increasing the sensing surface area and the electronic transmission rate. Besides, the addition of MnO2 could effectively improve the selectivity and specificity of L-cysteine determination. The morphology and composition of GO/CCNTs/AuNPs@MnO2 were characterized by scanning electron microscope, energy dispersive spectrometer, fourier transform infrared spectroscopy and X-ray diffractometer and the results evidenced that GO/CCNTs/AuNPs@MnO2 flower-like structure was efficiently synthesized. The determination results of L-cysteine indicated that the surface area, electronic transmission rate and sensitivity of GO/CCNTs/AuNPs@MnO2 sensor were highly increased. Under the optimal conditions, the electrochemical sensor exhibited excellent analytical performance with good selectivity, reproducibility and stability. The linear range of L-cysteine was from 1.0×10-8 to 7.0×10-6 mol/L and the detection limit was 3.40×10-9 mol/L (38). The proposed electrochemical sensor was successfully applied to the determination of trace L-cysteine in spiked water samples.An electrochemical sensor based on porous graphene/silanization p-cyclodextrin-gold nanoparticles was fabricated. These interesting characteristics can form stable host-guest structure to determine curcumin. The characterization of the sensor was studied by differential pulse voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry techniques. The porous graphene/silanization ?-cyclodextrin-gold nanoparticles were utilized to improve electrochemical response and sensitivity of the sensor. This sensor has proved high ultrasensitive and selective. Under the optimized conditions, the prepared electrode material showed a fast rebinding dynamics, which was successfully applied to curcumin detection with a wide linearity range from 1.00×10-8 to 1.00×10-5 mol/L and a detection limit of 3.33×10-9 mol/L. The proposed the imprinted electrochemical sensor also exhibited high repeatability (relative standard deviation of 4.199%) and stability (4.400%) for the analysis of real samples.