Weitao Su

Defects regulating of graphene ink for electrochemical determination of ascorbic acid, dopamine and uric acid

A simple water immersing treatment has been established for regulating the electrocatalytic activity of commercial graphene ink. This process enables to remove additives in graphene ink and consequently expose the surface defects. A graphene ink coated glass has been fabricated as an example platform for simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Cyclic voltammetry studied indicated electrocatalytic reaction can be initiated after the additives leaching during the water immersing treatment. Under optimal conditions, the linear calibration curves were achieved in the range of 50-1000, 3-140, and 0.5-150μM, with detection limits of 17.8, 1.44 and 0.29μM for AA, DA, and UA, respectively. This work demonstrated that the removal of additives of the graphene ink after film coating could be applied as a simple and cost-effective electrochemical platform for sensing application.

A glassy carbon electrode modified with N-doped carbon dots for improved detection of hydrogen peroxide and paracetamol

AbstractNitrogen doped carbon dots (NCDs) were synthesized using a low temperature approach and used to modify a glassy carbon electrode (GCE) via dipping. The oxygen groups on the surface of the NCDs, and the charge delocalization of the NCDs warrant an excellent electrocatalytic activity of the GCE toward oxidation ofxa0paracetamol (PA) andxa0reduction of H2O2. PA and H2O2 were detected at 0.34xa0V and −0.4xa0V (bothxa0vs. Ag/AgCl) using differential pulse voltammetry and amperometric I-T measurement, respectively. The modified GCE has a linear response to PA in the 0.5 to 600xa0μM concentration range, and to H2O2 in the 0.05xa0μM to 2.25xa0mM concentration range. The detection limits are 157xa0nM and 41xa0nM, respectively. In our perception, the modified GCE holds promise for stable, selective and sensitive determination of PA and H2O2 in pharmaceutical analysis.n Graphic abstractNitrogen doped carbon dots (NCDs) were synthesized and used to modify a glassy carbon electrode. Surface functional groups on NCDs can trigger electrocatalytic reactions toward paracetamol oxidation and H2O2 reduction with high sensitivities.

Electrochemical antioxidant screening based on a chitosan hydrogel

A chitosan based hydrogel has been fabricated using silver ions as crosslinking agent. Silver redox behavior in the hydrogel is suppressed due to complexation. However, hydrogen peroxide induced hydroxyl radicals could attract the glucoside bonds and consequently restore silver redox behavior. Therefore, we used this hydroxyl radical induced chitos and epolymerization mechanism as an indicator for antioxidant capacity evaluation. Therefore, we used this hydroxyl radical induced chitos and epolymerization as an indicator for antioxidant capacity evaluation. Due to the low cost, portability and avoidance of the need for electrode modification, we believe the proposed hydrogel sensing platform shows great potential for antioxidant screening applications.

A rapid electrochemical sensor fabricated using silver ions and graphene oxide

Electrode surface modification is a common method for designing sensitive electrochemical sensors. However, a long time fabrication process is a key issue for their practical applications. In this work, we proposed a simple in situ electroless dipping deposition process for commercial electrode surface modification. Graphene and Ag NPs have been used as examples and stepwise fabricated on a glassy carbon electrode (GCE) surface. Each fabrication cycle only takes 1xa0min. Besides the fast fabrication process, the performance of the electrode can be easily adjusted by changing dipping cycle numbers. Based on the proposed procedure, a H2O2 electrochemical sensor was fabricated as an example with excellent performance. We believe the proposed approach could be extended for further nanomaterial-modified electrode design.

Enhanced electrochemical voltammetric fingerprints for plant taxonomic sensing

Graphene-embedded plant tissues show a high sensitivity to electrochemical signals, which enables a screen-printed electrode to be used for electrochemical fingerprint recording. The electrochemical fingerprints obtained under different conditions can be transformed into multidimensional recognition modes for plant identification. These electrochemical fingerprints reflect the types and quantities of the electrochemically active substances in plant tissues such that the fingerprints can be used for chemotaxonomic investigations. In this paper, five species of Lycoris bulbs, including L. chinensis, L. radiate, L. aurea, L. sprengeri and L. straminea, were successfully recognized by electrochemical fingerprinting. The speciess interspecific relationships were also investigated. L. chinensis and L. aurea show highly similar morphology but have a relatively distant relationship. Hybridized L. radiata shows a notably close relationship with L. straminea, suggesting that one of its parents may be L. radiata. In addition, L. chinensis also shows a close relationship with L. straminea, suggesting that the L. straminea may be produced by cross-breeding L. chinensis and L. radiate. The results mentioned above indicate that the proposed electro-chemotaxonomic methodology is an inexpensive and quick taxonomic method that can provide additional evidence for the existing taxonomy system.