Caiping Yang

Carbon nanotubes functionalized electrospun nanofibers formed 3D electrode enables highly strong ECL of peroxydisulfate and its application in immunoassay

A new biosensing platform based on electrospun carbon nanotubes nanofibers (CNTs@PNFs) composite, which enabled strong electrochemiluminescent emission of peroxydisulfate, was firstly developed for immunoassay with favorable analytical performances, and then was utilized to evaluate the interaction between antibody and antigen in vitro. Moreover, the obvious ECL image of peroxydisulfate on the prepared sensing platform was firstly recorded in this report. In order to expand the application of peroxydisulfate ECL, the specific recognization biomolecules, α-fetoprotein (AFP) antibody was bound to the functionalized film via electrostatic interaction for fabricating label-free ECL immunosensor to detect α-AFP. Based on the ECL change resulting from the specific immunoreaction between antigen and antibody, the quantitative analysis for AFP with wide dynamic response in the range from 0.1 pg mL(-1) to 160 ng mL(-1) was realized. And the limit of detection was estimated to be 0.09 pg mL(-1). Therefore, the flexible sensing platform not only acted as the sensitized sensing element, but also offered a suitable carrier for immobilization of biological recognition elements with low-toxicity and eco-friendliness, which opened a promising approach to developing further electrospun nanofiber based amplified ECL biosensor with favorable analytical performances.

Direct electrochemistry of thermally denatured calf thymus DNA on a poly(methyl methacrylate)–graphite microcomposite electrode

Remarkable direct electrochemical behaviors of thermally denatured calf thymus DNA (ssDNA) on the poly(methyl methacrylate)-graphite powder microcomposite electrode (PMMA/GME) were observed and investigated. The result indicated that the PMMA/GME showed great promotion of the electrochemical response towards the ssDNA oxidation due to the specific characteristics of the nanostructured interface on the resultant composite electrode. Two irreversible oxidation peaks at +1.04 and +0.76 V with obvious negative movement of oxidation potential and increase of the oxidation current (vs. Ag/AgCl) were observed on the PMMA/GME, which corresponded to the oxidation of adenine and guanine residues in the ssDNA molecules. Therefore, detection of ssDNA was then performed at the PMMA/GME. Under the optimal conditions, a good linear relationship was obtained between the oxidation peak currents of guanine or adenine residues and the ssDNA concentration in the range of 5.9 × 10(-3) to ca. 1.1 mg mL(-1) with a detection limit of 1.0 μg mL(-1). This PMMA/GME exhibits some outstanding advantages, such as ease of fabrication, high stability, renewable surface, excellent stability, mechanical rigidity and high electrochemical reactivity, which holds huge promise for further DNA biosensor design.