Cong Zhang

Ferrocene-functionalized COF-derived Fe single-atom dispersed N-doped porous carbon was synthesized, exhibiting excellent catalytic activity and conductivity for efficient chloramphenicol electrochemical sensing in food and environmental matrices.

Polyoxometalates (POMs), as a unique kind of metal-oxygen cluster compounds, can undergo multi-electron transfer while maintaining their structures unchanged. In this work, an electrochemical sensor that can detect vanillic acid rapidly and sensitively was synthesized with vanadium substituted polyoxometalate (PMoV), reduced graphene oxide (rGO) and Pt nanoparticles (PtNPs), while the PMoV acting as both photoreductant and stabilizer. For this purpose, PMoV/rGO/Pt composite was firstly prepared and identified by various methods. Under the optimal conditions, the limit of detection (LOD) of the electrochemical sensor was attained to be 0.9 μM in 50–1350 μM. Also, the practical application of PMoV/rGO/Pt/GCE was considered by determining the concentration of vanillic acid in tap water and lake with good recovery (98.36%–102.11%, and 97.11%–100.22% respectively). The sensor prepared by this method can realize simple, rapid and economical detection of vanillic acid, and can be used as an important analytical tool in this direction.

Sensitive, specific, and accurate detection of circulating tumor cells (CTCs) is of great importance in the diagnosis and prognosis of cancer. Herein, an ultrasensitive ratiometric electrochemical biosensor was designed with a dual recognition strategy for highly specific and accurate detection of circulating MCF-7 human breast cancer cells based on gold film-modified porous organic cages loaded with ferrocene (Au/Fc@POCs) as the substrate and methylene blue-encapsulated covalent organic frameworks (MB@COFs) as the label material, producing two independent electrochemical signals from the Fc and MB probes, respectively. As the concentration of MCF-7 cells increases, the electrochemical signal of MB enhances significantly while the oxidation signal of Fc decreases remarkably. Under optimal experimental conditions, the ratios (I_MB/I_Fc) between the double signals showed a broad dynamic range of 10 to 1 × 10⁷ cells/mL with an effectively lower detection limit of 1 cells/mL (S/N = 3). Furthermore, the biosensor was able to accurately enumerate MCF-7 cells in human serum samples with excellent results. In this work, the developed ratiometric electrochemical biosensor offers a reliable and sensitive strategy for the quantitative determination of circulating MCF-7 human breast cancer cells as well as an effective approach for the clinical detection of rare cancer cells, especially in early stage cancer diagnosis.