Photoelectrochemical immunosensor based on CdSe@BiVO4 Co-sensitized TiO2 for carcinoembryonic antigen.

The fast and accurate detection of Carcinoembryonic Antigen (CEA) plays an important role in clinical cancer treatment and therapy. An ultrasensitive photoelectrochemical (PEC) immunosensor for the detection of CEA was constructed using CdSe@BiVO4 co-sensitized TiO2 nanorods as photoactive materials. TiO2 nanorods were assembled on the FTO modified electrode to immobilize capture antibodies. With a sandwich immunoassay format, CEA and signal antibodies labelled CdSe@BiVO4 were introduced in sequence via specific immunoreaction, and the ultrahigh sensitivity of this immunoassay results from the following three aspects. Firstly, the co-sensitization of BiVO4 and CdSe extends the absorption range of TiO2 from ultraviolet region to visible light region, which can adequately utilize the light energy; Secondly, the effective matching of energy levels among TiO2, CdSe and BiVO4 accelerates the separation and transfer of photogenerated electron-hole pairs and significantly improves the PEC performance; Finally, the introduced Au evidently expedites the interfacial electron transfer from TiO2 to FTO electrode, further resulting in noticeably increased photocurrent. Based on multiple signal amplification strategy, a largely linear detection range from 0.01 ng mL-1 to 50 ng mL-1 with a low detection limit (0.5 pg mL-1) were obtained. In addition, the prepared immunosensor with attractive properties provides a promising platform for PEC detection.

Ag nanoparticles decorated into metal-organic framework (Ag NPs/ZIF-8) for electrochemical sensing of chloride ion.

In this work, silver nanoparticles (Ag NPs) were decorated into the cavities of ZIF-8 to fabricate a novel Ag NPs/ZIF-8 modified glassy carbon electrode (GCE) for electrochemical sensing of chloride ion. Benefiting from the synergistic properties of ZIF-8 and Ag NPs, the Ag NPs/ZIF-8/GCE showed favorable performance towards chloride ion. For comparison, the electrochemical activity of Ag NPs wrapped by ZIF-8 (Ag NPs@ZIF-8) and Ag NPs coating on ZIF-8 (Ag NPs-on-ZIF-8) were also investigated and it was found that Ag NPs/ZIF-8 possessed the best performance. Some experimental parameters including pH of the supporting electrolyte and scan rate were also investigated. Under optimal conditions, the proposed sensor exhibited excellent stability, reproducibility and selectivity for the determination of chloride ion with a wide linear detection range from 5 to 4000 µmol dm-3 and a low detection limit of 0.61 µmol dm-3 (S/N = 3). The proposed sensor was successfully applied to the determination of chloride ion spiked in human serum. All these results indicated that the developed Ag NPs/ZIF-8/GCE sensor was superior.

Synthesis, DNA-binding, and photocleavage properties of a serious of porphyrin-daunomycin hybrids.

It is widely accepted that the pharmacological activities of anthracyclines antitumor agents express when the quinone-containing chromophore intercalates into base pairs of the duplex DNA. We have successfully synthesized and investigated the DNA-interactions of hybrids composed with quinone chromophore and cationic porphyrin. Herein, a clinic anticancer drug, daunomycin, is introduced to the porphyrin hybrids through different lengths of amide alkyl linkages, and their interactions and cleavage to DNA were studied compared with the previous porphyrin-quinone hybrids. Spectral results and the determined binding affinity constants (Kb) show that the attachment of daunomycin to porphyrin could improve the DNA-binding and photocleaving abilities. The porphyrin-daunomycin hybrids may find useful employment in investigating the ligand-DNA interaction.