Preparation of P-g-C3N4-WS2 nanocomposite and its application in photoelectrochemical detection of 5-formylcytosine

Abstract

DNA formylation (5-formylcytosine, 5fC) is a major epigenetic modification involved in alterations in the DNA double helix structure and protein identification. Due to the low amount in all mammalian tissues and cells, it is necessary to develop a rapid, sensitive and efficient method for detecting 5fC for further understanding the biological functions of 5fC. Thus, a novel PEC biosensor was constructed using P-g-C₃N₄-WS₂ nanocomposite as photoactive material. Firstly, AuNPs/P-g-C₃N₄-WS₂/ITO electrode was prepared as substrate electrode. Secondly, the probe DNA and complementary DNA (containing 5fC base) was modified to the electrode surface based on the formation of Au-S bonds between AuNPs and thiol group on the probe DNA and hybridization, respectively. Finally, the amino functionalized MnO₂ nanoflowers were further modified to the electrode surface by covalent interaction between the aldehyde group on the 5fC and the amino group on MnO₂ nanoflowers. The sensitive and specific detection of 5fC can be achieved by oxidizing ascorbic acid with MnO₂ nanoflowers and quenching the photoactivity of P-g-C₃N₄-WS₂ nanocomposite. The sensor has a detection range of 0.01-200 nM and a detection limit of 3.8 pM. Moreover, this sensor has excellent detection specificity, stability and reproducibility.

Keywords: DNA formylation; Heterojunction; MnO(2) nanoflowers; Photoelectrochemical biosensor; Protonated g-C(3)N(4) nanosheets; WS(2) nanosheets.