Photoelectrochemical immunosensor for DNA hydroxymethylation based on PTCA-sensitized perovskite Bi4TaO8Cl

DNA hydroxymethylation is an important epigenetic modification, which plays crucial roles in many biological processes, such as gene expression and cell differentiation. Herein, a novel photoelectrochemical immunosensor was built for detecting 5-hydroxymethylcytosine (5hmC), where the perovskite Bi4TaO8Cl sensitized by 3,4,9,10-perylenetetracarboxylicacid (PTCA) was implemented as photoactive material, anti-5hmC antibody was served as target recognition reagent, ZrO2 was used for connecting more modifications, and ferrocene was adopted as signal amplification unit. The prepared nanomaterials of Bi4TaO8Cl, PTCA and ZrO2 were well characterized. The possible mechanism for the improved PEC response of Bi4TaO8Cl sensitized by PTCA was investigated carefully, indicated that the matched energy band facilitated the migration of photogenerated electron. In addition, the possible mechanism for signal amplification caused by ferrocene was investigated, showing that ferrocene acted as electron donor to accelerate electron transfer. Under the optimal condition, the biosensor manifested wide detection range from 0.02 to 100 nM with the low detection limit of 5.2 pM (S/N = 3). Moreover, the applicability of the biosensor was demonstrated by investigating the effect of heavy metal Cd2+ and perfluorooctanoic acid on 5hmC content in the leaves and roots of wheat seedlings, as well as the effect of ALV-J on 5hmC content in chicken serum.

Automated summary

In this study, a novel photoelectrochemical immunosensor was developed for detecting DNA hydroxymethylation. Through characterization of the materials and investigation of the mechanisms, the sensor achieved high sensitivity and a wide detection range. It was also successfully applied to study the effects of heavy metals and perfluorooctanoic acid on DNA hydroxymethylation levels in biological samples.