Photoelectrochemical biosensor for DNA hydroxymethylation detection based on the enhanced photoactivity of in-situ synthesized Bi4NbO8Cl@Bi2S3 heterojunction

As an important epigenetic modification, 5-hydroxymethylcytosine (5hmC) aroused wide concern about the distribution and the function. Due to the necessity of 5hmC detection, a novel photoelectrochemical (PEC) biosensor was established based on the in-situ generated heterojunction of Bi4NbO8Cl@Bi2S3, which was employed as the substrate material with excellent photoelectric property. The specific recognition of 5hmC relied on the covalent reaction between -CH2OH of 5hmC and -SH on the substrate electrode under the catalysis of M.HhaI methyltransferase. Afterwards, ZrO2 was used as signal amplification unit capturing by the specific reaction of Zr with the phosphate group of 5hmC. The experimental results demonstrated well specificity and sensitivity of this biosensor. Under optimal conditions, the linear relationship between the photocurrent and the logarithm value of 5hmC concentration was constructed with the range from 0.3 to 300 nM and the detection limit of 0.0779 nM (S/N = 3). The procedures of constructing this biosensor were compact and convenient, and this biosensor realized actual detection of 5hmC level in wheat sample. Significantly, this biosensor was applied to a preliminary study that the heavy metal Pb2+ and the perfluorooctanoic acid influence the expression of 5hmC in the genomic DNA of wheat seedling roots and leaves.