Photoelectrochemical biosensor for N6-methyladenosine detection based on enhanced photoactivity of TiO2-X and MoS2 nanocomposite

A novel and selective photoelectrochemical immunosensor was successfully prepared for N6-methyladenosine (m6A) detection based on the in-situ production of electron donor strategy. Black titanium dioxide (TiO2-x) and molybdenum sulfide (MoS2) heterojunction (TiO2-x-MoS2) was employed as photoactive material, m6A antibody was used as target molecule recognition reagent, biotin-functionalized phos-tag (Phos-tag-biotin) was adopted as bridging reagent to link m6A and avidin-functionalized alkaline phosphatase (avidin-ALP). With the catalytic effect of ALP, its substrate of L-ascorbic acid 2-phosphate trisodium salt in detection buffer can be hydrolyzed to produce ascorbic acid (AA), which will offer electron to capture the hole of photoactive material, improve the photoelectrochemical response and increase the detection sensitivity. Under the optimal conditions, the detection range for m6A is ranged from 0.005 - 35 nM, and the detection limit is 2.57 pM (S/ N = 3). The biosensor has good selectivity, reproducibility and stability. Moreover, the applicability of this biosensor was also assessed by investigating the effect of antibiotics on the content of m6A in root, stem and leaf of rice seedlings.