Photoelectrochemical Bioanalysis Platform for Cells Monitoring Based on Dual Signal Amplification Using in Situ Generation of Electron Acceptor Coupled with Heterojunction.

By using in situ generation of electron acceptor coupled with heterojunction as dual signal amplification, a simple photoelectrochemical (PEC) bioanalysis platform was designed. The synergic effect between the photoelectrochemical (PEC) activities of carbon nitride (C3N4) nanosheets and PbS quantum dots (QDs) achieved almost nine-fold photocurrent intensity increment compared with the C3N4 alone. After the G-quadruplex/hemin/Pt nanoparticles (NPs) with catalase-like activity toward H2O2 were introduced, oxygen was in situ generated and acted as electron donor by improving charge separation efficiency and further enhancing photocurrent response. The dually amplified signal made enough sensitivity for monitoring H2O2 released from live cells. The photocathode was prepared by the stepwise assembly of C3N4 nanosheets and PbS QDs on indium tin oxide (ITO) electrode, which was characterized by scanning electron microscope. A signal-on protocol was achieved for H2O2 detection in vitro due to the relevance of photocurrent on the concentration of H2O2. Under the optimized condition, the fabricated PEC bioanalysis platform exhibited a linear range of 10-7000 μM with a detection limit of 1.05 μM at S/N of 3. Besides, the bioanalysis platform displayed good selectivity against other reductive biological species. By using HepG2 cells as a model, a dual signal amplifying PEC bioanalysis platform for monitoring cells was developed. The bioanalysis platform was successfully applied to the detection of H2O2 release from live cells, which provided a novel method for cells monitoring and would have prospect in clinical assay.