Organic photoelectrochemical transistor biosensor for the detection of histone deacetylase Sirt1 based on the cleavage of deacetylated peptide chain by recombinant lysine endopeptidase

As a new analytical method, organic photoelectrochemical transistor (OPECT) biosensor has a good application in biological analysis. In this experiment, a novel organic photoelectrochemical transistor (OPECT) biosensor was successfully prepared for the specific and sensitive detection of histone deacetylase Sirt1, in which Bi-MOF@BiVO4 was served as the photosensitive material, and the hydrolysis reaction of Recombinant Lysine Endopeptidase (RLys-C) to the deacetylated short peptide was used as the gate regulatory unit. The construction of Bi-MOF@BiVO4 heterojunction improved the photovoltaic property of BiVO4, which in turn enhanced the sensitive modulation of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) -based OPECT. In addition, it was found that acetylated lysine had a significant inhibitory effect on RLys-C enzyme activity, and thus the attempt was made to use the enzymatic cleavage of deacetylated peptides by RLys-C to improve the detection signal. Under the specific cleavage of the deacetylated peptide chain by RLys-C, the dielectric properties of the gate surface are changed, and the modulation response of OPECT was caused under zero gate bias. By monitoring the channel current, the detection of the target molecule Sirt1 was realized. The concentration range of Sirt1 enzyme detected by the sensor was 0.001–10 nM, and there was a linear relationship between the logarithm and the photocurrent signal. The detection limit was 0.395 pM (3σ). In addition, the effects of sodium acetate and sodium butyrate on Sirt1 enzyme activity were studied by OPECT bioassay, which is expected to become a general method for screening Sirt1 enzyme inhibitors.