Biological modulating organic photoelectrochemical transistor through in situ enzymatic engineering of photoactive gate for sensitive detection of serum alkaline phosphatase

Innovative optoelectronics are expected to play more important role in clinical diagnosis. In this study, on the basis of sensitive gating effect by in situ enzymatic functionalization of semiconductors, a novel organic photoelectrochemical transistor (OPECT) detection of serum alkaline phosphatase (ALP) level was demonstrated. Specifically, the OPECT detection operates upon the ALP-catalyzed hydrolysis of sodium thiophosphate to yield hydrogen sulfide (H2S), which could in situ generate CdS on the TiO2 electrode in the presence of Cd2+ cations. Correlated to the ALP level, the CdS directly formed on and interfacing with the TiO2 could sensitively gating the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) channel, allowing unique optoelectronic detection of serum ALP level with a linear range from 0.005 to 15 U L-1 and a detection limit corresponding to 0.0012 U L-1 (S/N = 3). This study offers not only an optoelectronic method for detection of serum ALP level, but also a perspective for unique OPECT gating and application. Moreover, the general catalytic abilities of enzymes to produce functional species and their rich interactions with various gate substrates further provide great space for futuristic OPECT detection in enzyme-associated diseases.