Detection of alkaline phosphatase activity in blood serum using a recombination-based semiconductor sensor

Background. Most pathologies of the human body (malignant liver tumors, chole­stasis, preeclampsia, gestational diabetes, prostate cancer, etc.) are accompanied by a violation of the integrity of cells in target tissues and the release of intracellular macro­molecules into the extracellular environment. Thus, an important diagnostic and prognostic indicator is the level of activity of certain enzymes, which are normally intracellular, in blood serum. One of the most promising areas of modern medical electronics and biophysics is the development and optimization of enzyme screening methods in biological fluids. In this study, we aimed to investigate the biophysical characteristics of alkaline phosphatase (ALP) using a recombination sensor for determining activity in biological fluids. Materials and Methods. Experiments were performed on preparations of stan­dard human blood serum. The reference determination of alkaline phosphatase acti­vity was carried out photo­metrically. The passage of the alkaline phosphatase reaction was experimentally recorded by measuring the photocurrent of a silicon structure with a buried barrier under several additional factors, such as modified electric fields or modu­lated illumination. Results. The biophysical features were studied. The detection of ALP becomes possible due to cleaving 4-nitrophenyl phosphate to phenol. These chemical reactions are accompanied by a redistribution of the reagent charges, particularly an increase in negative charge. The effect is explained by the local electrostatic influence on the parameters of the recombination centers near the silicon surface, which leads to a change in the surface recombination rate. Conclusions. Our approach can be regarded as promising for the development of a highly sensitive method for the detection of ALP. It has been experimentally shown that effective detection is possible due to the rearrangement of electronic states at the SiOx/Si interface of the deep barrier silicon following the adsorption.