A Novel Electrochemical Sensing Strategy Based on Poly (3, 4-ethylenedioxythiophene): Polystyrene Sulfonate, AuNPs, and Ag+ for Highly Sensitive Detection of Alkaline Phosphatase

Abstract

Alkaline phosphatase (ALP) is a crucial marker for the clinical analysis and detection of many diseases. In this study, an accurate signal amplification strategy was proposed for the sensing and quantification of alkaline phosphatase using poly (3, 4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), gold nanoparticles (AuNPs), and Ag+. Signal amplification was achieved by the modification of PEDOT:PSS and AuNPs on glassy carbon electrodes. Atomic force microscopy was performed to characterize the morphology of the modified nanomaterials. To detect ALP, 1-naphthyl phosphate (1-NP) was used as the substrate, and alkaline phosphatase catalyzed 1-NP into 1-naphthol (1-N), which resulted in the reduction of Ag+ to Ag0 on the surface of the modified electrode (AuNPs/PEDOT:PSS/GCE). The deposition of Ag drastically enhanced the detection signal. Differential pulse voltammograms of 1-N, which is the enzymatic product from the ALP reaction with 1-NP, were recorded. In the linear range of 0.1–120 U L−1, a quantitative analysis of alkaline phosphatase was achieved, with high sensitivity and a low detection limit of 0.03 U L−1. Stable, selective, and reproducible electrochemical sensors were designed. Moreover, the proposed electrochemical sensor exhibited a prominent sensing performance in the spiked diluted human serum. Thus, the sensor can be used in numerous applications in alkaline phosphatase or other analyte detection.