Development of Poly(L-arginine)/PSSA/QDs Modified Biosensor for Simultaneous Detection of Different Glucocorticoids in Wastewater

Due to poor electro-active and less structural differences of glucocorticoids, it is still a challenge to realize simultaneous electrochemical detection of different glucocorticoids in wastewater. In this study, an electrochemical biosensing platform was constructed through electrochemical in situ polymerization. A poly(sulphosalicylic acid) (PSSA) composite electrode was prepared based on polymerized L-arginine (Arg) doped with carbon quantum dots (QDs) and GCE-Arg-PSSA-QD sensor was obtained. Transmission electron microscopy, scanning electron microscopy and energy dispersive spectrometer were used to characterize the morphology and physical property of obtained electrodes. The PSSA layer mimics the sulfonated metabolism of glucocorticoids in vivo, allowing for direct reduction of glucocorticoids on the surface of electrode, thus enabling the capture of different glucocorticoids. Meanwhile, the fast electron transfer of QDs and the signal magnification effect of Arg allow a sensitive and direct detection of dexamethasone (DXM) and hydrocortisone (HC) simultaneously. Differential pulse voltammetry was used to investigate the analytical properties of prepared biosensing platform. The results show that GCE-Arg-PSSA-QD sensor delivered an analytical performance for both DXM and HC with a limit of detection of 9 nM and 37 nM. Then, the method was utilized for simultaneous detection of DXM and HC in real wastewater samples with favorable results.

Automated summary

This study constructed an electrochemical biosensing platform to simultaneously detect different glucocorticoids in wastewater, addressing the challenge posed by poor electro-active and structural differences of glucocorticoids. The surface of the electrode, prepared by polymerizing L-arginine doped with carbon quantum dots (QDs), allows for direct capture and reduction of glucocorticoids. The fast electron transfer of QDs and the signal magnification effect of Arg enable sensitive and direct detection of dexamethasone and hydrocortisone. The prepared GCE-Arg-PSSA-QD sensor exhibited favorable analytical performance in both experiments and real wastewater samples.