Clitoria ternatea-mediated ZnO nanoparticles for enzyme-free photoelectrochemical cholesterol detection

Abstract

A reliable and enzyme-free investigation of cholesterol is essential for the timely detection and diagnosis of cardiac disorders. Herein, we report the synthesis of zinc oxide (ZnO) nanoparticles via a wet chemical method, incorporating the Clitoria ternatea (CT) flower extract as a sustainable phytochemical-mediated approach, where the CT-ZnO/nickel foam (NF) acts as an active material for a novel photoelectrochemical (PEC) biosensor. The study highlights the significant improvement in sensitivity for cholesterol sensing in light mode, with a value of 956 µA mM⁻¹ cm⁻², which is twice as high as without light (492.5 µA mM⁻¹ cm⁻²). Improvements in the limit of detection (LOD) (35 µM and 28 µM, respectively) and limit of quantification (LOQ) (110 µM and 95 µM, respectively) without and with light were observed in 0.1 M KOH with a response time of 2 s. The above findings reveal a linear detection range of 0 µM–2 mM. The CT-ZnO/NF PEC biosensor demonstrated exceptional cyclic stability, retaining 98.8% of its efficiency for 90 days. In addition, the reliable performance of CT-ZnO/NF demonstrated remarkable sensing abilities of 88–93% when testing on human serum samples. This research illustrates the dual electrochemical and photoelectrochemical properties of novel green-engineered ZnO, providing an effective and sustainable platform for non-enzymatic cholesterol monitoring in healthcare diagnostics.