Enhancing H. pylori detection: ultrasensitive electrochemical aptasensor with Au-doped CQDs and polythiophene conjugation

This study presents a novel approach for developing an Hsp60 biosensor with enhanced sensitivity and selectivity, utilizing a nanocomposite with an aptamer-recognition surface. The biosensor was fabricated by modifying a glassy carbon electrode (GCE) with a nanocomposite composed of carbon quantum dots (CQDs), gold nanoparticles (AuNPs), and polythiophene (PTP). The integration of these constituents within the CQDs/Au/PTP nanocomposite yielded a range of advantageous attributes. These encompass elevated stability, a notable ratio of surface area to volume, outstanding electrical conductivity, considerable compatibility with biological systems, and durable resistance to both mechanical and chemical influences. The introduction of functional groups into the CQD/Au/PTP nanocomposite created multiple sites that facilitated the successful covalent attachment of aptamers (Apt), thereby enhancing the stability and sensitivity of the developed aptasensor. The measurement techniques employed in this study were Square Wave Voltammetry (SWV), Electrochemical Impedance Spectroscopy (EIS), and Cyclic Voltammetry (CV) utilizing a probe solution. The Hsp60 protein’s interaction with the immobilized aptamers resulted in a decline in electron transfer at the electrode and electrolyte junction. This caused a decrease in peak current in SWV and an increase in resistance in EIS. The changes in peak current were used to construct a calibration curve. The aptasensor that was created showed an outstanding ability to detect at a limit of 7.38 nM and was able to measure within a linear range spanning from 0.01 to 0.25 µM. Additionally, the CQDs/Au/PTP/Apt Hsp60 aptasensor exhibited favorable reproducibility, high selectivity, rapid response time, and excellent stability during storage. These characteristics make the aptasensor highly promising for various applications in biomedicine bioengineering and clinical studies. Graphical abstract