AuNPs-/c-MWCNT-/GQDs-modified electrode-based genosensor for early diagnosis of rheumatic heart disease.

In the present work, a specific DNA sensor has been fabricated by immobilizing 5'-NH₂-labeled single-stranded DNA probe (ssG-DNA) specific to S. pyogenes on AuNPs-/c-MWCNT-/GQDs-based screen-printed electrode. Further, hybridization studies were performed using different concentrations of DNA isolated from bacteria and swab samples from susceptible patients. Electrode surface modifications were characterized using scanning electron microscopy (SEM). Electrochemical response in terms of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) was recorded and analyzed to validate DNA hybridization. The limit of detection (LOD) and the sensitivity of the developed sensor were found to be 0.2 pg/µL and 1095.2 µAcm^{− 2} ng⁻¹, respectively. The sensor was found stable for 6 months with 9–10% loss in initial DPV current at 4 °C. The sensor is highly specific, simple, and sensitive with patient swab samples and takes only 20 min for detection of S. pyogenes infection. [ABSTRACT FROM AUTHOR]