Karakteristik Elektroda Termodifikasi Kitosan/GQDs/MnO2 dalam Mengukur Kolesterol dengan Metode Voltametri Siklik

Abstract

Chitosan/graphene quantum dots (GQDs)/manganese dioxide (MnO₂) modified electrode was successfully employed for cholesterol measurement using the cyclic voltammetry method. The incorporation of MnO₂ was proven to enhance the electrode’s performance. The electrode was fabricated via electrodeposition with a volume ratio of 2:1:1, using 1.5% chitosan solution, 250 mg/L GQDs, and varying MnO₂ concentrations of 100, 200, 300, 400, 500, and 600 mg/L. The Surface characterization of the electrode was carried out using Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), and X-Ray Diffraction (XRD). Sensor performance testing was conducted with cyclic voltammetry within a potential range of −1 V to +1 V and a scan rate of 125 mV/s. Measurements were performed using cholesterol solutions with concentrations of 50, 100, 150, 200, 250, and 300 mg/dL, as well as blood serum samples with concentrations of 123, 144, 180, and 205 mg/dL. The results showed that the chitosan/GQDs/MnO₂ modified electrode with a concentration of 400 mg/L exhibited the best performance in detecting choletserol, achieving a limit of detection (LoD) of 14.52 mg/dL and a limit of quantification (LoQ) of 48.42 mg/dL. Testing with real samples also confirmed good cholesterol detection capability. Validation using blood serum showed strong agreement between actual and measured concentrations, with low relative deviation. Therefore, the chitosan/GQDs/MnO₂ modified electrode holds promising potential to be further developed as a thin-film working electrode material for cholesterol sensing in blood.