Fabrication and Characterization of Eco-Friendly Screen-Printed Electrode Using Activated Rice Husk Carbon Ink for Electrochemical Detection of SAR-CoV-2

Abstract

Rice husk in Malaysia has been treated as agricultural waste until now. It is usually burnt for disposal, which has caused air pollution. Few researchers have sought to reduce this pollution by transforming rice husk into useful products, such as composite panels for furniture. Similar to other organic substances, rice husk can be treated to become activated carbon through a controlled carbonization and activation process. Activated rice husk carbon has been reported to be developed for multiple uses, such as in battery storage or fertilizer applications, due to its high porosity properties and its flexibility to be surface-modified with various functional groups. This study focuses on developing a conductive ink based on activated rice husk carbon (ARHC) to enhance the performance of conventional screen-printed electrodes (SPEs) for detecting SARS-CoV-2 (COVID-19). To synthesize the ARHC, rice husk was carbonized at 500°C for 2 hours and further treated with an activation process at 850°C for 2 hours in NaOH soaking. To prepare the conductive ink, the synthesized ARHC was mixed with chitosan. The ARHC conductive ink was then applied on the conventional SPE’s working electrode (WE) surface. The synthesized ARHC was characterized through surface morphology (SEM and FESEM), surface area (BET), surface functionality (FTIR and EDX), and crystallinity (XRD). For the COVID-19 detection test, the ARHC WE were first functionalized with (3-Aminopropyl) triethoxysilane (APTES) and further immobilized with spike protein (SP) antibodies. These surface modification steps enable selective detection of SARS-CoV-2 through the spike protein (SP) target. For sensitivity analysis, a current-voltage (I-V) test was carried out across various concentrations of SP targets, ranging from micromolar to picomolar. All these results were compared with those of the original conventional carbon SPE to determine whether implementing ARHC in the SPE system could enhance the performance of SPE as a COVID-19 biosensor. Based on the project findings, hydroxyl (OH) groups formed on the ARHC surface after synthesis enhance its sensitivity and selectivity toward specific biomolecules, making it a promising candidate for the development of low-cost and eco-friendly biosensors. The ARHC-SPE provides a real-time, label-free platform for detecting COVID-19 and uses agricultural waste as an efficient early-detectiontool that helps prevent the further spread of infectious diseases.