Carboxylated Multi-Walled Carbon Nanotubes Modified Screen-Printed Electrodes for Early Detection of Rice Diseases Using Immunosensor Approach

Abstract

Normal practice in detecting rice disease relies on symptoms’ confirmation by pathologists. Serological and molecular analysis, on the other hand, require the infected samples to be sent to the laboratories, are time-consuming, and only can be operated by technical personnel. In recent years, the electrochemical biosensor technique has been gaining attention in rapid test analysis owing to the system’s practicality, portability, and simplicity of construction. We described an antibody-based electrochemical biosensor development for the early detection of three major rice diseases in Malaysia, namely bacterial leaf blight (BLB), bacterial leaf streak (BLS) and blast. Polyclonal antibodies against causal agents of the diseases, i.e., Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas oryzae pv. oryzicola (Xoc) and Pyricularia oryzae were produced and purified in-house. Modification of screen-printed carbon electrodes (SPCEs) was achieved via electrodeposition of functionalized multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy) network on the surface, followed by antibody immobilization. Using an enzyme labelled primary antibody via chronoamperometry measurement, the functionalized SPCEs showed good R² values in the standard curves’ development. The immunosensor technique exhibited a good correlation of more than 80% with the polymerase chain reaction (PCR) method for all artificially infected samples. A stability study showed that the functionalized SPCEs are stable for up to 44 weeks at 40C storage for a bacterial concentration of 104 CFU mL^-1.