MODIFICATION OF SURFACE PLASMON RESONANCE (SPR) BIOSENSOR USING TRANSITION METAL DICHALCOGENIDES MOS2 FOR CFP-10 PROTEIN DETECTION OF MYCOBACTERIUM TUBERCULOSIS

• Main Author: Wulandari, Chandra
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67175
• Institution: Institut Teknologi Bandung

Tuberculosis is a respiratory system disease caused by Mycobacterium tuberculosis (Mtb). Tuberculosis is categorized as a tropical disease and has received special attention from various health institutions because of the high number of sufferers and the harmful effects disease. Handling tuberculosis involves multiple strategies, including developing rapid detection technology. Surface plasmon resonance (SPR)-based biosensor is a promising detection method because it has real-time detection features with performance that competes with other conventional methods. The SPR biosensor can be modified by adding materials on top of Au thin film, which then functions as a bioreceptor immobilization matrix to increase surface plasmon activity. Dichalcogenide transition metals are a group of 2D materials with a large surface area and high optical absorption efficiency. They are stable and do not interfere with the surrounding biochemical reactions. Therefore, this material has the potential as a modifier of SPR biosensors that can significantly improve detection performance. In this study, the SPR biosensor was modified using one type of transition metal dichalcogenides material, molybdenum disulfide (MoS2), to detect CFP-10 Mtb protein. The CFP-10 protein was chosen because it is an early Mtb secretory protein and is not found in other types of Mycobacterium. MoS2 was synthesized by hydrothermal method to obtain a flower-like morphology with a small particle size to provide abundant immobilization sites. MoS2 modification was done by varying the pH (6, 7, and 8) and the trisodium citrate concentration (0.125; 0.25; 0.5 g). Trisodium citrate (Na3Ct) is a reducing agent in the synthesis, so it is expected to reduce the particle size. Based on XRD results, both pH and Na3Ct affect the diffraction peak's intensity, indicating the crystallinity of MoS2. Meanwhile, based on the results of SEM, the effect of pH was not seen significantly, but there was an evident change in particle size from the variation of Na3Ct. It obtained flower-like MoS2 with the smallest particle size of ~500 – 600 nm from the synthesis at pH 7 with 0.5 g Na3Ct. The synthesis product was then used in the SPR test by depositing it on the Au chip with various deposition cycles (6L, 9L, 12L, and 15L) to see the effect of thickness on detection performance. The functionalized Au chip with various active groups and CFP-10 antibody was tested to detect CFP-10 protein with a concentration variation of 62.5; 100; 125; 250; and 500 ng/mL. Each chip shows a detection response in the form of an increase in unit response change (?RU) as the analyte concentration increases. Increasing the deposition cycle also increases the sensitivity of the biosensor on the 6L – 12L chip, but then decreases again on the 15L chip. The best detection performance resulting from this study was demonstrated by the 12L Au/MoS2/CFP-10Ab chip with sensitivity and limit-of-detection (LOD) of -1.0059 and 3.45 ng/mL, respectively. Compared to the LOD with the bare Au/CFP-10Ab chip, which is 7.66 ng/mL, the Au/MoS2/CFP-10Ab 12L provides at least ~45% better performance. This biosensor also has good selectivity and uniformity based on testing on various analytes and repeated measurements on 6 different chips. From this study, it has been proven that MoS2 can significantly improve the performance of SPR biosensors. Therefore, this Au/MoS2/CFP-10Ab-based SPR biosensor has the potential to be further developed and applied as a detection technology for CFP-10 Mtb protein in monitoring and diagnosing tuberculosis.