Development of carbon nanotube-based biosensors for multi-concentration glucose detection

Suhaimi, Safwan Najmi (2025) Development of carbon nanotube-based biosensors for multi-concentration glucose detection. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

In the In developing nanoelectronic biosensors for glucose detection, nanomaterials like carbon nanotubes (CNTs) or graphene are commonly used as sensing elements. Functionalizing these nanomaterials with biomolecules, such as enzymes, enhances selectivity by forming specific bonds with glucose molecules. The interaction between glucose and biomolecules induces changes in the electrical properties of the nanomaterial, assessed using techniques like electrochemical impedance spectroscopy or cyclic voltammetry. However, challenges such as detection limits, time, and specificity remain. This study employs a methodical biosensor fabrication approach, incorporating glucose oxidase (GOx) for enzymatic detection and EDC/NHS chemistry for immobilization. The morphological characteristics of GOx/EDC-NHS/PPy-MWCNT composites on gold and indium tin oxide (ITO) electrodes were examined using field emission scanning electron microscopy (FESEM). To meet the demand for highly sensitive and specific biosensors, this study optimizes multiwalled carbon nanotube (MWCNT)-based biosensors for glucose detection across concentrations, achieving detection limits of 0.5 mM and 1.0 mM. A polypyrrole (PPy)/MWCNT nanofilm was fabricated via the chronoamperometry method using an AutoLAB potentiostat with NOVA 2.0 software for electrodeposition and cyclic voltammetry. FESEM analysis revealed a uniform distribution of nanostructures with average particle sizes of 45±5 nm for gold composites and 62±7 nm for ITO composites. For chronoamperometry, gold and ITO electrodes were sonicated in MWCNT for three hours and mixed with a PPy solution. Cyclic voltammetry in PBS solution at a scan rate of 50 mV/s (potential window: -0.8V to +0.4V) showed currents of 2.89 mA in PBS, 3.072 mA in 0.5 mM glucose, and 3.29 mA in 1 mM glucose for the gold electrode. Corresponding ITO electrode currents were 0.052 mA, 0.054 mA, and 0.071 mA. In conclusion, these findings confirm successful glucose detection, demonstrating the biosensor's effectiveness. This study advances biomedical diagnostics by creating a robust, MWCNT-based biosensor with remarkable sensitivity and stability. Optimized polymer coatings and nanoparticle integration improve performance, offering a potential alternative to traditional glucose monitoring with enhanced accuracy and reliability.

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