Deposition of Polypyrrole-Carboxylated Multi-Walled Carbon Nanotube Nanohybrid Thin Film for Surface Plasmon Resonance Sensor

Immobilization of the enzyme is the main problem and critical factor in producing high selectivity and sensitivity of a surface plasmon sensor (SPR). This study is aimed at fabricating a uniform polypyrrole (PPy) -Carboxylated Multi-Walled Carbon Nanotube (MWCNT-COOH) nanohybrid film as a mediator, thereby enhancing the functional groups to attach and immobilize the enzymes for the SPR sensor. This nanohybrid thin film of PPy-MWCNT-COOH was electrodeposited on the surface of gold (Au)/chromium (Cr) by chronoamperometry using potentiostat at 0.7V for 5s and 10s. For the first time, the MWCNT-COOH is utilized and combined with conductive polymer PPy to investigate the SPR sensor at two different wavelengths which are 670 nm and 785 nm. The SPR curves and resonance angle are red-shifted and shallower when the time of electropolymerization increases. However, the resonance angle for the 785 nm optical wavelength is blue-shifted and the full-width-at-half-maximum (FWHM) is smaller compared to the 670 nm optical wavelength. The Fourier-transform infrared spectroscopy (FTIR) spectrum examination reveals the presence of the required functional groups from the fabricated PPy-MWCNT-COOH nanohybrid thin film to attach the enzyme immobilization in future work. In conclusion, the findings of this research can broaden exciting possibilities for the low-cost fabrication of promising SPR sensors at longer wavelengths.