Optimization of Gold Nanoparticles for Functionalized PDMS in Microbacteria Detection

Flexibility, biocompatibility, and chemical stability make polydimethylsiloxane (PDMS) a popular silicon-based polymer for biomedical and technical applications. Due to their unique optical, electrical, and catalytic capabilities, gold nanoparticles (AuNPs) have been used to functionalize PDMS to improve its performance. This study deposits AuNPs on PDMS using gold (III) chloride and ethanol to enable direct nanoparticle development. After functionalization with 16-mercaptohexadecanoic acid (16-MDA), thiol-gold chemistry forms a stable interface, boosting chemical stability and biocompatibility for biosensing and biomedical applications. EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide) and NHS (N-hydroxysuccinimide) improve 16-MDA binding to PDMS by forming amide bonds and stabilizing the reactive ester intermediate. XPS and FESEM characterize modified PDMS samples. By comprehending surface-modified PDMS and its applications, this comprehensive investigation advances nanocomposite materials and biomedical devices. The study finds that spectrophotometer peak intensity of 0.341 au indicates the best functionalization effectiveness at 0.6% (w/v) AuNPs. x-ray Photoelectron Spectroscopy (XPS) investigation confirmed the effective surface modification of PDMS coated with AuNPs, 16-MDA, and EDC/NHS. The Au 4f peaks observed at ~84 eV (Au 4f7/2) and~88 eV (Au 4f5/2) confirm the presence of gold nanoparticles (AuNPs) on the PDMS surface. A clear carbon peak at ~285 e V, which can be attributed to the carbon atoms in the alkyl chain of 16-MDA. A key peak at ~402 eV, representing nitrogen peak, indicates the presence of nitrogen, which was introduced via the EDC/NHS coupling reaction. This nitrogen peak confirms the successful activation of the carboxyl groups through the formation of the NHS ester, which is reactive towards primary amines, forming stable amide bonds on the surface. FESEM images showAuNPs and 16-MDA dispersion and integration in PDMS composites. These results indicate that the composite is suitable for high-performance applications that require better surface characteristics and biocompatibility.