Nanotubos de carbono ancorados em filmes de nanopartículas de ouro para futura utilização em sensores ópticos de fibra óptica

Abstract

Metallic nanoparticles (NPs), such as the gold, show interesting optical properties due the surface plasmon resonance (SPR) in the visible region of the spectrum and are easily detected by UV-Vis spectroscopy. Their energies are dependent by four factors: electron density, format and size of the NPs and also the dielectric environment in which they are, making them great nanomaterials to apply in optical sensors devices. In this work, nanocomposites of multi-walled carbon nanotubes (MWCNTs) anchored on films of gold nanoparticles (AuNPs) were synthesized over a silica substrate functionalized with 3-aminopropyltrietoxysilane (APTES) for future application on optical fiber based sensors. Here, two films of AuNPs with different optical properties (AAT and BHT samples) were prepared using different reductor agents (ascorbic acid and sodium borohydride). The MWCNTs were functionalized with n-(3-dimethylaminopropyl)-n′-ethylcarbodiimide hydrochloride (EDC) and n-hydroxysuccinimide (NHS) and attached to the AuNPs film assisted by cysteamine. Plasmon band blue shifts around 109 nm were obtained for samples comprising only of AuNPs after termic treatment and red shifs around 63 nm were obtained after attaching the carbon nanotubes. The shifts were more noticiable for the AAT samples. The result obtained here shows an easy method to modulate the plasmonic band to different wavelenghts, increasing its applications for sensoring.