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Optical Fiber Based Localized Surface Plasmon Resonance Sensor Prepared by Self-assembled Gold Nanoparticles on Block Copolymer Monolayer

A simple self-assembled methodology relying on a thin block copolymer film of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) to immobilize gold nanoparticles (AuNPs) on the optical fiber substrate was demonstrated for localized surface plasmon resonance (LSPR) sensing. The procedure was applied to 31 nm AuNPs, forming a monolayer of AuNPs with high uniformity and density. The resonance wavelength and refractive index sensitivity was increased with larger nanoparticle diameter and smaller gap between particles. In comparison with other AuNP deposition methods using (3-aminopropyl) trimethoxysilane (APTMS) and polyelectrolytes, the sensitivity for the PS-b-P4VP templating method was found to be 3-fold better than the other two methods, a consequence of the smaller gap between particles and the presence of only a few AuNP aggregates.