Use of Gold Nanoparticle Embedded Polyelectrolyte Multilayer Films as SERS Substrates

Date

2023-9-11

Author

Özdemir, Sezin

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Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for enhancement in Raman scattering of molecules adsorbed on SERS active surfaces. It is commonly used in chemical, material and life sciences applications. This study examined the the potential use of nanoparticles (NPs) containing layer-by-layer (LbL) films as SERS substrates. Firstly, the effects of chemical nature of the LbL building blocks, surface morphology and the film architecture on SER signal have been investigated. Poly(allylamine hydrochloride) (PAH) was used as the polycation, whereas poly(acrylic acid) (PAA) and tannic acid (TA) were used as polyanions for the construction of LbL films. The surface of PAH and PAA films were smoother compared to PAH/TA multilayers with highly rough surface morphology. The enhancement factor (EF) of PAH/TA, best system of this part, was calculated as 10 6 . Secondly, positively-charged, branched poly ethylene imine (BPEI)-capped Au NPs were synthesized in solution. The effects of BPEI concentration and pH of NPs growth solution on the size of NPs were examined. Multilayers using BPEI-capped Au NPs and TA or polystyrene sulfonate (PSS) as polyanions increased SERS signal approximately 3 times as compared to 1-layer NP including films. Both LbL systems (NPs/TA and NPs/PSS) provided more reproducible SER signal as compared to 1-layer NP including films. Lastly, LbL films (PAH/TA, PAH/PAA, BPEI/TA) were used as in situ photoreactors for the synthesis of both Au and Ag NPs. The effects of assembly conditions on SER signals of CV molecule were investigated. In order to obtain reproducible and better SER signals among multilayer systems, PAH/TA worked well for in situ synthesis of Ag NPs using Xe radiation.

Subject Keywords

Raman Spectroscopy, SERS Substrate, Layer-by-Layer Technique, Polyelectrolyte, Nanoparticle

URI

https://hdl.handle.net/11511/105599

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Graduate School of Natural and Applied Sciences, Thesis