Size-selected silver clusters on polymer surfaces as plasmonic transducers for nano-biosensors

• Autor(a) principal: Brasil, Francisco Maria Cristão Marques Luquet
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/64178
• topic: Optical nano-biosensors; localized plasmon resonance; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

The phenomenon of localized surface plasmon resonance (LSPR) was used for detection of proteins incubated on size-selected silver clusters embedded in poly (methyl methacrylate) (PMMA) layers. The silver clusters were produced by magnetron sputtering and subsequently sizeselected by electrostatic quadrupole mass spectrometer (EQMS). The size-selection process was followed by the deposition of silver clusters with low kinetic energies, i.e. in a soft-landing regime on PMMA, in order to avoid the deformation and/or fragmentation of the silver clusters. The role of PMMA hardness (viscosity) on cluster immersion was investigated to control the homogeneity in distribution of clusters, which can be partly or fully embedded in PMMA. The viscosity of the polymers was found to be an essential part in the immersion of the silver nanoparticles into the polymer, which can be controlled through tuning of its viscosity or hardness utilizing simple thermal annealing of the samples. The optical properties of the silver clusters - in particular the localized surface plasmon resonance (LSPR) – were measured with the optical absorption spectra of the silver clusters, in which was possible to clearly identify an intensity and a resonance band of the deposited clusters. Proteins of interest were incubated on the clusters utilizing antibody-antigen scheme and clear change in the parameters of the LSPR band was observed allowing protein detection and demonstrating applicability of the fabricated composites in bio-sensing.