A study of metallic and polymeric nanostructure-solution based platforms for optical and chemical arbovirus biosensing

• Autor(a) principal: MAHMOOD, Hafiz Zeeshan
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFPE
• Texto Completo: https://repositorio.ufpe.br/handle/123456789/35964
• topic: Engenharia Elétrica; Sensoriamento; Ressonância plasmônica de superfície; Nanopartículas; Nanomateriais; Biossensores poliméricos

The metallic nanoparticles support localized surface plasmon resonance (LSPR) by interacting with time varying electromagnetic field. LSPR of noble metal nanoparticles are reliant on multiple factors such as size, shape and material composition. It is found that metallic nanoparticles (NPs) scatter or absorb light with remarkable efficiency at the plasmon resonance frequency. Therefore, metal nanostructures are increasingly receiving attention as important starter for the development of molecular biosensors for medical diagnosis. In this study, several parameters that govern on LSPR sensor performance such as refractive index sensitivity, figure of merit and molecular sensing, were evaluated. Finite Element Method and experimental results were used to explore the optical characteristics of plasmonic structures to employ their uses for LSPR sensors. Firstly, we had investigated theoretically the sensing performance of the dielectric-metal core-shell that support plasmon resonances as a function of refractive index of the surroundings in connection with varying core radius and shell thickness. Furthermore, our results possess high figure of merit for Ag nano shell (3.0), higher than Au nano shell (2.50) having same silica shell thickness 5 nm but different metallic core radius (46 nm & 34 nm) for Au/Ag nano shells, respectively. Then we had explored the optical behaviour in dimmer of gold nanorod (AuNR) bridge by thin silica cylinder to sub-nanometer regime, where light−matter interactions have been anticipated in which quantum nature of free electrons in metals might be strongly affected. Our results reveal that an increase in aspect ratio causes a red shift in dimer connected mode, leading to significantly higher sensitivity 717 nm/RIU and figure of merit 16.9 compared to a single dimer having 300 nm/RIU sensitivity with similar dimensions. Due to high surface to volume ratio, Au nanorods prove good candidate for LSPR-based optical sensors as compared to Au/Ag nanoshells. Moreover, in this work, the application of polymeric nanoparticles for the detection of chikungunya virus will be elucidated. A Sandwich like structure was designed for the detection of chikungunya RNA and it was observed that our proposed structure was suitable and stable for chemical sensor under probe.