Stimuli-Responsive Polymer-Based Devices for Surface Plasmon Resonance Spectrometer Sensing

Abstract

Surface plasmon resonance (SPR) has emerged as a powerful tool in sensing and biosensing for decades due to its label free and real-time data collection characteristics. In the first part of this thesis, a custom-built high performance SPR spectrometer with broad range of scanning angle, high resolution of 0.001° and multi operation mode is described in Chapter 2. The second part of the thesis (Chapters 3-5) focuses on development of a novel SPR sensor substrate that is able to detect small molecules (< 400 Da) in low concentration with high sensitivity. Stimuli-responsive polymers, especially poly(N-isopropylacrylamide) (pNIPAm)-based microgels, were used in the assay development for SPR signal enhancement (Chapters 3-4). In addition, a cost effective method was developed to fabricate hexagonal close packed Au nano arrays by directly painting the Au@pNIPAm hybridized core shell particles on the substrate and plasma etching after deposition; this can potentially be used in SPR sensor substrate and surface-enhanced Raman spectroscopy. Due to the thermoresponsivity of the pNIPAm shell, the interparticle Au nanoarray distance can be dynamically tuned and controlled by varying the painting temperature. In Chapter 6, a temperature-light dual responsive photonic device composed of Au@pNIPAm core-shell microgels is reported and its optical properties were investigated under the stimuli of temperature and light. In addition, the dependence of AuNPs distribution in microgel composites on light responsive performance was compared in terms of optical heterogeneity and responsive kinetics. In Chapter 7, a pNIPAm-brush based optical device with multi-responsiveness was reported, which can potentially be used for sensing and biosensing, drug delivery or other applications that require light manipulation and wavelength filtration.