Li, Yunhua2021-12-192021-12-192020-06-26vt_gsexam:26337http://hdl.handle.net/10919/107126Stabilization of highly sensitive noble metal nanoparticles is essential for their practical application. Bionanocomposites in which various types of noble metal nanoparticles, especially anisotropic noble metal nanoparticles, are immobilized into a macroscopic biomaterial membrane show promising applications in biomedical, catalytic, and environmental fields. This research focuses on developing two fabrication methods to generate novel bionanocomposite materials by immobilizing gold (Au) or silver (Ag) nanoparticles onto a "green" biomaterial, namely an eggshell membrane (ESM). Furthermore, the applications of the resulting bionanocomposite materials were demonstrated by studying their use as catalysts for environmental pollutant conversion and for the detection of two pollutant chemicals. The first fabrication method immobilizes ex situ synthesized nanoparticles onto a chemically modified ESM. Disulfide originating from the ESM was reduced by dithiothreitol into free thiol groups for binding to Au nanoparticles with different morphologies. The immobilization of Au nanoparticles greatly enhances their stability, making it possible to apply the resulting bionanocomposites for catalyzing the reduction reaction to convert pollutant p-nitrophenol (PNP) to p-aminophenol (PAP), with a great increase in their lifetime use from 2 to 10 reaction cycles. The second fabrication method utilizes the zwitterionic property of the protein based ESM for binding with Ag nanoparticles to form bionanocomposites. A seed mediated nanoparticle synthesis method originally performed in suspension was modified and adapted for the in situ synthesis of Ag nanodisks in this research. Ag nanoseeds were first immobilized onto an eggshell membrane using the static interaction between the nanoseeds and the membrane. Subsequently, Ag nanodisks were further grown directly on the Ag nanoseeds on the ESM. The final distribution density of Ag nanodisks can be adjusted by tuning the distribution density of Ag nanoseeds immobilized on the ESM. The performance of the resulting bionanocomposites were evaluated for both catalysis, and their application as substrates for surface enhanced Raman spectroscopy (SERS). The material performance was found to depend on the final distribution density of the Ag nanodisks on the ESM, offering the possibility to optimize bionanocomposite material performance by adjusting this density. A SERS based technique was further developed for detecting pollutant chemical species using the Ag nanodisks/ESM bionanocomposite material as a SERS substrate. Direct detection of thiram, a commonly used pesticide, was achieved at a concentration that is lower than that regulated by the US EPA. By using crystal violet as a SERS probe molecule, mercury, a heavy metal without an intrinsic Raman fingerprint, was indirectly detected not only at a limit of detection lower than most reported in the scientific literature, but also with a selectivity against a group of metal ions including Ba, Cu, Ca, Co, Mg, Mn, Ni, and Zn. It was also found that the detection sensitivity can be optimized by adjusting the Ag nanodisk distribution density on the ESM. The development of the fabrication approach and the use of ESM as a matrix material for immobilizing noble metal nanoparticles to form bionanocomposite materials demonstrates a novel strategy for meeting the needs of a variety of applications. The development of bionanocomposites for detecting pollutant species with different SERS activities by simply tuning the nanoparticle distribution density on the surface of the substrate, is a novel discovery, as it does not appear to have been previously reported in the literature.ETDIn CopyrightnanoparticlebiomaterialnanocompositeSERSenvironmentalpollution detectionDissertation