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TITLE: Biocompatible Plasmonic Nanostructures for Bioimaging Applications ABSTRACT: Traumatic brain injury (TBI) is a severe injury with a broad spectrum of symptoms and disabilities. The impact on a person’s life and his or her family can be devastating. Blood brain barrier (BBB) disruption following TBI can lead a long-term and diffuse neuroinflammation due to blood leakage in the brain, which is hard to detect on its inception. Optical brain imaging is one of the proposed approaches for TBI detection which has grown into a rich and diverse field in the last 30 years. Among various optical brain imaging techniques, Evan’s Blue (EB) assays are generally applied for the detection of TBI. This approach relies on the injection in the patient of a high concentration of EB solution followed by the visualization of the leakage of EB in vascular via fluorescence imaging. However this method suffers from low sensitivity, cannot detect minor leakages and cannot assess the global extent of vascular leakage within the brain (i.e., limited spatial resolution). Plasmonic materials have been extensively investigated during the last few decades, and are attracting significant attention in the biomedical area. However, a biocompatible and flexible plasmonic platform that can be deployed in a clinical setting has yet to be demonstrated. In our work, a novel biocompatible plasmon-enhanced nanostructure approach was realized based on the combination of metal nanoparticles, light emitting nanostructures, and cellulose nanofiber templates via a one-step facile electrospinning process which can easily be applied to scalable biomedical devices. Following this approach, we recently demonstrated plasmon-enhanced Si nanocrystals embedded in nanoscale fibers and enhanced random lasing by doping cellulose fibers with metal nanoparticles of different sizes, which holds the potential for in-vivo biosensing and bioimaging applications. In addition, combined with top down nanodeposition we are able to fabricate core-shell Ag nanofibers for surface enhanced Raman scattering (SERS) with stable signal enhanced by the random network morphology in a novel resonant medium. Aided by multivariate data analysis techniques, we demonstrate fingerprinting SERS spectra of different bacteria strains entrapped in the nanofibers network. Our experimental results showed spectroscopic discrimination between two different bacteria strains including E.coli C and E.coli K12. In my future work, I will demonstrate light emitting and random lasing polymer nanostructures enhanced with plasmonic particles specifically targeting TBI early optical detection. This will be accomplished by detecting the enhanced emission of EB molecules embedded inside biodegradable polyester nanoparitcles also containing metal nanoparticles in solution. In collaboration with the Team of Prof. Lee Goldstein at the medical campus, I will also address the optical imaging for TBI detection in-vivo based on the combination of enhanced photoluminescence, plasmon scattering and random lasing. The proposed thesis work will set the foundation for the design and optimization of a novel class of plasmonic active systems based on electrospinning of nanostructures that are fully compatible with biomaterials. The ability to demonstrate scalable and inexpensive plasmonic nanostructures and resonant materials that are suitable for integration with biomedical devices is the overarching goal of my thesis activities. COMMITTEE: Advisor: Luca Dal Negro, MSE/ECE, Soumendra N. Basu, MSE/ME, Lee Goldstein, MSE/BME, Bjorn M. Reinhard, MSE/Chemistry