Cluster Ion Beam Induced Nano Metallic Ripple Structure for Localized Surface Plasmon Resonance (LSPR) Based Biosensor and Bacterial Growth on Nano Ripple Glass Substrate under the Influence of Weak Magnetic Fields



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This thesis is comprised of two sections. First section describes the development of a simple and cost-effective scheme for bio-sensing, described as the detection of various biological elements inside a system or a body (that can be harmful or dangerous) with the help of specific biological receptor units. Gold nano-ripple pattern is prepared using a gas cluster ion beam (GCIB) system. When the nano-ripple surface is exposed to electromagnetic light, it shows localized surface plasmon resonance (LSPR) effect. Because of this plasmonic behavior, interaction of the targeted biomolecules and the receptors on the surface, sends optical signals that is processed to determine the presence of the specific biomolecule in the body. This LSPR nano-ripple gold biosensor was used to detect antibody-antigen reaction of rabbit X-DENTT antibody and DENTT blocking peptide (antigen) using adsorbate-induced LSPR-wavelength shift from the nano-ripple gold surface and its dependence on the antigen concentration. This approach does not require any chemical processes for its design and has the prominent advantage of possibility of large surface area coverage and applicability to different starting materials. These biosensors have monolayer scale sensitivity and high selectivity. The nano-ripple biosensor can be further developed to obtain a real time analytical detection mechanism. The second section presents the experimental results based on the effect of weak magnetic field on the growth of bacteria on glass nano structures. Bacteria is found to adhere more on nano-ripple pattern and larger bacterial colonies were observed in comparison to the plain glass surface. Moreover, magnetic field affects the growth by reducing the size of colonies. In another experiment, we examined the effects of different magnetic field configurations, including static (homogeneous and non-homogeneous) and time-varying magnetic fields, on various species of bacteria on a plain glass surface based on their growth rates. Magnetic field suppresses the growth of bacteria and slowest growth rate was observed in bacteria treated with time-varying magnetic field.



Gas cluster ion beam, Nano-ripples, Plasmonic property, Localized surface plasmon resonance (LSPR), Bacterial growth, Magnetic field effect


Portions of this document appear in: Saleem, Iram, William Widger, and Wei-Kan Chu. "A new technique to detect antibody-antigen reaction (biological interactions) on a localized surface plasmon resonance (LSPR) based nano ripple gold chip." Applied Surface Science 411 (2017): 205-209. And in: Saleem, Iram, and Wei-Kan Chu. "Gold nano-ripple structure with potential for bio molecular sensing applications." Sensing and Bio-Sensing Research 11 (2016): 14-19. And in: Saleem, Iram, Buddhi P. Tilakaratne, Yang Li, Jiming Bao, Dharshana N. Wijesundera, and Wei-Kan Chu. "Cluster ion beam assisted fabrication of metallic nanostructures for plasmonic applications." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 380 (2016): 20-25.