Methods for the Detection of Biological Analytes on Dendritic Surface-Enhanced Raman Scattering (SERS) Substrates
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Authors
Azimi, Shamim
Date
2024-11-01
Type
thesis
Language
eng
Keyword
Biosensors , Surface-Enhances Raman scattering
Alternative Title
Abstract
The demand for point-of-use sensors is rising due to health risks from biochemical hazards, illicit drugs, and environmental toxicants. These sensors must be portable, affordable, and easy to use. Surface-enhanced Raman scattering (SERS) is a promising method for detecting chemical compounds in various media. However, traditional SERS struggles with direct detection due to weak signals and inconsistent results, stemming from low analyte concentration at SERS-active sites and irregular formation of “hotspots,” essential for signal enhancement.
This doctoral research aims to develop a direct, sensitive SERS-based approach for detecting biological targets, such as proteins and viruses. The study uses electrochemically deposited silver dendritic nanostructures on planar microelectrode arrays. With features spanning micrometer and nanometer scales, these structures generate a dense hotspot array, enabling sensitive molecular detection. By integrating dendritic layers with microelectrodes, the research examines how electric fields can improve analyte transport and concentration on the SERS-active surface, enhancing sensitivity.
Key factors in this study include how alternating current (AC) electric field parameters—frequency, voltage, and collection time—impact biomolecule capture. Additionally, the study introduces a technique that sandwiches analytes between two metallic layers: the silver dendritic substrate below and silver nanoparticles above, boosting hotspot density and plasmonic effects for stronger SERS signals. This method, named "LESS" (Label-free, Electric field-assisted, Sandwich-based, Surface-enhanced Raman scattering), demonstrates effectiveness in detecting kidney disease markers like creatinine and albumin, and the M13 virus at concentrations as low as 1.7 × 10² pfu/ml.
LESS holds promise as a point-of-need diagnostic tool. Combining SERS with microelectrodes and electrokinetic techniques offers a viable approach for field applications. Furthermore, the research investigates Ag/Au bimetallic nanostructures functionalized with antibodies for improved selectivity, ensuring precise biomolecule detection. This proof-of-concept study highlights the potential of advanced SERS-based systems for chemical and biological sensing, with implications for diagnostics and environmental monitoring.
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ProQuest PhD and Master's Theses International Dissemination Agreement
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.