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Degree

Master of Science (MS), Wright State University, Chemistry, 2012.

Abstract

Silver nanoparticles (AgNPs) are currently widely-used in consumer products, therapeutics, biomedical devices, and electronics. Yet, one application for which AgNPs have been used extensively is surface-enhanced Raman spectroscopy (SERS)-based sensing. However, AgNP size and aggregation state are known to greatly influence these applications. This works aimed 1) to synthesize a large volume of unfunctionalized, Creighton AgNPs, to characterize their chemical and physical properties, 2) then to size-select AgNPs of 1-50 nm and 50-100 nm in diameter and to concentrate them using a three-step, “green” tangential flow ultrafiltration (TFU) process. 3) Finally, to determine and compare the SERS-based sensing capabilities of the Creighton AgNPs of various sizes (1-50 nm, 50-100 nm, and 1-100 nm). It was hypothesized that the concentrated colloidal AgNPs (1-50 nm and 50-100 nm) will lead to greater SERS enhancement factors compared to that of the original Creighton colloid due the presence of a significantly larger number of SERS “hot spots” within the focal volume. The three aims were successfully accomplished, and the proposed hypothesis was validated. AgNPs of 50-100 nm in diameter were found to have the best SERS-based sensing capabilities in non-resonant conditions due to a greater abundance of optimally sized AgNPs. The surface enhancement factor of these AgNPs was 2.1 x 10⁶ at 10^-8 M of rhodamine 6G, which facilitated the detection of ~11 molecules within the focal volume.

Subject Headings

Nanoscience; Nanotechnology; Physical Chemistry

Keywords

Raman Spectroscopy; SERS; Physical Chemistry; Silver Nanoparticles; Nanoscience; Nanotechnology

Committee / Advisors

Ioana E.P. Sizemore, PhD (Advisor)
Steven R. Higgins, PhD (Committee Chair)
Norma C. Adragna, PhD (Committee Member)

Pages

75p.

Document number: wright1344523437
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=wright1344523437

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