Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Dean's Office

Major Professor

Shyam S. Mohapatra, Ph.D.

Co-Major Professor

Daniel J. Denmark, Ph.D.

Committee Member

Eleni Markoutsa, Ph.D.

Keywords

Creatinine, Immunoassay, Iron Oxide Magnetic Nanoparticles, Mesoporous Silica Nanoparticles, Point-of-Care, Tacrolimus

Abstract

Point-of-care (POC) tests are a reliable, portable, easy to use, and more affordable alternative to regular laboratory diagnostic tests. They bypass the necessity of expensive equipment, human labor, and technical expertise. The personal glucose meter (PGM) is a POC device that measures glucose levels in blood. Lately, the PGM have been used as a tool to detect other bioanalytes in different applications. There are two analytes which POC detection would be beneficial for patients: creatinine and tacrolimus. Creatinine is used to calculate glomerular filtration rate, a measurement of kidneys function that can help to diagnose kidney failure, and other nephropathies. Tacrolimus is an immunosuppressant drug used after organ transplantation to avoid rejection. Tacrolimus has a narrow therapeutic window, and keeping the right amount drug in blood circulation is crucial for the treatment. Hence, the design of a POC technique to detect such analytes, without the cost and difficulty factors of current detection methods, is the priority of this research project. Two strategies to detect these bioanalytes are being proposed.

First, an invertase-mediated strategy, which uses magnetic nanoparticles, is described. It relies on a competitive immunoassay for which the competitor is an invertase conjugate. The magnetic nanoparticles were functionalized with antibody coated gold. Their particle size distribution was 20 nm approximately. Three approaches were tried in order to conjugate invertase to the analytes. An EDC-NHS crosslinking of creatinine butanoic acid and invertase seems to be the most promising technique. Nevertheless, the final immunoassays were not successful.

The second strategy was based in glucose-loaded mesoporous silica nanoparticles (MSN) capped with antibody coated gold nanoparticles (AuNP-Ab). MSN were prepared with a modification of the Stöber method, and then coated with polyethylenimine. The AuNP-Ab were made following a modified version of the Turkevich method. After characterization, both nanoparticles looked and behaved as expected, PEI-MSN particle size was near the 200 nm, and AuNP-Ab size was around 16 nm. However, immunoassays did not succeed. An optimization of the ratio of AuNP-Ab and MSN is suggested in order to reach the goal of bioanalyte detection using glucose-loaded MSN.

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