Date of Award

6-2025

Document Type

Thesis - SCU Access Only

Publisher

Santa Clara : Santa Clara University, 2025

Department

Bioengineering

First Advisor

Zhiwen Zhang

Second Advisor

Fr. Dat T. Tran S. J.

Third Advisor

Justen Whittall

Abstract

Aspergillus niger (A. niger) is a soilborne, airborne, and seedborne fungal pathogen which is causing significant postharvest losses in agricultural crops. In this work, a novel quartz crystal microbalance (QCM) and aptamer-based biosensor capable of detecting A. niger conidia, with high specificity and sufficient sensitivity, was developed. The detection of A. niger conidia involves the use of selective aptamers (AN01-R9-006) immobilized on the active electrode on the QCM, causing complex mass loading phenomena resulting in resonant frequency shifts of the QCM. Under optimal conditions, the resonant frequency shifted non-linearly according to an empirically derived equation, △f = −1.64 · Ps0.28 , with an increasing A. niger conidia concentration over a range of 103 conidia/mL to 107 conidia/mL. Due to the high specificity of the A. niger conidia binding aptamer, AN01-R9-006, this QCM A. niger conidia biosensor exhibits high selectivity. The aptamer-based QCM biosensor allows label-free, easy to use, and cost-effective detection of A. niger conidia showing great promise for on-field detection of A. niger.

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