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UBC Theses and Dissertations

Development of molecularly imprinted fluorescence sensor chips Wusiman, Muersha

Abstract

In recent years, molecularly imprinted fluorescence sensors have received significant attention because of their high sensitivity and selectivity. However, the commonly applied liquid-phase molecularly imprinted fluorescence sensing platform has many drawbacks, making it unsuitable for practical in-field applications. In this study, the first of its kind, portable zinc oxide (ZnO)-based molecularly imprinted fluorescence sensor chips were developed to overcome the limitations of liquid fluorescence sensors. The fluorescence sensing material was prepared with biocompatible ZnO quantum dots (QDs) and tailor-made synthetic receptor molecularly imprinted polymer (MIP). Fluorescence sensor chips were formed using a facile thin-film coating method and the sensor signals were detected with a portable fluorescence detector. The combination of these materials enabled the development of green molecularly imprinted fluorescence sensor chips that are not restricted by complex immobilization process and detection procedure. A frequently studied herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was targeted at the first stage of fluorescence sensor development to examine the detection ability of ZnO QDs, the performance of the physical immobilization method, and the reliability of the portable detector. After obtaining a high sensor sensitivity (0.0233) and a good linear correlation (0.98) for 2,4-D measurement, efforts were made to adapt the sensing material to detect algae bloom toxin microcystin-LR (MCLR) to prove the capability of the sensor to perform water analysis. The solid fluorescence sensor was able to distinguish MCLR concentration as low as 1µg/L with good selectivity. Finally, to further demonstrate the flexibility of the developed system, biological analyte lactate was targeted for developing bio-sensor chips. Sensor selectivity was optimized by employing two different MIPs to compete with the commonly used enzyme-based sensors. The final sensor achieved a sensitivity of 0.0217 with a correlation coefficient of 0.97 for lactate in phosphate-buffered saline (PBS). The ability of the sensor to exhibit a linear sensing range for 0–30 mM of lactate with good selectivity indicated its applicability for sweat analysis. The high performance, target-flexibility, and portability of the fluorescence sensor chips demonstrated in this study can pave the way for developing lab-on-chip image-based sensing devices for environmental analysis and health monitoring applications.

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Attribution-NonCommercial-NoDerivatives 4.0 International