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Parcheforosh, Ali

University of British Columbia

Molecularly imprinted polymer (MIP) sensing platforms are emerging as promising alternatives to enzyme-based sensors. Carbon quantum dots (CQDs) are semiconductor nano sized particles that emit fluorescence when excited by ultraviolet (UV) radiation. Utilizing CQDs during MIP fabrication leads to the creation of molecularly imprinted fluorescence sensors (MIFSs). The resulting product exhibits a combination of the high sensitivity inherited from the CQDs and strong selectivity provided by the MIPs. However, the existing literature lacks investigations into the utilization of MIPs integrated with CQDs for the measurement of lactate in human sweat across the broad applicable concentration range of 0–120 mM. In this research, we addressed this knowledge gap by designing, fabricating and evaluating the performance of a composite material comprising silica-capped nitrogen-doped CQDs integrated with a mesoporous MIP. Constructing a mesoporous structure using cetrimonium bromide (CTAB) as a surfactant in the synthesizing process increased the sensitivity of the sensor significantly from 0.0003 mMˉ¹ to 0.1. To generate the fluorescent signals, we applied nitrogen-doped carbon quantum dots, known for their cost effectiveness and environmental friendliness. To address the characteristic aggregation associated with these quantum dots, which could lead to a lowering of the fluorescence emission, a silica shell was applied. This also resulted in a twofold enhancement of the fluorescence emission. The liquid sensor exhibited a discernible response of 0.1 mMˉ¹ at low concentrations, ranging from 0 to 10 mM, and a commendable response of 0.0076 mMˉ¹ at higher concentrations. Consequently, our sensor demonstrated significant sensitivity at lower concentration ranges, ensuring precision, while maintaining a robust response at higher concentration ranges. Negligible responses were observed from typically interfering molecules, such as ascorbic acid, glucose, and uric acid, highlighting the sensor’s selectivity. The potential for developing a point-of-care measurement system was explored by correlating changes in the red, green, and blue (RGB) values of the emission with lactate concentrations. This was done by leveraging the excellent sensitivity of a smartphone camera to RGB value alterations. Lastly, efforts were made to fabricate a cost-effective solid sensing stripe on paper, using a straightforward chemical binding process.

Text

2024-01-03

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87044

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/