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Khodaei Tehrani, Ali

University of British Columbia

Motivated by the growing need for lactate measurement in human biofluids, this study presents a novel fluorescent sensing device that is integrated with a commercial smartphone camera to analyze lactate concentrations. Highly fluorescent carbon quantum dots (CQDs) were chosen as the signal-generating element for the device, and these were modified by nitrogen doping and silica capping for a more robust performance. The molecularly imprinted polymer (MIP) technique was employed to create reception sites on the sensing layer and to provide the sensor with specificity toward lactate molecules. The synthesis was done using 3-aminopropyltriethoxysilane (APTES) as the functional monomer and tetraethyl silicate (TEOS) as the cross-linker to develop the sensor in the initial, liquid phase. Subsequently, the direct polymer deposition method was used to immobilize the sensing layer on small pieces of filter paper (sensing paper) and thus obtain a solid-phase sensor. The sensing papers were tested by exposure to varying lactate concentrations, ranging from 5 to 500 mM, in aqueous media, thus covering the full concentration range of lactate typically found in human sweat. A commercial smartphone camera was used to take photos of the sensing papers, and these photos were later analyzed against red-green-blue (RGB) and hue-saturation-lightness (HSL) color models. Linear correlations between the color values and the lactate concentrations were derived using their blue and saturation values. For concentrations below 100 mM, the blue values changed, showing a consistent pattern in relation to lactate concentrations; while for the higher concentrations of up to 500 mM, the saturation values changed, showing increasing sensitivity. According to the R² values obtained, both correlations were excellent fits with the data. The sensor responses to potentially interfering molecules, including glucose, ascorbic acid, and uric acid, were also evaluated, confirming the device's selectivity for lactate. The sensor fabricated demonstrated promising results for the quantitative measurement of lactate without requiring complex laboratory equipment, and it also showed great potential for further development in measuring other biomarkers in the human body.

Text

2025-01-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89410

Chemical and Biological Engineering

University of British Columbia

UBCV

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