Garlic peel-based carbon quantum dots as a sustainable alternative for the sensitive and green spectrofluorometric quantification of molnupiravir in pharmaceutical capsules

Searching for natural alternatives to replace environmentally harmful chemical reagents in analysis is just as crucial as finding easily accessible analytical tools. To reinforce these concepts, this study proposes a simple spectrofluorometric approach using natural carbon quantum dots (n-CQDs) as fluorescence probes for sensitive and environmentally friendly measurement of molnupiravir, an antiviral drug that was initially developed for influenza and has demonstrated potential efficacy against COVID-19. n-CQDs were synthesized using garlic peels (GP), a waste material, via a microwave-assisted method. n-CQDs have a characteristic broad absorbance and narrow emission spectrum, making it easier to analyze several targets. The GP-based n-CQDs showed maximum excitation/emission at 265/347 nm with an acceptable quantum yield. After reaction with molnupiravir, the produced n-CQDs demonstrated unique features to determine the tested analyte. Different factors influencing the synthesis of n-CQDs and their interaction with the studied drug, molnupiravir, were investigated and optimized. Using GP-based n-CQDs as fluorescent probe for measuring molnupiravir byfluorescence (FL), a green analytical approach based on the probes' fluorescence quenching was developed (GP- n-CQDs -QN-FL). The method demonstrated good linearity from 0.5 to 30 μg/mL and detection/quantitation limits of 0.19/0.5 μg/mL. Validation studies confirmed accuracy (98–102 % recovery), precision (