Molecularly imprinted polymer electrochemiluminescence sensor based on biomass carbon quantum dots from cantaloupe peel for ultrasensitive and specific detection of methylene blue

This study presents the first synthesis of biomass carbon quantum dots (CQDs) with exceptional luminescent properties derived from discarded cantaloupe peels. Furthermore, these CQDs were utilized as luminescent reagents in conjunction with molecular imprinting technology to develop a molecularly imprinted electrochemiluminescence (ECL) sensor for the sensitive determination of methylene blue (MB). The sensor significantly enhances its sensitivity through two pathways: first, by loading CQDs onto Ti₃CN to increase the amount of luminescent reagents on the electrode surface; second, by employing the electron-conducting polymer PM6 to load Au NPs, which facilitates electron transfer within the system. Moreover, the introduction of molecularly imprinted polymers (MIPs) enables the specific recognition of MB. Under optimal conditions, this sensor demonstrates a linear response to MB concentrations ranging from 5.0 × 10⁻¹² to 5.0 × 10⁻⁷ M, with a detection limit as low as 1.67 × 10⁻¹² M (S/N = 3), showcasing remarkable advantages in stability, sensitivity, and reproducibility. It has been successfully applied for the detection of MB in actual fish samples. This work not only provides a green pathway for the reutilization of discarded fruit peels but also offers a novel method for the sensitive and specific detection of trace contaminants in food safety.