Development of a new spectrofluorometric method based on carbon quantum dots doped with nitrogen, sulfur, phosphorus and chlorine to determination of vancomycin in the exhaled breath condensate

Abstract

Introduction: Vancomycin is a vital glycopeptide antibiotic effective against gram-positive bacteria. Due to its narrow therapeutic range, insufficient or excessive levels can lead to bacterial resistance or adverse effects. Therefore, a rapid, cost-effective and precise method for measuring vancomycin concentration in biological fluids including exhaled breath condensate (EBC) is necessary.Objective: This study aims to introduce a rapid technique utilizing carbon quantum dots doped with nitrogen, sulfur, phosphorus, and chlorine to detect vancomycin in EBC.Methodology: carbon quantum dots (CQDs) were synthesized from a solution containing glucose, ethylene diamine (EDA), sulfuric acid (H2SO4), hydrochloric acid (HCl), and phosphoric acid (H3PO4). A specific volume of the synthesized CQD nanoparticles was added to the vancomycin containing EBC sample in adjusted pH. After the 5-minute incubation time, the fluorescence intensity was measured at a wavelength of 496 nm. The difference in fluorescence intensity with and without vancomycin was measured as the analytical signal. Additionally, the effects of various parameters such as pH, reaction time, and nanoparticle concentration on the intensity of the analytical response were examined. Ultimately, the drug concentration was computed using the calibration curve equation, and the quantity of the drug in the EBC samples was identified.Results: The developed nanosensor demonstrated effective analytical capabilities for measuring the concentration of vancomycin across a broad linear range of 0.01 to 2 μg.mL−1, with a detection limit of 0.005 μg.mL−1. The intra-day and inter-day RSD values for various concentrations in the EBC sample were observed to be between 1.1-1.4%, and between 2.3- 3.2%, respectively, which demonstrates the method's strong reproducibility.Discussion and conclusion: The fluorescent sensor described has benefits including repeatability, ease of use, and rapid performance for measuring vancomycin, making it a dependable instrument for this purpose.