Fluorescent detection of molybdate (MoO42−) based on amoxicillin carbon nanodots and in-situ sequential sensing strategy for catecholamines

Amoxicillin is used as a precursor to rapidly prepare amoxicillin carbon nanodots (AMO-CDs) via microwave method. The AMO-CDs exhibit high fluorescence recognition and quickly quantitative detection properties for molybdate (MoO 4 2− ), through the rapid coordination, obtain the amoxicillin-molybdenum complex system (AMO-CDs@Mo). The fluorescence intensity of the AMO-CDs@Mo is ∼14.7 times than that of the AMO-CDs. The detection range is from ∼10 to 100 μmol/L and the detection limit is ∼4.8 μmol/L. Based on the similar coordination manner of catecholamines and MoO 4 2− , the AMO-CDs@Mo composite solution (mixture of AMO-CDs and MoO 4 2− ) initially detects MoO 4 2− and then shows a good fluorescence linear response to catecholamines (detection range ∼40–480 μg/mL and detection limit ∼9.4 μg/mL), demonstrating a sequential detection process. In simulated urine detection experiment, the fluorescent intensity of the AMO-CDs@Mo composite solution shows a sensitive linear response to different catecholamine concentrations (detection range ∼40–480 μg/mL with detection limit of ∼10.6 μg/mL), with good anti-interference to the other main substances of urine. This study provides new insights into the development of multifunctional fluorescence sensing platforms, enabling precise analysis of multiple targets.