Assembly-fission synthesized fluorescent sulfur quantum dots combined with tyrosinase catalytic oxidation for selective detection of p-aminophenol in water samples

p-Aminophenol (p-AP) is widespread in various aquatic environments with teratogenic effects, nephrotoxicity, and genotoxicity. Hence, developing a quick, sensitive, and focused approach for p-AP detection is crucial. In this study, monodisperse, evenly dispersed fluorescent sulfur quantum dots (SQDs) with a 5–10 nm size were produced via the “assembly-fission” technique. Tyrosinase (Tyr) catalyzes the oxidation of p-AP to 4-amino-1, 2-benzoquinone, which efficiently quenches the fluorescence of SQDs through the internal filtering effect (IFE) between the oxidative product and SQDs. The quenching mechanism of the SQDs/Tyr/p-AP system is demonstrated by analyzing the fluorescence, zeta potential, and UV-Vis absorption spectrum overlap. When the concentration of p-AP is between 0.5 and 120 μM in the presence of Tyr, the fluorescence quenching efficiency of SQDs exhibits a strong linear relationship. The limit of detection is 0.15 μM, which is comparable to those of most other methods, and also shows a wider linear range with less matrix interference. With outstanding recoveries of 93.2–105.8% and relative standard deviations (RSDs) of 1.8–3.7% and 3.6–6.6%, respectively, the newly proposed approach has been effectively used to detect p-AP in a variety of water samples. Overall, this proposed method with high recoveries and low detection limits has great potential application in actual determination of p-AP in different water samples.