A high quantum yield xanthene-based fluorescent probe for the specific detection of tyrosinase and cell imaging.

[Display omitted] • This is a rhodamine-based "off-on" fluorescent probe with a novel structure to detect tyrosinase activity. • The rhodamine fluorophore structure was improved by expanding the π-conjugation system, asymmetric synthesis, and fixing the N terminus, which greatly improved the fluorescence quantum yield of the fluorophore. • The use of 3-hydroxybenzyl oxygen as the recognition group of the probe effectively avoids the interference of reactive oxygen species in the detection of tyrosinase and improves the selectivity of the probe for tyrosinase. Tyrosinase (TYR) detection will be crucial in the prevention and early diagnosis of some illnesses, including epilepsy, albinism, and melanoma, due to the close linkage of abnormal expression of TYR with the occurrence of these diseases. Therefore, how to obtain a fluorescent probe that has a high fluorescence quantum yield and high specificity for detecting TYR activity will be of significance. In this work, we improved the rhodamine structure by expanding the π-conjugation system and using asymmetric synthesis to provide a fluorescent probe with good optical properties for the specific detection of TYR. The fluorescence quantum yield of fluorophore released from the probe by the enzymatic reaction with TYR was as high as 0.22, which was significantly greater than that of other previously reported fluorescent probes. We also chose 3-hydroxybenzyl oxygen as the recognition group, which can successfully lessen the interference from reactive oxygen species (ROS). At the same time, the probe demonstrated great sensitivity in detecting TYR activity, and the detection limit of TYR for the probe was calculated to be 0.45 U/mL. In addition, the probe has currently been successfully utilized to evaluate TYR activity in cells. Therefore, this probe is anticipated to be crucial in identifying TYR activity in challenging settings. [ABSTRACT FROM AUTHOR]