Drug-induced injury has attracted increasing attention in public health issues. Among them, hepatotoxicity has been regarded as the leading clinical problem caused by drug toxicity. However, owing to the complexity of the involved pathophysiological mechanisms and the lack of noninvasive, straightforward, and real-time tools, drug-induced hepatotoxicity has rarely been predicted satisfactorily. In this paper, by utilizing the reactive species peroxynitrite (ONOO⁻) as a biomarker, we present a two-photon fluorescent probe, TP-KA, holding rapid response, high specificity and sensitivity towards ONOO⁻, to investigate drug (acetaminophen and tolcapone)-related liver injury and the remediate effect of N-acetyl cysteine (NAC). With the support of TP-KA, we obtained direct and visual evidence of the upregulation of ONOO⁻ during drug challenge both in live cells and mice, which was accompanied by liver tissue injury and tyrosine nitration. These findings demonstrate that ONOO⁻ is a good and appropriate biomarker of hepatotoxicity, and nitrosative stress may be necessary for acetaminophen and tolcapone to exert their toxicity. Moreover, TP-KA can be employed as a powerful tool to pre-detect drug-induced organism injury and study the effect of antidotes.

Lyso-TPFP presents lysosomal targetability and an acidic pH-activatable response toward formaldehyde. Thus, it exclusively visualizes lysosomal formaldehyde and is immune against it in neutral cytosol and other organelles. In addition, two-photon fluorescence imaging endows Lyso-TPFP with the capability of in situ tracking formaldehyde in live cells and animals.

A fluorescent probe with superior sensing performance enables two-photon ratiometric imaging of biogenic hypochlorous acid in live cells and animals.