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The liver is the largest detoxification organ in the human body, with an array of functions that help support metabolism, immunity, digestion, and vitamin storage, among other functions, and maintains the health and stability of the internal environment. Liver injury causes the concentration fluctuation of related biomarkers, small molecules, and enzymes, and in turn, the structure and function of the liver are changed by those alterations. With the principles of early detection, early diagnosis, and early treatment, it is crucial to design and synthesise a tool for detecting related biomarkers during liver damage and lesion, among which fluorescent probes have attracted attention in recent years. In the course of liver diseases, the asialoglycoprotein receptors (ASGPR) are overexpressed on the hepatoma cells, which can specifically recognize the galactose variant. Several galactose-based fluorescent probes have been developed to target hepatocytes via specific receptor-mediated endocytosis and release fluorophores after reacting with specific small molecules and enzyme biomarkers. The change in fluorescence intensity reflects the level of substances, such as reactive oxygen species, reactive nitrogen species, reactive sulfur species, enzymes or metal ions, etc. The application of fluorescent probes in vivo can aid in monitoring the dynamic changes of endogenous and exogenous biomarkers. This Highlight provides an update on the progress, limitations, and prospects of galactose-based fluorescent probes applications in the early diagnosis of liver diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • GPCRs enable the body to perceive changes in the internal or external environment. • GPCRs are pharmacologically important targets for drug discovery. • Fluorescent probes can monitor the behavior of receptors in disease conditions. Scientists Robert J. Lefkowitz and Brian K. Kobilka won the Nobel Prize in 2012 for reporting a groundbreaking discovery that revealed a crucial member of the receptor family, the G-protein-coupled receptors (GPCRs). GPCRs are the collective names for over 1,000 seven-transmembrane receptors that are responsible for multiple types of cell signaling responses. When activated by various stimuli (e.g., photons and small molecules), GPCRs interact with intracellular proteins to mediate downstream signals. The role of GPCRs in physiological and pathological processes renders them candidate targets in the development of many drugs. Recent research on GPCR structural biology has considerably improved our knowledge of GPCR signaling. However, the precise binding mechanism of diverse ligands to GPCRs to generate unique signal transduction and the involvement of GPCRs in disease pathogenesis remain controversial. The designing of tools for studying the pharmacology of GPCRs is critical to identifying safer and more effective therapies. Various molecular probes for investigating receptor structure and function have proven essential in GPCR research. This review summarizes the physiological functions of some GPCRs and discusses the molecular design strategies, applications, and development status of small molecule organic fluorescence probes of various GPCRs in humans. [ABSTRACT FROM AUTHOR]