Advances in Optical Imaging of Nonalcoholic Fatty Liver Disease

Abstract

Nonalcoholic fatty liver disease (NAFLD), emerging as one of the most common chronic liver diseases including simple steatosis and non‐alcoholic steatohepatitis (NASH), is likely to progress to liver fibrosis and hepatic carcinoma if not treated in time. Therefore, early diagnosis and treatment of NAFLD are necessary. Currently, liver biopsy, as the gold standard for clinical diagnosis of NAFLD, is not widely accepted by patients due to its invasiveness. However, other non‐invasive methods that had been reported for NAFLD (such as magnetic resonance imaging, positron emission tomography, and ultrasound) still suffer from low resolution and sensitivity, which are available as a guide for liver biopsy sometimes. As a non‐invasive modality with high spatiotemporal resolution and superior sensitivity, optical imaging methods have been widely favored in recent years, mainly including fluorescence imaging, photoacoustic imaging, and bioluminescence imaging. With these optical imaging approaches, a series of optical probes based on optical and molecular‐specific design have been developed for the biomarker diagnosis and research of diseases. In this review, we summarize the existing non‐invasive optical imaging probes for the detection of biomarkers in NAFLD, including microenvironment (viscosity, polarity), ROS, RSS, ions, proteins, and nucleic acids. Design strategies for optical imaging probes and their applications in NAFLD bioimaging are discussed and focused on. We also highlight the potential challenges and prospects of designing new generations of optical imaging probes in NAFLD studies, which will further enhance the diversity, practicality, and clinical feasibility of NAFLD research.

Quasi-LD-Targeted and ONOO–-Responsive Fluorescent Probe for Investigating the Interaction of Nonalcoholic Fatty Liver with Drug-Induced Liver Injury

“…However, these clinical diagnostic methods cannot identify NAFLD early because they are insensitive indicators of late-stage liver dysfunction. Recently, fluorescence imaging techniques have been used to evaluate and understand the mechanisms underlying human disease − and to achieve the visualized imaging and photoactivated treatment of tumors. − With the advantages of noninvasive and high sensitivity, some fluorescent probes have successfully achieved the dynamic tracking of LDs and the evaluation of fatty liver disease. − In addition, free fatty acids (FFA) can induce reactive oxygen species (ROS) and LD production, and ROS interacts with LDs to be associated with fatty liver disease . Based on this, combining these two important factors can better and more accurately diagnose and research the early process of NAFLD.…”

Effects of Halogenation on Quinoline‐Malononitrile‐based AIEgens: Photophysical Properties Investigation and Wash‐Free Imaging

“…Owing to the high sensitivity, remarkable resolution, and excellent specificity of fluorescence imaging technology, scientists have developed a series of fluorescent probes to explore the role of small molecular fluorescent probes in disease diagnosis and clinical treatment. [1][2][3][4][5][6] Unfortunately, because traditional fluorescent dyes generally have a large planar conjugate structure, there is a severe π-π stacking interaction between molecules, so the energy in the excited state is released via nonradiative pathways, causing dye molecules to show weak fluorescence in the aggregate state, the phenomenon of which is called aggregation-caused quenching (ACQ) effect. [7] Therefore, considerable efforts have been made to provide new opportunities for overcoming the ACQ effect, for instance, introducing water medium through peripheral substituents and axial ligands to alleviate aggregation concerns.…”

Dual-Channel Fluorescent Probe for Detecting Viscosity and ONOO– without Signal Crosstalk in Nonalcoholic Fatty Liver

“…Despite all this, studies have shown that NAFLD is highly associated with obesity, abnormal mitochondrial function, oxidative stress, and metabolic syndrome . In the pathogenesis of NAFLD, lipids accumulate excessively in hepatocytes, accompanied by the increase of reactive oxygen species (ROS) and the change of intracellular microenvironment, which further cause oxidative stress and abnormal lipid metabolism and accelerate the deterioration of NAFLD. − Among various ROS and microenvironmental parameters, peroxynitrite (ONOO – ) and viscosity have recently been found to be highly associated with NAFLD and liver injury, so ONOO – and viscosity were suggested to be potential biomarkers of NAFLD. − Therefore, the effective detection of ONOO – and viscosity will be particularly useful for the clinical diagnosis and treatment of NAFLD (Scheme A).…”