In situ visualization of peroxisomal viscosity in the liver of mice with non-alcoholic fatty liver disease by near-infrared fluorescence and photoacoustic imaging

Non-alcoholic fatty liver disease (NAFLD) can gradually develop into hepatic failure, and early diagnosis is crucial to improve treatment efficiency. The occurrence of NAFLD is closely related to lipid metabolism. Peroxisomes act as the first and main site for lipid metabolism in the hepatocytes, so abnormal lipid metabolism might directly affect peroxisomal viscosity. Herein, we developed a new near-infrared fluorescence (NIRF) and photoacoustic (PA) imaging probe (PV-1) for the real-time visualization of peroxisomal viscosity in vivo. This PV-1 encompasses the malononitrile group as the rotor, which emits strong NIRF (at 705 nm) and PA (at 680 nm) signals when rotation is hindered as viscosity increases. Through dual-mode imaging, we discovered distinctly higher viscosity in the liver of NAFLD mice for the first time. We further found the remarkable amelioration of NAFLD upon treatment with N-acetylcysteine (NAC). Therefore, we anticipate that the PV-1 imaging method is promising for the early diagnosis and prognostic evaluation of NAFLD.