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Updated: Nov 30, 2025
Fluorescence-quenching of a Liposomal-encapsulated Near-infrared Fluorophore as a Tool for In Vivo Optical Imaging
Published on: January 5, 2015
Engineering a lipid droplet targeting fluorescent probe with a large Stokes shift through ester substituent rotation
Xing Wei1, Hongxing Zhang, Yuanqiang Sun
1College of Chemistry, Green Catalysis Center, Henan Joint International Research Laboratory of Green Construction of Functional Molecules and Their Bioanalytical Applications, Zhengzhou Key Laboratory of Functional Nanomaterial and Medical Theranostic, Zhengzhou University, Zhengzhou 450001, China. yqsun@zzu.edu.cn zhaohui.li@zzu.edu.cn.
Abstract:
Great progress has been made with lipid droplet targeting fluorescent probes in a wide range of biomedical fields. However, the Stokes shifts of most fluorescent probes are relatively small, leading to strong biological background fluorescence, poor signal-to-noise ratios, self-quenching in the commonly used microscopes and the need for in vivo imaging systems. In this manuscript, the ester substituent rotation of fluorophores was supposed to result in a large Stokes shift via steric hindrance effects and resonance effects. A lipid droplet targeting fluorescent probe 1 was achieved by simply appending a 4-substituted ester group onto the classic coumarin fluorophore. Probe 1 exhibited large Stokes shifts (122 to 184 nm) in both high polarity and weak polarity solvents with good lipophilicity and polarity responsive ability (3500 fold fluorescence enhancement). Probe 1 was suitable for washing-free imaging of lipid droplets in living cells with excellent specificity and rapidity (<2 min). Probe 1 was applied for distinguishing cancer cells from normal cells by taking advantage of the abnormalities of lipid droplets of cancer cells. Due to its huge Stokes shift, probe 1 can be used for in vivo tumor imaging by the excitation of a blue laser, which is important for biomedical research.
