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Nano Research

Article Title

Temperature-sensitive polymeric nanogels encapsulating with β-cyclodextrin and ICG complex for high-resolution deep-tissue ultrasound-switchable fluorescence imaging

Authors

Ruilin Liu, Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Tingfeng Yao, Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Yang Liu, Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Shuai Yu, Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Liqin Ren, Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
Yi Hong, Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA
Kytai T. Nguyen, Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA
Baohong Yuan, Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, the University of Texas at Arlington, Arlington, TX 76019, USA Joint Biomedical Engineering Program, the University of Texas at Arlington and the University of Texas Southwestern Medical Center, Dallas, TX 75390, USA

Keywords

deep tissue imaging, high-resolution, ultrasound-switchable NIR fluorescence imaging, in vivo imaging

Abstract

One of the thorny problems currently impeding the applications of the fluorescence imaging technique is the poor spatial resolution in deep tissue. Ultrasound-switchable fluorescence (USF) imaging is a novel imaging tool that has recently been explored to possibly surmount the above-mentioned bottleneck. Herein, a β-cyclodextrin/indocyanine green (ICG) complex-encapsulated poly(N-isopropylacrylamide) (PNIPAM) nanogel was synthesized and studied for ex vivo/in vivo deep tissue/high-resolution near infrared USF (NIR-USF) imaging. To be specific, our results revealed that the average diameter of the as-prepared nanogels was significantly decreased to ~ 32 nm from ~ 335 nm compared to the reported ICG-PNIPAM nanoparticles. Additionally, the excitation/ emission characteristics of the ICG itself in present nanogels were almost completely retained, and the resultant nanogel exhibited high physiological stability and positive biocompatibility. In particular, the signal-to-noise ratio of the USF image for the PNIPAM/ β-cyclodextrin/ICG nanogel (33.01 ± 2.42 dB) was prominently higher than that of the ICG-PNIPAM nanoparticles (18.73 ± 0.33 dB) in 1.5-cm-thick chicken breast tissues. The NIR-USF imaging in 3.5-cm-thick chicken breast tissues was achieved using this new probe. The ex vivo NIR-USF imaging of the mouse liver was also successfully obtained. Animal experiments showed that the present nanogels were able to be effectively accumulated into U87 tumor-bearing mice via enhanced permeability and retention effects, and the high-resolution NIR-USF imaging of in vivo tumor was efficiently acquired. The metabolism and in vivo biodistribution of the nanogels were evaluated. Overall, the results suggest that the current nanogel is a highly promising NIR-USF probe for deep tissue and high-resolution USF imaging.

Graphical Abstract

Publisher

Tsinghua University Press

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