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International Journal of Molecular Sciences

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Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement). In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA)2, were conducted. Besides, multiple potential biomedical applications of this switchable fluorescent probe have been demonstrated, including wash-free live-cell fluorescence imaging, in vivo tissue fluorescence imaging, temperature sensing, and ultrasound-switchable fluorescence (USF) imaging. The fluorescence of the ADP(CA)2 is extremely sensitive to the microenvironment, especially polarity and viscosity. Our investigations showed that the fluorescence of ADP(CA)2 can be switched on by low polarity, high viscosity, or the presence of protein and surfactants. In wash-free live-cell imaging, the fluorescence of ADP(CA)2 inside cells was found much brighter than the dye-containing medium and was retained for at least two days. In all of the fluorescence imaging applications conducted in this study, high target-to-noise (>5-fold) was achieved. In addition, a high temperature sensitivity (73-fold per Celsius degree) of ADP(CA)2-based temperature probes was found in temperature sensing.

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This work was supported in part by funding from the NSF CBET-1253199 (BY), the NHARP 13310 (BY), the NIH/NIBIB 7R15EB012312-02 (BY), the CPRIT RP120052/170564 (BY), and the NSF MSN 1110942 and 1401188 (FD). We also thank Dr. Hong Weng for her help in the animal related work, Mr. Tingfeng Yao for his help in the measurement of the spectra in different solvents, and Dr. Zhiwei Xie and Dr. Jian Yang (Pennsylvania State University) for measuring the quantum yields.

Department of Bioengineering, The University of Texas at Arlington


Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.