Theranostics 2017; 7(15):3794-3802. doi:10.7150/thno.20912

Research Paper

Improved Tumor Targeting and Longer Retention Time of NIR Fluorescent Probes Using Bioorthogonal Chemistry

Xianghan Zhang1, Bo Wang1, Na Zhao1, Zuhong Tian3, Yunpeng Dai1, Yongzhan Nie3, Jie Tian1, 2, Zhongliang Wang1✉, Xiaoyuan Chen4

1. Engineering Research Center of Molecular-imaging and Neuro-imaging of ministry of education, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710026, China;
2. Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China;
3. Institute of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China;
4. Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, 20892 USA.

Abstract

The traditional labeling method for targeted NIR fluorescence probes requires directly covalent-bonded conjugation of targeting domains and fluorophores in vitro. Although this strategy works well, it is not sufficient for detecting or treating cancers in vivo, due to steric hindrance effects that relatively large fluorophore molecules exert on the configurations and physiological functions of specific targeting domains. The copper-free, “click-chemistry”-assisted assembly of small molecules in living systems may enhance tumor accumulation of fluorescence probes by improving the binding affinities of the targeting factors. Here, we employed a vascular homing peptide, GEBP11, as a targeting factor for gastric tumors, and we demonstrate its effectiveness for in vivo imaging via click-chemistry-mediated conjugation with fluorescence molecules in tumor xenograft mouse models. This strategy showed higher binding affinities than those of the traditional conjugation method, and our results showed that the tumor accumulation of click-chemistry-mediated probes are 11-fold higher than that of directly labeled probes. The tracking life was prolonged by 12-fold, and uptake of the probes into the kidney was reduced by 6.5-fold. For lesion tumors of different sizes, click-chemistry-mediated probes can achieve sufficient signal-to-background ratios (3.5-5) for in vivo detection, and with diagnostic sensitivity approximately 3.5 times that of traditional labeling probes. The click-chemistry-assisted detection strategy utilizes the advantages of “small molecule” probes while not perturbing their physiological functions; this enables tumor detection with high sensitivity and specific selectivity.

Keywords: click chemistry, NIR fluorescence probes, GEBP11, gastric cancer.

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How to cite this article:
Zhang X, Wang B, Zhao N, Tian Z, Dai Y, Nie Y, Tian J, Wang Z, Chen X. Improved Tumor Targeting and Longer Retention Time of NIR Fluorescent Probes Using Bioorthogonal Chemistry. Theranostics 2017; 7(15):3794-3802. doi:10.7150/thno.20912. Available from http://www.thno.org/v07p3794.htm