A genetic engineering strategy for editing near-infrared-II fluorophores

• Published in: Nature communications Vol. 13; no. 1; p. 2853
• Main Authors: Tian, Rui, Feng, Xin, Wei, Long, Dai, Daoguo, Ma, Ying, Pan, Haifeng, Ge, Shengxiang, Bai, Lang, Ke, Chaomin, Liu, Yanlin, Lang, Lixin, Zhu, Shoujun, Sun, Haitao, Yu, Yanbao, Chen, Xiaoyuan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.05.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 59; 631/1647/245/2225; 639/638/309/436/1729; Albumin; Albumins; Biocompatibility; Bioengineering; Biological properties; Chemical compounds; Chemical synthesis; Contrast agents; Contrast media; Covalent bonds; Cyanine dyes; Dyes; Fluorescence; Fluorophores; Genetic engineering; Heavy metals; Humanities and Social Sciences; I.R. radiation; multidisciplinary; Near infrared radiation; Pharmacokinetics; Pharmacology; Probes; Proteins; Science; Science (multidisciplinary); Wavelength
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-30304-9

The second near-infrared (NIR-II) window is a fundamental modality for deep-tissue in vivo imaging. However, it is challenging to synthesize NIR-II probes with high quantum yields (QYs), good biocompatibility, satisfactory pharmacokinetics, and tunable biological properties. Conventional long-wavelength probes, such as inorganic probes (which often contain heavy metal atoms in their scaffolds) and organic dyes (which contain large π-conjugated groups), exhibit poor biosafety, low QYs, and/or uncontrollable pharmacokinetic properties. Herein, we present a bioengineering strategy that can replace the conventional chemical synthesis methods for generating NIR-II contrast agents. We use a genetic engineering technique to obtain a series of albumin fragments and recombinant proteins containing one or multiple domains that form covalent bonds with chloro-containing cyanine dyes. These albumin variants protect the inserted dyes and remarkably enhance their brightness. The albumin variants can also be genetically edited to develop size-tunable complexes with precisely tailored pharmacokinetics. The proteins can also be conjugated to biofunctional molecules without impacting the complexed dyes. This combination of albumin mutants and clinically-used cyanine dyes can help widen the clinical application prospects of NIR-II fluorophores. It is currently difficult to synthesise NIR-II probes with good quantum yields, biocompatibility and pharmacokinetics. Here the authors report a strategy to alter these properties by modifying the protein coatings with biofunctional molecules, and generate long-wavelength fluorophores for in vivo imaging.