A small-molecule carrier for the intracellular delivery of a membrane-impermeable protein with retained bioactivity.

Ma, Xiqi; Zhang, Zhixiong; Barba-Bon, Andrea; Han, Dongxue; Qi, Zichun; Ge, Baosheng; He, Hua; Huang, Fang et al. · Proc Natl Acad Sci U S A · 2024

basic_science · Level V

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Abstract

Intracellular protein delivery has the potential to revolutionize cell-biological research and medicinal therapy, with broad applications in bioimaging, disease treatment, and genome editing. Herein, we demonstrate successful delivery of a functional protein, cytochrome c (CYC), by using a boron cluster anion as molecular carrier of the superchaotropic anion type (B<sub>12</sub>Br<sub>11</sub>OPr<sup>2-</sup>). CYC was delivered into lipid bilayer vesicles as well as living cells, with a cellular uptake ratio approaching 90%. Mechanistic studies showed that CYC was internalized into cells through a permeation pathway directly into the cytoplasm, bypassing endosomal entrapment. Upon carrier-assisted internalization, CYC retained its bioactivity, as reflected by an induced cell apoptosis rate of 25% at low dose (1 µM). This study furbishes a direct protein delivery method by a molecular carrier with high efficiency, confirming the potential of inorganic cluster ions as protein transport vehicles with an extensive range of future cell-biological or biomedical applications.

Medical subject headings