Intracellular Delivery of Functional Proteins and Native Drugs by Cell-Penetrating Poly(disulfide)s

The
efficient delivery of bioactive compounds into cells is a major
challenge in drug discovery. We report herein the development of novel
methods for intracellular delivery of functional proteins (including
antibodies) and native small-molecule drugs by making use of cell-penetrating
poly­(disulfide)­s (CPDs). CPDs were recently shown to be rapidly taken
up by mammalian cells in endocytosis-independent pathways, but their
applications for delivery of proteins and native small-molecule drugs
have not been demonstrated. With our newly developed, CPD-assisted
approaches, rapid and “bioorthogonal” loading of cargos
was carried out with pre-synthesized CPDs, in two steps and in a matter
of minutes under aqueous conditions. The resulting CPD–cargo
conjugates were used immediately for subsequent cell delivery studies.
With the versatility and flexibility of these methods, we further
showed that they could be used for immediate delivery of a variety
of functional cargos with minimum chemical and genetic manipulations.
The minimal cell cytotoxicity of these CPDs and their cargo-loaded
conjugates further highlights the unique advantage of this new cell-transduction
method over other existing strategies and ensures that our entire
delivery protocol is compatible with subsequent live-cell experiments
and biological studies.