Methods for enhancing cellular uptake of cargo molecules by boronating the cargo molecule, particularly with one or more phenylboronic acid groups. Cellular uptake includes at least partial uptake into the cytosol. Boronation includes ligating, crosslinking or otherwise bonding one or more phenylboronic acids substituted to contain a reactive group to a cargo molecule. Boronation also includes ligating, crosslinking or otherwise bonding a phenylboronated oligopeptide to a cargo molecule. The phenylboronate groups are optionally conjugated to the cargo molecule via linking moieties that can be selectively cleaved, such cleavable linkers can allow the phenylboronate groups to be removed from the cargo molecule after the boronated cargo molecule is introduced into the cell. The invention includes certain phenylboronates which are boronation reagents, certain boronated oligopeptides and certain boronated peptides and proteins. The invention also includes kits for enhancing cellular uptake of cargo molecules by boronation with one or more phenylboronates or boronated oligopeptides.
