Table 1.

Absolute quantification of cytosolic arrival after 4 h incubation of STxB‐BG‐biotin conjugate C, BG‐biotin‐TAT conjugate C, or BG‐Biotin‐TAT‐PEG₆‐GFWFG conjugate C on NG‐SNAP cells.^[a]

Vector	Incubation concentration [μm]	Total number of molecules/cell	Number of cytosolic molecules/cell	% of cytosolic molecules
STxB	0.04	4.9×106 (σ=1.4×106)	2.3×104 (σ=9.2×103)	0.47
TAT	0.2	3.2×107 (σ=9.6×106)	2.7×104 (σ=7.1×103)	0.08
	10	1.1×108 (σ=1.1×107)	4.2×105 (σ=1.7×104)	0.38
	20	1.1×108 (σ=2.4×107)	7.3×105 (σ=9.1×104)	0.66
TAT‐PEG6‐GFWFG	0.2	3.2×107 (σ=5.6×106)	1.8×104 (σ=3.1×103)	0.06
	10	7.4×107 (σ=2.9×106)	4.0×105 (σ=1.1×105)	0.54
	20	1.2×108 (σ=1.6×107)	7.4×106 (σ=4.3×106)	6.2

[a] As STxB is a homopentamer, it carries up to 5 substitutions per STxB molecule. A 5‐times higher TAT concentration (0.2 μm) compared to STxB (0.04 μm) was chosen to compare their drug delivery potential from the same drug concentration. Three independent experiments were performed at each concentration.