Overview of activatable cell-penetrating peptides (ACPPs) triggered through conformational changes. Amino acids are indicated via the single letter code. PEG = poly(ethylene) glycol; CPT = camptothecin; PTX = paclitaxel; probe = IR-probe; SC= side chain; LK = leucine and lysine rich CPP; trans-Ab = trans-azobenzene; Tamra = Tamra red dye; RhoB = rhodamineB dye; y^Ahx = O-aminohexylated d-tyrosine; FITC = fluorescein.

	Premise	CPP	Inhibiting factor	Cargo	Trigger	Ref.
pH sensitive conformational changes
1		Tat	PEG	DOX loaded micelle	pH drop	63
2		TH	H side chain charge	CPT	pH drop	64
		LH		CPT		66
		TH		PTX probe		65
3		K97	SC modi-fications with imi-dazole or carboxylic acids		pH drop to 6.0	67
Light sensitive conformational changes
4		LK	trans-Ab	Tamra	365 nm, 5 min, 8 mW cm−2	68
5		R9	E9	RhoB	λ = 488, 1–1.5 μW, ∼60 ms μm−2	69
6		RRF-yAhxP-FRR	Circular structure	FITC	λ = 590 nm	70