Table 1.

Selected examples of backbone modified CPPs and CTPs described in this review.

Peptide	Sequence	Modification	Application	References
CPPs in cancer detection and treatment
1. Poly(arginine)	rn = 3–12	D-Arg	Cell uptake studies and siRNA delivery	Tünnemann et al., 2008; Chung et al., 2017
2. cFΦR4Q	Cyclo(FΦRRRRQ)a	Cyclic-poly(Arg)	FITC delivery	Qian et al., 2013
3. [WR]5	Cyclo(WWWWWRRRRR)	Cyclic-poly(Arg)	Au and Se nanoparticles for drug delivery	Shirazi et al., 2014a,b
4. cTAT	Cyclo(GRKKRRQRRRPQ)	Cyclic-poly(Arg)	GFP delivery	Nischan et al., 2015
5. MPG-8	bAFLGWLGAWGTMGWSPKKKRK-Cya	β-Alab, Cyac	siRNA delivery	Crombez et al., 2009
6. Poly(lysine)	${\text{k}}_{\text{n}}^{\text{d}}$	D-Lys	CpGg delivery	Hanagata, 2012
7. Poly(lysine)	(Gly–Lys63(NH2)64)	Poly(lysine) dendron	pDNA and siRNA delivery	Al-Jamal et al., 2006; Janiszewska et al., 2016
CTPs in cancer detection and treatment
8. RGD	Cyclo(RGDfV)	Cyclic-RGD D-Phe	Radiotracer and near IR label delivery	Janssen et al., 2002; Ye et al., 2006
9. RGD	Cyclo(RGDf[N-Me]V)	Cyclic-RGD D-Phe, N-Me Val	αvβ3 integrin receptor inhibitor	Marinelli et al., 2003
10. Pep-42	CTVALPGGYVRVC-Val-Cit-PABA	Cite, PABAf	Drug delivery	Yoneda et al., 2008
11. D-SP5	prpspkmgvsvs	Retro-inverso D-peptide	pDNA delivery	Li et al., 2015

^aWhere Φ is L-2-naphthylalanine.

^bβ-Ala is β-alanine.

^cCya is cysteamide.

^dVariable number of D-Lys units.

^eCit is citrulline.

^fPABA is p-aminobenzyl alcohol.

^gCpG is cytosine-phosphate-guanosine.