Table 2.

Functional groups incorporated into the vector for regulating environmental interactions

Targeting ligands	Target	Cell types	Refs.
Folate	Folate receptor	Malignant cells e.g. ovarian carcinomas	[22]
Transferrin	Transferrin receptor	Malignant cells e.g. leukemia cells	[23]
RGD	Integrin	Broad range of cells e.g. endothelial cells	[24]
EGF (epidermal growth factor)	EGF receptor	Malignant cells e.g. epidermal carcinoma cells	[25]
Anti-CD3	CD3	T-cells	[26]
Vector stabilization	Mechanism		Refs.
PEG (poly(ethylene glycol))	Provides stability against serum components		[22]
Polysaccharides (e.g. β-cyclodextrin, chitosan, polyglucaramidoamine)	Reduces toxicity and inflammation, provides stability against serum components		[17,19,52]
Biomaterial immobilization	Material		Refs.
Biotin	Neutravidin modified hyaluronic acid		[36]
Non-specific interactions (e.g. charge)	Poly(lactide-co-glycolide) (PLG)		[30]