Table 3.

Summary of tumor targeting strategies for improved tumor cellular uptake.

	Targeting agent	Targeting receptor	Therapeutic agent	Functions	Refs
Polymers	HA	CD44	DOX, PTX	Synergistic chemotherapy	[120]
			DOX, Gn	Synergistic chemotherapy	[93]
			DOX, proapoptotic peptide KLA	Chemotherapy	[33]
			MTX, DOX ICG	Chemo-phototherapy, dual tumor targeting	[121]
			Curcumin	Chemotherapy	[122]
			MTX	Chemotherapy, dual tumor targeting	[123]
Small molecule	FA	Folate receptor	PTX	Chemotherapy	[13,90]
			2-tert-butyl-9,10-di(naphthalen-2yl)anthracene (TBADN)	Imaging	[64]
			NPAPF	Bioimaging	[76]
	Biotin	Biotin receptor	IR780, quercetin	Chemo-phototherapy	[124]
	MTX	Folate receptor	MTX, HCPT	Synergistic chemotherapy, diagnosis	[37]
			MTX, PTX, HCPT	Synergistic chemotherapy	[74]
			MTX, CPT, DiR	Synergistic chemotherapy, imaging	[125]
			MTX, UA	Synergistic chemotherapy	[126]
	LA	ASGPR	DOX	Chemotherapy	[127]
			UA, ICG	Chemo-phototherapy, Imaging	[128]
Biomolecules	HER2 aptamer	HER2 receptor	UA, DOX	Synergistic chemotherapy	[129]
	RGD tetrapeptide	Integrin receptor	CPT	Chemotherapy	[130]
			PTX	Chemotherapy	[89]
			CPT, ICy5	Chemo-photodynamic therapy	[131]
			metallized Au(III) tetra-(4-pyridyl) porphine	Chemo-photothermal therapy	[132]
	RGD-FA	Integrin receptor Folate receptor	PTX	Chemotherapy, dual tumor targeting	[133]
	AS1411 aptamer	Nucleolin	3′,5′- dioleoyl clofarabine (DOC)	Chemotherapy	[134]
Cancer cell membranes	CCCM		DOX, ICG	Chemo-photothermal therapy	[135]
			HCPT, ICG	Chemo-photothermal therapy	[136]