Table 2.

Chemical vectors used for nonviral gene delivery

Delivery system	Nucleic acid	Cells/Model	Effects	Reference
Cationic lipid-based
DOTMA-based ether and DOTAP-based ester trichain	gWIZ-luciferase plasmid	B104 cells	• The third hydrophobic chain of at least 12 carbon had a substantial influence on lipid packing in the presence of DNA • Transfection efficacies of trichain lipids were found to be higher than dichain analogs	[239]
Cationic liposomes composed of DOTAP, DOPE and Cholesterol (3:4:3 molar ratio)	CYP1A1 siRNA	In vitro: A549 cells In vivo: A549 tumor-bearing BALB/c nude mice	• Downregulation of CYP1A1 mRNA, protein, and enzymatic activity • Reduced in vivo tumor growth upon silencing of CYP1A1 gene	[240]
PEGylated cationic liposomes (PCL) composed of DOPE: POPC: Cholesterol: DC-6-14 (3:2:3:2 molar ratio)	pEGFP-N1 or siGFP	Male BALB/c mice (healthy mice), male BALB/c nude mice (T cell-deficient mice), and female MRL/lpr mice (SLE-prone mice)	• The intravenous injection of PCL-associated nucleic acids (pDNA or siRNA) induced anti-nucleic acids (IgM) in healthy mice but did not cause SLE and did not trigger lupus nephritis • PCL-associated nucleic acids might exacerbate SLE symptoms in SLE-prone mice with pre-existing anti-nuclear antibodies	[241]
Cationic polymer-based
Poly(3-hydroxybutyrate) (PHB)-co-PEI nanoparticles	miR-128-encoding plasmid	U87 cells	• Adequate protection of plasmid DNA against serum nucleases • Efficiently transfected U87 cells and initiated apoptosis	[242]
Low molecular weight PEI conjugated guar gum (GG-g-LPEI)	EGFP-N1 plasmid DNA	MDA-MB-231 and HeLa cells	• The GG-g-LPEI polymer displayed excellent biocompatibility and blood compatibility • The GG-g-LPEI polymer demonstrated high in vitro transfection efficiency in MDA-MB-231 cells	[243]
PLL-g-PEG polymer	HIF-1α plasmid	Healthy and diabetic rats	• PLL-g-PEG polymer effectively condensed plasmid DNA • PLL-g-PEG mediated HIF-1α delivery led to differential gene expression in vivo and initiated angiogenesis in cutaneous wounds	[170]
Methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan (MABCC), thiolated trimethyl chitosan (TMC-Cys), and thiolated trimethyl aminobenzyl chitosan (MABC-Cys)	EGFP-N1 plasmid	HEK-293T, SKOV-3, and MCF-7 cells	• All three polymers effectively condensed plasmid DNA at N/P ≥2, and polyplexes had negligible cytotoxicity • MABC-Cys exhibited the maximum gene expression in HEK-293T cells, while TMC-Cys was most effective in SKOV-3 and MCF-7 cells	[244]
Linoleic acid and penetratin dual-functionalized chitosan (CS-Lin-Pen)	gWiz-βGal and gWiz-GFP plasmids	HEK293, CHO, and HeLa cells	• Enhanced DNA protection, cell uptake, and endosomal escape • Improved gene transfection	[245]
Folate-conjugated amphiphilic cationic methoxy- poly(ethylene glycol)- b- poly(ε-caprolactone)- b- poly(ethylene imine) copolymer (MPEG–PCL–PEI-FA)	pLuc and Nur77 gene	HEK293 and HeLa/Bcl-2 cells	• MPEG-PCL-PEI-FA copolymer showed lower cytotoxicity and better gene transfection efficiency than PEI • Exhibited effective growth inhibition of therapeutic resistant HeLa/Bcl-2 cancer cells	[246]
Thiolated trimethylated chitosan/pDNA/folate conjugated cis-aconitic amide-PEI ternary complex (FA-PEI-AcO/TMC-SS/pDNA)	pEGFP	HeLa cells	• TMC-SS acquired good pDNA condensation and redox-responsive pDNA release. • FA-PEI-AcO/TMC-SS/pDNA demonstrated lowered cytotoxicity and enhanced gene transfection than TMC-SS/pDNA polyplexes in folate receptor positive tumor cells	[247]
TAT-functionalized PEI-grafting rice bran polysaccharides (PRBP-TAT)	EGFP plasmid	HEK293T, BRL, and HepG2 cells	• Effective DNA condensation and protection at low N/P ratio (i.e., 1–3.5) • PRBP-TAT showed lower cytotoxicity and higher gene transfection efficiency than PEI	[80]
Hydroxyl-rich poly (glycidyl methacrylate) (PGMA)-based cationic glycopolymers	EGFR-siRNA	HeLa cells	• The optimized formulation showed ∼52% knockdown efficiency • The polymer was found to be cytocompatible	[248]
Dendrimer-based
G5 PAMAM dendrimers, and L-PEI	GFP plasmid	HEK 293A cells	• pDNA loaded in cells using PAMAM dendrimer and endosomal release was mediated by L-PEI • The addition of L-PEI led to a 10-fold higher gene expression	[249]
Coumarin-anchored PAMAM dendrimers	TRAIL plasmid	MDA-MB-231 and HEK293 cells	• Light-responsive drug release behavior and light-enhanced anticancer activity • TRAIL plasmid and 5-Fu combination therapy resulted in improved anticancer activity	[250]
Polypeptide-based
Tat–RGD peptide		Fibroblasts (FB) and smooth muscle cells (SMC) derived from pulmonary arteries and A549 cells	• The improvement of DNA internalization by Tat–RGD polymer was primarily mediated by caveolae-dependent endocytosis • Efficient gene delivery to human pulmonary cells	[204]
Inorganic nanoparticles
Carbon quantum dots (CQDs)	TGFβ1 plasmid	3T6 cells	• CQDs played dual roles as gene vectors and bioimaging probes at the same time. • CQDs displayed strong DNA condensing capacity, good biocompatibility, and high transfection efficiency	[251]
Gold nanoparticles	pCMVp53 plasmid	In vitro: SKOV-3 cells In vivo: SKOV-3 tumor xenograft mouse model	• The nanoparticle/pDNA complex was serum-stable and protected complexed pDNA from DNase-I digestion. • The nanoparticle/pDNA complex demonstrated considerable tumor targeting and tumor regression	[252]
Zwitterion-functionalized dendrimer-entrapped gold nanoparticles	pGFP and pLuc	HeLa cells	• Compaction of pDNA to form polyplexes • Effectively transfected cancer cells at an N/P ratio of 4	[253]
Lipid nanoparticles
iRGD functionalized solid lipid nanoparticle	siPDL1 and siEGFR	In vitro: U87 and GL261 cells In vivo: orthotopic glioblastoma (GL261) xenograft mouse model	• Nanoparticles provided efficient protection of siRNAs against the harsh biological environment • Significant tumor inhibition led to prolonged mouse survival	[254]

DOTMA: 1,2-di-O-octadecenyl-3-trimethylammonium propane; DOTAP: 1,2-dioleoyl-3-trimethylammonium propane; DOPE: 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine; POPC: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine; DC-6-14: O,O′-ditetradecanoyl-N-(alpha-trimethylammonio acetyl) diethanolamine chloride; SLE; systemic lupus erythematosus.