Table 3.

Nanoparticles surface modifying agent/(bio) molecules used for stabilization and biocompatibility

Surface modifying agent	Properties	Advantages/applications	References
Polyethylene Glycol (PEG)	Hydrophilic, water-soluble,	Increase the biocompatibility, internalization efficiency, dispersions and circulation times	[127, 129–131]
Polyvinylpyrrolidone (PVP)	Water-soluble polymer made from the monomer N-vinylpyrrolidone	Enhances the blood circulation time and stabilizes the colloidal solution, used as binder	[132]
Polyvinyl Alcohol (PVA)	Hydrophilic linear polymer that forms copolymers	Biocompatible, PVA coating onto the particle surface prevents their agglomeration, giving rise to monodisperse particles
Chitosan	An alkaline, non-toxic, hydrophilic	Biocompatible and biodegradable	[133–135]
Alginate	Electrolytic polysaccharide with carboxyl groups	Stability and functionalization	[136–139]
Cellulose	Hydrophilic polymer	Entrap hydrophilic drugs, impart stealth character to nanocarriers, controlled drug release, and increase half-life	[126, 138, 140]
Gelatin	Gelling agent, hydrophilic	Emulsifier, biocompatible, natural polymer	[3, 141]
Polypeptides	Selectivity for hydrophilicity and hydrophobicity	Increase nanoparticle binding ability to the ligand and cellular internalization, target drug delivery	[125, 142, 143]
Fatty acids	Carboxylic acid with a long aliphatic tail	Colloidal stability, terminal functionalization using carboxyl groups	[144, 145]
Dextran	α-linked D-glucopyranosyl repeating units	Enhances the blood circulation time, stabilizes the colloidal solution	[146, 147]
Silica	Oxide of silicon, Commonly found in nature	Prevent aggregation, improve chemical stability, biocompatible	[148]
Nucleic acid	Easy to absorb on the nanoparticle surface	Surface functionalization, Gene delivery, regulation of gene expression	[149]
Thiol	Functional group of amino acid	Surface functionalization, target drug delivery	[2, 150]