Roles of Polyethylene Glycol on the Surface of Nanoparticles for Targeted Drug Delivery

The rapid development of drug nanocarriers has benefited from surface hydrophilic polymers of particles, which has improved the drug's pharmacokinetics. Polyethylene glycol (PEG) is a kind of polymeric material with unique hydrophilicity and electrical neutrality. PEG coating is a crucial factor to improve the biophysical and chemical properties of nanoparticles and is widely studied. Protein adherence and macrophage removal are effectively relieved due to the existence of PEG on the particles. This review introduces PEGylated methods of nanoparticles and the related techniques to detect PEG coverage density and thickness on the particle's surface in recent years. The molecular weight (MW) and coverage density of PEG coating on nanoparticles' surface are then described to explain the effects on nanoparticles' biophysical and chemical properties.