Achievements and Bottlenecks of PEGylation in Nano-delivery Systems

Poly(ethylene glycol) (PEG) has been widely applied in the biomedical field as a gold standard. The conjugation of PEG to proteins, peptides, oligonucleotides (DNA, small interfering RNA (siRNA), microRNA (miRNA)) and nanoparticles, also known as PEGylation, is a common method to improve the efficiency of drug delivery and pharmacokinetics in vivo. The effect of PEGylation on the in vivo fate of various formulations has been and continues to be extensively studied based on the successful PEGylation of proteins to improve in vivo circulation time and reduce immunogenicity. The PEG shell protects the particles from aggregation, immune recognition, and phagocytosis, thereby prolonging the in vivo circulation time. This article mainly describes the development background, advantages and applications of PEGylation in the field of drug delivery, its defects or development bottlenecks, and possible alternatives.