Effect of different parameters on the PEGylation of protein nanoparticles

PEGylation (i.e. the covalent link of PEG strands) is a well known technique used to improve pharmaceutical properties of bioactive proteins and peptides. This polymer is nontoxic, non-immunogenic, non-antigenic, highly soluble in water and FDA approved. In particular, for many proteins fast clearance from the body and potential immunogenicity are severe limitations, which cannot be easily overcome without taking into consideration a purposely designed drug delivery system. The PEG-nanoparticle conjugates have several advantages: a prolonged residence in body, a decreased degradation by metabolic enzymes and a reduction or elimination of nanoparticle immunogenicity. Thanks to these favorable properties, PEGylation now plays an important role in drug delivery, enhancing the potentials of peptides and proteins as therapeutic agents [1, 2].In the early days of PEGylation, researchers directed their attention towards the amino groups as suitable conjugation site, because they are the most represented groups in proteins, generally exposed to the solvent and can be modified with a wide selection of chemical strategies