Surface modifications of biodegradable polymeric nanoparticles and their characterization by advanced electron microscopy techniques

Polymeric nanoparticles have been the focus for nanocarrier preparation in numerous biomedical applications such as cancer treatment, disease diagnosis, vaccination, in the last two decades. They have been variably surface modified using copolymers, Polyethylene glycol (PEG), dextran, cyclodextrin, cytokines, small molecules to improve their efficiency and efficacy. The resulting nano-formulations include polymer-protein conjugate, polymeric micelle, polymer-small molecule conjugate, dendrimer, polymeric vesicles, nano-hybrids, hydrogels etc. These may have intrinsic immunogenicity and require accurate characterization in order to improve their pharmacological targeting, pharmacokinetic profiles and to reduce adverse reactions. Therefore, we have reviewed the polymeric nanoparticles and the electron microscopy techniques available for their characterization in the context of their surface modifications and functionalization.