Facile synthesis of ultrasmall polydopamine-polyethylene glycol nanoparticles for cellular delivery.

Very small polydopamine (PDA) polyethylene glycol (PEG) crosslinked copolymer (PDA-PEG) nanoparticles have been prepared following a convenient one-step procedure in aqueous solution. Particle sizes and colloidal stabilities have been optimized by varying PEG in view of chain length and end group functionalities. In particular, amine-terminated PEG3000 [PEG(3000)(NH2)(2)] reacted with polydopamine intermediates so that very small, crosslinked PDA-PEG nanoparticles with sizes of less than 50 nm were formed. These nanoparticles remained stable in buffer solution and no sedimentation occurred. Chemical functionalization was straight-forward as demonstrated by the attachment of fluorescent dyes. The PDA-PEG nanoparticles revealed efficient cellular uptake via endocytosis and high cytocompatibility, thus rendering them attractive candidates for cell imaging or for drug delivery applications. (c) 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.