Preparation and characterization of cationic pluronic for surface modification and functionalization of polymeric drug delivery nanoparticles

Biodegradable poly(lactic-co-glycolic acid) copolymer, PLGA nanoparticles (NPs) with a surface layer of poly (ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers, Pluronics, are promising drug carrier systems. With the aim to increase the potential of targeted drug delivery the end group derivative of Pluronics was synthe- sized in a straightforward way to obtain Pluronic-amines. The formation of functional amine groups was confirmed by flu- orescamine method and NMR analysis of their N-(tert-Butoxycarbonyl)-L-phenylalanine (Boc-Phe-OH) and N-(9-Fluo- renylmethoxycarbonyl)-L-phenylalanine (Fmoc-Phe-OH) conjugates. Pluronic and Pluronic-amine stabilized PLGA NPs prepared by nanoprecipitation were characterized by dynamic light scattering and zeta potential measurements. All of the systems showed high colloidal stability checked by electrolyte induced aggregation, although the presence of Pluronic- amine on the surface decreased the zeta potential in some extent. The introduction of reactive primary amine groups into the surface layer of PLGA NPs while preserving the aggregation stability, provides a possibility for coupling of various ligands allowing targeted delivery and also contributes to the improved membrane affinity of NPs.