Block copolymers (BCP) play a critical role in nanoparticle/nanocarrier (NC) drug delivery. We produce NCs for the delivery pharmaceutical actives and diagnostics by block-copolymer-directed assembly during rapid precipitation. Nanocarriers are formed using block copolymers with hydrophobic anchor blocks of polystyrene (PS), poly-ε-capralactone (PCL), poly-d,l-lactide (PLA), and polypropylene sulfide (PPS) with hydrophilic blocks of polyethylene glycol (PEG) with various molecular weights, from 1.5 kg/mol to 20 kg/mol. We discuss how polymer properties control three aspects of NC formation and drug delivery. (1) Molecular weight and polymer type of the hydrophobic block. We show that equivalent NCs can be produced from any of the hydrophobic block copolymers, and present the scaling rules for how NC size can be predicted. This is important when transitioning from model polymers, which may not be FDA approved, to approved, biocompatible polymers. (2) Interaction energy between the hydrophobic polymer block and the core material. The anchoring energy of the hydrophobic block on the NC surface determines the PEG density on the surface and the drug release rate from the NC. (3) PEG surface density and targeting. The PEG steric layer limits protein adsorption, which drives NC clearance by recognition by the RES (reticuloendothelial system). The circulation time is extremely sensitive to the PEG density, which depends on the architecture of both the hydrophobic and hydrophilic blocks. In addition, functionalization of the PEG chains with targeting ligands can direct NCs to specific sites to enhance drug delivery.

Block copolymer-directed assembly of pharmaceutical nanoparticles: Effects of Mw and chemistry on assembly, delivery, and in vivo performance

253rd National Meeting (2017)

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