Polymeric Nanoparticles
Self-assembling polymers, which are either amphiphilic block copolymers with hydrophobic and hydrophilic blocks, hydrophilic polymer backbones substituted with hydrophobic units or polymers with a low aqueous solubility, may all be used to prepare aqueous
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Polymeric Nanoparticles Ijeoma F. Uchegbu, Aikaterini Lalatsa, and Dennis Wong
Abstract Self-assembling polymers, which are either amphiphilic block copolymers with hydrophobic and hydrophilic blocks, hydrophilic polymer backbones substituted with hydrophobic units or polymers with a low aqueous solubility, may all be used to prepare aqueous dispersions of polymeric nanoparticles. The amphiphilic variants form polymeric micelles and polymeric bilayer vesicles. The hydrophobic polymers form dense amorphous polymeric particles. Polymeric particles, of whichever nature, may be loaded with hydrophobic and hydrophilic drugs, and the bioavailability of the drug compound is altered by this encapsulation within a polymeric nanoparticle. This simple concept has been exploited heavily to yield enhancements in oral, tumour and brain bioavailability and some of these polymeric nanoparticle formulations have undergone clinical testing and even been commercialised, e.g. the nanoparticle paclitaxel formulation Abraxane.
9.1 Introduction A book on pharmaceutical nanoscience would be incomplete without a chapter on polymer nanoparticles. Polymers are extensively used in pharmacy (Uchegbu and Schatzlein 2006) and form the backbone to a number of nanomedicines. Polymers I.F. Uchegbu (*) UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK e-mail: [email protected] A. Lalatsa School of Pharmacy & Biomedical Sciences, University of Portsmouth, St. Michael Building, Portsmouth PO1 2DT, UK e-mail: [email protected] D. Wong University of Strathclyde, Glasgow G4 0NR, UK I.F. Uchegbu et al. (eds.), Fundamentals of Pharmaceutical Nanoscience, DOI 10.1007/978-1-4614-9164-4_9, © Springer Science+Business Media New York 2013
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are excellent materials to use in the fabrication of pharmaceutical nanoparticles as the size of the nanoparticle may be controlled via the polymer chemistry [i.e. polymer molecular weight (Wang et al. 2001a) and polymer hydrophobicity (Wang et al. 2004)] and polymer nanoparticles may be easily loaded with both hydrophobic (Qu et al. 2006; Siew et al. 2012) and hydrophilic (Dufes et al. 2000) drugs, with hydrophilic drugs being encapsulated within polymeric bilayer vesicles (Dufes et al. 2000), for example. The polymers that have been most commonly used to prepare polymeric nanoparticles include the polyesters [e.g. poly(d,l-lactide coglycolide) (Seju et al. 2011; Yang et al. 2012), poly(d,l-lactide)-co-poly(ethylene glycol) (PLA-PEG) (Hrkach et al. 2012), poly(d,l-lactide co-glycolide)-copoly(ethylene glycol) (Ensign et al. 2012; Hrkach et al. 2012)], chitosans [e.g. N-monomethyl, N,N-dimethyl, N,N,N-trimethyl, N-palmitoyl, 6-O-glycol chitosan—quaternary ammonium palmitoyl glycol chitosan (GCPQ) (Uchegbu et al. 2001; Qu et al. 2006; Lalatsa et al. 2012b), 5β-cholanic acid glycol chitosan (Min et al. 2008), cross-linked chitosan (Trapani et al. 2013), alginate–chitosan coacervates (Sarmento et al. 2007)], polyamino acids [e.g.
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