Poly(vinyl benzoate) nanoparticles for molecular delivery: Studies on their preparation and in vitro properties

The preparation and properties of poly(vinyl benzoate) nanoparticle suspensions as molecular carriers are described for the first time. These nanoparticles can be formed by nanoprecipitation of commercial poly(vinyl benzoate) in water using Pluronic F68 as surfactant, to create spherical nanostructures measuring 200-250 nm in diameter. These nanoparticles are stable in phosphate buffer and blood serum, and only slowly degrade in the presence of esterases. Pluronic F68 stabilizes the nanoparticle and also protects it from enzymatic degradation. Up to 1.6% by weight of a lipid-soluble molecule such as coumarin-6 can be introduced into the nanoparticle during nanoprecipitation, compared to a water-soluble compound (5(6)-carboxyfluorescein) which gave almost no loading. Kinetics experiments in phosphate buffer indicate that 78% of the coumarin-6 was encapsulated within the polymer matrix of the nanoparticle, and the residual 22% of coumarin-6 was surface-bound and quickly released. The nanoparticles are non-toxic in vitro towards human epithelial cells (IC50> 1000 mu g/mL) and primary bovine aortic endothelial cells (IC50>500 mu g/mL), and non-bactericidal against a selection of representative test microbes (MIC >250 mu g/mL). These properties suggest that the poly(vinyl benzoate) nanoparticles may be suitable carriers for molecular delivery of lipophilic small molecules such as pharmaceutical and imaging agents. (C) 2010 Published by Elsevier B.V.