Web Release Date: October 16,
pH-Sensitive Polymer Nanospheres for Use as a Potential Drug Delivery Vehicle
Research Center for Biomolecular Nanotechnology, Department of Life Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea
Received May 11, 2007
Revised August 28, 2007

Abstract:
We report the development and characterization of pH-sensitive poly(2-tetrahydropyranyl methacrylate) [poly(THPMA)] nanospheres and demonstrate their feasibility as an effective drug delivery vehicle. Poly(THPMA) nanospheres were prepared using either the double emulsion or single emulsion method for the encapsulation of, respectively, water soluble (rhodamine B) or organic soluble (paclitaxel) payloads. The resulting nanospheres showed pH-dependent dissolution behavior, resulting in significant morphologic changes and loss of nanoparticle mass under mild acidic conditions (pH 5.1) with a half-life of 3.3 days, as compared to physiologic condition (pH 7.4) with a half-life of 6.2 days. The in vitro drug release profile of the paclitaxel-loaded poly(THPMA) nanospheres revealed that the rate of drug release in pH 5.1 acetate buffer was relatively faster than that in pH 7.4 HEPES buffer. Furthermore, poly(THPMA) nanospheres showed lower cytotoxicity and higher cellular uptake as compared to the FDA-approved PLGA-based nanospheres currently in clinical practice.
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