Wednesday, 2 November 2005

Development of Thermally Responsive Graft Copolymers for High Temperature-Activated Drug Delivery

Induvadana Ankareddi and Christopher S Brazel. Department of Chemical and Biological Engineering, The University of Alabama, 126 7th Avenue, Tom Bevill Building, Tuscaloosa, AL 35487

Thermosensitive hydrogels based on poly (2-hydroxyethyl methacrylate g N- isopropyl acrylamide), P(HEMA g NIPAAm) were synthesized to control the release of imbedded drugs. Utilizing PNIPAAm's lower critical solution temperature (LCST) of approximately 32o C, the release rate can be modulated by changing thermal conditions.

The LCST of PNIPAAM was tuned by making copolymer grafts with hydrophobic butyl methacrylate (BMA) and hydrophylic methacrylic acid (MAA) comonomers. Low molecular weight (~ 3000) polymers of NIPAAm were synthesized and grafted onto a HEMA backbone to control the mesh size for drug diffusion with variations in temperature.Theophylline and inulin release profiles were studied using PHEMA and P(HEMA g NIPAAm) at three different temperatures (17, 22 and 37C) with drug diffusion coefficients determined as a function of graft composition, graft length, graft density, temperature and drug type. The graft length was determined using gel permeation chromatography. The molecular weights between crosslinks and mesh sizes of both plain PHEMA and grafted PHEMA were calculated using Flory-Rehner and rubber-elasticity theories. The Biocompatibility of the polymers was studied using Drosophila Melanogaster cells to determine the relative toxicity as compared to sodium azide.

See more of #431 - Poster Session: Drug and Gene Delivery (15015)
See more of Food, Pharmaceutical & Bioengineering Division

See more of The 2005 Annual Meeting (Cincinnati, OH)