Breath figure PLGA films for controlled drug delivery applications
Thiruselvam Ponnusamy1, Louise B. Lawson2, Vijay T. John1
1Dept of Chemical & Biomolecular Engineering, 2Dept of Microbiology and Immunology, Tulane University, New Orleans
Biodegradable polymers are of significant interest in the design of controlled drug delivery application. We describe the breath figure method1,2 of synthesizing highly porous poly lactic-co-glycolic acid (PLGA) films for the controlled release of drug compounds. The breath figure method is a versatile and simple way of generating porous structures by evaporating solutions of a polymer in a volatile solvent in a humid environment. Condensation of water droplets on the polymer due to the cooling produced by evaporating solvent leads to patterned pore formation upon eventual droplet removal. The facile removal of the pore template is a specifically appealing aspect of breath film technology.
Because of the highly porous nature of breath figures, it is possible that release characteristics of encapsulated pharmaceutical compounds can be significantly modified in comparison to nonporous films of the same material. It is therefore important to characterize such release especially in connection with the fact that the polymer film degrades with time. This work describes the synthesis of drug-loaded porous PLGA films prepared using the breath figure method and attempts to correlate the release kinetics to the degradation characteristics. A single stage process combining spin coating and the breath figure technique was used to obtain drug incorporated porous thin films. In addition to PLGA, poly (ethylene glycol) (PEG) was used as a plasticizer to modify pore structures and release characteristics through incorporation of the hydrophilic polymer into the film. Salicylic acid and Ibuprofen were used as model drug compounds. A five-week film degradation study showed a gradual deterioration of the pore structure. In vitro drug release experiments for the PLGA film in pH 7.4 phosphate buffered saline solution (PBS) showed a sustained release of drug for a month with initial burst release. The release profile showed that the drug compounds released markedly higher for the porous films compared to the non-porous films. The addition of hydrophilic PEG accelerated the drug release from porous films.
1) Mohan Srinivasarao, et al, Science, 292, 79(2001)
2) U.H.F.Bunz, Advanced Materials, 18, 973-989(2006)