Preparation and characterization of elastin-like polypeptide scaffolds for local delivery of antibiotics and proteins.

Tissue engineering applications could benefit from simultaneous release of growth factors, signaling molecules, and antibiotics to obtain optimal healing of tissues. Elastin-like polypeptides (ELPs) are genetically engineered polymers that possess good biocompatibility, are biodegradable, and exhibit mechanical properties similar to natural elastin. In addition, ELPs exhibit a characteristic inverse phase transition temperature (T(t)). This T(t) behavior is widely exploited in hyperthermia mediated drug delivery. The objectives of this research were to prepare ELP hydrogel scaffolds using a novel ultrasonication method and to investigate the release of a model protein (bovine serum albumin, BSA) and a commonly used antibiotic in periodontal therapy (doxycycline) from the scaffolds at two different temperatures (25 °C <T(t) vs. 37 °C >T(t)). Both BSA and doxycycline showed a gradual time dependent release and showed a trend of higher release fractions with higher loading doses. Based on the comparison between the release profiles at the two selected temperatures, the release was higher at 37 °C compared to that at 25 °C for both the loading concentrations of doxycycline (0.05 and 0.1 % v/v) and only one of the loading concentrations of BSA (0.5 % v/v) studied, while the release was higher at 25 °C compared to that at 37 °C only for the other loading concentration of BSA (1 % v/v) studied. These results suggested that the drug molecular weight and loading concentration were significant factors that affected the release kinetics. The experiments in this study demonstrated that the ELP hydrogel scaffolds can successfully release proteins and antibiotics critical to tissue engineering.