Thermoresponsive Gelatin/Monomethoxy Poly(ethylene glycol)-poly(d,l- lactide) Hydrogels: Formulation, Characterization, and Antibacterial Drug Delivery
Purpose. The primary objective of this study was to prepare novel thermoresponsive binary component hydrogels composed of gelatin and monomethoxy poly(ethylene glycol)-poly(d,l-lactide) (MPEG-PDLLA) diblock copolymer and to obtain optimal formulations capable of forming gels upon a narrow temperature range between body temperature and room temperature. Methods. MPEG-PDLLA diblock copolymers with a lower critical solution temperature (LCST) feature were synthesized by using a ring-opening polymerization method. The starting weight ratio of MPEG/DLLA was varied to obtain a series of copolymers with a wide range of molecular weight and hydrophilicity. The copolymers were characterized by 1H nuclear magnetic resonance (1H NMR) and thermogravimetric analysis. MPEG (2K)-PDLLA (1:4) was chosen to construct hydrogels with gelatin. To obtain optimal thermoresponsive formulation, various hydrogels were formulated and quantified in terms of sol-gel phase transition kinetics and rheological properties. Selected hydrogels were studied as drug carrier for gentamicin sulfate. Results. Gelatin/MPEG-PDLLA hydrogels underwent gelation in less than 15 min when 30 wt.% MPEG (2K)-PDLLA (1:4) was mixed with 10, 50, or 100 mg/mL gelatin. Hydrogels showed rapid gelation when 100 mg/mL gelatin was mixed with 15, 20, or 25 wt.% MPEG-PDLLA as temperature fell from 37°C to room temperature. The viscosity of hydrogels depended on the frequency applied in the rheological tests, the environment temperature, and the concentration of both polymer components. The time needed for 50% gentamicin sulfate release was 5 days or longer at room temperature, and the release lasted up to 40 days. 1H NMR confirmed that MPEG-PDLLA hydrolyzed under in vitro situations. Conclusions. The incorporation of a second polymer component MPEG-PDLLA into the gelatin hydrogel could modify the thermal characteristic of gelatin and the resulting binary component hydrogels obtained different thermal characteristics from the individual polymer components. Formulation of gelatin/MPEG-PDLLA hydrogels could be varied for obtaining such gels that can undergo gelation promptly upon a narrow temperature change.
H. Yang and W. J. Kao, "Thermoresponsive Gelatin/Monomethoxy Poly(ethylene glycol)-poly(d,l- lactide) Hydrogels: Formulation, Characterization, and Antibacterial Drug Delivery," Pharmaceutical Research, vol. 23, no. 1, pp. 205-214, Springer Science+Business Media, LLC, Jan 2006.
The definitive version is available at https://doi.org/10.1007/s11095-005-8417-z
Chemical and Biochemical Engineering
Keywords and Phrases
Gentamicin sulfate; In vitro degradation; Rheology; Thermoresponsive; Tissue engineering
International Standard Serial Number (ISSN)
Article - Journal
© 2006 Springer Science + Business Media, Inc., All rights reserved.
01 Jan 2006