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Polymers 2014, 6(1), 39-58;

Synthesis of Gelatin-γ-Polyglutamic Acid-Based Hydrogel for the In Vitro Controlled Release of Epigallocatechin Gallate (EGCG) from Camellia sinensis

School of Chemical Engineering and Chemistry, Mapua Institute of Technology, Muralla St., Intramuros, Manila 1002, Philippines
Department of Biomedical Engineering and Center for Nanotechnology, Chung Yuan Christian University, 200, Chung Pei Rd., Chung Li 32023, Taiwan
Department of Chemistry, Xavier University-Ateneo de Cagayan, Cagayan de Oro City 9000, Philippines
Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien 97002, Taiwan
Taoyuan Armed Forces General Hospital, Taoyuan 32551, Taiwan
Author to whom correspondence should be addressed.
Received: 31 October 2013 / Revised: 12 December 2013 / Accepted: 16 December 2013 / Published: 27 December 2013
(This article belongs to the Special Issue Polymers for Drug Delivery)
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The antioxidant property and other health benefits of the most abundant catechin, epigallocatechin gallate (EGCG), are limited because of poor stability and permeability across intestine. Protecting the EGCG from the harsh gastrointestinal tract (GIT) environment can help to increase its bioavailability following oral administration. In this study, EGCG was loaded to hydrogel prepared from ionic interaction between an optimized concentration of gelatin and γ-polyglutamic acid (γ-PGA), with ethylcarbodiimide (EDC) as the crosslinker. Physicochemical characterization of hydrogel was done using Fourier transform-infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The dependence of the swelling degree (SD) of the hydrogel to the amount of gelatin, γ-PGA, EDC, swelling time and pH was determined. A high SD of the crosslinked hydrogel was noted at pH 4.5, 6.8 and 9.0 compared to pH 7.4, which describes pH-responsiveness. Approximately 67% of the EGCG from the prepared solution was loaded to the hydrogel after 12 h post-loading, in which loading efficiency was related to the amount of EDC. The in vitro release profile of EGCG at pH 1.2, 6.8 and 7.4, simulating GIT conditions, resulted in different sustained release curves. Wherein, the released EGCG was not degraded instantly compared to free-EGCG at controlled temperature of 37 °C at different pH monitored against time. Therefore, this study proves the potential of pH-responsive gelatin-γ-PGA-based hydrogel as a biopolymer vehicle to deliver EGCG. View Full-Text
Keywords: ionic hydrogel; EGCG; gelatin; γ-PGA; in vitro drug release ionic hydrogel; EGCG; gelatin; γ-PGA; in vitro drug release

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Garcia, J.P.D.; Hsieh, M.-F.; Doma, B.T., Jr.; Peruelo, D.C.; Chen, I.-H.; Lee, H.-M. Synthesis of Gelatin-γ-Polyglutamic Acid-Based Hydrogel for the In Vitro Controlled Release of Epigallocatechin Gallate (EGCG) from Camellia sinensis. Polymers 2014, 6, 39-58.

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