Results and Discussion PREPARATION OF NANOHYDROGEL STRUCTURE BASED ON PLA-PCL-PEG-PCL-PLA PENTABLOCK COPOLYMER FOR CURCUMIN DELIVERY Trần Thị Quỳnh Mai1, Huỳnh Đại Phú2 1Department of Chemical Engineering, Industrial University of HCMC 2Department of Material Engineering, Ho Chi Minh University of Technology Abstract Methods and Materials Materials: Pentablock copolymer PLA-PCL-PEG-PCL-PLA was synthesized by ring opening copolymerization of ε-caprolactone and lactide acid with macroinitiator as poly(ethylene glycol). Curcumin was purchased from Vietnam Institute Dietary Supplement (Hanoi, Vietnam). All chemicals used in this study were of reagent grade. Methods: The hydrogel was synthesized by using an inverting test-tube method through a 10 ml tightly screw-capped vial with inner diameter of 12 mm. The copolymer solutions were prepared by dissolution various amount of copolymer in distilled water. The solutions were transferred into test tube and slowly heated to 80°C, then the samples was slowly cool down. The sol-gel transition was observed visually by inverting the vials and condition of gel was defined in 1 min [4]. For curcumin-loaded hydrogel, the 20% (w/w) copolymeric solution contained curcumin was prepared and formed hydrogel as described above. In this article, thermo-sensitive hydrogel based on poly(lactide acid)- poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone)-poly(lactide acid) (PLA-PCL-PEG-PCL-PLA) was successfully synthesized by using inverting test-tube method. The composition and surface morphology of hydrogel were characterized by FT-IR and SEM. The SEM image indicated the hydrogel was composed of copolymeric network and nano-sized particles. The curcumin was entrapped into copolymeric hydrogel. In vitro drug release behavior was studied in PBS buffer. The result showed that controlled curcumin release was observed. The release capacity decreased with increasing curcumin entrapped into hydrogel, and it decreased with increasing of copolymer content. Figure 2. FTIR of pentablock popolymer (a), catechin (b) and catechin-loaded hydrogel (c). Introduction Medicines derived from plants play an important role in the healthcare of many cultures, both ancient and modern. Curcumin (diferuloylmethane, a polyphenol) is an active principle of the perennial herb Curcuma longa (commonly known as turmeric). Curcumin, a naturally occurring polyphenolicphytoconstituent which presents anticancer, antioxidant, anti-inflammatory, hyperlipidemic, antibacterial, wound healing and hepatoprotective activities. The therapeutic efficacy of curcumin is limited due to its poor aqueous solubility and extensive first pass metabolism. Hydrogels are water-swollen polymeric networks and crosslinked polymeric structures produced by the simple reaction of one or more monomers, or by association bonds such as hydrogen bonds and strong Van der Waals interactions between chains. Hydrogels are extremely useful as biomaterials and can be synthesized to be responsive for external stimuli. For the last decades, scientists concentrate to prepared hydrogel based on diblock and triblock copolymers such as: PEG-PCL, PCL-PEG-PCL, PLA-PEG-PLA and so on. They realized that high molecular weight PCL need about one year to complete in vitro biodegradation. Therefore, the combination of fast degradation PLA with PCL was to improve the biodegradation and controlled drug release. Figure 3. SEM of hydrogel with different magnifications Results and Discussion a. Synthesis hydrogel pentablock copolymer PLA-PCL-PEG-PCL-PLA hydrogel based on central PCL and PLA blocks and end PEG blocks showed temperature-dependent sol-gel transition (Figure 1) The identities of hydrogel and curcumin-loaded hydrogel were evaluated by FTIR (Figure 2). Interior morphology of hydrogel was investigated by SEM. Hydrogel was frozen in liquid nitrogen and lyophilized for 12 h before the test (Figure 3). b. In vitro drug release behavior In vitro release behavior of curcumin from PLA-PCL-PEG-PCL-PLA hydrogel was investigated, which is presented in Figure 4. Figure 4. In vitro drug release behavior from hydrogel Future work In this contribution, we synthesized hydrogel based on PLA-PCL-PEG-PCL-PLA copolymer by using test-tube inverting method. The structures of hydrogel and curcumin-loaded hydrogel were confirmed by FT-IR. The porous and 3D structures were observed by SEM. Additionally, some nanosized micelles were also seen in SEM. The in vitro drug release behavior show that, hydrogel releases drug by swelling, diffusing and degradation than dissolving. The hydrogel exhibited the controlled drug release. Importantly, this study has demonstrated that the hydrogel can provide delivery of curcumin for biomedical applications. Figure 1. Copolymeric solution at low temperature (a) and gel form at 37 oC (b) Contact References Dr. aaaaa Department of Chemical Engineering Email: a@iuh.edu.vn 1. Junmin Zhu and Roger E Marchant. Design Properties Of Hydrogel Tissue-Engineering Scaffolds. Expert Rev Med Devices 8(5): 607-626 (2011). 2. T. Kissel, Y. Li, F. Unger, ABA-triblock copolymers from biodegradable polyester A-blocks and hydrophilic poly(ethylene oxide) B-blocks as a candidate for in situ forming hydrogel delivery systems for proteins, Adv. Drug Deliv. Rev., 54, 99-134 (2002). 3. D. P. Huynh, M. K. Nguyen, B. S. Pi, M. S. Kim, S. Y. Chae, K. C. Lee, B. S. Kim, S. W. Kim, D. S. 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