Polymeric and Self Assembled Hydrogels: From Fundamental Understanding to Applications
CHAPTER 7: Injectable Temperature- and pH/Temperature-Sensitive Block Copolymer Hydrogels
Published:19 Nov 2012
C. Truc Huynh and D. Sung Lee, in Polymeric and Self Assembled Hydrogels: From Fundamental Understanding to Applications, ed. X. J. Loh and O. A. Scherman, The Royal Society of Chemistry, 2012, pp. 139-166.
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In the past two decades, physically stimuli-sensitive polymeric hydrogels have attracted considerable attention, because of their potential biomedical and pharmaceutical applications, such as in drug/protein delivery and tissue engineering. These polymeric hydrogels have many advantages, such as the formulation and administration of therapeutic agents with sustained release behaviour using a simple procedure requiring no organic solvent. This results in less systematic cytotoxicity in addition to being able to deliver both hydrophobic and hydrophilic drugs as well as ionic bioactive molecules. Their aqueous solutions exhibit a sol–gel phase transition in response to external stimuli, such as pH, temperature, glucose, electric fields, magnetic fields, ionic strength or a combination of these. The hydrogel precursors exist in the solution state and can be mixed with bioactive molecules or cells and then simply injected into the body at specific sites for release purposes. Substantial progress has been made in the development of novel hydrogel systems and their applications. In this chapter, a short review of temperature- and pH/temperature-sensitive block copolymer physical hydrogels is presented. Representatives of temperature-sensitive hydrogels using poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers, and pH/temperature-sensitive hydrogels using cationic PEG-poly(amino ester urethane) [PEG-PAEU]x block copolymers, are reported in detail.