Volume 103, Issue 3 pp. 1276-1290
Review Article

Thermosensitive block copolymer hydrogels based on poly(ɛ-caprolactone) and polyethylene glycol for biomedical applications: State of the art and future perspectives

Monica Boffito

Monica Boffito

Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, Italy

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Paolo Sirianni

Paolo Sirianni

Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, Italy

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Anna Maria Di Rienzo

Anna Maria Di Rienzo

Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, Italy

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Valeria Chiono

Corresponding Author

Valeria Chiono

Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, Italy

Correspondence to: V. Chiono; e-mail: [email protected]Search for more papers by this author
First published: 10 June 2014
Citations: 72

Abstract

This review focuses on the challenges associated with the design and development of injectable hydrogels of synthetic origin based on FDA approved blocks, such as polyethylene glycol (PEG) and poly(ɛ-caprolactone) (PCL). An overview of recent studies on inverse thermosensitive PEG/PCL hydrogels is provided. These systems have been proposed to overcome the limitations of previously introduced degradable thermosensitive hydrogels [e.g., PEG/poly(lactide-co-glycolic acid) hydrogels]. PEG/PCL hydrogels are advantageous due to their higher gel strength, slower degradation rate and availability in powder form. Particularly, triblock PEG/PCL copolymers have been widely investigated, with PCL–PEG–PCL (PCEC) hydrogels showing superior gel strength and slower degradation kinetics than PEG–PCL–PEG (PECE) hydrogels. Compared to triblock PEG/PCL copolymers, concentrated solutions of multiblock PEG/PCL copolymers were stable due to their slower crystallization rate. However, the resulting hydrogel gel strength was low. Inverse thermosensitive triblock PEG/PCL hydrogels have been mainly applied in tissue engineering, to decrease tissue adherence or, in combination with bioactive molecules, to promote tissue regeneration. They have also found application as in situ drug delivery carriers. On the other hand, the wide potentialities of multiblock PEG/PCL hydrogels, associated with the stability of their water-based solutions under storage, their higher degradation time compared to triblock copolymer hydrogels and the possibility to insert bioactive building blocks along the copolymer chains, have not been fully exploited yet. A critical discussion is provided to highlight advantages and limitations of currently developed themosensitive PEG/PCL hydrogels, suggesting future strategies for the realization of PEG/PCL-based copolymers with improved performance in the different application fields. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1276–1290, 2015.

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