Thermo-Responsive Nanocomposite Hydrogels Based on PEG-b-PLGA Diblock Copolymer and Laponite.

Tomoki Maeda,Midori Kitagawa,Satoshi Koizumi,Atsushi Hotta

doi:10.3390/polym11020250

Tomoki Maeda, Midori Kitagawa + Show 2 more

Open Access

https://doi.org/10.3390/polym11020250

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Journal: Polymers	Publication Date: Feb 2, 2019
Citations: 20	License type: CC BY 4.0

Affiliation: Keio University, Ibaraki University

Abstract

Poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (PEG-b-PLGA) diblock copolymers are widely known as polymeric surfactants for biomedical applications, and exhibit high solubility in water compared to PLGA-b-PEG-b-PLGA triblock copolymers known as gelation agents. In order to overcome the difficulties in the preparation of thermo-responsive hydrogels based on PLGA-b-PEG-b-PLGA due to the low solubility in water, the fabrication of thermo-responsive hydrogels based on PEG-b-PLGA with high solubility in water was attempted by adding laponite to the PEG-b-PLGA solution. In detail, PEG-b-PLGA with high solubility in water (i.e., high PEG/PLGA ratio) were synthesized. Then, the nanocomposite solution based on PEG-b-PLGA and laponite (laponite/PEG-b-PLGA nanocomposite) was fabricated by mixing the PEG-b-PLGA solutions and the laponite suspensions. By using the test tube inversion method and dynamic mechanical analysis (DMA), it was found that thermo-responsive hydrogels could be obtained by using PEG-b-PLGA, generally known as polymeric surfactants, and that the gelation temperature was around the physiological temperature and could be regulated by changing the solution composition. Furthermore, from the structural analysis by small angle neutron scattering (SANS), PEG-b-PLGA was confirmed to be on the surface of the laponite platelets, and the thermosensitive PEG-b-PLGA on the laponite surface could trigger the thermo-responsive connection of the preformed laponite network.

Highlights

Block copolymers with hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(D,L-lactide-co-glycolide) (PLGA)such as PEG-b-PLGA, PLGA-b-PEG-b-PLGA, and PEG-b-PLGA-b-PEG are known as the promising block copolymers for biomedical applications.The hydrophilic PEG block introduces the biocompatibility to the block copolymers, and the hydrophobic PLGA block composed of lactide (LA) and glycolide (GA) introduces the biodegradability to the block copolymers because of the ester backbones [1]
We focused on PEG-b-PLGA diblock copolymers with high PEG/PLGA ratio and attempted to obtain the thermo-responsive hydrogels with PEG-b-PLGA diblock copolymers through the nanocomposite approach [12]
The PEG-b-PLGA diblock copolymer is generally known as a polymeric surfactant for drug delivery and was not used as a gelling agent

Summary

Introduction

Block copolymers with hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(D,L-lactide-co-glycolide) (PLGA)such as PEG-b-PLGA, PLGA-b-PEG-b-PLGA, and PEG-b-PLGA-b-PEG are known as the promising block copolymers for biomedical applications.The hydrophilic PEG block introduces the biocompatibility to the block copolymers, and the hydrophobic PLGA block composed of lactide (LA) and glycolide (GA) introduces the biodegradability to the block copolymers because of the ester backbones [1]. Block copolymers with hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(D,L-lactide-co-glycolide) (PLGA). Such as PEG-b-PLGA, PLGA-b-PEG-b-PLGA, and PEG-b-PLGA-b-PEG are known as the promising block copolymers for biomedical applications. The hydrophilic PEG block introduces the biocompatibility to the block copolymers, and the hydrophobic PLGA block composed of lactide (LA) and glycolide (GA) introduces the biodegradability to the block copolymers because of the ester backbones [1]. In terms of the molecular structures, PEG-b-PLGA diblock copolymers are generally used as polymeric surfactants or nanoparticles for drug delivery. PLGA-b-PEG-b-PLGA and PEG-b-PLGA-b-PEG triblock copolymers are generally used as thermo-responsive hydrogels for drug delivery systems and injectable cell scaffold matrixes [2,3,4,5,6,7,8]

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