Preparation of Pendant Group-Functionalized Diblock Copolymers with Adjustable Thermogelling Behavior.

Bo Keun Lee,Seung Hun Park,Bun Yeoul Lee,Sang Jin Lee,Se Heang Oh,Moon Suk Kim,Jae Ho Kim,Ji Hoon Park

doi:10.3390/polym9060239

Bo Keun Lee, Seung Hun Park + Show 6 more

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https://doi.org/10.3390/polym9060239

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Abstract

Recently, several thermogelling materials have been developed for biomedical applications. In this study, we prepared methoxy polyethylene glycol (MPEG)-b-(poly(ε-caprolactone)-ran-poly(2-chloride-ε-caprolactone) (PCL-ran-PfCL)) (MP-Cl) diblock copolymers at room temperature via the ring-opening polymerization of caprolactone (CL) and 2-chloride-ε-caprolactone (fCL) monomers, using the terminal alcohol of MPEG as the initiator in the presence of HCl. MPEG-b-(poly(ε-caprolactone)-ran-poly(2-azide-ε-caprolactone) (PCL-ran-PCL-N3)) (MP-N3) was prepared by the reaction of MP-Cl with sodium azide. MPEG-b-(poly(ε-caprolactone)-ran-poly(2-amine-ε-caprolactone) (PCL-ran-PCL-NH2)) (MP-NH2) was subsequently prepared by Staudinger reaction. MP-Cl and MP-N3 showed negative zeta potentials, but MP-NH2 had a positive zeta potential. MP-Cl, MP-N3, and MP-NH2 solutions formed opaque emulsions at room temperature. The solutions exhibited a solution-to-hydrogel phase transition as a function of the temperature and were affected by variation of the chloride, azide, and the amine pendant group, as well as the amount of pendant groups present in their structure. Additionally, the phase transition of MP-Cl, MP-N3, and MP-NH2 copolymers was altered by pendant groups. The solution-to-hydrogel phase transition was adjusted by tailoring the crystallinity and hydrophobicity of the copolymers in aqueous solutions. Collectively, MP-Cl, MP-N3, and MP-NH2 with various pendant-group contents in the PCL segment showed a solution-to-hydrogel phase transition that depended on both the type of pendant groups and their content.

Highlights

Over the past few decades, several thermogelling materials have been investigated extensively for a broad range of biomedical applications, such as in drug- or cell-delivery carriers [1]
MPEG-b-PCL Diblock Copolymer (MP)-Cl was synthesized at room temperature via the ring-opening polymerization of the monomer CL and functional caprolactone (fCL) using the terminal alcohol of methoxy polyethylene glycol (MPEG) as the initiator in the presence of HCl·Et2 O
Formed emulsion in the aqueous solution and showed no phase transition. These results indicate that the phase transition and the gelation time of the MP-Cl, MPEG-b-(poly(εcaprolactone)-ran-poly(2-azide-ε-caprolactone) (PCL-ran-PCL-N3)) (MP-N3) and MPEG-b-(poly(ε-caprolactone)-ran-poly(2-amine-ε-caprolactone) (PCL-ran-PCL-NH2)) (MP-NH2) copolymers were affected by the variation of the chloride, azide and amine pendant groups as well as the amount of pendant groups present in their structure

Summary

Introduction

Over the past few decades, several thermogelling materials have been investigated extensively for a broad range of biomedical applications, such as in drug- or cell-delivery carriers [1]. Thermogelling materials can absorb water and swell in aqueous environments, which allow them to retain large amounts of fluids [2,3,4]. Hydrated thermogelling material solutions can incorporate various therapeutic agents such as drugs, growth factors, gene products, or cells by simple mixing. Thermogelling material solutions can be injected and solidified at the specific injected body site [5,6,7]. Block copolymers consisting of (methoxy)polyethylene glycol (MPEG), poly(propylene oxide), and biodegradable polyesters, such

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