Preparation of zwitterionic sulfobetaine end-functionalized poly(ethylene glycol)-b -poly(caprolactone) diblock copolymers and examination of their thermogelling properties

Abstract

To investigate thermogelling behavior, in this study, we prepared a methoxy poly(ethylene glycol)-b-poly(e-caprolactone) diblock copolymer (MPC) with varying hydrophobic poly(e-caprolactone) (PCL) lengths and an MPC featuring a zwitterionic sulfobetaine (MPC-ZW) at the chain end of the PCL segment. The terminal zwitterionic sulfobetaine was stoichiometrically modified to the terminal MPC diblock copolymer. The introduction of the zwitterionic end group lowered the crystallization enthalpies of the PCL block segments and increased the solubility of the diblock copolymer. The MPC and MPC-ZW copolymers thus obtained formed translucent emulsions at room temperature when prepared as 20 wt %. When the temperature was increased above room temperature, MPC and MPC-ZW exhibited a sol-to-gel phase transition. The phase transition and the gelation time of MPC and MPC-ZW were affected by the length of the hydrophobic segments and the zwitterionic end group. Furthermore, introducing a zwitterionic end group into the PCL segment altered the onset temperature of gelation. Thus, we conclude that zwitterionic end groups introduced into PCL segments of distinct lengths could serve as key determinants in the thermogelling behavior of copolymers.

Electrostatically Interactive Injectable Hydrogels for Drug Delivery

“…Polyampholytes, with both cationic and anionic repeat groups, which are called zwitterionic groups, can electrostatically interact or repel. There are typical polyampholytes with phosphobetaine, sulfobetaine, and carboxybetaine as zwitterionic groups [53][54][55]. The polyampholyte solutions can make electrostatically interactive in situ-forming hydrogels.…”

Biodegradable zwitterionic polymers as PEG alternatives for drug delivery

“…A terminal-functionalized ZP has only one or two zwitterions, and may not be water-soluble if the base polymer is not hydrophilic. 60,61 When ZPs possess several zwitterions per macromolecule, typically as side groups carried by polymer main-chains, they have increased but still limited hydrophilicity. 62,63 Only ZPs bearing numerous zwitterions have high hydrophilicity that ensures aqueous solubility 31,48,64 ; these water-soluble ZPs are particularly important as PEG alternatives for in vivo applications.…”

In-situ forming injectable GFOGER-conjugated BMSCs-laden hydrogels for osteochondral regeneration

“…The diblock copolymer methoxy polyethylene glycol- b -polycaprolactone (MPEG-PCL) is an ideal candidate material for in situ hydrogel scaffold in cartilage tissue engineering 14 . The phase transition of MPEG-PCL occurs near body temperature without any cross-linkers 19 , 20 . In addition, the in situ forming MPEG-PCL hydrogel has shown excellent retention capabilities for mesenchymal stem cells (MSCs) 21 – 23 .…”