Thiol-ene Clickable Poly(glycidol) Hydrogels for Biofabrication

Abstract

In this study we introduce linear poly(glycidol) (PG), a structural analog of poly(ethylene glycol) bearing side chains at each repeating unit, as polymer basis for bioink development. We prepare allyl- and thiol-functional linear PG that can rapidly be polymerized to a three-dimensionally cross-linked hydrogel network via UV mediated thiol-ene click reaction. Influence of polymer concentration and UV irradiation on mechanical properties and swelling behavior was examined. Thiol-functional PG was synthesized in two structural variations, one containing ester groups that are susceptible to hydrolytic cleavage, and the other one ester-free and stable against hydrolysis. This allowed the preparation of degradable and non-degradable hydrogels. Cytocompatibility of the hydrogel was demonstrated by encapsulation of human bone marrow-derived mesenchymal stem cells (hBMSCs). Rheological properties of the hydrogels were adjusted for dispense plotting by addition of high molecular weight hyaluronic acid. The optimized formulation enabled highly reproducible plotting of constructs composed of 20 layers with an overall height of 3.90 mm.

TGF‐β1‐Modified Hyaluronic Acid/Poly(glycidol) Hydrogels for Chondrogenic Differentiation of Human Mesenchymal Stromal Cells

“…PG is chemically closely related to PEG and biologically similarly inert but provides the possibility of a higher functionalization density due to side chain functionalization . This is also true for PG‐based hydrogels, as we were able to show recently by utilizing thiol‐ and allyl‐modified PG for the generation of thiol‐ene clickable PG hydrogels. By replacing the thiol‐modified PG component with bioactive thiol‐modified HA, the deposition of cartilage‐specific matrix components secreted by encapsulated MSCs, was significantly improved when compared to pure PG hydrogels .…”

Thiol‐ene Cross‐Linkable Hydrogels as Bioinks for Biofabrication

“…P(AGE‐ co ‐G) was synthesized via anionic polymerization of AGE and EEGE in bulk as reported before . Briefly, for polymerization, AGE (6.30 mmol) and EEGE (54.0 mmol) were mixed with the initiator KO t Bu (1.00 mmol) under inert atmosphere and stirred at 60 °C.…”

“…Interestingly, this promising chemistry has so far not been applied for biofabrication. We have recently reported the synthesis of allyl‐ and thiol‐functionalized polyglycidols (PG) and the application of this system together with hyaluronic acid as rheological additive with beneficial bioactivity for biofabrication . We further discuss this system here as well as future possibilities of this approach within biofabrication.…”

From Shape to Function: The Next Step in Bioprinting

“…Photo‐crosslinking systems are widely used in biofabrication, as they offer rapid and on demand triggering of the polymerization reaction. Early biofabrication approaches have utilized photoinitiators, like Irgacure 2959, that rely on ultraviolet (UV) light to generate radicals, which induce the crosslinking reaction . As UV light can potentially be harmful for cells, the irradiation dose should be limited and several studies have indeed identified irradiation times that permit preservation of cell viability and functionality .…”