A thermoresponsive PEG-based methacrylate triblock terpolymer as a bioink for 3D bioprinting

Thermoresponsive polymers have been extensively reported for their use in tissue engineering and drug delivery applications. They have a wide range of thermoresponsive and rheological properties controlled by their structural characteristics, such as composition and architecture. Here, the considerable potential of a PEG based, non-ionic triblock thermoresponsive copolymer, namely OEGMA300₁₃-b-BuMA₂₂-b-DEGMA₁₂ as a bioink for 3D printing with cell encapsulation is identified. The rheological tests showed that the gel transition temperature is 8 °C with 35% w/w concentration in PBS. The printability and cytotoxicity of the thermoresponsive gel were characterised and compared with those of commercial thermoresponsive polymer Pluronic®F127 in detail. Specifically, the 35% w/w triblock copolymer presented great printability with a printing speed of 450 mm min^-1 at 37 °C, and was less cytotoxic than F127 at both 20% and 30% w/w concentrations. A one-layer structure of human mesenchymal stem cell (hMSC) embedded triblock copolymer was successfully printed onto a glass slide at 37 °C. This provides an option to create a scaffold for stem cell culture and programming for further tissue engineering applications via direct printing of a cell-laden thermoresponsive polymer.