Laponite nanoclay-modified sacrificial composite ink for perfusable channel creation via embedded 3D printing

Vascularization is a major hurdle in developing in vitro thick tissue constructs. Fortunately, embedded sacrificial printing has emerged as a promising technology to fabricate perfusable channels. The objective of this study is to develop a Laponite nanoclay-modified polyvinyl alcohol (PVA) sacrificial composite ink that has improved printability, minimized interdiffusivity, and satisfactory post-printing removability during embedded printing of perfusable channels. With the addition of Laponite nanoclay, not only the printability of the PVA-Laponite nanoclay composite ink is significantly improved, but also the interdiffusion between the gelatin precursor solution and the PVA-Laponite nanoclay composite ink is largely mitigated. The diffusion of the gelatin precursor solution into the PVA-Laponite nanoclay composite ink is of great importance for printing controllable perfusable channels since the diffused gelatin may cross-link as the gelatin composite matrix does during and after printing, resulting in residual gelatin gel in the channel and altered channel dimensions. In particular, the PVA-2.0% Laponite nanoclay sacrificial ink shows good printability and minimized interdiffusivity while maintaining good post-printing removability, which can be a good sacrificial composite ink for thick perfusable tissue creations. The channel diameter reduction due to the gelatin solution diffusion can be satisfactorily predicted based on the unidirectional diffusion model. This study further demonstrates the feasibility of using the proposed sacrificial ink for vascular tissue engineering applications.