Harnessing electrostatic interactions for enhanced printability of alginate-based bioinks

Abstract

3D bioprinting has received great attention in recent years because of its remarkable advantage in the fabrication of personalized biomaterial designs. In order to meet the full potential of bioprinting, it is necessary to develop new or improved bioinks with appropriate physicochemical properties supporting biological function. One potential bioink is sodium alginate (SA), an anionic polymer which can form an “egg-box” three-dimensional network complex with the introduction of cations. The rapid network formation allows for stabilization of extrudable alginate, making it suitable for use as a bioink in bioprinting applications. In this study, the complexation of positively charged chitosan (CS) and laponite (Lap) with negatively charged SA was investigated. 1-layer, 2-layer, and multi-layer models were established to evaluate and compare the printability of SA, SA-CS, and SA-Lap bioinks, including metrics of extrudability, filament stability, pore circularity, and structure fidelity. In addition, material properties of each bioink, including viscosity, compressive modulus, swelling rate, and biocompatibility, were assessed. The results showed the printability of SA was improved with the addition of CS or Lap. Moreover, the swelling rate of composite bioinks was reduced to half of that of sodium alginate counterparts. In addition, cell compatibility studies demonstrated that all bioinks were capable of maintaining cell proliferation over five days. As a whole, this work highlights the importance of electrostatic interactions of alginate-based bioinks for bioprinting.