Simple fabrication of inner chitosan-coated alginate hollow microfiber with higher stability

Sodium alginate (NaA) has been widely used as microfiber-based scaffold material. However, Ca-alginate microfiber might disintegrate in the physiological environment due to the loss of calcium ions, which will limit its long-term application in tissue engineering. In this work, to enhance the stability of Ca-alginate microfiber in the physiological environment, an inner chitosan coating was introduced to Ca-alginate hollow microfiber by one step via a microfluidic device. A more stable composite microfiber with double cross-linking layers was generated. The stability of the microfiber was studied in the PBS solution (pH 7.4) to identify the coating effect on the hollow structure. The results revealed that chitosan component bonded an NaA layer to form a stable polyelectrolyte complex membrane in the inner wall of the microfiber, which stabilized the hollow region even though the Ca-alginate shell was disintegrated by PBS solution. In addition, the introduction of chitosan coating improved the inner environment of the low affinity of alginate to cell surfaces and facilitated the cell adhesion and culture in the microfiber. HepG2 cells in the microfibers displayed favorable cell viability and proliferation ability. We believe that this work will lead to the development of innovative methodologies and materials for both cell culture and tissue engineering application. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2527-2536, 2019.