Chitosan has been used as a scaffolding material in tissue engineering due to its mechanical properties and biocompatibility. With increased appreciation of the effect of micro- and nanoscale environments on cellular behavior, there is increased emphasis on generating microfabricated chitosan structures. Here we employed a microfluidic coaxial flow-focusing system to generate cell adhesive chitosan microtubes of controlled sizes by modifying the flow rates of a chitosan pre-polymer solution and phosphate buffered saline (PBS). The microtubes were extruded from a glass capillary with a 300 μm inner diameter. After ionic crosslinking with sodium tripolyphosphate (TPP), fabricated microtubes had inner and outer diameter ranges of 70-150 μm and 120-185 μm. Computational simulation validated the controlled size of microtubes and cell attachment. To enhance cell adhesiveness on the microtubes, we mixed gelatin with the chitosan pre-polymer solution. During the fabrication of microtubes, fibroblasts suspended in core PBS flow adhered to the inner surface of chitosan-gelatin microtubes. To achieve physiological pH values, we adjusted pH values of chiotsan pre-polymer solution and TPP. In particular, we were able to improve cell viability to 92 % with pH values of 5.8 and 7.4 for chitosan and TPP solution respectively. Cell culturing for three days showed that the addition of the gelatin enhanced cell spreading and proliferation inside the chitosan-gelatin microtubes. The microfluidic fabrication method for ionically crosslinked chitosan microtubes at physiological pH can be compatible with a variety of cells and used as a versatile platform for microengineered tissue engineering.
Bibliographical noteFunding Information:
Acknowledgements This research was funded by National Science Foundation CAREER Award (DMR 0847287), the Office of Naval Research Young National Investigator Award, National Institutes of Health (HL092836, EB008392, DE021468, AR057837, EB012597, HL099073, GM095906), and US Army Corps of Engineers. We thank the following funding sources for support: Natural Sciences and Engineering Research Council of Canada Postdoctoral Fellowship (K.K.) and Innovative Medical Tech Co. (J.O.). A.K.G. acknowledges financial support through the MIT-Portugal Program (MPP-09Call-Langer-47). J.O., K.K., and S.W.W. contributed equally to this work. J.O., K.K., S.W.W., and A.K. designed the research strategy. J.O., K.K., and S.W.W. conducted the experiments and analyzed the data. C.C. prepared materials and performed cell experiment. A.K.G. measured mechanical properties of chitosan and chitosan-gelatin composite hydrogels. J.O., K.K., S.W.W., A.K.G., C.C., and A.K. wrote the manuscript with comments and editing by S.S., H.B., K.H.L., D.H.L., and S.-H.L..
- Cell viability
- Chitosan-gelatin hydrogel
- Microfluidic flow-focusing
ASJC Scopus subject areas
- Biomedical Engineering
- Molecular Biology