Ro Il Juhn, Kwon Ick-Chan
Department of Mechanical Engineering, University of Colorado at Boulder, 80309-0427, USA.
J Biomater Sci Polym Ed. 2002;13(7):769-82. doi: 10.1163/156856202760197401.
The material properties and the microstructure of the scaffold are important parameters that determine the suitability of a material for tissue growth and controlled drug release. Because of its non-toxic, biocompatible, biodegradable, and antithrombogenic nature, chitosan has generated enormous interest for such applications. Chitosan bead-type scaffolds having various microstructures without any other material introduction were fabricated. For fabricating pure chitosan beads, a modified wet process and an extended thermally induced phase separation (TIPS) process were adapted. In the modified wet process, an acidic chitosan solution was phase-separated by changing its pH using an NaOH solution. The microstructure of the chitosan beads became looser with a decrease in the initial chitosan concentration, an increase in the acetic acid concentration, as well as with the addition of PEG to the dope solution. In contrast, the microstructure densified with an increase in the NaOH concentration in the coagulation bath. Through the modified wet process, porous chitosan beads with a relatively small pore size (0.01-13 microm) and moderate porosity (33-71%) could be prepared. In the extended TIPS process, chitosan solutions cast at different temperatures below 0 degrees C resulted in different microstructures wherein the microstructure densified with an increase in the quenching rate. The chitosan beads fabricated via extended TIPS had large pore sizes (26-120 microm) and high porosity (85-92%). All of these matrices showed good interconnected pores.
支架的材料特性和微观结构是决定材料是否适合组织生长和控制药物释放的重要参数。由于壳聚糖具有无毒、生物相容性、可生物降解和抗血栓形成的特性，因此在这类应用中引起了极大的关注。制备了具有各种微观结构且未引入任何其他材料的壳聚糖珠型支架。为了制备纯壳聚糖珠，采用了改进的湿法和扩展的热致相分离（TIPS）工艺。在改进的湿法中，通过使用NaOH溶液改变其pH值使酸性壳聚糖溶液发生相分离。壳聚糖珠的微观结构随着初始壳聚糖浓度的降低、乙酸浓度的增加以及向纺丝液中添加PEG而变得更松散。相反，随着凝固浴中NaOH浓度的增加，微观结构变得致密。通过改进的湿法，可以制备出孔径相对较小（0.01 - 13微米）且孔隙率适中（33 - 71%）的多孔壳聚糖珠。在扩展的TIPS工艺中，在低于0摄氏度的不同温度下浇铸壳聚糖溶液会导致不同的微观结构，其中微观结构随着淬火速率的增加而致密。通过扩展TIPS制备的壳聚糖珠具有大孔径（26 - 120微米）和高孔隙率（85 - 92%）。所有这些基质都显示出良好的相互连通的孔隙。
