低强度脉冲超声激发的声微流增强藻酸钙凝胶支架材料的孔隙率和通透性研究

低强度脉冲超声(LIPUS)激发的声微流场所产生的剪切应力可作用于细胞膜表面,从而显著增强细胞膜的通透性。构建了三维藻酸钙凝胶支架培养系统,来模拟有利于细胞生长的营养供给和新陈代谢体内微环境;基于扫描电子显微镜、体内荧光图像和激光共聚焦图像观测技术,对LIPUS增强三维藻酸钙凝胶支架材料的孔隙率和通透性的作用机制和参数相关性进行了系统的研究。结果表明,三维藻酸钙凝胶支架材料的孔隙率和通透性可随着LIPUS的驱动声压的升高而显著增强。此外,通过对三维支架材料内的细胞增殖情况分析,发现在适当的LIPUS驱动声压(如P-=0.055 MPa)下,HeLa细胞在LIPUS作用下的三维藻酸钙凝胶支架材料中可获得更高的增殖率。 

Improvement on the porosity and permeability of three-dimensional alginate scaffolds with low-intensity-pulsed-ultrasound-induced microstreaming

The microstreaming induced by low-intensity pulsed ultrasound (LIPUS) causes the shear stress, which has been often used to enhance the permeability of cells' membrane. In the present study, to simulate the in vivo microenvironment, three-dimensional (3-D) scaffold culture systems were constituted, which would provide benefits for nutrition supply and metabolism during cell growth. Porosity and permeability of the 3-D alginate scaffolds were enhanced by using LIPUS with varied acoustic pressures, and the mechanism involved in the processes was investigated in detail. The porosity and permeability of the 3-D alginate scaffolds were quantitatively evaluated based on the scanning electron microscopy examination, in vivo fluorescence image observation, and laser con-focal image observation. The results indicated that the microstreaming generated by ultrasound-driven microbubble oscillations enhanced the porosity and permeability of the scaffolds, and the enhancement effect were increased with the increasing LIPUS driving pressures. In addition, the cell proliferation assessments verified that, HeLa cell grew better in the treated 3-D alginate scaffolds at an appropriate LIPUS pressure (e.g., 0.055 MPa), because the improved scaffold porosity and permeability could provide more cell growth space and benefit the nutrition supply.