Edward P. Fitts Department of Industrial and Systems Engineering, North Carolina State University, Raleigh, North Carolina 27695-7906, United States.
Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina 27606, United States.
ACS Biomater Sci Eng. 2020 Sep 14;6(9):5191-5201. doi: 10.1021/acsbiomaterials.0c00806. Epub 2020 Jul 31.
Sterilization is a necessary step during the processing of biomaterials, but it can affect the materials' functional characteristics. This study characterizes the effects of three commonly used sterilization processes-autoclaving (heat-based), ethanol (EtOH; chemical-based), and ultraviolet (UV; radiation-based)-on the chemical, mechanical, printability, and biocompatibility properties of alginate, a widely used biopolymer for drug delivery, tissue engineering, and other biomedical applications. Sterility assessment tests showed that autoclaving was effective against Gram-positive and Gram-negative bacteria at loads up to 10 CFU/mL, while EtOH was the least effective. Nuclear magnetic-resonance spectroscopy showed that the sterilization processes did not affect the monomeric content in the alginate solutions. The differences in compressive stiffness of the three sterilized hydrogels were also not significant. However, autoclaving significantly reduced the molecular weight and polydispersity index, as determined via gel permeation chromatography, as well as the dynamic viscosity of alginate. Printability analyses showed that the sterilization process as well as the extrusion pressure and speed affected the number of discontinuities and spreading ratio in printed and cross-linked strands. Finally, human adipose-derived stem cells demonstrated over 90% viability in all sterilized hydrogels over 7 days, but the differences in cellular metabolic activity in the three groups were significant. Taken together, the autoclaving process, while demonstrating broad spectrum sterility effectiveness, also resulted in most notable changes in alginate's key properties. In addition to the specific results with the three sterilization processes and alginate, this study serves as a roadmap to characterize the interrelationships between sterilization processes, fundamental chemical properties, and resulting functional characteristics and processability of hydrogels.
灭菌是生物材料处理过程中的必要步骤，但它会影响材料的功能特性。本研究描述了三种常用灭菌方法（湿热灭菌法、乙醇灭菌法和紫外线灭菌法）对海藻酸钠的化学、机械、可打印性和生物相容性的影响，海藻酸钠是一种广泛用于药物输送、组织工程和其他生物医学应用的生物聚合物。无菌性评估测试表明，在 10 CFU/mL 负载下，高压蒸汽灭菌法对革兰氏阳性菌和革兰氏阴性菌有效，而乙醇的效果最差。核磁共振波谱表明，灭菌过程不影响海藻酸钠溶液中的单体含量。三种经灭菌水凝胶的压缩刚度差异也不显著。然而，高压蒸汽灭菌法显著降低了凝胶渗透色谱法测定的分子量和多分散指数，以及海藻酸钠的动态粘度。打印性能分析表明，灭菌过程以及挤出压力和速度会影响打印和交联链的不连续性数量和扩展比。最后，人脂肪源性干细胞在所有经灭菌水凝胶中 7 天内的存活率均超过 90%，但三组细胞代谢活性的差异具有统计学意义。总之，高压蒸汽灭菌法虽然具有广谱的灭菌效果，但也导致了海藻酸钠关键性质的最显著变化。除了三种灭菌方法和海藻酸钠的具体结果外，本研究还为描述灭菌过程、基本化学性质以及水凝胶的功能特性和可加工性之间的相互关系提供了路线图。
