Johnston Robert K, Harper Jason C, Tartis Michaelann S
Department of Materials Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Pl, Socorro, New Mexico 87801, United States.
Sandia National Laboratories, Bioenergy and Biodefense Technologies, Albuquerque New Mexico 87185, United States.
ACS Biomater Sci Eng. 2017;3(9):2098-2109. doi: 10.1021/acsbiomaterials.7b00185. Epub 2017 Jul 13.
Over the last twenty years, many strategies utilizing sol-gel chemistry to integrate biological cells into silica-based materials have been reported. One such strategy, Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition, shows promise as an efficient encapsulation technique due to the ability to vary the silica encapsulation morphology obtained by this process through variation of SG-CViL reaction conditions. In this report, we develop SG-CViL as a tunable, multi-purpose silica encapsulation strategy by investigating the mechanisms governing both silica particle generation and subsequent interaction with phospholipid assemblies (liposomes and living cells). Using Dynamic Light Scattering (DLS) measurements, linear and exponential silica particle growth dynamics were observed which were dependent on deposition buffer ion constituents and ion concentration. Silica particle growth followed a cluster-cluster growth mechanism at acidic pH, and a monomer-cluster growth mechanism at neutral to basic pH. Increasing silica sol aging temperature resulted in higher rates of particle growth and larger particles. DLS measurements employing PEG coated liposomes and cationic liposomes, serving as model phospholipid assemblies, revealed electrostatic interactions promote more stable liposome-silica interactions than hydrogen bonding and facilitate silica coating on suspension cells. However, continued silica reactivity leads to aggregation of silica coated suspensions cells, revealing the need for cell isolation to tune deposited silica thickness. Utilizing these mechanistic study insights, silica was deposited onto adherent HeLa cells under biocompatible conditions with micron scale control over silica thickness, minimal cell manipulation steps, and retained cell viability over several days.
在过去二十年中，已经报道了许多利用溶胶-凝胶化学将生物细胞整合到硅基材料中的策略。其中一种策略，即溶胶生成化学气相到液相（SG-CViL）沉积，由于能够通过改变SG-CViL反应条件来改变通过该过程获得的二氧化硅封装形态，显示出作为一种有效封装技术的潜力。在本报告中，我们通过研究控制二氧化硅颗粒生成以及随后与磷脂组装体（脂质体和活细胞）相互作用的机制，将SG-CViL开发为一种可调谐的多功能二氧化硅封装策略。使用动态光散射（DLS）测量，观察到线性和指数型二氧化硅颗粒生长动力学，其取决于沉积缓冲液的离子成分和离子浓度。在酸性pH下，二氧化硅颗粒生长遵循簇-簇生长机制，在中性至碱性pH下遵循单体-簇生长机制。提高二氧化硅溶胶老化温度导致颗粒生长速率更高且颗粒更大。使用聚乙二醇包被的脂质体和阳离子脂质体作为模型磷脂组装体的DLS测量表明，静电相互作用比氢键促进更稳定的脂质体-二氧化硅相互作用，并促进二氧化硅在悬浮细胞上的包被。然而，持续的二氧化硅反应性导致二氧化硅包被的悬浮细胞聚集，这表明需要进行细胞分离以调节沉积的二氧化硅厚度。利用这些机理研究的见解，在生物相容条件下将二氧化硅沉积到贴壁的HeLa细胞上，对二氧化硅厚度进行微米级控制，细胞操作步骤最少，并且在数天内保持细胞活力。
