Harper-Leatherman Amanda S, Wallace Jean Marie, Rolison Debra R
Chemistry and Biochemistry Department, Fairfield University, 1073 North Benson Road, Fairfield, CT, 06824, USA.
Nova Research, Inc., 1900 Elkin Street, Suite 230, Alexandria, VA, 22308, USA.
Methods Mol Biol. 2017;1504:149-163. doi: 10.1007/978-1-4939-6499-4_12.
Sol-gel-derived aerogels are three-dimensional, nanoscale materials that combine large surface area with high porosity. These traits make them useful for any rate-critical chemical process, particularly sensing or electrochemical applications, once physical or chemical moieties are incorporated into the gels to add their functionality to the ultraporous scaffold. Incorporating biomolecules into aerogels, other than such rugged species as lipases or cellulose, has been challenging due to the inability of most biomolecules to remain structurally intact within the gels during the necessary supercritical fluid (SCF) processing. However, the heme protein cytochrome c (cyt.c) forms self-organized superstructures around gold (or silver) nanoparticles in buffer that can be encapsulated into wet gels as the sol undergoes gelation. The guest-host wet gel can then be processed to form composite aerogels in which cyt.c retains its characteristic visible absorption. The gold (or silver) nanoparticle-nucleated superstructures protect the majority of the protein from the harsh physicochemical conditions necessary to form an aerogel. The Au~cyt.c superstructures exhibit rapid gas-phase recognition of nitric oxide (NO) within the bioaerogel matrix, as facilitated by the high-quality pore structure of the aerogel, while remaining viable for weeks at room temperature. More recently, careful control of synthetic parameters (e.g., buffer concentration, protein concentration, SCF extraction rate) have allowed for the preparation of cyt.c-silica aerogels, sans nucleating nanoparticles; these bioaerogels also exhibit rapid gas-phase sensing while retaining protein structural stability.
溶胶 - 凝胶衍生的气凝胶是三维纳米级材料，具有大表面积和高孔隙率。一旦将物理或化学部分掺入凝胶中以将其功能添加到超多孔支架中，这些特性使其可用于任何对速率要求严格的化学过程，特别是传感或电化学应用。将生物分子掺入气凝胶中，除了诸如脂肪酶或纤维素等坚韧的物种外，一直具有挑战性，因为大多数生物分子在必要的超临界流体（SCF）处理过程中无法在凝胶内保持结构完整。然而，血红素蛋白细胞色素c（cyt.c）在缓冲液中围绕金（或银）纳米颗粒形成自组织超结构，当溶胶凝胶化时，这些超结构可以被封装到湿凝胶中。然后可以对客体 - 主体湿凝胶进行处理以形成复合气凝胶，其中cyt.c保留其特征性可见吸收。金（或银）纳米颗粒成核的超结构保护大部分蛋白质免受形成气凝胶所需的苛刻物理化学条件的影响。Au~cyt.c超结构在生物气凝胶基质中表现出对一氧化氮（NO）的快速气相识别，这得益于气凝胶的高质量孔结构，同时在室温下可存活数周。最近，通过仔细控制合成参数（例如缓冲液浓度、蛋白质浓度、SCF提取速率），可以制备不含成核纳米颗粒的cyt.c - 二氧化硅气凝胶；这些生物气凝胶也表现出快速的气相传感，同时保持蛋白质结构稳定性。
