Kimura Reo, Chatani Sunao, Inui Masahiko, Motozuka Satoshi, Liu Zizhen, Tagaya Motohiro
Department of Materials Science and Bioengineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka 940-2188, Japan.
Production Department, Ohara Quartz, Minato 1850, Wakayama, Wakayama 640-8404, Japan.
Langmuir. 2024 Apr 30;40(17):8939-8949. doi: 10.1021/acs.langmuir.4c00114. Epub 2024 Apr 18.
Amorphous silica particles (ASPs) have low biotoxicity and are used in foodstuffs; however, the adsorption states of proteins on their surfaces have not yet been clarified. If the adsorption states can be clarified and controlled, then a wide range of biological and medical applications can be expected. The conventional amorphous silica particles have the problem of protein adsorption due to the strong interaction with their dense silanol groups and denaturation. In this study, the surfaces of amorphous silica particles with a lower silanol group density were modified with a small amount of chlorine during the synthesis process to form a specific surface layer by adsorbing water molecules and ions in the biological fluid, thereby controlling the protein adsorption state. Specifically, the hydration state on the surface of the amorphous silica particles containing trace amounts of chlorine was evaluated, and the surface layer (especially the hydration state) for the adsorption of antibody proteins while maintaining their steric structures was evaluated and discussed. The results showed that the inclusion of trace amounts of chlorine increased the silanol groups and Si-Cl bonds in the topmost surface layer of the particles, thereby inducing the adsorption of ions and water molecules in the biological fluid. Then, it was found that a novel surface layer was formed by the effective adsorption of Na and phosphate ions, which would change the proportion of the components in the hydration layer. In particular, the proportion of the free water component increased by 21% with the doping of chlorine. Antibody proteins were effectively adsorbed on the particles doped with trace amounts of chlorine, and their steric adsorption states were evaluated. It was found that the proteins were clearly adsorbed and maintained the steric state of their secondary structure. In the immunoreactivity tests using streptavidin and biotin, biotin bound to the chlorine-doped particles showed efficient reactivity. In conclusion, this study is the first to discover the surface layer of the amorphous silica particles to maintain the steric structures of adsorbed proteins, which is expected to be used as a carrier particle for antibody test kits and immunochromatography.
无定形二氧化硅颗粒（ASPs）具有低生物毒性，被用于食品中；然而，蛋白质在其表面的吸附状态尚未明确。如果能够阐明并控制吸附状态，那么有望实现广泛的生物和医学应用。传统的无定形二氧化硅颗粒由于其密集的硅醇基团和变性作用而存在蛋白质吸附问题。在本研究中，在合成过程中用少量氯对硅醇基团密度较低的无定形二氧化硅颗粒表面进行改性，通过吸附生物流体中的水分子和离子形成特定的表面层，从而控制蛋白质的吸附状态。具体而言，评估了含微量氯的无定形二氧化硅颗粒表面的水合状态，并对用于吸附抗体蛋白同时保持其空间结构的表面层（尤其是水合状态）进行了评估和讨论。结果表明，微量氯的加入增加了颗粒最表层的硅醇基团和Si-Cl键，从而诱导生物流体中离子和水分子的吸附。然后发现，通过Na和磷酸根离子的有效吸附形成了一种新型表面层，这将改变水合层中各成分的比例。特别是，随着氯的掺杂，自由水成分的比例增加了21%。抗体蛋白有效地吸附在掺杂微量氯的颗粒上，并对其空间吸附状态进行了评估。发现蛋白质被清晰地吸附并保持其二级结构的空间状态。在使用链霉亲和素和生物素的免疫反应性测试中，与氯掺杂颗粒结合的生物素显示出高效的反应性。总之，本研究首次发现了无定形二氧化硅颗粒的表面层能够保持吸附蛋白质的空间结构，有望用作抗体检测试剂盒和免疫层析的载体颗粒。
