金磁纳米微粒表面蛋白偶联率的测定

Coupling efficiency measurement of proteins immobilized on gold magnetic nanoparticle′s surface

金磁纳米微粒因兼具独特的光学性质及超顺磁性而受到广泛关注.对这种复合材料表面标记蛋白的定量为后续应用提供了必要的前提,也为免疫探针的构建提供了空间分布的基本信息.鉴于此,本研究对金磁纳米微粒表面偶联蛋白进行定量.表面改性的金磁纳米微粒表面含有大量羧基,为后续的蛋白偶联提供了偶联位点,以碳二亚胺(EDC)作为连接因子可将链亲合素(SA)化学键合于金磁纳米微粒表面.为得到准确的蛋白偶联率,以三氯乙酸排除EDC对Lowry法的干扰,结合金磁纳米微粒密度的计算以及SA的相对分子量,可以确定其偶联率为18个SA/金磁微粒.

Gold magnetic nanoparticles have attracted considerable interest in biomedicine fields due to their unique optical properties and super paramagnetism.The determination of protein content provide prerequisite for further applications and necessary messages to investigate the micro-construction of immunoassay probe based on gold magnetic nanoparticle,so we studied coupling efficiency of streptavidin（SA）immobilizing on the composite nanoparticle′s surface in this paper.In order to achieve the greatest coupling efficiency,particles were firstly coated by polymers to get plenty carboxyl groups on the surface,then 1-（3-dimethyllaminopropyl）-3-ethyl carbodiimide hydrochloride（EDC）was explored as a linker to achieve chemical bond.During the process of protein determination,trichloroacetic acid was used to remove the interference of EDC in Lowry method.At last the coupling efficiency about 18SA/nanoparticle was achieved by calculations based on composite nanoparticle′s density and streptavidin′s relative molecular mass.