基于表面电荷对抗体分子状态调控的研究

Regulation of antibody molecular states based on surface charges

抗体功能化纳米粒子(Ab-NPs)由于高亲和力和特异性的优势而得到广泛应用,但抗体分子在纳米粒子表面的分子状态及应用过程中的非特异性吸附均会影响其抗原结合能力。研究制备了一系列不同表面电性和电荷密度的二氧化硅纳米粒子,并分别通过物理吸附和共价偶联法对抗α-HCG(人绒毛促性腺激素)单克隆抗体进行了固定。实验表明抗体在正电荷纳米粒子表面倾向于Fab朝外,随电荷密度升高抗体固定量减少,抗原结合强度降低;在负电荷纳米粒子表面抗体取向随电荷密度的增高逐渐趋向于Fc片段朝外,抗原结合强度降低。相对于稳定的共价偶联法,物理吸附抗体的纳米粒子在非特异性吸附血清蛋白后会引起抗体取向的重排,使得更多的抗体呈现出Fab片段朝外的取向,从而导致抗原结合能力增加。通过研究电性和电荷密度对表面抗体取向的调控将有助于开发具有高灵敏度、高特异性的生物检测体系。

Antibody functionalized nanoparticles(Ab-NPs) are applied in various fields due to high affinity and specificity. However, lack of control of the antibody molecular states and non-specific adsorption reduce antigen binding avidity. Herein, a series of silica nanoparticles with different surface electrical properties and charge densities were prepared. Anti α-HCG(human chorionic gonadotropin) antibody was immobilized on the surface via either physical adsorption or covalent coupling. The results indicate that the Fab domain of antibody tends outward on positively charged nanoparticles, while Fc domain tends outward with the increase of negatively charged density. Compared with covalent coupling, the immobilized antibodies via physical adsorption were reoriented because of non-specific adsorption. The tuning of antibody orientation by this method facilitates the development of bio-detection systems.