Aggregation of Silica Nanoparticles Directed by Adsorption of Lysozyme
Aggregation of Silica Nanoparticles Directed by Adsorption of Lysozyme
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DOI：
10.1021/la201898v
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发表时间：
2011-08-16
期刊：
影响因子：
3.9
通讯作者：
Findenegg, Gerhard H.
中科院分区：
文献类型：
--
作者：
Bharti, Bhuvnesh;Meissner, Jens;Findenegg, Gerhard H.
球形蛋白质溶菌酶与直径为20 nm的二氧化硅纳米颗粒的相互作用进行了研究，在pH值范围之间的等电点（IEPs）的二氧化硅和蛋白质（pH 3-11）。溶菌酶在二氧化硅颗粒上的吸附亲和力和吸附量随pH值的增加而增加，吸附的蛋白质引起二氧化硅颗粒的桥接聚集。在固定的蛋白质与二氧化硅浓度比下，研究了聚集体的结构性质作为pH的函数，所述固定的蛋白质与二氧化硅浓度比对应于在pH > 6的完全结合方案中远低于完整单层的蛋白质的表面浓度。沉降研究表明，在pH 4-6和pH 7-9的松散的絮凝网络的存在下，在溶菌酶的IEP附近的聚集体的大小急剧下降。通过低温透射电子显微镜（cryo-TEM）和小角X射线散射研究了桥联二氧化硅聚集体的结构。由散射剖面导出的结构因子S（q）显示了粒子间短程吸引势相互作用的特征，可用Percus-Yevick方阱势模型表示，势深不超过3 k（B）T.
The interaction of the globular protein lysozyme with silica nanoparticles of diameter 20 nm was studied in a pH range between the isoelectric points (IEPs) of silica and the protein (pH 3-11). The adsorption affinity and capacity of lysozyme on the silica particles is increasing progressively with pH, and the adsorbed protein induces bridging aggregation of the silica particles. Structural properties of the aggregates were studied as a function of pH at a fixed protein-to-silica concentration ratio which corresponds to a surface concentration of protein well below a complete monolayer in the complete-binding regime at pH > 6. Sedimentation studies indicate the presence of compact aggregates at pH 4-6 and a loose flocculated network at pH 7-9, followed by a sharp decrease of aggregate size near the IEP of lysozyme. The structure of the bridged silica aggregates was studied by cryo-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering. The structure factor S(q) derived from the scattering profiles displays characteristic features of particles interacting by a short-range attractive potential and can be represented by the square-well Percus-Yevick potential model, with a potential depth not exceeding 3k(B)T.