Munz Martin, Bella Angelo, Ray Santanu, Bell Nia C, Shard Alexander G, Minelli Caterina
Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
Biointerphases. 2016 Dec 23;11(4):04B312. doi: 10.1116/1.4972417.
Engineered peptides capable of binding to silica have been used to provide contrast in chemical force microscopy and tested for their capacity to selectively capture silica nanoparticles (NPs). Gold coated atomic force microscopy (AFM) microcantilevers with integrated tips and colloidal probes were functionalized with engineered peptides through a thiol group of a terminal cysteine which was linked via a glycine trimer to a 12-mer binding sequence. The functionalized probes demonstrated a significantly increased binding force on silicon oxide areas of a gold-patterned silicon wafer, whereas plain gold probes, and those functionalized with a random permutation of the silica binding peptide motif or an all-histidine sequence displayed similar adhesion forces to gold and silicon oxide. As the functionalized probes also allowed contact mode imaging subsequently to the adhesion mapping, also the associated friction contrast was measured and found to be similar to the adhesion contrast. Furthermore, the adsorption of silica NPs onto planar gold surfaces functionalized in the same manner was observed to be selective. Notably, the surface coverage with silica NPs was found to decrease with increasing pH, implying the importance of electrostatic interactions between the peptide and the NPs. Finally, the adsorption of silica NPs was monitored via the decrease in fundamental resonance frequency of an AFM microcantilever functionalized with silica binding peptides.
能够与二氧化硅结合的工程肽已被用于在化学力显微镜中提供对比度，并测试其选择性捕获二氧化硅纳米颗粒（NPs）的能力。带有集成尖端的金涂层原子力显微镜（AFM）微悬臂梁和胶体探针通过末端半胱氨酸的硫醇基团用工程肽进行功能化，该半胱氨酸通过甘氨酸三聚体与一个12聚体结合序列相连。功能化探针在金图案硅片的氧化硅区域上显示出显著增加的结合力，而普通金探针以及用二氧化硅结合肽基序的随机排列或全组氨酸序列功能化的探针在金和氧化硅上表现出相似的粘附力。由于功能化探针在粘附力映射后也允许进行接触模式成像，因此还测量了相关的摩擦对比度，发现其与粘附对比度相似。此外，观察到二氧化硅NPs以同样方式功能化的平面金表面上的吸附是选择性的。值得注意的是，发现二氧化硅NPs的表面覆盖率随着pH值的增加而降低，这意味着肽与NPs之间静电相互作用的重要性。最后，通过用二氧化硅结合肽功能化的AFM微悬臂梁的基频共振频率的降低来监测二氧化硅NPs的吸附。
