title: Peptide engineered microcantilevers for selective chemical force microscopy and monitoring of nanoparticle capture.
abstract: 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.
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
authors.forename: Martin
authors.initials: M
authors.lastname: Munz
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
authors.forename: Angelo
authors.initials: A
authors.lastname: Bella
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
authors.forename: Santanu
authors.initials: S
authors.lastname: Ray
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
authors.forename: Nia C
authors.initials: NC
authors.lastname: Bell
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Shard
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
authors.forename: Caterina
authors.initials: C
authors.lastname: Minelli
mesh_terms: D006046:Gold / Q000378:metabolism; D018625:Microscopy, Atomic Force / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism*; D010087:Oxides / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism*; D017655:Silicon Compounds / Q000378:metabolism
chemical_list: D010087:Oxides; D011994:Recombinant Proteins; D017655:Silicon Compounds; D006046:Gold