Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Abstract

Adhesion forces between functionalized gold colloidal nanoparticles (Au NPs) and scanning probe microscope silicon tips were experimentally investigated by atomic force microscopy (AFM) equipped with PeakForce QNM (Quantitative Nanoscale Mechanics) module. Au NPs were synthesized by a seed-mediated process and then functionalized with thiols containing different functional groups: amino, hydroxy, methoxy, carboxy, methyl, and thiol. Adhesion measurements showed strong differences between NPs and silicon tip depending on the nature of the tail functional group. The dependence of the adhesion on ligand density for different thiols with identical functional tail-group was also demonstrated. The calculated contribution of the van der Waals (vdW) forces between particles was in good agreement with experimentally measured adhesive values. In addition, the adhesion forces were evaluated between flat Au films functionalized with the same molecular components and silicon tips to exclude the effect of particle shape on the adhesion values. Although adhesion values on flat substrates were higher than on their nanoparticle counterparts, the dependance on functional groups remained the same.

The indispensable contribution of s38 protein to ovarian-eggshell morphogenesis in Drosophila melanogaster

“…It should be noted that local-surface structural changes significantly alter the values of adhesion forces applied. Specifically, the adhesion-force value of an AFM tip in contact with poor density-packed surfaces, structurally disordered and short self-assembled chains is smaller than the one of well-packed and rigid surfaces, with long self-assembled molecular chains 53 . The observed inability of s38-downregulated eggs to resist deformation induced by mechanical stress might be, among others, associated with defective eggshell hardening, likely due to inefficient and/or aberrant formation of di- and tri-tyrosine covalent bonds among chorion proteins 15 , 54 .…”

The effect of heat treatment on the morphology and mobility of Au nanoparticles

“…The small size and the enhanced properties of Au nanoparticles (NPs) compared to bulk gold make them important for the development of novel applications, for example, in the field of drug delivery [1], sensor technology [2], printing [3] and catalysis [4]. Due to their inert state, geometrical diversity and convenient synthesis, Au NPs are an attractive model system for nanotribological manipulation experiments [5][6][7][8][9][10][11][12] and simulations [13]. Additional flexibility is provided by the ability to tune the properties of the NPs by varying the size [14] , shape [14] and chemical composition of the outer layer covering the NP [5].…”

“…Due to their inert state, geometrical diversity and convenient synthesis, Au NPs are an attractive model system for nanotribological manipulation experiments [5][6][7][8][9][10][11][12] and simulations [13]. Additional flexibility is provided by the ability to tune the properties of the NPs by varying the size [14] , shape [14] and chemical composition of the outer layer covering the NP [5]. These modifications become especially important for tribological applications since they can affect the interfacial behavior during contact.…”

The effect of heat-treatment on morphology and mobility of Au nanoparticles

“…The small size and the enhanced properties of Au nanoparticles (NPs) compared to bulk gold makes them important for the development of novel applications including drug delivery [1], sensors [2], printing [3] and catalysts [4]. Due to relative inertness, geometrical diversity and ease of synthesis Au NPs are attractive model material for nanotribological manipulation experiments [5]- [12], and simulations [13]. Additional flexibility is provided by the ability to tune the properties of the NPs by varying the size [14], shape [14] and chemical composition of the outer layer covering the NP [5].…”

“…Due to relative inertness, geometrical diversity and ease of synthesis Au NPs are attractive model material for nanotribological manipulation experiments [5]- [12], and simulations [13]. Additional flexibility is provided by the ability to tune the properties of the NPs by varying the size [14], shape [14] and chemical composition of the outer layer covering the NP [5]. These modifications become especially important for tribological applications since they can affect the interfacial behavior during contact.…”