Electrostatic Double-Layer Interaction at the Surface of Rough Cluster-Assembled Films: The Case of Nanostructured Zirconia

Abstract

Here, we investigated the influence of the nanoscale surface morphology on the electrostatic double layer at corrugated surfaces in aqueous electrolytes. For this purpose, we have produced cluster-assembled nanostructured zirconium dioxide (ns-ZrO , x ≈ 2) films with controlled morphological properties by supersonic cluster beam deposition (SCBD) and measured the double-layer interaction by atomic force microscopy with colloidal probes. SCBD allowed tuning the characteristic widths of the corrugated interface (root-mean-square roughness, correlation length) across a wide range of values, matching the width of the electrostatic double layer (Debye length) and the typical size of nanocolloids (proteins, enzymes, and catalytic nanoparticles). To accurately characterize the surface charge density in the high-roughness regime, we have developed a two-exponential model of the electrostatic force that explicitly includes roughness and better accounts for the roughness-induced amplification of the interaction. We were then able to observe a marked reduction of the isoelectric point of ns-ZrO surfaces of increasing roughness. This result is in good agreement with our previous observations on cluster-assembled nanostructured titania films and demonstrates that the phenomenon is not limited to a specific material, but more generally depends on peculiar nanoscale morphological effects, related to the competition of the characteristic lengths of the system.

Adhesion force spectroscopy with nanostructured colloidal probes reveals nanotopography-dependent early mechanotransductive interactions at the cell membrane level

“…Clusters are collected directly on the CPs intercepting the beam, in the deposition chamber. Upon landing on the probe surface, which is locally flat due to the large radius, clusters form a nanostructured, highly porous, high-specific area, biocompatible ns-ZrO2 film 44,58,59,81,82 . The oxidation of the nanostructured film further proceeds upon exposure to air, up to an almost complete stoichiometry, although rich of local defects.…”

Mechanotransduction in neuronal cell development and functioning

“…Further details on IAC maturation are outlined in "Mechanosensing and mechanotransduction". The figure contains adapted elements of images with permission from and, Copyright (2015) Springer Nature;Barnes et al (2017), Copyright (2017) Company of Biologists LTD; and an adapted element with permission fromBorghi et al (2018), Copyright (2018) American Chemical Society.…”

The glycocalyx affects the mechanotransductive perception of the topographical microenvironment

“…The protocol for the functionalisation of the colloidal probes with the nanotopographical surfaces achieved by zirconia cluster-assembling is detailed in Chighizola et al 19 . The specific surface area, the rms roughness (defined as the standard deviation of the height of the surface, , where h i is the height of the surface in a specific point, N is the number of pixels of the map and is the average height), the average lateral dimensions of the largest morphological features (the correlation length ξ) typically increase with ZrO 2 film thickness 96,98,99 .…”