Micro/Nanopatterned Superhydrophobic Surfaces Fabrication for Biomolecules and Biomaterials Manipulation and Analysis

Abstract

Superhydrophobic surfaces display an extraordinary repulsion to water and water-based solutions. This effect emerges from the interplay of intrinsic hydrophobicity of the surface and its morphology. These surfaces have been established for a long time and have been studied for decades. The increasing interest in recent years has been focused towards applications in many different fields and, in particular, biomedical applications. In this paper, we review the progress achieved in the last years in the fabrication of regularly patterned superhydrophobic surfaces in many different materials and their exploitation for the manipulation and characterization of biomaterial, with particular emphasis on the issues affecting the yields of the fabrication processes and the quality of the manufactured devices.

Wall-free droplet microfluidics for probing biological processes by high-brilliance X-ray scattering techniques

“…Polymeric substrates generate, however, often an unwanted diffuse X-ray scattering background. Microfabricated SHSs based on a microscale pattern of pillars etched into a Si wafer with a nonwetting surface layer ( Figure 2B ) generate a very low X-ray scattering background ( Accardo et al, 2014 ; Gentile et al, 2014 ; Allione et al, 2021 ). A limitation of a planar array of homogeneous pillars is the lack of a stable position for a droplet in the Fakir state, requiring droplet pre-alignment in the focal spot and its tracking during evaporation.…”

“…The concept of droplets as close-to wall-free micro-reactors ( Accardo et al, 2014 ; Allione et al, 2021 ) allows exploring and optimizing specific reaction pathways, supported by flow simulations and complementary spectroscopic as well as imaging techniques. The power of this approach has been demonstrated for amyloid fibrillation of Tau441 protein molecules.…”

“…Indeed, aqueous droplets deposited on a water-repellant, superhydrophobic surface (SHS) with a high contact-angle Θ [ Figure 1A (left), inset] can be conceptionally considered as close-to wall-free confinements for water, aqueous solutions or suspensions including crystallites. Such droplets can serve as micro-reactors for probing molecular aggregation, assembly or transformations including chemical reactions by X-ray scattering and complementary techniques ( Accardo et al, 2013a ; Accardo et al, 2014 ; Allione et al, 2021 ). We will also review the deposition of droplets on surfaces with low Θ-values, with subsequent spreading and interaction with the bulk substrate by diffusion and/or reaction [ Figure 1A (right)].…”

“…(C) Pinned Wenzel state. (D) Retraction of contact-line of the droplet from the outermost pillars of a pillared SHS during evaporation ( Allione et al, 2021 ). (E) Simulation of change in Θ for a 6 μL droplet during evaporation at r. t. The decrease of Θ above t∼2,600 s is due to the wetting transition.…”

Multi-Scale Structure and Directional Hydrophobicity of Titanium Alloy Surface Using Electrical Discharge

“…The study of the surface wettability properties [1] of materials has largely been derived from observing the unique structures of the body surfaces of plants and animals in nature, such as the self-cleaning properties of lotus leaves [2][3][4][5] and the high adhesion of rose petals [6][7][8][9]. These properties are attributed to their unique Macro-micro composite structures and their combined forms.…”