Selective Adhesion of Bacillus cereus Spores on Heterogeneously Wetted Silicon Nanowires (original) (raw)
Related papers
Langmuir, 2008
We report on the use of patterned superhydrophobic silicon nanowire surfaces for the efficient, selective transfer of biological molecules and nanoparticles. Superhydrophilic patterns are prepared on superhydrophobic silicon nanowire surfaces using standard optical lithography. The resulting water-repellent surface allows material transfer and physisorption to the superhydrophilic islands upon exposure to an aqueous solution containing peptides, proteins, or nanoparticles.
Thin Solid Films, 2013
Bio-inspired superhydrophobic surfaces have attracted considerable attention due to their potential applications. Although various techniques to fabricate artificial superhydrophobic surfaces have been demonstrated, most of the methods lack water adherence or controllable wetting properties of the surfaces, which hinders their practical usage. In this paper, we present a simple approach to fabricate water-adhesive superhydrophobic silicon nanowire (Si NW) surfaces by applying a thermal annealing treatment in oxygen ambient. The Si NW arrays were fabricated using a metal assisted chemical etching method. After the cycled rapid thermal annealing (RTA) process at 1000°C under oxygen ambient, the water contact angle of the Si NW surface changed dramatically from 0 to 154.3°with high water-adhesive properties. This drastic change of the wettability could be attributed to the formed siloxane groups (−Si-O-Si-) on the thermally-treated Si NW surfaces; H 2 O is released from two adjacent silanol groups (-Si-O-H) to form siloxane groups during the RTA process. When the annealed Si NW was exposed in air, the wettability of the superhydrophobic Si NW was reconverted due to the re-formation of silanol groups (-Si-O-H). The wettability conversion of Si NW between superhydrophilic and superhydrophobic was repeated with good reversibility.
Biomimetic Nanopillar Silicon Surfaces Rupture Fungal Spores
International Journal of Molecular Sciences
The mechano-bactericidal action of nanostructured surfaces is well-documented; however, synthetic nanostructured surfaces have not yet been explored for their antifungal properties toward filamentous fungal species. In this study, we developed a biomimetic nanostructured surface inspired by dragonfly wings. A high-aspect-ratio nanopillar topography was created on silicon (nano-Si) surfaces using inductively coupled plasma reactive ion etching (ICP RIE). To mimic the superhydrophobic nature of insect wings, the nano-Si was further functionalised with trichloro(1H,1H,2H,2H-perfluorooctyl)silane (PFTS). The viability of Aspergillus brasiliensis spores, in contact with either hydrophobic or hydrophilic nano-Si surfaces, was determined using a combination of standard microbiological assays, confocal laser scanning microscopy (CLSM), and focused ion beam scanning electron microscopy (FIB-SEM). Results indicated the breakdown of the fungal spore membrane upon contact with the hydrophilic n...
Applied Physics Letters, 2017
The recently discovered bactericidal properties of nanostructures on wings of insects such as cicadas and dragonflies have inspired the development of similar nanostructured surfaces for antibacterial applications. Since most antibacterial applications require nanostructures covering a considerable amount of area, a practical fabrication method needs to be cost-effective and scalable. However, most reported nanofabrication methods require either expensive equipment or a high temperature process, limiting cost efficiency and scalability. Here, we report a simple, fast, low-cost, and scalable antibacterial surface nanofabrication methodology. Our method is based on metal-assisted chemical etching that only requires etching a single crystal silicon substrate in a mixture of silver nitrate and hydrofluoric acid for several minutes. We experimentally studied the effects of etching time on the morphology of the silicon nanospikes and the bactericidal properties of the resulting surface. W...
Micro-and nanostructured silicon-based superomniphobic surfaces
Journal of Colloid and Interface Science, 2014
We report on the fabrication of silicon nanostructured superhydrophobic and superoleophobic surfaces also called ''superomniphobic'' surfaces. For this purpose, silicon interfaces with different surface morphologies, single or double scale structuration, were investigated. These structured surfaces were chemically treated with perfluorodecyltrichlorosilane (PFTS), a low surface energy molecule. The morphology of the resulting surfaces was characterized using scanning electron microscopy (SEM). Their wetting properties: static contact angle (CA) and contact angle hysteresis (CAH) were investigated using liquids of various surface tensions. Despite that we found that all the different morphologies display a superhydrophobic character (CA > 150°for water) and superoleophobic behavior (CA % 140°for hexadecane), values of hysteresis are strongly dependent on the liquid surface tension and surface morphology. The best surface described in this study was composed of a dual scale texturation i.e. silicon micropillars covered by silicon nanowires. Indeed, this surface displayed high static contact angles and low hysteresis for all tested liquids.
Fast and large area fabrication of hierarchical bioinspired superhydrophobic silicon surfaces
Journal of the European Ceramic Society, 2016
In this work we present a new method to generate hierarchical surfaces, inspired by lotus leaf, on a silicon substrate. Mimicking leafs with particular properties, such as low adhesion, water repellence and self-cleaning, is an interesting case of study in the branch of bioinspired materials. These properties arise from a combination of surface chemistry and topography. The lotus leaf surface exhibits a highly controlled specific roughness, which has been studied and imitated by several researchers. The great challenge that has still to be solved is to reproduce lotus-inspired surfaces rapidly and on large areas. Our method consists in a combination of wet and dry etch with soft lithography, able to generate nano-and microhierarchical structures on silicon surfaces. Two different kinds of hierarchical structures are generated by changing the order of the etch steps. The surfaces generated were then characterized by measuring both the contact angle and the sliding angle. Finally, to validate experimental results, analytical models were implemented to predict the contact angle. The best surface displayed wetting performances superior even to those of the natural lotus leaf, thanks to the hierarchical structure, with a contact angle of 171 and a tilt angle of 4⁰ with production time of about 90 minutes per silicon wafer, or 30 s/cm 2 .
An Effect of Silicon Micro-/Nano-Patterning Arrays on Superhydrophobic Surface
Journal of Nanoscience and Nanotechnology, 2011
Superhydrophobic surface can be fabricated by creating a rough surface at very fine scale and modify it with low-surface energy material. To obtain the optimum superhydrophobicity, the surface roughness must be maximized. To avoid the limitation of scaling down the pattern size by using an expensive lithography tools, the surface roughness factor (r was increased by means of changing an asperity shape so as to increase its overall surface area. In this paper, the patterns of the asperities under studied were wave stripes, line stripes, cylindrical pillars, square pillars, pentagonal pillars, hexagonal pillars, and octagonal pillars. All pillar shapes were arranged in square arrays, hexagonal arrays, and continuous stripes. The asperities sizes and the pitches were varied from 1 to 5 m with 10 m of asperity height. Then the patterned surfaces were coated with polydimethylsiloxane mixed with 10 wt% dicumylperoxide. It was found that the stripe asperities can generate only hydrophobic surface with water contact angle (WCA) of 135 to 145. The pillars with square and hexagonal arrays had the WCA of 149 to 158. The pentagonal pillars with square and hexagonal arrays achieved the highest WCA with an average WCA of 156. It was evident that the pillar shape had significant effect on the superhydrophobicity.
NANOSTRUCTURED SILICON TRAPPING FOR SINGLE ESCHERICHIA COLI BACTERIA DETECTION
Digest Journal of Nanomaterials and Biostructures, 2018
The detection for Single Escherichia Coli Bacteria has attracted great interest and in biology and physics applications. A nanostructured porous silicon (PS) is designed for rapid capture and detection of Escherichia coli bacteria inside the micropore. PS has attracted more attention due to its unique properties. Several works are concerning the properties of nanostructured porous silicon. In this study PS is fabricated by an electrochemical anodization process. The surface morphology of PS films has been studied by scanning electron microscope (SEM) and atomic force microscope (AFM). The structure of porous silicon was studied by energy-dispersive X-ray spectroscopy (EDX). Details of experimental methods and results are given and discussed. The values obtained were compared with the published data.
Guided Transport of Water Droplets on Superhydrophobic–Hydrophilic Patterned Si Nanowires
ACS Applied Materials & Interfaces, 2011
We present a facile method to fabricate hydrophilic patterns in superhydrophobic Si nanowire (NW) arrays for guiding water droplets. The superhydrophobic Si NW arrays were obtained by simple dip-coating of dodecyltrichlorosilane (DTS). The water contact angles (CAs) of DTS-coated Si NW arrays drastically increased and saturated at the superhydrophobic regime (water CA ≥ 150°) as the lengths of NWs increased. The demonstrated superhydrophobic surfaces show an extreme water repellent property and small CA hysteresis of less than 7°, which enable the water droplets to easily roll off. The wettability of the DTScoated Si NW arrays can be converted from superhydrophobic to hydrophilic via UV-enhanced photodecomposition of the DTS, and such wettability conversion was reproducible on the same surfaces by repeating the DTS coating and photodecomposition processes. The resulting water guiding tracks were successfully demonstrated via selective patterning of the hydrophilic region on superhydrophobic Si NW arrays, which could enable water droplets to move along defined trajectories.