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Nanostructuring surfaces is an emergent strategy to endow materials with abilities to combat pathogenic bacteria. Nevertheless, it remains challenging to create nanospike structures on the curved surfaces of polymer materials, including gauze and other microfibrous medical materials. Additionally, the effects of nanostructured surfaces on bacteria in the presence of proteins and in vivo remain largely unexplored. Herein, we demonstrated the decoration of gauze microfiber surfaces with nanospike structures via the self-assembly of cello-oligosaccharides and investigated the effects of the nanospiked gauze on bacteria in the presence of proteins. The nanospiked gauze had low bacterial adhesion properties in the absence of proteins, whereas in the presence of proteins, it promoted bacterial adhesion. Analyses suggested that the adsorbed protein layers on the nanospikes were involved in the promoted bacterial adhesion. Furthermore, the bacterial adhesion-promoting effects were exploited to remove pathogenic bacteria from burn wounds with exudate containing proteins using the nanospiked gauze.

Insects and plants exhibit bactericidal properties through surface nanostructures, such as nanospikes, which physically kill bacteria without antibiotics or chemicals. This is a promising new avenue for achieving antibacterial surfaces. However, the existing methods for fabricating nanospikes are incapable of producing uniform nanostructures on a large scale and in a cost-effective manner. In this paper, a scalable nanofabrication method involving the application of nanosphere lithography and reactive ion etching for constructing nanospike surfaces is demonstrated. Low-cost silicon nanospikes with uniform spacing that were sized similarly to biological nanospikes on cicada wings with a 4-inch wafer scale were fabricated. The spacing, tip radius, and base diameter of the silicon nanospikes were controlled precisely by adjusting the nanosphere diameters, etching conditions, and diameter reduction. The bactericidal properties of the silicon nanospikes with 300 nm spacing were measured quantitatively using the standard viability plate count method; they killed E. coli cells with 59 % efficiency within 30 h. The antibacterial ability of the nanospike surface was further indicated by the morphological differences between bacteria observed in the scanning electron microscopic images as well as the live/dead stains of fluorescence signals. The fabrication process combined the advantages of both top-down and bottom-up methods and was a significant step toward affordable bio-inspired antibacterial surfaces., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In the present study, the adsorption of a protein on a nanoparticle with a nanostructured surface, which is created using successively patterned Gaussian pillars (GPs), is simulated by considering the charge regulation within the electrical double layer of a silica nanoparticle (NP). Namely, the mathematical models for the adsorption mechanism, such as classical Langmuir model, extended Langmuir model, and two-state model, are coupled with charge regulation model. By this means, size and pH variables are able to included to the calculations. Moreover, free space, surface curvature, and conformational changes are also taken into account. For systematic investigation, the solution's pH, surface charge density, initial protein concentration, electrostatic charge of the protein, and the diameter of the spherical NP are varied. As a result, the vital properties of a nanoparticle, such as protonation/deprotonation, polarization, topography, and morphology, are considered in the current simulations. The surface charge density and surface chemistry change with NP and GP sizes. The present results reveal that the protein adsorption on an NP with a smooth surface reaches a faster complete surface coverage than an NP with a nanostructured surface. Both states of conformational changes are also affected by the presence of the GP., (© 2022 Wiley-VCH GmbH.)

Mechano-bactericidal surfaces deliver lethal effects to contacting bacteria. Until now, cell death has been attributed to the mechanical stress imparted to the bacterial cell envelope by the surface nanostructures; however, the process of bacterial death encountering nanostructured surfaces has not been fully illuminated. Here, we perform an in-depth investigation of the mechano-bactericidal action of black silicon (bSi) surfaces toward Gram-negative bacteria Pseudomonas aeruginosa . We discover that the mechanical injury is not sufficient to kill the bacteria immediately due to the survival of the inner plasma membrane. Instead, such sublethal mechanical injury leads to apoptosis-like death (ALD) in affected bacteria. In addition, when the mechanical stress is removed, the self-accumulated reactive oxygen species (ROS) incur poststress ALD in damaged cells in a nonstressed environment, revealing that the mechano-bactericidal actions have sustained physiological effects on the bacterium. This work creates a new facet and can introduce many new regulation tools to this field.

A method for obtaining composite gas-diffusion PdCu-Nb-PdCu membranes modified with a nanostructured crystalline coating was developed to increase the performance of Nb-based membranes. A modifying functional layer with a controlled size and composition was synthesized by electrochemical deposition, which made it possible to determine a certain geometric shape for palladium nanocrystallites. Developed PdCu-Nb-PdCu membranes have demonstrated flux values up to 0.232 mmol s -1 m -2 in the processes of diffusion purification of hydrogen at 400 °C. A very significant difference in the hydrogen fluxes through the modified and non-modified composite PdCu-Nb-PdCu membranes reached 1.73 times at the lower threshold temperature of 300 °C. Cu doping of protective layer did not affect the selective properties of the membranes, which was confirmed by the obtained high selectivity values up to 1323, and made it possible to reduce the noble metal content. The research data indicate that the modification of the membrane surface significantly accelerates the hydrogen transfer process at sufficiently low temperatures due to the acceleration of dissociative-associative processes on the surface. The reported approach demonstrates new possibilities for creating productive and cost-efficient membranes based on niobium.

The mechano-bactericidal property of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, especially in the current era of spreading antibiotic resistance. However, the mechanisms underlying nanostructured surfaces mechanically damaging bacteria remain unclear, which ultimately limits translational potential toward real-world applications. Using finite element simulation technique, we developed the three-dimensional thin wall with turgor pressure finite element model (3D-TWTP-FEM) of bacterial cell and verified the reliability of this model by the AFM indentation experiment simulation of the cell, and the cell model is able to simulate suspended bacterial cell and the process of cell adhering to the flat and nanopillar surfaces. Since bacterial cells suffer greater stress and deformation on the nanopillar surfaces, a two-stage model of the elastic and creep deformation stage of the cells on the nanostructured surfaces was developed. The calculations show that the location of the maximum stress/strain on the cells adhered to the nanopillar surfaces is at the liquid-cell-nanopillar three phase contact line. The computational results confirmed the ability of nanostructured surfaces to mechanically lyse bacteria and gave the effect of nanopillar geometry on the efficiency and speed of bacterial cell rupture. This study provides fundamental physical insights into how nanopillar surfaces can serve as effective and fast mechanical antimicrobial materials., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The mechano-bactericidal activity of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, particularly in the current era of emerging antibiotic resistance. This work demonstrates the effects of an incremental increase of nanopillar height on nanostructure-induced bacterial cell death. We propose that the mechanical lysis of bacterial cells can be influenced by the degree of elasticity and clustering of highly ordered silicon nanopillar arrays. Herein, silicon nanopillar arrays with diameter 35 nm, periodicity 90 nm and increasing heights of 220, 360, and 420 nm were fabricated using deep UV immersion lithography. Nanoarrays of 360-nm-height pillars exhibited the highest degree of bactericidal activity toward both Gram stain-negative Pseudomonas aeruginosa and Gram stain-positive Staphylococcus aureus bacteria, inducing 95 ± 5% and 83 ± 12% cell death, respectively. At heights of 360 nm, increased nanopillar elasticity contributes to the onset of pillar deformation in response to bacterial adhesion to the surface. Theoretical analyses of pillar elasticity confirm that deflection, deformation force, and mechanical energies are more significant for the substrata possessing more flexible pillars. Increased storage and release of mechanical energy may explain the enhanced bactericidal action of these nanopillar arrays toward bacterial cells contacting the surface; however, with further increase of nanopillar height (420 nm), the forces (and tensions) can be partially compensated by irreversible interpillar adhesion that reduces their bactericidal effect. These findings can be used to inform the design of next-generation mechano-responsive surfaces with tuneable bactericidal characteristics for antimicrobial surface technologies., Competing Interests: The authors declare no competing interest.

Surface plasmon resonance imaging (SPRI) is a powerful label-free imaging modality for the analysis of morphological dynamics in cell monolayers. However, classical plasmonic imaging systems have relatively poor spatial resolution along one axis due to the plasmon mode attenuation distance (tens of μm, typically), which significantly limits their ability to resolve subcellular structures. We address this limitation by adding an array of nanostructures onto the metal sensing surface (25 nm thick, 200 nm width, 400 nm period grating) to couple localized plasmons with propagating plasmons, thereby reducing attenuation length and commensurately increasing spatial imaging resolution, without significant loss of sensitivity or image contrast. In this work, experimental results obtained with both conventional unstructured and nanostructured gold film SPRI sensor chips show a clear gain in spatial resolution achieved with surface nanostructuring. The work demonstrates the ability of the nanostructured SPRI chips to resolve fine morphological detail (intercellular gaps) in experiments monitoring changes in endothelial cell monolayer integrity following the activation of the cell surface protease-activated receptor 1 (PAR1) by thrombin. In particular, the nanostructured chips reveal the persistence of small intercellular gaps (<5 μm 2 ) well after apparent recovery of cell monolayer integrity as determined by conventional unstructured surface based SPRI. This new high spatial resolution plasmonic imaging technique uses low-cost and reusable patterned substrates and is likely to find applications in cell biology and pharmacology by allowing label-free quantification of minute cell morphological activities associated with receptor dependent intracellular signaling activity., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Cellular dynamics under complex topographical microenvironments are important for many biological processes in development and diseases, but systematic investigation has been limited due to the lack of technology. Herein, we developed a new dynamic cell patterning method based on a cell-friendly photoresist polymer that allows in situ control of cell dynamics on nanostructured surfaces. Using this method, we quantitatively compared the spreading dynamics of cells on nanostructured surfaces to those on flat surfaces. Furthermore, we investigated how cells behaved when they simultaneously encountered two topographically distinct surfaces during spreading. This method will allow many exciting opportunities in the fundamental study of cellular dynamics.

Exploring the biological interfaces of metallic implants has been an important issue in achieving biofunctional success. Here we develop a biointerface with nanotopological features and bioactive composition, comprising a carbon nanotube (CNT) and chitosan (Chi) hybrid, via an electrophoretic deposition (EPD). The physicochemical properties, in vitro biocompatibility, and protein delivering capacity of the decorated nanohybrid layer were investigated, to address its potential usefulness as bone regenerating implants. Over a wide compositional range, the nanostructured hybrid interfaces were successfully formed with varying thicknesses, depending on the electrodeposition parameters. CNT-Chi hybrid interfaces showed a time-sequenced degradation in saline water, and a rapid induction of hydroxyapatite mineral in a simulated body fluid. The nanostructured hybrid substrates stimulated the initial adhesion events of the osteoblastic cells, including cell adhesion rate, spreading behaviors, and expression of adhesive proteins. The nanostructured hybrid interfaces significantly improved the adsorption of protein molecules, which was enabled by the surface charge interaction, and increased surface area of the nanotopology. Furthermore, the incorporated protein was released at a highly sustained rate, profiling a diffusion-controlled pattern over a couple of weeks, suggesting the possible usefulness as a protein delivery device. Collectively, the nanostructured hybrid CNT-Chi layer, implemented by an electrodeposition, is considered a biocompatible, cell-stimulating, and protein-delivering biointerface of metallic implants.

Photonic crystal surfaces offer a compelling platform for improving the sensitivity of surface-based fluorescent assays used in disease diagnostics. Through the complementary processes of photonic crystal enhanced excitation and enhanced extraction, a periodic dielectric-based nanostructured surface can simultaneously increase the electric field intensity experienced by surface-bound fluorophores and increase the collection efficiency of emitted fluorescent photons. Through the ability to inexpensively fabricate photonic crystal surfaces over substantial surface areas, they are amenable to single-use applications in biological sensing, such as disease biomarker detection in serum. In this review, we will describe the motivation for implementing high-sensitivity, multiplexed biomarker detection in the context of breast cancer diagnosis. We will summarize recent efforts to improve the detection limits of such assays though the use of photonic crystal surfaces. Reduction of detection limits is driven by low autofluorescent substrates for photonic crystal fabrication, and detection instruments that take advantage of their unique features., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The paper presents results of several experiments to determine the cytotoxicity of porous silicon structures synthesized by different methods. Crystalline and amorphous, micro- and nanoporous silicon layers with and without annealing were studied. Cytotoxicity was studied by fluorescence micrographs and by standard colorimetric MTT testing. [ABSTRACT FROM AUTHOR]

Purpose: The use of nanotechnology to enhance endosseous implant surfaces may improve the clinical control of inter facial osteoblast biology. This study investigated the influence of a nanostructure-coated implant surface on osteoblast differentiation and its effects on bone-to-implant contact (BIC) and removal torque values. Materials and Methods: Titanium disks were machined (M) or machined and subsequently treated by acid etching (Ac) or by dipping in an aluminum oxide solution (Al2O3). Surfaces were characterized by scanning electron microscopy, atomic force microscopy, and x-ray microanalysis. For the in vitro experiment, rat mesenchymal stem cells (rMSCs) were grown in osteogenic supplements on the disk surfaces for 3 days. Real-time polymerase chain reaction (PCR) was used to measure mRNA levels of several gene products (bone sialoprotein, osteocalcin, osteopontin, and RUNX-2). For the in vivo experiment, titanium implants were placed in rat tibiae and harvested after 3 to 21 days for measurement of bone-specific mRNA levels by real-time PCR. Removal torque and BIC were measured 3 to 56 days after placement. Results: Average height deviation (Sa, in nm) values for M, Ac, and Al2O3 implants were 86.5, 388.4, and 61.2, respectively. Nanostructured Al2O3 topographic features applied to machined implants promoted MSC commitment to the osteoblast phenotype. Greater bone-specific gene expression was observed in tissues adjacent to Al2O3 implants, and associated increases in BIC and torque removal were noted. Conclusion: Nanostructured alumina may directly influence cell behavior to enhance osseointegration. [ABSTRACT FROM AUTHOR]

It remains a great challenge to construct nanostructures and modify two-dimensional (2D) nanomaterials on the cylindrical surface of a micro-scale biosensor to enhance its performance. In the paper, a novel fiber surface plasmon resonance (SPR) biosensor was proposed to enhance the sensitivity of glucose monitoring by forming nanostructures and coating graphene on the gold film. Ultrasonic cavitation was used for the first time to form nanostructures on the cylindrical gold film surface, thus inducing local surface plasmon resonance (LSPR). To enhance the adsorption of glucose molecules, a liquid transfer method was innovatively proposed to cover the surface of the cylindrical roughened gold film of the biosensor with multilayer chemical vapor deposition (CVD) graphene. According to the experimental results, the SPR sensor treated with ultrasonic cavitation for 15 min and modified with two-layer graphene achieved top sensitivity, exhibiting about 3.57 times enhancement compared to the untreated one. This result verifies the sensitivity enhancement effect of both methods, ultrasonic cavitation to construct nanostructures and the liquid transfer of graphene, which may also be applied to construct nanostructures and modify 2D nanomaterials on arbitrary shapes of micro-scale biosensors. [Display omitted] • A novel fiber SPR glucose biosensor with treated cylindrical surface is fabricated. • Ultrasonic cavitation creates nanostructures on the micro cylindrical gold film. • Multi-layer graphene is covered on micro cylindrical surface by liquid transfer. • The sensitivity of the SPR sensor improves about 3.57 times after the treatments. • The two methods can be applied to arbitrary shapes of micro-scale biosensors. [ABSTRACT FROM AUTHOR]

The experimental results present the phenomenon of moving lines on electron spectra which are linked spatially and in time with the localization and durability of the processes of new surface producing in folds and grain boundaries. This effect was also realized for a thin-layer composite 'organic on metal films on dielectric substrate' in modeling non-equilibrium conditions which are created by the intensive electron beam pulse impact. It was found that the nature of the inceptive adsorption layer, in addition to the metal film, determines the initial positions of moving lines on the spectra. The main accents in these investigations were in observations of appearance of the moving lines, dynamics of their displacements on the spectra, final stages when these lines vanished, and finding the general regularities between the spontaneous and induced events. [ABSTRACT FROM AUTHOR]

We demonstrate the fabrication of sophisticated nanostructures using nanosphere lithography (NSL). These include periodic triangular and pyramidal islands as well as periodically perforated thin films and cavities on the nanoand microscale. Furthermore, periodic arrays of vertically standing multiwalled carbon nanotubes are grown by plasma enhanced chemical vapor deposition from catalyst islands that were prepatterned by NSL. Moreover, we discuss the applicability of NSL to rough surfaces and show that the ratio between nanosphere size and roughness is determinant of the resulting nanostructure produced. Excellent, limited, and bad applicability of NSL are shown for smooth, rough, and very rough surfaces, respectively. Finally, we demonstrate that NSL is applicable to orthopedic implants. The results of this work will facilitate the fabrication of different nanostructured surfaces with well-defined morphologies and properties towards the customized rational design of medically relevant surfaces. [ABSTRACT FROM AUTHOR]

By deposition in ultra-high vacuum of cobalt on a Ge(111)- c(2 × 8) surface, Mocking et al. obtained a [ABSTRACT FROM AUTHOR]

A simplified model of the nanostructured polymeric surface was proposed, characterized by a one-dimensional periodic stripe patterned surface with alternate planar and homeotropic anchoring. We investigate the effect of both the coupling of nematic liquid crystals with alignment layer polymers and the coupling of the polymers with the substrate surface on the anchoring of nematic liquid crystals at such a surface using the extended anisotropic surface energy form proposed by Alexe-Ionescu et al. In our theoretical treatment, we assume the equal anchoring strength of the two anchoring regions. Our results show that the coupling of the polymer with the surface will affect the director field of the nematic, and reduce the relaxation distance as well as the total free energy of the system. [ABSTRACT FROM AUTHOR]

Abstract: Gold electrodes were functionalized with an electropolymerized matrix of Au nanoparticles modified with 2-mercaptoethanesulfonic acid, 3-mercaptophenyl boronic acid and p-aminothiophenol. The resulting nanostructured electroconductive matrix was used as support for the oriented immobilization of horseradish peroxidase to construct a reagentless amperometric biosensor for H2O2. The electrode, poised at 0.0mV, exhibited a rapid response within 8s and a linear calibration range from 5μM to 1.1mM H2O2. The sensitivity of the biosensor was determined as 498μA/Mcm2, and its detection limit was 1.5μM H2O2 at a signal-to-noise ratio of 3. The electrode retained 95% and 72% of its initial activity after 21 and 40 days of storage at 4°C. [Copyright &y& Elsevier]

Abstract: To understand the effect of substrate microstructure on formation of ZrO2 nanotubes, anodic oxidizations of commercially pure zirconium subjected to surface mechanical attrition treatment (SMATed-Zr), SMATed-Zr annealed at 550°C for 10h and unSMATed-Zr in an aqueous solution containing (NH4)2SO4 and NH4F were investigated. The SMATed-Zr and annealed SMATed-Zr exhibit nanocrystallized surface layers containing high density of grain boundaries compared with unSMATed-Zr. The anodization results show that the formed ZrO2 nanotube layer on the SMATed-Zr is slightly thicker than that on the annealed SMATed-Zr, but thicker than that on the unSMATed-Zr. It is indicated that nanocrystallized Zr is propitious to the growth of ZrO2 nanotubes; and grain boundaries, compared with dislocations, play the leading role in accelerating the reaction rate during anodization, in turn enhancing the crystallinity of ZrO2 nanotubes at top-end. [Copyright &y& Elsevier]

Abstract: Molecular dynamic (MD) simulations have been carried out to study the effect of the nanostructures on the evaporation rate of the ultra-thin liquid film at the solid surface. Simple Lennard-Jones (LJ) fluids are simulated as the ultra-thin liquid film in the non-equilibrium simulation system. The liquid film is confined in a nanochannel composed of two solid surfaces designed with nanostructures in a shape of molecular-scale unevenness. The potential function between solid and liquid molecules is represented by a modified LJ function to conduct the solid–liquid interfaces of different surface wettability. For the steady non-equilibrium MD simulation, the liquid film is subjected to the steady heat flux passing through the nanostructured surfaces. It is found that the interface thermal resistance decreases at the nanostructured surface and apparent heat transfer enhancement is achieved due to the surface area increment. For the unsteady non-equilibrium MD simulation, the vapor has been sandwiched between the liquid films in contact with the nanostructured surfaces of high and low temperature respectively. It is found that the evaporation rate of the ultra-thin liquid film has a larger value than that of the flat surface when the film thickness is larger than that of the adsorbed layer. [Copyright &y& Elsevier]

Responses of welded joint of carbon steel to surface mechanical attrition treatment (SMAT) and shot peening (SP) were investigated. Experimental evidences showed that the microstructure of treated surface in the welded joint by means of SMAT was characterised by nanometre grains of about 13·6 nm in size and that of SP was characterised by highly dense dislocation configuration. The similar microhardness profiles with different peak values in the top surface were observed for three typical zones of welded joints processed by SMAT and SP. Compared with as welded specimens, SMAT and SP processes have improved the fatigue strength by as much as 61 and 36·3% respectively based on fatigue life 2×106 cycles. The observed enhanced fatigue behaviours of the welded joint processed by SMAT and SP should be attributed to the combined influences of compressive residual stress, work hardening, nanostructure and elimination of microdiscontinuities in the vicinity of welded joints. [ABSTRACT FROM AUTHOR]

Abstract: Nanostructuring surfaces in order to improve the quality of determinations, in terms of detection limit and signal-to-noise ratio, had received a great attention in the last years. At this effect, a potentiometric for the determination of lactate, based on a nanostructured (ND) Si4N3 surface, is presented here. The potentiometric sensor developed is an electrolyte–membrane–insulator–semiconductor (EMIS). The surface was first modified by a polyacrylic acid (PAA) layer, deposited by plasma enhanced chemical vapor deposition (PECVD), that can covalently link to the NH2 groups of the lactate dehydrogenase. Secondly, the nanostructures were formed on the surface by colloidal lithography. The obtained nanostructured surface was characterized. The stability of the biosensor in aqueous media was investigated obtaining a sensitivity of 49.7mV per decade. The detection limit for the determination of lactate was 2×10−7 M, with a linear range up to 10−5 M. The intra- and inter-electrode standard deviation were about 2.4% and 11%, respectively. Nanostructuring leads to a signal amplification of one order of magnitude when compared to the values obtained with the same device based on flat surface. [Copyright &y& Elsevier]

Conversion electron Mo¨ssbauer spectroscopy and X-ray diffraction analysis have been used to investigate the relationship between character of phase transformation and treatment time in surface nanocrystallized 304 stainless steel (SS) induced by high-energy shot peening (HESP). The results demonstrate that the amount of martensite phase increases remarkably with increasing HESP treatment time, till a maximum value (91%) is reached for 15 min treatment. Longer treatment duration only results in a slight decrease of the amount of martensite phase. Two types of martensite with different magnetic hyperfine fields are observed in the Mo¨ssbauer spectra. A theoretical model based on a random distribution of the non-iron atoms in 304 SS is presented to illustrate the relationship between the magnetic hyperfine field and the number of coordinating non-iron atoms. The calculation agrees well with the experimental results. [Copyright &y& Elsevier]

This review presents the results of the local formation of nanostructured porous silicon (NPSi) on the surface of silicon wafers by anodic etching using a durite intermediate ring. The morphological and crystallographic features of NPSi structures formed on n- and p-type silicon with low and relatively high resistivity have also been investigated. The proposed scheme allows one to experiment with biological objects (for example, stem cells, neurons, and other objects) in a locally formed porous structure located in close proximity to the electronic periphery of sensor devices on a silicon wafer. [ABSTRACT FROM AUTHOR]

Abstract: The Brownian diffusion of sub-micrometer-sized particles (diameter 0.52 μm) in the vicinity of a nanostructured surface was experimentally characterized. The surface consisted of a repeating pattern of rectangular grooves with depth 35 nm and pitch 400 nm. It was found that the one-dimensional particle diffusivity parallel to the nanogrooves was significantly higher than the diffusivity perpendicular to the grooves ( (S.E.) μm2/s compared to ). No such anisotropy in the one-dimensional Brownian diffusivity was found for particles near a flat surface. [Copyright &y& Elsevier]