Search

To obtain a quantitative understanding of the transformation rules and mechanisms of wettability at the molecular level, an advanced sampling method of forward flux sampling is adopted to effectively solve the problem of time scale separation in direct molecular dynamics simulations for sampling rare events. The entire process of the wettability transition of droplets from Cassie state to Wenzel state on inverted triangular nanostructured surfaces with different solid-liquid interaction strengths is observed. The simulation results show that there are two mechanisms for the wettability mode transition with increasing solid-liquid interaction strength. One is that under weak solid-liquid interactions, the solid-liquid contact line is always pinned at the corner line of the rectangular nanoparticle protrusion structure, and the droplet deforms locally in the nanogroove under the curved surface. Another approach is that under slightly stronger solid-liquid interactions, the solid-liquid contact line moves downward along the inner wall of the nanogroove, and the curved surface inside the groove maintains its original smooth boundary. The wettability mechanisms obtained from research can help improve the stability of superhydrophobic surfaces and provide guidance for designing and manufacturing superhydrophobic nanostructured surfaces. [ABSTRACT FROM AUTHOR]

Explosive boiling is a fast-phase transition from an ultra-thin liquid film to vapor under an extremely high heat flux, which typically has been studied using the molecular dynamics simulation (MDS) method. The present MDS study investigated the explosive boiling of a liquid argon nanofilm over different solid copper surfaces with different nanowall patterns, including parallel and cross nanowalls. For each surface, atomic motion trajectories, the number of liquid and vapor argon atoms, heat flux, and, mainly, the onset time of explosive boiling were investigated. The simulation results indicated that explosive boiling occurs earlier on parallel and cross nanowall surfaces than on an ideally smooth surface, regardless of the topology and configuration of the nanowalls. Moreover, the results revealed that by using the cross nanowall surfaces, the onset time of explosive boiling decreased by 0.7–4% compared to the parallel nanowall surfaces. In addition, it was found that the onset time of explosive boiling strongly depends on the potential energy barrier and the movement space between nanowalls for both parallel and cross nanowall surfaces. Furthermore, the simulation findings showed that even though increasing the height of cross nanowalls increases the heat flux and temperature of the fluid argon domain, it does not necessarily result in a shorter onset time for explosive boiling. These findings demonstrate the capability of cross nanowall surfaces for explosive boiling, thereby being utilized in future surface design for thermal management applications. [ABSTRACT FROM AUTHOR]

The use of biocidal agents is a common practice for protection against biofouling in biomass-rich environments. In this paper, oligohexamethyleneguanidine (OHMG) polymer, known for its biocidal properties, was further modified with para-aminosalicylic acid (PAS) to enhance its properties against microorganisms coated with a lipid membrane. The structure of the product was confirmed by 1H NMR, 13C NMR, and FTIR spectroscopy. The values of the minimum inhibitory concentration (MIC) against Mycobacterium smegmatis ATCC 607 and Pseudomonas chlororaphis 449 were found to be 1.40 and 1.05 μg/mL, respectively. The synthesized substance was used as an additive to the polymer matrix of the composite optical oxygen sensor material. A series of samples with different contents of OHMG-PAS was prepared using a co-dissolution method implying the fabrication of a coating from a solution containing both polymers. It turned out that the mutual influence of the components significantly affects the distribution of the indicator in the matrix, surface morphology, and contact angle. The optimal polymer content turned out to be wt.3%, at which point the water contact angle reaches almost 122°, and the fouling rate decreases by almost five times, which is confirmed by both the respiratory MTT assay and confocal microscopy with staining. This opens up prospects for creating stable and biofouling-resistant sensor elements for use in air tanks or seawater. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) can be described as nanozymes, species that are able to mimic the catalytic activities of several enzymes, such as oxidase/peroxidase, reductase, or catalase. Most studies in the literature focus on the colloidal suspension of AuNPs, and it is obvious that their immobilization could open the doors to new applications thanks to their increased stability in this state. This work aimed to investigate the behavior of surfaces covered by immobilized AuNPs (iAuNPs). Citrate-stabilized AuNPs (AuNPs-cit) were synthesized and immobilized on glass slides using a simple dip coating method. The resulting iAuNPs were characterized (surface plasmon resonance, microscopy, quantification of immobilized AuNPs), and their multi-enzymatic-like activities (oxidase-, peroxidase-, and catalase-like activity) were evaluated. The comparison of their activities versus AuNPs-cit highlighted their added value, especially the preservation of their activity in some reaction media, and their ease of reuse. The huge potential of iAuNPs for heterogeneous catalysis was then applied to the degradation of two model molecules of hospital pollutants: metronidazole and methylene blue. [ABSTRACT FROM AUTHOR]

In the current study, bulk tungsten material surfaces are exposed to hydrogen, deuterium, and helium plasmas in the radiofrequency domain (13.56 MHz) at an input power of 250 W using the hollow-cathode configuration. The ejected material is collected on titanium substrates at various distances (from 6 mm up to 40 mm). Therefore, the exposed tungsten materials are investigated for surface changes (blister occurrence, dust formation, or nano-structuration), along with the crystallinity, depending on the plasma's exposure times (from 30 min up to 120 min for each plasma type). Also, the collected materials are analyzed (morphological, structural, and statistical investigations) for dust and dust film-like appearance. Plasma discharges are analyzed using two methods: optical emission spectroscopy, and single Langmuir probes, to emphasize the nature of the used plasmas (cold discharges, ~2 eV), along with the presence of tungsten emission (e.g., WI 406.31 nm, WI 421.31 nm) during the plasma lifetime. By using a dedicated protocol, a method was established for obtaining fusion-relevant tungsten surfaces in the hydrogen and deuterium plasma discharges. By using the implemented method, the current paper introduces the possibility of obtaining a new tungsten morphology, i.e., the dandelion-like shape, by using helium plasma, in which the W18O49 compound can be found. [ABSTRACT FROM AUTHOR]

Bacteria are difficult to be eliminated because of their multi‐drug resistance, which brings significant threats to public health. Among the antibacterial methods, mechanobactericidal surfaces provide a possible approach to solving this problem. In this study, a generally used mechanical sterilization is developed by fabricating a nanostructured coating. The functional coating is simply fabricated by growing zeolitic imidazolate frameworks (ZIFs, ZIF‐8 mixed with ZIF‐67) nanospikes on the surface of the fabric substrate in situ. The fabricated ZIF nanospikes are stable and effective, with the sterilization efficiency approaching 99.9999%. This technique provides a fast, safe, and low‐cost antibacterial method without drug resistance, which can be potentially used in hospitals, emergency treatments, and superbug protection in the future. [ABSTRACT FROM AUTHOR]

A synthesis strategy for the manufacture of inexpensive highly efficient nanostructured catalysts has been developed. The developed unique nonplatinoid copper-based catalysts with different surface morphology were investigated as a functional layer with high activity in the ethanol oxidation in alkaline media. A modifying layer with controlled morphology, composition, and excellent electrocatalytic activity was synthesized by electrochemical deposition by varying such synthesis parameters as deposition temperature and time, concentration of structure-forming additives, and electrodeposition current. The dependence of the samples' electrocatalytic activity on the shaping factors was established. According to the electrochemical study results, the highest current density peak of up to 33.01 mA cm−2, and hence the highest catalytic activity in comparison to other samples, were possessed by a catalyst with a regular cubic particle shape. A catalyst consisting of plate-like nanoparticles with a certain percentage of disclinations had similar, but slightly less activity, with a current density peak of up to 31.59 mA cm−2. The samples' activity values are 8 times higher for cubic particles and 7.5 times higher for particles with a triangular plate shape than for an unmodified smooth copper film. The developed samples can be considered as quite competitive to platinoid catalysts, which significantly outperform copper analogues. [ABSTRACT FROM AUTHOR]

Superhydrophobic coatings are widely studied for fluid regulation due to their water-repellent surface characteristics. However, there are not many reports on fluid behavior when it flows from a region of higher wettability to that of lower wettability. A fundamental understanding of such behavior would be very useful for regulating the fluid flow through a superhydrophobic channel. Therefore, this work focused on the fabrication of superhydrophobic nanostructured coatings inside fine cylindrical channels and the investigation of the fluid flow behavior through them. The superhydrophobic SiO2 coatings were obtained through an ultrasound-assisted one-step immersion technique. A self-stratified mechanically durable conformal superhydrophobic coating was obtained inside millimeter-sized fine 3D structures. A binder-free precursor solution has low viscosity and thereby enhances the penetration of the solvent into the polymer surface through ultrasonication. The self-stratification-based surface formation mechanism was explained using scanning electron microscopy images. The fluid behavior inside the superhydrophobic channels was experimentally investigated by analyzing the flow through the hollow cylindrical superhydrophobic channels. Experiments were conducted for different channel lengths (l) and radii (r), and mathematical formulations were developed to determine the maximum pressure (Pmax) that the superhydrophobic cylinders could hold when the fluid inside the channel was under static equilibrium. Finally, a self-regulated fluid delivery system was postulated based on the experimental and theoretical findings. [ABSTRACT FROM AUTHOR]

A controlled strategy for the electrochemical synthesis of mono- and bimetallic nanoparticles with a unique and complex morphology has been developed. The investigation of the effect of changing the surfactant concentration and current density regulating the medium pH has revealed the fundamental patterns of nanoparticle growth. The developed method has allowed to synthesis of nanoparticles with a controlled pentabranched structure for the monometallic palladium as well as for favorable combinations of metals—Pd-Ag and Pd-Pt. The obtained nanoparticles were investigated in alkaline methanol oxidation. The results demonstrated quite high catalytic activity up to 83.51 mA cm−2 and long-term stability, which are caused by the increase in electrochemically active surface area by increasing the active center's number. This was made possible due to the creation of unusual nanoparticle morphology, namely the presence of high-energy high-index facets. The developed nanoparticles were also studied as a modifying coating for hydrogen-permeable membranes in the processes of hydrogen transport. The membranes coated with the nanoparticles demonstrated sufficiently high hydrogen flux up to 11.33 mmol s−1 m−2 and high H2/N2 selectivity up to 2254. Such results can be explained by the obvious acceleration of surface processes through the application of the developed nanoparticles. The novel synthesis strategy can potentially be extended to other metal nanoparticle systems. Thus it can be an effective way to solve relevant problems of design of controlled synthetic methods allowing the nanoparticle morphology tuning according to the required functional properties. [ABSTRACT FROM AUTHOR]

In the last decade, there has been continuous competition between two methods for detecting the concentration of dissolved oxygen: amerometric (Clark electrode) and optical (quenching of the phosphorescence of the porphyrin metal complex). Each of them has obvious advantages and disadvantages. This competition is especially acute in the development of biosensors, however, an unbiased comparison is extremely difficult to achieve, since only a single detection method is used in each particular study. In this work, a microfluidic system with synchronous detection of the oxygen concentration by two methods was created for the purpose of direct comparison. The receptor element is represented by Saccharomyces cerevisiae yeast cells adsorbed on a composite material, previously developed by our scientific group. To our knowledge, this is the first work of this kind in which the comparison of the oxygen detection methods is carried out directly. [ABSTRACT FROM AUTHOR]

The possibility of the developing a biochemical oxygen demand (BOD) biosensor based on electroactive biofilms of activated sludge grown on the surface of a graphite-paste electrode modified with carbon nanotubes was studied. A complex of microscopic methods controlled biofilm formation: optical microscopy with phase contrast, scanning electron microscopy, and laser confocal microscopy. The features of charge transfer in the obtained electroactive biofilms were studied using the methods of cyclic voltammetry and electrochemical impedance spectroscopy. The rate constant of the interaction of microorganisms with the extracellular electron carrier (0.79 ± 0.03 dm3(g s)−1) and the heterogeneous rate constant of electron transfer (0.34 ± 0.02 cm s−1) were determined using the cyclic voltammetry method. These results revealed that the modification of the carbon nanotubes' (CNT) electrode surface makes it possible to create electroactive biofilms. An analysis of the metrological and analytical characteristics of the created biosensors showed that the lower limit of the biosensor based on an electroactive biofilm of activated sludge is 0.41 mgO2/dm3, which makes it possible to analyze almost any water sample. Analysis of 12 surface water samples showed a high correlation (R2 = 0.99) with the results of the standard method for determining biochemical oxygen demand. [ABSTRACT FROM AUTHOR]

Periprosthetic joint infection (PJI) is a devastating complication of orthopedic implant surgeries, such as total knee and hip arthroplasties. Treatment requires additional surgeries because antibiotics have limited efficacy due to biofilm formation and resistant bacterial strains such as methicillin‐resistant Staphylococcus aureus (MRSA). A non‐pharmaceutical approach is needed, and examples of this are found in nature; dragonfly and cicada wings are antibacterial because of their nanopillar surface structure rather than their chemistry. Carbon‐infiltrated carbon nanotube (CICNT) surfaces exhibit a similar nanopillar structure, and have been shown to facilitate osseointegration, and it is postulated that they might provide a structurally‐derived resistance to bacterial proliferation and biofilm formation. The objective of this study was to test the biofilm resistance of CICNT coatings. Two types of CICNT were produced: a vertically aligned CNT forest on a silicon substrate using a layer of iron as the catalyst (CICNT‐Si) and a random‐oriented CNT forest on stainless steel (SS) substrate using the substrate as the catalyst (CICNT‐SS). These were tested against SS and carbon controls. After 48 h in an MRSA biofilm reactor, samples demonstrated that both types of CICNT coatings significantly (p < 0.0001) reduced MRSA biofilm formation by 60%–80%. Morphologically, biofilm presence on both types of CICNT was also significantly reduced. Clinical Significance: Results suggest that a CICNT surface modification could be suitable and advantageous for medical devices susceptible to MRSA cell attachment and biofilm proliferation, particularly orthopedic implants. [ABSTRACT FROM AUTHOR]

Angiotensin I-converting enzyme (ACE) is a peptidase widely presented in human tissues and biological fluids. ACE is a glycoprotein containing 17 potential N-glycosylation sites which can be glycosylated in different ways due to post-translational modification of the protein in different cells. For the first time, surface-enhanced Raman scattering (SERS) spectra of human ACE from lungs, mainly produced by endothelial cells, ACE from heart, produced by endothelial heart cells and miofibroblasts, and ACE from seminal fluid, produced by epithelial cells, have been compared with full assignment. The ability to separate ACEs' SERS spectra was demonstrated using the linear discriminant analysis (LDA) method with high accuracy. The intervals in the spectra with maximum contributions of the spectral features were determined and their contribution to the spectrum of each separate ACE was evaluated. Near 25 spectral features forming three intervals were enough for successful separation of the spectra of different ACEs. However, more spectral information could be obtained from analysis of 50 spectral features. Band assignment showed that several features did not correlate with band assignments to amino acids or peptides, which indicated the carbohydrate contribution to the final spectra. Analysis of SERS spectra could be beneficial for the detection of tissue-specific ACEs. [ABSTRACT FROM AUTHOR]

The nanostructure-based surface texturing can be used to improve the materials wettability. Regarding oil–water separation, designing a surface with special wettability is as an important approach to improve the separation efficiency. Herein, a ZnO nanostructure was prepared by a two-step process for sol–gel process and crystal growth from the liquid phase to achieve both a superhydrophobicity in oil and a superoleophobic property in water. It is found that the filter material with nanostructures presented an excellent wettability. ZnO-coated stainless-steel metal fiber felt had a static underwater oil contact angle of 151.4° ± 0.8° and an underoil water contact angle of 152.7° ± 0.6°. Furthermore, to achieve water/oil separation, the emulsified impurities in both water-in-oil and oil-in-water emulsion were effectively intercepted. Our filter materials with a small pore (~5 μm diameter) could separate diverse water-in-oil and oil-in-water emulsions with a high efficiency (>98%). Finally, the efficacy of filtering quantity on separation performance was also investigated. Our preliminary results showed that the filtration flux decreased with the collection of emulsified impurities. However, the filtration flux could restore after cleaning and drying, suggesting the recyclable nature of our method. Our nanostructured filter material is a promising candidate for both water-in-oil and oil-in-water separation in industry. [ABSTRACT FROM AUTHOR]

The infection of surgically placed implants is a problem that is both large in magnitude and that broadly affects nearly all surgical specialties. Implant-associated infections deleteriously affect patient quality-of-life and can lead to greater morbidity, mortality, and cost to the health care system. The impact of this problem has prompted extensive pre-clinical and clinical investigation into decreasing implant infection rates. More recently, antimicrobial approaches that modify or treat the implant directly have been of great interest. These approaches include antibacterial implant coatings (antifouling materials, antibiotics, metal ions, and antimicrobial peptides), antibacterial nanostructured implant surfaces, and antibiotic-releasing implants. This review provides a compendium of these approaches and the clinical applications and outcomes. In general, implant-specific modalities for reducing infections have been effective; however, most applications remain in the preclinical or early clinical stages. [ABSTRACT FROM AUTHOR]

Introduction. In modern dentistry the oral rehabilitation of patients with the help of dental implants has a very high success rate. However, the problem is the situation of patients with serious chronic diseases in which the insertion of dental implants is problematic or dental procedures can complicate or aggravate the patients' disease. Case report. We presented the case of a patient with associated chronic diseases who benefited from the insertion of implants with a nanostructured surface. The nanotube surface of the dental implant has been loaded with anti-inflammatory drugs to promote healing and stimulate the process of osteogenesis. Conclusions. Within the limitations of this study, we consider the therapy with avant-garde nanostructured dental implants to represent a viable treatment option for patients with a medical history with complicated chronic diseases. [ABSTRACT FROM AUTHOR]

A method has been developed that has allowed a fivefold symmetry to be achieved for the first time in palladium nanocrystallites grown on the Pd–Cu film surface. Modification of the Pd–40% Cu membrane by pentatwinned (branched) palladium nanocrystallites with high-index facets ensured ultrahigh permeability for hydrogen reaching up to 10.1 mmol s–1 m–2 at 100°C. This level (comparable with the permeability of high-temperature analogs) is anomalous, since the expected values must be more than two times lower than obtained. This result is explained by the acceleration of dissociative adsorption and recombinative desorption due to the ultrahigh activity of pentatwinned particles in reactions involving hydrogen, which is confirmed by data on the selectivity of the modified membranes. [ABSTRACT FROM AUTHOR]

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]

Angiotensin I‐converting enzyme (ACE) is a glycoprotein, consisting of two homologous domains within a single polypeptide chain. ACE concentration in biological fluids is an important parameter of clinical observation; its increase or decrease may accompany various pathologies. Currently, the exact crystal structure of the two‐domain ACE form is still unknown because of microheterogeneity and intensity of the enzyme glycosylation. Raman spectroscopy provides the qualitative and quantitative analysis of many compounds, including proteins. For the first time, surface‐enhanced Raman scattering (SERS) spectra of native and thermo‐denatured human ACE have been demonstrated with full assignment. Denaturation leads to SERS intensity increase and bands shifting. Detailed band assignment and discussion are included to elucidate the potential site of ACE interaction with the silver surface. Based on SERS spectra, we characterized the region on the ACE molecule in contact with the substrate and demonstrated the model of the two‐domain ACE adsorbed on a silver matrix. [ABSTRACT FROM AUTHOR]

A new approach to the acceleration of the surface processes of hydrogen transport through Pd–40%Cu membranes by depositing a developed catalytic coating consisting of nanoparticles with a novel crystallographically atypical pentagonal structure is demonstrated. The number of localized potentially more active regions of the membrane surface increases significantly due to the presence of high-index facets with a large number of reactive undercoordinated atoms in such particles. This modification leads to a shift of the limiting stage, significantly accelerating the recombinative desorption on the surface, and to an increase in the influence of the diffusion stage. This improves the gas transport characteristics of the membrane, making it possible to achieve permeability of up to 8.9 mmol s−1 m−2 in the low-temperature mode (up to 100°C). The value obtained is up to sixfold higher than the corresponding value for smooth membranes and up to twofold higher for membranes modified with classical palladium black. [ABSTRACT FROM AUTHOR]

Nanostructured surfaces represent pertinent material technologies to improve the biocompatibility aspects of orthopedic implant surfaces. The present work reports the development of nanostructured titania surface on a low-modulus TNZT (Ti-35Nb-7Zr-5Ta) beta titanium alloy. The major focus is to gain more insights into the wettability, surface energy and corrosion resistance of the developed nanostructures. The developed nanomorphologies have been found to be nanopetal-like structures with nanotopographies and composed predominantly of anatase phase. Wettability studies revealed a highly hydrophilic surface with a concurrent enhancement in surface energy (68% increment in polar surface energy) advantageous for improved osseointegration. The developed layer has demonstrated comparable corrosion resistance with untreated surface. By incorporating the multiple aspects of low-modulus TNZT alloy, hydrophilic titania surface with elevated surface free energy and comparable corrosion resistance, the present work opens prospective avenues for effective biomaterial surface design paradigms. [ABSTRACT FROM AUTHOR]

Our study aimed to produce SERS substrates using nanostructured copper (Cu) surfaces prepared by laser ablation in water. A laser ablation schema was designed for this purpose. The laser power and laser irradiation time for creating a nanostructured surface suitable for SERS were determined. To increase the enhancement factor (EF) of the SERS substrates, gold (Au) and silver (Ag) nanoparticles were deposited on the ablated Cu surfaces to produce AuNP/aCu and AgNP/aCu substrates. The Au (and Ag) nanoparticles were also prepared by laser ablation of a Au (and Ag) piece in ethanol. The EFs for SERS of the AuNP/aCu and AgNP/aCu substrates are 1.2 × 106 and 6 × 106, respectively. The SERS spectra of malachite green with low concentrations of 0.1 ppm can be detected with high quality by using these SERS substrates. [ABSTRACT FROM AUTHOR]

The paper proposes the manufacturing methods for modifying coatings for gas-diffusion membranes made of palladium-silver alloy comprising 23% Ag. Highly developed surface structures are synthesized to intensify chemisorption and dissociation and to accelerate the overall process of hydrogen transmission through the membrane. At a 0.6 MPa hydrogen overpressure and 100°C temperature, the density of the hydrogen flow through Pd/Ag23 wt.% membrane with the developed surface is 7 times higher than through the similar membrane without the modifying layer. The analysis of the proposed methods shows that the hydrogen density passing through the membranes with the modifying coating synthesized by a method with the included recrystallization stage, is 1.3 times higher than through the similar membranes synthesized in accordance with the standard procedures. The experiments show that the hydrogen transmission rate can be increased in the surface limited regime by creating a highly developed structure of the membrane surface. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objectives: It is well known that surface treatments of dental implants have a great impact on their rate of osseointegration. The aim of this study was to compare the biocompatibility and the bone–implant contact (BIC) of titanium dental implants with different surface treatments. Material and methods: Test implants (Biotech Dental) had a nanostructured surface and control implants (Anthogyr) were grit‐blasted with biphasic calcium phosphate and acid‐etched surface. Both titanium implants were inserted in mandible and maxillary bones of 6 Yucatan minipigs for 4 and 12 weeks (n = 10 implants/group). Biocompatibility and osseointegration were evaluated by non‐decalcified histology and back‐scattered electron microscopy images. Results: The reading of histology sections by an antomo‐pathologist indicated that the test implants were considered non‐irritating to the surrounding tissues and thus biocompatible compared with control implants. The BIC values were higher for test than for control dental implants at both 4 and 12 weeks. Conclusions: In summary, the new nanostructured titanium dental implant is considered biocompatible and showed a better osseointegration than the control implant at both 4 and 12 weeks. [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]

Coarse-grained molecular dynamics simulations were carried out to investigate the frictional properties of lubricant molecules on nanostructured metal surfaces. The simulation cell consists of a lubricant film enclosed between two metal surfaces. The attractive potential of specific iron atoms on the surface was modified such that the lubricant molecule adsorb preferentially on these atoms. These particular iron atoms were arranged to reproduce a grain boundary surface nanostructure. It is found that below the critical normal stress, the strength of the interaction between Fe and the lubricant molecule has little effect on the friction coefficient. However, the behavior of the lubricant film on the metal surface is sensitive to the interaction strength. Large attraction forces increase the adherence of the lubricant film. [ABSTRACT FROM AUTHOR]

This study investigated the effect of a preformed nanostructured surface on the corrosion behavior of 9Cr2WVTa reduced activation ferritic/martensitic (RAFM) steel and 9Cr+AlSi steel (9Cr2WVTa with the 0.12 wt.% Al and 0.68 wt.% Si addition) at 700 °C in air and at 550 °C in liquid lead–bismuth eutectic (LBE) alloys. The nanostructured surface layer was fabricated by surface mechanical rolling treatment (SMRT). The results showed that the SMRT 9Cr+AlSi sample has a lower oxidation rate than the SMRT 9Cr2WVTa steel at 700 °C in air, due to the faster diffusion rates of Al, Cr and Si in the nanostructure and a higher diffusion driving force increased by Cr. The SMRT 9Cr+AlSi sample at 550 °C in oxygen-saturated LBE alloy also had a higher oxidation rate, due to the formation of Al and Si oxides in the internal oxide layer. [ABSTRACT FROM AUTHOR]

Abstract: Wrinkled surfaces have extraordinary characteristics, such as enlarged surface area and enhanced adhesion, which form the basis of several emerging applications in electrical, mechanical, and biological processes. Furthermore, wrinkles at a nanoscale display additional ultrahigh functions offering enhanced Raman scattering and superhydrophobicity; however, artificial nanowrinkled morphology is mostly limited to simple planar surfaces. Here, a microfluidics‐based approach to create tunable nanowrinkles on nonplanar surfaces is developed. In this approach, polyethylene glycol microposts using photolithography in a polydimethylsiloxane microfluidic channel are first fabricated. A syringe pump is then used with a washing solvent, ethanol, to remove the excess unpolymerized monomer from the microfluidic channel. In combination with nonuniform photopolymerization, this washing postprocess results in microposts with a fully cured inner layer and a partially cured outer layer. The partially cured layer spontaneously forms nanowrinkles upon plasma treatment. Their wavelengths are tunable by controlling the thickness of the partially cured layer during the washing process. The effect of the flow rate and duration of the washing fluid on the wavelength of nanowrinkle formed is investigated. [ABSTRACT FROM AUTHOR]

Microprobes are used to repair neuronal injury by recording electrical signals from neuronal cells around the surface of the device. Following implantation into the brain, the immune response results in formation of scar tissue around the microprobe. However, neurons must be in close proximity to the microprobe to enable signal recording. A common reason for failure of microprobes is impaired signal recording due to scar tissue, which is not related to the microprobe itself. Therefore, the device-cell interface must be improved to increase the number of neurons in contact with the surface. In this study, we developed nanostructured SU-8 microprobes to support neuronal growth. Nanostructures of 200 nm diameter and depth were applied to the surface of microprobes, and the attachment and neurite outgrowth of PC12 cells on the microprobes were evaluated. Neuronal attachment and neurite outgrowth on the nanostructured microprobes were significantly greater than those on non-nanostructured microprobes. The enhanced neuronal attachment and neurite outgrowth on the nanostructured microprobes occurred in the absence of an adhesive coating, such as poly- l-lysine, and so may be useful for implantable devices for long-term use. Therefore, nanostructured microprobes can be implanted without adhesive coating, which can cause problems in vivo over the long term. [ABSTRACT FROM AUTHOR]

Polypyrrole-coated polyethylene terephthalate is very attractive for various applications as electrically conductive fiber. This paper investigates the importance of polyester pre-treatment on the quality of the polypyrrole coating and its conductivity efficiency. The results showed nucleophilic pre-treatments by Grignard reagents resulting in the significantly higher surface quality and strongest adhesion of the polypyrrole coating to the polyester fibers compared to the other published methods. Moreover, several Grignard reagents were used for altering the hydrophobicity and morphology of the surface. [ABSTRACT FROM AUTHOR]

The addition of nanopillars to electrodes increases their electrochemical capabilities through an increase in electroactive surface area. The nanopillars can be applied on either cathodes or anodes to engage in reduction-oxidation reactions. This minireview summaries some work on cyclic voltammetry, chronoamperometry, impedance change on nanopillared surface and compared their electrochemistry behavior on planar surfaces. [ABSTRACT FROM AUTHOR]

In the present work, the influence of surface mechanical attrition treatment (SMAT) parameters on the microstructural and mechanical properties of an aluminum-magnesium-silicon alloy AA 6061 was studied using design of experiment technique. Balls of three different diameters were used, and SMAT was done for three different durations. The microstructural features of the surface layer fabricated by SMAT were characterized by cross-sectional scanning electron microscopic observations, x-ray diffraction technique and transmission electron microscopy. The microindentation hardness, nanoindentation hardness and surface roughness were determined. Due to SMAT, nanocrystallites formed on the surface and near-surface regions, and hardness and surface roughness increased. The ball diameter was the most influencing SMAT parameter compared to the treatment duration. However, interaction between ball diameter and treatment duration could not be ignored. Regression equations were developed relating the process parameters to the surface properties. The ball diameter and treatment duration could thus be properly selected as per the required values of roughness and/or the hardness. [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]

The electrochemical reduction of chloroacetic acid is studied by voltammetric techniques on nanostructured nickel electrodes with the surface modified with sharp elements, in aqueous solutions of this acid with supporting lithium perchlorate. It is shown that the surface structure substantially affects the stages and the rate of the chloroacetic acid reduction process. The dehalogenation on sharp nickel structures proceeds at much lower electrode potential values as compared with the smooth electrode being accompanied by almost 10-fold increase in the current density. The observed increase of the process rate on nanostructured electrodes is explained by the energy characteristics of the current-producing processes on the sharp nickel structures. [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]

Silica nanoparticles were applied onto the fiber surface of an interbonded three-dimensional polycaprolactone fibrous tissue scaffold by an electrostatic layer-by-layer self-assembly technique. The nanoparticle layer was found to improve the fiber wettability and surface roughness. Osteoblast cells were cultured on the fibrous scaffolds to evaluate the biological compatibility. The silica nanoparticle coated scaffold showed enhanced cell attachment, proliferation, and alkaline phosphatase activities. The overall results suggested that interbonded fibrous scaffold with silica nanoparticulate coating could be a promising scaffolding candidate for various applications in bone repair and regeneration. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3803-3812, 2014. [ABSTRACT FROM AUTHOR]

We report a fundamentally new approach to enhance fluorescence in which surface adsorbed fluorophore-tagged biomolecules are excited on a photonic crystal surface that functions as a narrow bandwidth and tunable mirror of an external cavity laser. This scheme leads to ∼10× increase in the electromagnetic enhancement factor compared to ordinary photonic crystal enhanced fluorescence. In our experiments, the cavity automatically tunes its lasing wavelength to the resonance wavelength of the photonic crystal, ensuring optimal on-resonance coupling even in the presence of variable device parameters and variations in the density of surface-adsorbed capture molecules. We achieve ∼105× improvement in the limit of detection of a fluorophore-tagged protein compared to its detection on an unpatterned glass substrate. The enhanced fluorescence signal and easy optical alignment make cavity-coupled photonic crystals a viable approach for further reducing detection limits of optically-excited light emitters that are used in biological assays. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [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]

Photonic crystal (PC) surfaces have been demonstrated as a compelling platform for improving the sensitivity of surface-based fluorescent assays used in disease diagnostics and life science research. PCs can be engineered to support optical resonances at specific wavelengths at which strong electromagnetic fields are utilized to enhance the intensity of surface-bound fluorophore excitation. Meanwhile, the leaky resonant modes of PCs can be used to direct emitted photons within a narrow range of angles for more efficient collection by a fluorescence detection system. The multiplicative effects of enhanced excitation combined with enhanced photon extraction combine to provide improved signal-to-noise ratios for detection of fluorescent emitters, which in turn can be used to reduce the limits of detection of low concentration analytes, such as disease biomarker proteins. Fabrication of PCs using inexpensive manufacturing methods and materials that include replica molding on plastic, nano-imprint lithography on quartz substrates result in devices that are practical for single-use disposable applications. In this review, we will describe the motivation for implementing high-sensitivity fluorescence detection in the context of molecular diagnosis and gene expression analysis though the use of PC surfaces. Recent efforts to improve the design and fabrication of PCs and their associated detection instrumentation are summarized, including the use of PCs coupled with Fabry-Perot cavities and external cavity lasers. [ABSTRACT FROM AUTHOR]

The article describes the multifunctionality of a novel black silicon (BS) nanostructured surface covered with a thin layer of noble metal prepared in the a microfluidic channel. It is focused on the separation properties of the BS substrate with direct detection of the separated analytes utilizing surface enhanced Raman spectroscopy. The same BS substrate is providing the stationary phase and a surface enhancement of the Raman signal that has been measured previously to be around 10. As tested molecules, the common components of explosives 1,3 dinitrobenzene and 2,4 dinitrotoluene were used. The separation of selected molecules was achieved with the dried toluene as a mobile phase in a 25 micrometers deep, 5 mm wide, and 4 cm long microfluidic channel during the 2 min. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A gold-nanostructured surface has been obtained by stable deposition of chemically synthesized gold nanoparticles (2.1-5.5 nm size range) on a gold substrate through a dithiol linker. The method proposed for the obtainment of the nanostructure is suitable for the further stable anchoring of a peptide nucleic acid oligomer through four amine groups of lysine terminal residues, leading to fairly reproducible systems. The geometric area of the nanostructured surface is compared with those of a smooth and of an electrochemically generated nanostructured surface by depositing a probe bearing an electrochemically active ferrocene residue. Despite the area of the two nanostructures being quite similar, the response toward a 2 nM target oligonucleotide sequence is particularly high when using the surface built up by nanoparticle deposition. This aspect indicates that morphologic details of the nanostructure play a key role in conditioning the performances of the genosensors. [ABSTRACT FROM AUTHOR]

The reflectivity of transparent polymers can be reduced with a proper nanotextured layer on the surface according to the 'moth eye' effect. Plasma etching has been proved to be a reliable method to generate self-organized nanostructures on the surface of various polymers. In the present work this method, directly carried out in one step, has been tested on polycarbonate for application as low reflective transparent material. CF4 and O2 fed plasma processes have been compared at different treatment time. Chemical (X-ray photoelectron spectroscopy), morphological (scanning electron microscopy), and optical (diffuse and specular reflectance, normal and grazing incidence) features have been evaluated. Results indicate that the CF4-to-O2 feed ratio significantly affects shape and distribution of the generated structures. O2 plasma, in particular, leads to taller structures with wire-like aspect and more homogeneous distribution, which are more effective in reducing reflectance with a broadband character (visible and near-infrared). Treatment duration, which instead affect mainly the dimension scale of the structures, must be tailored in order to control diffuse component of reflectance. [ABSTRACT FROM AUTHOR]

This paper outlines the experience of using track-etched membranes (TMs) from poly(ethylene terephthalate) with a nanostructured surface as an explantodrainage for the management of refractory glaucoma. To nanostructure the membrane surface layer, the membranes were processed in nonpolymerizing gas plasma. It is shown that the implantation of our explantodrainage allows one to achieve a stable normalization of intraocular pressure and a long-term preservation of the formed pathways for the intraocular fluid outflow. [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]

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. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]