Inert Surface Research Articles

Real-time monitoring of voltage-responsive biomolecular binding onto electro-switchable surfaces.

Voltage-responsive biosensors capable of monitoring real-time adsorption behavior of biological analytes onto electroactive surfaces offer attractive strategies for disease detection, separations, and other adsorption-dependent analytical techniques. Adsorption of biological analytes onto electrically switchable surfaces can be modelled using neutravidin and biotin. Here, we report self-assembled monolayers formed from voltage-switchable biotinylated molecules on gold surfaces with tunable sensitivity to neutravidin in response to applied voltages. By using electrochemical quartz crystal microbalance (EQCM), we demonstrated real-time switchable behavior of these bio-surfaces and investigate the range of sensitivity by varying the potential of the same surfaces from -400 mV to open circuit potential (+155 mV) to +300 mV. We compared the tunability of the mixed surfaces to bare Au surfaces, voltage inert surfaces, and switchable biotinylated surfaces. Our results indicate that quartz crystal microbalance allows real-time changes in analyte binding behavior, which enabled observing the evolution of neutravidin sensitivity as the applied voltage was shifted. EQCM could in principle be used in kinetic studies or to optimize voltage-switchable surfaces in adsorption-based diagnostics.

Enhancing fiber-reinforced asphalt binders via graphene oxide grafting: A novel interfacial modulation strategy

This study reports a novel interfacial enhancement strategy for fiber-reinforced asphalt binders. The graphene oxide (GO) nanosheets were used and grafted onto polyester (PET) and polyacrylonitrile (PAN) fibers in order to enhance the performance of modified asphalt binders. Prior to this, ultraviolet ozone (UVO) treatment was primarily adopted for activating the inert surface of fibers. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Scanning electron microscope (SEM) confirmed that GO-modified fibers were successfully prepared via surface modification. For the rheological properties determined by dynamic shear rheometer (DSR), the asphalt binders with GO-modified fibers exhibit improved high-temperature rutting resistance, better creep and recovery characteristics and increased anti-fatigue properties. Remarkably, it demonstrates that the recovery (R) value of GO-PAN modified asphalt binder is increased by 21.9 %, and the non-recoverable compliance (Jnr) value of GO-PET modified asphalt binder has been reduced by 31.9 % compared to that reinforced with the unmodified fiber in multiple stress creep recovery (MSCR) tests. These enhancements are mainly attributed to the increased roughness and modulus of the GO-grafted fibers, which promote effective stress transfer at the fiber-asphalt interfaces. Results from the atomic force microscope (AFM) indicate that the Young’s modulus of GO-PET and GO-PAN is 94.2 % and 260.0 % higher than that of PET and PAN, respectively. This research not only provides a simple and cost-effective method for improving the rheological performance, but also elucidates the enhancement mechanism of interfacial behavior in fiber-reinforced asphalt binders.

Neonicotinoid Residues on Filter Paper Lack Insecticidal Activity.

Neonicotinoid insecticides are used against agricultural, forest, and urban insect pests. Evaluation of dry neonicotinoid residues on treated filter paper is a commonly used method to determine the toxicity of active ingredients towards target and non-target organisms. Dry residues of four neonicotinoids, acetamiprid, dinotefuran, imidacloprid, and thiamethoxam, on filter paper did not cause significant levels of mortality in Hippodamia convergens (Guérin-Méneville) (Coleoptera: Coccinellidae) and Nezara viridula (L.) (Hemiptera: Pentatomidae) when compared to paired untreated groups. Conversely, nearly 100% mortality was observed when test insects were exposed to dry neonicotinoid residues on leaf discs and glass plate surfaces. On the other hand, dry residues of the pyrethroid bifenthrin on filter paper, leaf disks, and glass plates killed significantly more test insects when compared to untreated groups. Additional bioassays tested the toxicity of acetamiprid and thiamethoxam by evaluating the toxicity of dry residues on (1) the upper and (2) lower surfaces of treated filter paper, (3) on a glass plate underneath treated filter paper, (4) on the upper surface of treated filter paper treated with insecticide and adjuvant, and (5) dried residues on a glass plate after dipping treated filter paper in water and letting the solvent dry on the inert test surface. The results indicated that neonicotinoid insecticides applied to filter paper were adsorbed. Toxic compounds possibly move in between and binding to paper fibers so that no toxic residues were left on treated surfaces. However, adsorbed insecticides were still biologically active when washed out of filter paper and dried on an inert glass surface. The results reported here clearly demonstrate that the toxicity of neonicotinoid insecticides should not be evaluated using filter paper as a test surface.

Susceptibility of Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae) to cyantraniliprole and spinetoram

ABSTRACT Integrated pest management (IPM) uses a range of control strategies to diminish pest populations. Hence, the simultaneous utilisation of synthetic insecticides and biological control agents is desirable, although hindered by the possible impact of insecticides on non-target organisms. Plutella xylostella (L.) is a common target of several pesticides in Brassica crops. However, it can also be parasitised by Tetrastichus howardi (Olliff). This study examined the susceptibility of T. howardi to dry residue of cyantraniliprole and spinetoram on inert surfaces and treated kale (Brassica oleracea var. manteiga) leaf discs at field rates (FRs = 10 g a.i. ha−1 and 25 g a.i. ha−1, respectively), 50% of the FR, and at various time intervals (ranging from 2 h to 8 days after application). Survival of T. howardi remained unaffected by cyantraniliprole and spinetoram, regardless of the pesticide rate or spraying interval. Furthermore, the presence of cyantraniliprole and spinetoram in dry residue, when kale leaves were consumed by second-instar P. xylostella larvae at LC25 and LC50 levels, did not have any detrimental impact on the survival of the parasitoids. Similarly, the exposure of T. howardi to contaminated P. xylostella larvae did not have any impact on its ability to parasitise or on the emergence of the parasitoid. Given the minimal effect of cyantraniliprole and spinetoram on T. howardi, these control strategies appear to be suitable for incorporation into an integrated approach for the management of P. xylostella in Brassica crops.

Anhydride Photolysis on a Semiconductor Surface

The on-surface synthesis (OSS) method has facilitated the growth of diverse carbon-based nanomaterials, with the goal of integrating them into electronic devices. However, the reliance on metallic substrates in OSS restricts these materials' applications, necessitating strategies for transferring these materials into technological relevant substrates or direct synthesis on non-metallic surfaces, where the low absorption energies and lack of catalytic activity from the substrate complicate this approach. Addressing these limitations, we explore on-surface photochemistry as an alternative to thermally induced reactions, enabling controlled chemical processes at lower temperatures. While prior works have demonstrated light-induced reactions on metallic surfaces, where the hot electrons photogenerated from the metallic surface play a crucial role, synthesizing nanostructures directly on semiconducting or insulating surfaces through a purely intramolecular energy absorption remains challenging.The photolysis and pyrolysis of anhydrides has proven to be a suitable approach for the formation of arynes, as schematically shown in the Figure. Our study focuses on the selective photodissociation of maleic anhydride-containing precursors on a semiconductor surface (SnSe), unveiling their distinct photochemical behaviors. Specifically, tetraphenylphthalic anhydride (TPPA) undergoes successful photolysis on SnSe, forming tetraphenyl benzyne (TPBY) intermediates, and eventually, tetraphenyl benzene (TPBE) products. Furthermore, TPPA photolysis occurs efficiently also at room temperature, leading to the direct formation of TPBE. Contrastingly, benzo[ghi]perylene-1,2-dicarboxylic anhydride (BPA) possesses an extended pi-conjugated backbone and exhibits no photoactivity upon irradiation on the same semiconductor surface. Our calculations of TPPA and BPA excited states predict different behaviors, demonstrating the relationship between molecular structure, pi-conjugation, and photochemical reactivity, offering insights into the design principles for light-induced reactions on inert surfaces. Figure 1

The inert surface contamination of SARS-CoV-2 and the effect of disinfectants in one of the specialized and main responsible hospitals for COVID-19 patients in Ahvaz, Iran

The inert surface contamination of SARS-CoV-2 and the effect of disinfectants in one of the specialized and main responsible hospitals for COVID-19 patients in Ahvaz, Iran

Activation of inert surface of monolayer MoS2 by transition metal and nitrogen co-doping to promote hydrogen evolution reaction

In this work, we systematically investigate the possible H adsorption sites, charge density difference, partial density of states, p-band center and Bader charge of transition metal (TM) and nitrogen (N) co-doped monolayer MoS2. The results show that the equilibrium of H adsorption and desorption can be achieved in TM-N co-doped monolayer MoS2. The ΔGH at the S site of Co-N co-doped system is −0.05 eV, which is better than that of traditional Pt site (ΔGH=-0.09 eV) and Mo site at the MoS2 edge (ΔGH=0.08 eV). This work has important implications for designing more efficient electrocatalysts.

Innovative strategy for the facile construction of active multifunctional coating on inert thermal insulation surface

Ethylene propylene diene monomer rubber is highly attractive as a thermal insulation material for solid rocket motors but is plagued by its inherent low wettability. Existing methods have been used to solve this problem by manually or mechanically sanding the surface, which is environmentally hazardous. Herein, a multifunctional composite coating is constructed on the surface of inert thermal insulation materials using a two-step low temperature plasma surface treatment via an efficient hydrogen-bonding assembly strategy. The resultant composite coating exhibits excellent adhesion to the inert thermal insulation substrate. Benefitting from this, the coating retained its superhydrophilicity after 80 abrasion cycles and 12 h of agitation scrubbing with saturated salt water. Due to the superhydrophilicity of the coating, a self-cleaning effect for oils of different viscosities on the surface can be achieved by the simple action of water. Besides the adiabatic performance tests showed that the average top surface temperature of the coated thermal insulation was 30.9 °C lower than that of the original thermal insulation. Char residue analysis showed that the coating formed a more complete char layer at high temperatures, resulting in improved adiabatic performance. Our work would afford a new frontier to fabricate solid rocket motor thermal insulation materials with excellent surface comprehensive properties in a simple, eco-friendly and sustainable way, opening new possibilities for the advancement of high-performance inert materials.

Growth phase-dependent changes in conformational and physicochemical properties of bacterial surface biopolymers lead to changes in bacterial adhesion strength at nanoscale and macroscale

This study presents a detailed investigation into conformational, physicochemical and adhesive characteristics of biopolymers on the surfaces of Escherichia coli and potential probiotic Bacillus subtilis harvested from middle-exponential phase (mid-EP), late-exponential phase (late-EP) and early-stationary phase (early-SP) of growth. The lengths to which bacterial surface biopolymers extend (biopolymer brush lengths), densities of grafted bacterial surface biopolymers indicating the amounts of molecules covering the bacterial surfaces (biopolymer grafting densities), adhesion forces of bacterial surface biopolymers to the model inert surfaces of silicon nitride (Si3N4), and the pull-off distances of biopolymers from Si3N4 were measured in water by atomic force microscopy (AFM). The Weibull analysis of AFM adhesion data showed that as the culture aged, the adhesive bonds between Si3N4 AFM tips and surface molecules of E. coli harvested from the culture were broken with a higher applied force. However, the highest applied force to break the bonds was required for B. subtilis in late-EP, followed by those required for cells in early-SP and mid-EP, respectively. The results of a steric model fitting to AFM approach force-distance (FD) curves and analysis of the pull-off distances in the AFM retraction FD curves showed higher biopolymer grafting density for E. coli in early-SP and longer biopolymer brush layer for B. subtilis in late-EP, which were associated with stronger adhesion to Si3N4 in water. The results of thermodynamic adhesion energy calculations based on the Wu model showed that polar interaction energy dominated the bacterial adhesion at the macroscale, the strength of which varied as a function of the growth phase for both E. coli and B. subtilis. The growth phase-dependent variation in polar components of thermodynamic adhesion energies between the bacteria and Si3N4 in water was consistent with the growth phase-dependent variation in the bond strengths between the bacteria and Si3N4 in water as revealed by the Weibull analysis of AFM adhesion data. Therefore, information obtained by Weibull analysis of nanoscale AFM bacterial adhesion data can be used to predict macroscale bacterial adhesion to the model inert Si3N4 surface in water.

Insights into in situ surface reconstruction in cobalt perovskite oxides for enhanced catalytic activity

An depth understanding of the fundamental interactions between surface termination and catalytic activity is crucial to prompt the properties of functional perovskite materials. The elastic energy due to size mismatch and electrostatic attraction of the charged Sr dopant by positively charged oxygen vacancies induced inert A-site surface enrichment rearrangement for perovskites. Lower temperatures could reduce A-site enrichment, but it is difficult to form perovskite crystals. La0.8Sr0.2CoO3-δ (LSCO) as a model perovskite oxide was modified with additive urea to reduce the crystallization temperature, and suppress Sr segregation. The LSCO catalysts with 600 °C annealing temperature (LSCO-600) exhibited a 19.4-fold reaction reactivity of toluene oxidation than that with 800 °C annealing temperature (LSCO-800). Combined surface-sensitive and depth-resolved techniques for surface and sub-surface analysis, surface Sr enrichment was effectively suppressed due to decreased oxygen vacancy concentration and smaller electrostatic driving force. DFT calculations and in-situ DRIFTs spectra well revealed that tuning the surface composition/termination affected the intrinsic reactivity. The catalyst surface with lower Sr enrichment could easily adsorb toluene, cleave, and decompose benzene rings, thus contributing to toluene degradation to CO2. This work demonstrates a green and efficient way to control surface composition and termination at the atomic scale for higher catalytic activity.

Grafting Carbon Fibers with Graphene via a One-Pot Aryl Diazonium Reaction to Refine the Interface Performance of T1100-Grade CF/BMI Composites.

In this study, a one-pot aryl diazonium reaction was used as a simple and mild method to graft graphene onto the smooth and inert surface of T1100-grade carbon fiber (CF) through covalent bonding without any damage on CF, to refine the interface performance of CF/bismaleimide (BMI) composites. XPS, SEM, AFM, and dynamic contact angle testing (DCAT) were used to characterize chemical activity, morphologies, and wettability on untreated and grafted CF surfaces. Meanwhile, the impact of the graft method on the tensile strength of CF was also examined using the monofilament tensile test. IFSS between CF grafted with graphene and BMI resin achieved 104.2 MPa after modification, increasing from 85.5 MPa by 21.8%, while the tensile strength did not decrease compared to the pristine CF. The mechanism of this interface enhancement might be better chemical bonding and mechanical interlock between CF grafted with graphene and BMI resin, which is generated from the high surface chemical activity and rough structure of graphene. This study may propose a simple and mild method to functionalize the CF surface and enhance the interface performance of composites without compromising the tensile properties of T1100-grade CF.

Stably Grafting Polymer Brushes on Both Active and Inert Surfaces Using Tadpole-Like Single-Chain Particles with an Interactive "Head".

We report a "grafting to" method for stably grafting high-molecular-weight polymer brushes on both active and inert surfaces using tadpole-like single-chain particles (TSCPs) with an interactive "head" as grafting units. The TSCPs can be efficiently synthesized through intrachain cross-linking one block of a diblock copolymer; the "head" is the intrachain cross-linked single-chain particle, and the "tail" is a linear polymer chain that has a contour length up to micrometers. When grafted to a surface, the "head", integrating numerous interacting groups, can synergize multiple weak interactions with the surface, thereby enabling stable grafting of the "tail" on both active and traditionally challenging inert surfaces. Because the structural parameters and composition of the "heads" and "tails" can be separately adjusted over a wide range, the interactivity of the "heads" with the surface and properties of the brushes can be controlled orthogonally, accomplishing surface brushes that cannot be achieved by existing methods.

A solid-state surface-to-bulk modification with a multifunctional modified layer for 4.6 V LiCoO2

With the attempts of more than 30 years, the current commercial LiCoO2 (LCO) offers a reversible capacity of 185 mAh g−1 with a cut-off voltage of 4.5 V vs. Li+/Li. Further increasing the cut-off voltage, more lithium-ions can extract, deeply enhancing the capacity and energy density. However, it results in numerous side reactions and a significant decay in battery cycle performance. To address these issues, Nano-LiNbO3 as a coating agency is introduced by a solid-state surface-to-bulk modification process. To avoid the agglomeration and achieve uneven coating of Nano-LiNbO3 in the solid-state reaction, polyvinylpyrrolidone (PVP) is introduced as a dispersant, which effectively ensures the uniform and smooth coating along with the carbonization process. The modified LCO sample presents a specific reversible capacity of 215.5 mAh g−1 in the initial cycle and a capacity retention rate of 90 % after 100 cycles at 3–4.6 V and 0.5 C. Further analysis demonstrate that the LiNbO3 surface coating layer and the element gradient doping layer provide LCO a stable structure and an inert surface, which improves the surface stability, suppresses the oxygen release and ensures the enhanced electrochemical performance.

Covalent Heteroepitaxy of Large‐Area Vertical Hexagonal Boron Nitride for High‐Temperature VUV Photodetectors

AbstractHexagonal boron nitride (h‐BN) is a van der Waals (vdW) ultrawide bandgap semiconductor with high band‐edge absorption coefficient and chemical/thermal resistance, demonstrating great potential for vacuum ultraviolet (VUV) and UV‐C detection. Hitherto, most of their prevailing applications have exploited epitaxial films and multilayers either grown on substrates or transferred, which tend to form energy‐favorable noncovalent vdW epitaxy. Here, an alternative heteroepitaxy of 2‐inch h‐BN is reported with desirable thickness and vertically aligned vdW layers covalently bonded to sapphire, enabled by activating the inert substrate surface using ion impingement during deposition and the dislocation‐mediated epitaxial transition. The fabricated photodetectors allow efficient photon absorption and carrier collection using a simple planar device design, showing excellent VUV/UV‐C detection performance with ultrafast response of 270 ns/60 µs (rise/decay) and remarkable operating stability until 500 °C. This covalent heteroepitaxy of wafer‐scale h‐BN opens new avenues for optoelectronics and electronics significant to harsh environment applications.

Simulation and Modeling of the Adhesion of Staphylococcus aureus onto Inert Surfaces under Fluid Shear Stress.

Bacterial adhesion to biotic and abiotic surfaces under fluid shear stress plays a major role in the pathogenesis of infections linked to medical implants and tissues. This study employed an automated BioFlux 200 microfluidic system and video microscopy to conduct real-time adhesion assays, examining the influence of shear stress on adhesion kinetics and spatial distribution of Staphylococcus aureus on glass surfaces. The adhesion rate exhibited a non-linear relationship with shear stress, with notable variations at intermediate levels. Empirical adhesion events were simulated with COMSOL Multiphysics® and Python. Overall, COMSOL accurately predicted the experimental trend of higher rates of bacterial adhesion with decreasing shear stress but poorly characterized the plateauing phenomena observed over time. Python provided a robust mathematical representation of the non-linear relationship between cell concentration, shear stress, and time but its polynomial regression approach was not grounded on theoretical physical concepts. These insights, combined with advancements in AI and machine learning, underscore the potential for synergistic computational techniques to enhance our understanding of bacterial adhesion to surfaces, offering a promising avenue for developing novel therapeutic strategies.

Effect of certain physical and chemical factors on the development of biofilms in Lactobacillus plantarum

Lactobacillus plantarum is known to produce biofilms and planktonic cells. It has the ability to grow in MRS broth on inert surfaces. This study aimed to examine the ability of L. plantarum to generate biofilms and planktonic cells under diverse environmental conditions. The study also included the effect of temperature and pH changes on the growth of biofilms. In addition, the study investigated the effect of different sugars added to the MRS medium on biofilm formation. The results confirmed that the optimal temperature for biofilm growth is 37°C, and that the best pH 8. It was noted that the use of MacConkey's medium hinders bacterial growth.. Conversely, the addition of sugars to media environments significantly enhances biofilm formation, with biofilm production increasing alongside concentrations of glucose, sucrose, fructose, maltose and starch. The production of biofilms by L. plantarum holds importance for food processing and preservation, and presents diverse potential medical applications.

Robust and Lubricating Interface Semi-Interpenetrating Network on Inert Polymer Substrates Enabled by Subsurface-Initiated Polymerization.

Lubricating hydrogel coatings on inert rubber and plastic surfaces significantly reduce friction and wear, thus enhancing material durability and lifespan. However, achieving optimal hydration lubrication typically requires a porous polymer network, which unfortunately reduces their mechanical strength and limits their applicability where robust durability and wear-resistance are essential. In the research, a hydrogel coating with remarkable wear resistance and surface stability is developed by forming a semi-interpenetrating polymer network with polymer substrate at the interface. By employing a good solvent swelling method, monomers, and photoinitiators are embedded within the substrates' subsurface, followed by in situ polymerization under ultraviolet light, creating a robust semi-interpenetrating and entangled network structure. This approach, offering a thicker energy-dissipating layer, outperforms traditional surface modifications in wear resistance while preserving anti-fatigue, hydrophilicity, oleophobicity, and other properties. Adaptable to various rubber and plastic substrates by using suitable solvents, this method provides an efficient solution for creating durable, lubricating surfaces, broadening the potential applications in multiple industries.

Self-assembled coatings with durable flame retardancy for EPS foam

Layer by layer (LBL) self-assembly coatings upon expandable polystyrene (EPS) surface play an important role in improving its flame retardancy. However, a large number of layers is needed to achieve a satisfied fire performance, and the coatings are difficult to adhere on the inert EPS surface, resulting in the poor durability. In this work, the surface of EPS was activated by ultraviolet ozone (UVO) with the appearance of oxygen contained groups, then a LBL coating with only two bilayers (branched polyethyleneimine (BPEI)-kaolinite (kaol)-BPEI-diethylene triamine penta (methylene phosphonic acid)) was covalently connected on the EPS surface. Compared with neat EPS, the obtained E-K5D30 sample increased the value of limiting oxygen index (LOI) from 18.8 % to 37.7 %, improved the ignition time from 59 s to 95 s, reduced the peak heat release rate (pHRR) value from 282.0 kW/m2 to 220.9 kW/m2, and enhanced the char residues from 6.3 % to 32.3 % after the combustion. Moreover, an ultraviolet (UV) curing layer with P/N elements was prepared upon E-K5D30 sample to maximize the flame retardant durability. A novel amino-intercalated kaol was used to play a smoke suppression role. The results showed that E-K*5D30-P8N3 sample further increased the LOI to 39.2 %. Even after 12 h washing, the E-K*5D30-P8N3 sample exhibited a slight LOI reduction to 37.8 %, and fire performance index (FPI) value of 0.405 m2·s/kW, showing the successful construction of coatings with good fire safety and flame retardant durability.

Controlling On-Surface Photoactivity: The Impact of π-Conjugation in Anhydride-Functionalized Molecules on a Semiconductor Surface.

On-surface synthesis has become a prominent method for growing low-dimensional carbon-based nanomaterials on metal surfaces. However, the necessity of decoupling organic nanostructures from metal substrates to exploit their properties requires either transfer methods or new strategies to perform reactions directly on inert surfaces. The use of on-surface light-induced reactions directly on semiconductor/insulating surfaces represents an alternative approach to address these challenges. Here, exploring the photochemical activity of different organic molecules on a SnSe semiconductor surface under ultra-high vacuum, we present a novel on-surface light-induced reaction. The selective photodissociation of the anhydride group is observed, releasing CO and CO2. Moreover, we rationalize the relationship between the photochemical activity and the π-conjugation of the molecular core. The different experimental behaviour of two model anhydrides was elucidated by theoretical calculations, showing how the molecular structure influences the distribution of the excited states. Our findings open new pathways for on-surface synthesis directly on technologically relevant substrates.

Controlling On‐Surface Photoactivity: The Impact of π‐Conjugation in Anhydride‐Functionalized Molecules on a Semiconductor Surface

AbstractOn‐surface synthesis has become a prominent method for growing low‐dimensional carbon‐based nanomaterials on metal surfaces. However, the necessity of decoupling organic nanostructures from metal substrates to exploit their properties requires either transfer methods or new strategies to perform reactions directly on inert surfaces. The use of on‐surface light‐induced reactions directly on semiconductor/insulating surfaces represents an alternative approach to address these challenges. Here, exploring the photochemical activity of different organic molecules on a SnSe semiconductor surface under ultra‐high vacuum, we present a novel on‐surface light‐induced reaction. The selective photodissociation of the anhydride group is observed, releasing CO and CO2. Moreover, we rationalize the relationship between the photochemical activity and the π‐conjugation of the molecular core. The different experimental behaviour of two model anhydrides was elucidated by theoretical calculations, showing how the molecular structure influences the distribution of the excited states. Our findings open new pathways for on‐surface synthesis directly on technologically relevant substrates.