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Heterogeneous catalysis is essential to most industrial chemical processes. To achieve a better sustainability of these processes we need highly efficient and highly selective catalysts that are based on earth-abundant materials rather than the more conventional noble metals. Here, we discuss the potential of inorganic materials as catalysts for chemical transformations focusing in particular on the promising transition metal phosphides and sulfides. We describe our recent and current efforts to understand the interfacial chemistry of these materials that governs catalysis, and to tune catalytic reactivity by controlled chemical modification of the material surfaces and by use of interfacial electric fields.

The widespread utilization of plant cellulose fiber-inorganic fillers-synthetic fabric-reinforced laminates is the current trend in the research field. This investigation studies the effect of chemically treated and untreated water hyacinth/pineapple leaf, titanium carbide nanoparticles, Innegra, and carbon fabric reinforcement on the physical, mechanical, and thermal characteristics of ultra-violet resistant polyester hybrid composites. The chemically treated and untreated water hyacinth/pineapple leaf fibers were examined from Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and found that chemically treated fibers have an excellent interlocking bond with TiC nanoparticles, Innegra, carbon fabric, and polyester matrix. The maximum tensile, flexural, interlaminar shear, impact strength, and shore hardness also affirmed good interfacial bonding of fillers and textiles within the matrix as examined from SEM micrographs. The present investigation also determines the forecasting of the approaches and performance of artificial neural network (ANN) to model the material characteristics of fabricated polyester hybrid composite. Furthermore, the ANN model was more accurate and a valuable technique to optimize the material characteristics of the developed polyester hybrid composite.

Aromatic organic acids are among the common environmental pollutants that enter the water with washouts from agricultural lands, wastewater from chemical and pharmaceutical industries. Taking into account the high toxicity of aromatic substances, the important task of water purification is the removal of their trace amounts. This problem can be solved by using chemically modified inorganic materials, such as silicas, which have high mechanical, chemical, hydrolytic, and radiation stability. Therefore, they do not lose their sorption capacity during long-term use and do not pollute water with sorbent degradation products. The purpose of this work is the synthesis of a sorption-active material for removal of toxic aromatic acids by chemical immobilization of β-cyclodextrin functional groups on an aerosilogel (highly dispersed type of amorphous silica). A β-cyclodextrin-containing aerosilogel was synthesized by two-stage liquid-phase chemical modification of hydroxylated silica surface. Using the methods of IR spectroscopy, spectrophotometry, thermogravimetry, pH metry, low-temperature adsorption-desorption of nitrogen, chemical and elemental analysis of the surface, the surface structure and its quantitative chemical composition, and also parameters of porous structure of initial and chemically modified aerosilogels were determined. Sorption of benzoic, salicylic and β-resorcylic acids on aerosilogels from aqueous buffer solutions with pH=1 was studied. The insignificant contribution of silanol and aminopropyl groups and complete participation of chemically fixed β-cyclodextrin in the sorption of aromatic acids were proved. The results obtained are analyzed using kinetic models for pseudo-first and pseudo-second order processes, as well as Langmuir and Freundlich models for equilibrium adsorption on homogeneous and heterogeneous surfaces. It has been found that the sorption kinetic processes are well described by a pseudo-first order equation (in the presence of one type of functional groups on the surface) and a pseudo-second order equation for bi- and trifunctional aerosilogels. Experimental results on the equilibrium sorption of aromatic acids on β-cyclodextrin-containing aerosilogel are in good agreement with the Langmuir adsorption equation. This is evidence of decisive contribution of grafted oligosaccharide groups to the sorption of organic acids. The proposed chemical approach to increasing the sorption activity of aerosilogel can be used to obtain specific chromatographic carriers, as well as inorganic sorbents for the effective removal of small amounts of highly toxic organic substances from water and aqueous solutions. [ABSTRACT FROM AUTHOR]

Currently, the use of membrane techniques has undergone dynamic growth, particularly due to the diversification of their fields of application. This trend is expected to increase owing to new environmental protection requirements and thanks to the increasingly competitive energy and technical-economic performances offered by membrane processes. New research is constantly being carried out to better understand the functioning of membranes, to create more efficient or more specific membranes, and also to develop processes for new applications. The aim of this work is to improve the performance of a polyamide reverse osmosis membrane by chemical modification of its surface. Thin film polyamide reverse osmosis membranes are widely used for desalination. However, these membranes face a fouling issue that results in low permeation flux, which is undesirable in the reverse osmosis process. An interesting alternative to improve the properties of these polyamide composite membranes is the use of chemical surface modification. In this context, we studied the chemical grafting of vinyl acetate monomer on the surface of a polyamide membrane in order to improve the selectivity towards sodium ion. The chemical grafting was carried out by radical polymerization of vinyl acetate monomer in the presence of benzoil peroxide as an initiator in an organic medium. Unmodified, modified membranes and evolution of the polymerization reaction were analyzed by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), interferometric electron microscopy, and contact angle. An application with a front filtration module was investigated to confirm the improved selectivity for sea water. This study revealed an improved efficiency of the reverse osmosis PA membrane after the grafting of polyacetate monomer on the active layer of this membrane. [ABSTRACT FROM AUTHOR]

New complexing sorbents have been manufactured via chemical surface-modification of highly dispersed boehmite (γ-AlO(OH)) by phosphonic complexones (PCs), namely, by nitrilotri(methylenephosphonic) acid (NTP), 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), N-hydroxyethylimino-N,N-di(methylenephosphonic) acid (HEIDP), and imino-N,N-diacetic-N-methylenephosphonic acid (IDAMP). The manufactured PC–boehmite materials have been characterized by XRD, BET, SEM, TEM, and IR spectroscopy. Modified boehmites, in which the modifier anchor is one of the phosphonic functions of the complexone, exhibit the properties of a complexing support for double-charged metal ions. The kinetic characteristics and sorption capacities of PC–boehmites have been determined. The complexing selectivity on the modified surface are arranged in the following decreasing order: Pb(II) > Cu(II) > Zn(II) ≈ Ni(II) ≈ Co(II) ≈ Cd(II) > Ca(II). The stability of the sorbed state of metal ions changes along the series of surface-anchored complexones in the following order: IDAMP > NTP > HEDP > HEIDP. The trends elucidated point to a close correlation between complexa formation involving phosphonic complexones in solution and on the boehmite surface. [ABSTRACT FROM AUTHOR]

The reduction of silver nitrate with sodium borohydride in the presence of cetyltrimethylammonium bromide yielded stable sols of silver nanoparticles. Their subsequent treatment with cysteamine hydrochloride led to the chemical modification of the surface. Both initial and modified sols were used for the determination of Hg2+ ions in an aqueous medium. The limit of detection for the analyte and the linearity range of the analytical signal for the initial silver sols are lower in comparison with the analogues modified with cysteamine. [ABSTRACT FROM AUTHOR]

Hydrosols of silver nanoparticles chemically modified with cysteine and cysteamine are obtained. Their oxidation with solutions containing active oxygen and chlorine forms is studied. It is shown that the grafted layer of the modifier does not affect the oxidation of the metal core with sodium hypochlorite, but it does have a protective effect in the reaction with hydrogen peroxide. The orders of the reaction for the initial and chemically modified nanoparticles are 1 for sodium hypochlorite, and 0 for hydrogen peroxide. Chemically modified nanoparticles tend to form aggregates. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysis is essential to most industrial chemical processes. To achieve a better sustainability of these processes we need highly efficient and highly selective catalysts that are based on earth-abundant materials rather than the more conventional noble metals. Here, we discuss the potential of inorganic materials as catalysts for chemical transformations focusing in particular on the promising transition metal phosphides and sulfides. We describe our recent and current efforts to understand the interfacial chemistry of these materials that governs catalysis, and to tune catalytic reactivity by controlled chemical modification of the material surfaces and by use of interfacial electric fields., (Copyright 2024 Tzu-Chin Chang Chien, Murielle F. Delley. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

A method for the surface chemical modification of aluminum oxyhydroxide (boehmite γ-AlO (OH)) by the nitrilotris(methylene phosphonic) acid (NTP) complexing ligand is proposed. The unmodified and NTP-modified boehmites are characterized using X-ray powder diffraction, XPS, and IR spectroscopy; the acid–base and complex-forming properties of surface-grafted NTP are studied. One of the three phosphonic groups of NTP is found to be involved in binding to the boehmite surface. The surface concentration and stepwise dissociation constants of grafted NTP are determined. A study of the nickel(II) sorption as a function of aqueous acidity shows that the modifying coating increases the sorption capacity of boehmite (causing рН50 to shift by one unit toward lower values). In terms of surface complexation theory, nickel(II) sorption from aqueous solutions may be described by models involving ≡Al–ONi+ and ≡Al–ONi(OH) complexes in the case of boehmite and ≡Al–LHi Nii–3 (i = 0, 1, 2, or 3) complexes in the case of NTP-modified boehmite (NTP-boehmite). NTP anchorage to the surface decreases the stability of nickel(II) complexes compared to their analogues in solutions. A mechanism of nickel(II) ion binding by NTP-boehmite is suggested. The prepared new organomineral support can be used to immobilize those metal ions that form stable complexes with phosphonic acids. [ABSTRACT FROM AUTHOR]

The recent emergence of bio-based nanocomposites makes perfect sense from a technical and environmental point of view. Cellulose nanocrystals (CNCs) are novel bio-based nanomaterials with a wide range of beneficial properties. Their biodegradability, crystallinity, high surface area, and mechanical strength, as well as their highly reactive surface, make them ideal materials as nanofillers in polymeric matrices. However, most the bio-based polymers are hydrophobic, and the hydrophilicity of CNC is therefore a challenge to their incorporation in such matrices. In this study, a new procedure for surface modification of CNC with long aliphatic chains [lauric acid (12 carbons) and stearic acid (18 carbons)] was developed that limits the use of petro-chemicals and facilitates their potential recycling. A study of the dispersion state of CNC in acetone was performed first. Then, grafting efficiency was highlighted by several techniques and quantification of the amount of grafted fatty chains was investigated. Degrees of substitution on the bulk and on the surface of the CNC were calculated between 0.1 and 0.3, which provided enough grafted functions to confer hydrophobic behavior to modified CNCs, as highlighted by the increasing of contact angle from 65° for neat CNC to 80° after modification. Finally, conservation of CNC crystalline structure and morphology was proved by both X-ray diffraction and transmission electron microscopy analyses. Modified CNCs exhibit a crystallinity index close to 86% and length of approximately 350 nm. Thus, crystalline hydrophobic cellulosic nanomaterials were prepared using a more environmentally friendly procedure than those classically found in the literature. [ABSTRACT FROM AUTHOR]

The conditions of chemical modification of the surface of synthetic magnetic iron oxides (magnetite Fe3O4, maghemite γ-Fe2O3) by phosphonic complexones (PBTC, HEDP, HEIDPH, NTMP, EDTMP) are studied. It is shown that the maximum concentration of grafted groups is observed upon treating iron oxides with aqueous solutions of complexones containing two or three phosphonic groups at pH 2–3 and temperature of 50–60°C for 2–6 h. To characterize the grafted layer, various physicochemical research methods (XRD, FTIR spectroscopy, the BET method, thermal analysis, acid–base titration, sorption from solutions) were used. It is found that the modifying coating significantly increases the sorption ability of magnetic iron oxides towards metal cations (Cu(II), Cd(II)). A mechanism for binding of metal ions by modified sorbents is proposed. [ABSTRACT FROM AUTHOR]

The interaction of Ag+ ions existing on the surface of silver nanoparticles with complexing agents, such as ammonia, ammonium thiocyanate, and sodium thiosulfate, has been studied. Both the presence of complexing agents in the initial reaction mixture and their introduction into preliminarily synthesized sols of silver nanoparticles lead to a small shift of the absorption maximum toward long wavelengths and its considerable broadening. In both cases, there is a correlation of the absorption band width with the logarithm of formation constants of corresponding silver complexes. This can be evidence of analogous chemical processes that occur on the surface of nanoparticles. The surface complexation is of interest both for a fundamental understanding of the interaction nature and in the applied aspect for the determination of complexing agents in aqueous systems. [ABSTRACT FROM AUTHOR]

We fabricate crystalline dendritic gold (Au‐D) via a simple electrochemical method and characterize it using several techniques. Chemical modification by self‐assembled thiol molecules on the Au‐D is used to adjust the chemical environment of the substrate surface and to improve surface‐enhanced Raman scattering (SERS) performance. First, the Au‐D modified with different length chains of n‐alkyl thiols cause an enhancement of SERS, which follows a relationship of normalized intensity, IIo, versus (1 + dr) with a slope of −10 according to the electromagnetic mechanism. Subsequently, phenyl thiols with various end‐functional groups are attached to study the effect of chemical modification on SERS enhancement. The results indicate that the 4‐methylthiophenol‐ and thiophenol‐modified substrates do not exhibit significant SERS enhancement, resulting in intensity being dependent on distance. It is worth noting that the 4‐mercaptophenol‐ and 4‐aminothiophenol‐modified surfaces have an effective electric field effect and strong interaction with polarity probe molecules, and they produce a more intense signal than do bare Au‐D particles. [ABSTRACT FROM AUTHOR]

The review is devoted to the analysis of publications on the synthesis and chemical modification of the surface of silver and gold nanoparticles and their use in chemical and biochemical analysis by spectrometry. The formation and subsequent modification of the chemical composition of the surface layer of nanoparticles ensures the solution of problems of the group and individual determination of analytes, i.e., metal ions and organic and bioorganic compounds. The presence of an accessible well-developed surface bearing functional groups of different nature in combination with the effects of surface plasmon resonance and enhanced and surface-enhanced Raman scattering opens wide prospects for the application of nanoparticles to chemical and biochemical analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Date seed derived biochar production via slow pyrolysis. • Chemically modified activated carbons are derived from date seed using H 2 SO 4 as an activating agent. • Capacitive performance is highly affected by the ordered structure of biochar-based materials. The main aim of this research work is to make activated carbon (AC) materials based on biochar obtained from date seeds via pyrolysis and activated with H 2 SO 4. The study aimed to assess the potential of these biochar-based materials for energy storage in supercapacitor by investigating the impact of different activation temperatures on their electrochemical performance in an alkaline electrolyte. The focus was on identifying the most efficient material. Results from Raman Spectroscopy and XRD analysis revealed that sample DSAC-700 exhibited more ordered domains and suitable storage sites compared to the other biochar-based materials. Measured value of the ratio of intensity of D & G band (I D /I G) for DSBC-600, DSAC-700, DSAC-800, and DSAC-900 were 1.13, 0.83, 1.06, and 1.04, respectively. The lowest value of (I D /I G) for DSAC-700 indicated a higher ordered graphitic plane, resulting improved conductivity and diffusion of ions within the aligned graphitic domains, which positively impacted the electrochemical performance. Samples DSAC-700 showed 487.5 F/g specific capacitance at 1 A/g current density. Galvanic charge and discharge trends also showed that DSAC-700 had higher charge storage ability with less discharge. The biochar-based materials (BC and ACs) derived from DS showed promise as materials for energy storage applications, and they represent a step towards clean energy. [ABSTRACT FROM AUTHOR]

A natural zeolite of Kazakh origin, as well as its three different types of chemically modified versions, were assessed from the point of view of permanganate removal yield from aqueous solutions. Modification was carried out by means of di-dodecyl-dimethyl-ammonium bromide surfactant treatment type (1). Types (2) and (3) were treated prior to DDAB wth HCl or NaCl, respectively. All sorbents display broad ranges of particle size distribution. Modification of the natural form enhances the specific surface as well as the pore volume, yet influences not in the same way the sorption yield. The process is slow, however, short- and long-term effectiveness are affected by preparation procedures. The most promising yield is exhibited by the natural zeolite that was subject to a combined acid - surfactant treatment. [ABSTRACT FROM AUTHOR]

The main object of this research is chemical modification of the nanofibrillated cellulose (NFC) surface with a phenanthridinium silane salt to develop durable non-leaching antibacterial surface. Initially, (3-trimethoxysilylpropyl) phenanthridinium iodide (TMSPhI) as an antibacterial agent was synthesized using (3-chloropropyl trimethoxysilane) (CPTMS) and phenanthridine in the presence of potassium iodide. Subsequently, NFC was cationized by reaction of its hydroxyl groups with the trimethoxysilane group of TMSPhI to prepare the modified sample (NFC-TMSPhI). The synthesized TMSPhI was characterized by FT-IR, 1 H and 13 C NMR spectroscopies. The modified NFC samples were also characterized by FE-SEM/EDX, XRD, TGA, elemental analysis, contact angle measurement, FT-IR, UV–Visible and fluorescence spectroscopies. The obtained NFC–TMSPhI samples presented fluorescence property at the maximum emission wavelength in the range of 539-549 nm. Additionally, the antibacterial activity of the modified samples were evaluated quantitatively against Gram-positive ( S . aureus ) and Gram-negative ( E . coli ) bacteria. All the modified samples displayed promising results with at least bacteriostatic effect or bactericidal properties. Finally, the cytotoxic effect of the modified sample on human dermal fibroblasts (HDFs) and two cancer cell lines (MCF-7 and Hela) was investigated that showed dose- and surface charge-dependent toxicity. [ABSTRACT FROM AUTHOR]

Cellulose nanowhiskers (CWs) extracted from cotton fibers were successfully modified with distinct anhydrides structures and used as additives in poly(vinyl alcohol) (PVA) nanocomposite films. The surface modification of CWs was performed with maleic, succinic, acetic or phthalic anhydride to compare the interaction and action the carboxylic groups into PVA films and how these groups influence in mechanical properties of the nanocomposites. CWs presented a high degree of crystallinity and good dispersion in water, with average length at the nanoscale. The addition of specific amounts (3, 6 and 9 wt.%) of modified-CWs increased up to 4.4 times the storage modulus (PVA88-CWSA 9 wt.%), as observed from dynamic mechanical analysis (DMA), compared to the bare PVA films. A significant increase in mechanical properties such as tensile strength, elastic modulus, and elongation at break showed a close relationship to the amount and chemical surface characteristics of CWs added, suggesting that these modified-CWs could be explored as reinforcement additives in PVA films. [ABSTRACT FROM AUTHOR]

By coating surfaces with nano-crystalline diamond (NCD) particles, hydrophilicity can be altered via sidechain modifications without affecting surface texture. The present study aimed to assess the impact of NCD hydrophilicity on machined and rough SLA titanium discs on soft tissue integration, using a rodent model simulating submerged healing. Four different titanium discs (machined titanium = M Titanium, NCD-coated hydrophilic machined titanium = M-O-NCD, sand blasted acid etched (SLA Titanium) titanium, and hydrophilic NCD-coated SLA titanium = SLA O-NCD) were inserted in subdermal pockets of 12 Wistar rats. After one and four weeks of healing, the animals were sacrificed. Biopsies were embedded in methyl methacrylate (MMA), and processed for histology. The number of cells located within a region of interest (ROI) of 10 μm around the discs were counted and compared statistically. Signs of inflammation were evaluated descriptively employing immunohistochemistry. At one week, M-O-NCD coated titanium discs showed significantly higher amounts of cells compared to M Titanium, SLA Titanium, and SLA-O-NCD (p < 0.001). At four weeks, significant higher cell counts were noted at SLA-O-NCD surfaces (p < 0.01). Immunohistochemistry revealed decreased inflammatory responses at hydrophilic surfaces. Within the limits of an animal study, M-O-NCD surfaces seem to stimulate cell proliferation in the initial healing phase, whereas SLA-O-NCD surfaces appeared advantageous afterwards. [ABSTRACT FROM AUTHOR]

This study presents a comparison of two types of bifunctional structured surface that were made from the same polymer –– an antimicrobial polycation (a synthetic mimic of an antimicrobial peptide, SMAMP) and a protein-repellent polyzwitterion (poly(sulfobetaines), PSB). The first type of bifunctional surface was fabricated by a colloidal lithography (CL) based process where the two polymers were immobilized sequentially onto pre-structured surfaces with a chemical contrast (gold on silicon). This enabled site-selective covalent attachment. The CL materials had a spacing ranging from 200 nm to 2 µm. The second type of structured surface (spacing: 1 – 8.5 µm) was fabricated using a microcontact printing (µCP) process where SMAMP patches were printed onto a PSB network, so that 3D surface features were obtained. The thus obtained materials were studied by quantitative nanomechanical measurements using atomic force microscopy (QNM-AFM). The different architectures led to different local elastic moduli at the polymer-air interface, where the CL surfaces were much stiffer (Derjaguin-Muller-Toporov (DMT) modulus = 20 ± 0.8 GPa) compared to the structured 3D networks obtained by µCP (DMT modulus = 42 ± 1.1 MPa). The effects of the surface topology and stiffness on the antimicrobial activity against Escherichia coli, the protein repellency (using fibrinogen), and the compatibility with human gingival mucosal keratinocytes were investigated. The softer 3D µCP surfaces had simultaneous antimicrobial activity, protein repellency, and cell compatibility at all spacings. For the stiffer CL surfaces, quantitative simultaneous antimicrobial activity and protein repellency was not obtained. However, the cell compatibility could be maintained at all spacings. The optimum spacing for the CL materials was in the range of 500 nm–1 µm, with significantly reduced antimicrobial activity at 2 µm spacing. Thus, the soft polymer network obtained by µCP could be more easily optimized than the stiff CL surface, and had a broader topology range of optimal or near-optimal bioactivity.

Owing to excellent mechanical property and biodegradation, magnesium-based alloys have been widely investigated for temporary implants such as cardiovascular stent and bone graft; however, the fast biodegradation in physiological environment and the limited surface biocompatibility hinder their clinical applications. In the present study, magnesium alloy was treated by sodium hydroxide (NaOH) and hydrogen fluoride (HF) solutions, respectively, to produce the chemical conversion layers with the aim of improving the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that the chemical conversion layers of magnesium hydroxide or magnesium fluoride were obtained successfully. Sodium hydroxide treatment can significantly enhance the surface hydrophilicity while hydrogen fluoride treatment improved the surface hydrophobicity. Both the chemical conversion layers can obviously improve the corrosion resistance of the pristine magnesium alloy. Due to the hydrophobicity of magnesium fluoride, HF-treated magnesium alloy showed the relative better corrosion resistance than that of NaOH-treated substrate. According to the results of hemolysis assay and platelet adhesion, the chemical surface modified samples exhibited improved blood compatibility as compared to the pristine magnesium alloy. Furthermore, the chemical surface modified samples improved cytocompatibility to endothelial cells, the cells had better cell adhesion and proliferative profiles on the modified surfaces. Due to the excellent hydrophilicity, the NaOH-treated substrate displayed better blood compatibility and cytocompatibility to endothelial cells than that of HF-treated sample. It was considered that the method of the present study can be used for the surface modification of the magnesium alloy to enhance the corrosion resistance and biocompatibility. [ABSTRACT FROM AUTHOR]

In practical applications, cyclic heating and high temperature will worsen the stability of nanofluids. To enhance the practical application of nanofluids for mid-temperature solar collectors, WO 2.9 nanoparticles were modified by hexadecyl trimethoxysilane and the corresponding heat-transfer-oil-based nanofluids was prepared for mid-temperature solar collecting. Stability of nanofluids was evaluated by static observation, Zeta potential and thermal shock experiments at 200 °C. The results showed that nanofluids with mass fractions up to 4 wt% remained static stability beyond 5 weeks and 0.85 wt% nanofluids had thermal shock stability at 200 °C for over 2 weeks. This excellent performance makes them a suitable long-term working fluid medium for solar mid-temperature collectors. The increase in thermal conductivity also enhances the thermal performance of systems in industrial processes. It's noteworthy that preliminary exploration of the cyclic thermal stability mechanism of nanofluids provides a reference for further research on thermal shock stability of nanofluids in actual services. [Display omitted] • Hexadecyl trimethoxysilane is used to improve the stability of nanofluids. • The self-condensation products are beneficial to the stability of nanofluids. • Nanofluids with mass fractions up to 4% remain stable after 5 weeks of resting. • The nanofluids remain stable after thermal shock experiment at 200 °C for 2 weeks. • The nanofluids can be used in solar mid-temperature collectors for a long time. [ABSTRACT FROM AUTHOR]

By coating surfaces with nano-crystalline diamond (NCD) particles, hydrophilicity can be altered via sidechain modifications without affecting surface texture. The present study aimed to assess the impact of NCD hydrophilicity on machined and rough SLA titanium discs on soft tissue integration, using a rodent model simulating submerged healing. Four different titanium discs (machined titanium = M Titanium, NCD-coated hydrophilic machined titanium = M-O-NCD, sand blasted acid etched (SLA Titanium) titanium, and hydrophilic NCD-coated SLA titanium = SLA O-NCD) were inserted in subdermal pockets of 12 Wistar rats. After one and four weeks of healing, the animals were sacrificed. Biopsies were embedded in methyl methacrylate (MMA), and processed for histology. The number of cells located within a region of interest (ROI) of 10 µm around the discs were counted and compared statistically. Signs of inflammation were evaluated descriptively employing immunohistochemistry. At one week, M-O-NCD coated titanium discs showed significantly higher amounts of cells compared to M Titanium, SLA Titanium, and SLA-O-NCD (p < 0.001). At four weeks, significant higher cell counts were noted at SLA-O-NCD surfaces (p < 0.01). Immunohistochemistry revealed decreased inflammatory responses at hydrophilic surfaces. Within the limits of an animal study, M-O-NCD surfaces seem to stimulate cell proliferation in the initial healing phase, whereas SLA-O-NCD surfaces appeared advantageous afterwards.

The surface grafting of cellulose nanocrystals (CNC) is a valuable tool to increase opportunities for their application. This work had several goals designed to improve CNC: reduction of hornification, increased re-dispersibility after CNC drying, and tuning of the surface graft to enhance the adsorption of particular molecules. To achieve this, the CNC surfaces were modified chemically with aromatic surface grafts using widely employed methods: the creation of urethane linkages, silylation and esterification. Even a low degree of grafting sufficed to increase water contact angles to as much as 96°. The analysis of water sorption isotherms showed that at high water activities, capillary condensation could be suppressed and hysteresis was decreased. This indicates that hornification was significantly suppressed. However, although the contact angles increased, the water sorption isotherms were changed only slightly because of reduced hysteresis. The grafts were not able to shield the surface from water vapour sorption. A comparison of the sorption isotherms of anisole and cyclohexane, sorbates with a similar surface area, showed that the sorption of anisole was three times higher than that of cyclohexane. The specific sorption of aromatic molecules was achieved and the most efficient methodology was the esterification of CNC with carboxylic acids containing a flexible linker between the aromatic moiety and ester bond. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable binary nanofluids were prepared by surface modification with coupling agent. • Working condition was simulated by interval heating as well as magnetic stirring. • Thermal conductivity of nanofluids decreased within 3.5% after standing for 14 days. • Nanofluids remain stable after cyclic thermal shock experiment at 90 ℃ for 14 days. Binary nanofluid has excellent heat transfer performance and spectral selective absorption characteristic. However, when nanofluid is applied to actual systems, it is subject to severe thermal shock, which leads to quick agglomeration and therefore deterioration of the performances. This study aims to investigate the stability of tungsten oxide (WO 2.9)-silicon carbide (SiC) binary nanofluid in actual service environment. The surface of nanoparticles was chemically modified by the coupling agent method, and the process was optimized. Then, the binary nanofluid was prepared with the optimal process of unitary nanofluid and the improved two-step method. And the actual working condition was simulated by interval heating as well as magnetic stirring. Finally, the preparation process was optimized further from the aspects of particle size, particle concentration, and thermal shock temperature. The results show that the binary nanofluid prepared by the optimum preparation process can maintain great stability after cyclic thermal shock experiment at 90 ℃ for 14 days, which put a foundation for the application of binary nanoparticles into solar beam splitting and enhance its practicality. [ABSTRACT FROM AUTHOR]

Owing to excellent mechanical property and biodegradation, magnesium-based alloys have been widely investigated for temporary implants such as cardiovascular stent and bone graft; however, the fast biodegradation in physiological environment and the limited surface biocompatibility hinder their clinical applications. In the present study, magnesium alloy was treated by sodium hydroxide (NaOH) and hydrogen fluoride (HF) solutions, respectively, to produce the chemical conversion layers with the aim of improving the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that the chemical conversion layers of magnesium hydroxide or magnesium fluoride were obtained successfully. Sodium hydroxide treatment can significantly enhance the surface hydrophilicity while hydrogen fluoride treatment improved the surface hydrophobicity. Both the chemical conversion layers can obviously improve the corrosion resistance of the pristine magnesium alloy. Due to the hydrophobicity of magnesium fluoride, HF-treated magnesium alloy showed the relative better corrosion resistance than that of NaOH-treated substrate. According to the results of hemolysis assay and platelet adhesion, the chemical surface modified samples exhibited improved blood compatibility as compared to the pristine magnesium alloy. Furthermore, the chemical surface modified samples improved cytocompatibility to endothelial cells, the cells had better cell adhesion and proliferative profiles on the modified surfaces. Due to the excellent hydrophilicity, the NaOH-treated substrate displayed better blood compatibility and cytocompatibility to endothelial cells than that of HF-treated sample. It was considered that the method of the present study can be used for the surface modification of the magnesium alloy to enhance the corrosion resistance and biocompatibility.

One of the techniques for a reduction in particle cohesiveness is the admixing of nano-particles. However, the mechanism of cohesiveness reduction has not yet been clarified. In this study we focused on a compressed packing fraction as one of the values reflecting the cohesiveness and flowability in a compressed particle flow. In order to estimate the mechanism of the reduction, the effects of an adhesive force of admixed particles on the packing fraction were investigated experimentally. In the experiments, silica particles with 397 and 8 nm diameters were used as the main and the admixed particles, respectively. The surfaces of the admixed particles were modified chemically in order to vary their adhesive force with maintaining morphological and mechanical characteristics. At more than 2.0% mixing mass ratios, the decreasing rate with increasing the mass ratio in net difference value of packing fraction for modified admixed particles was smaller than that for the raw particles. A calculation of the packing fraction of the admixed particles in the voids of main particles revealed that difference of the decreasing rates could be attributed to the difference of cohesivenesses between raw and modified admixed particles. The maximum packing fraction achieved by the modified admixed particles was lower than that achieved by the raw admixed particles. However, when a mixture of main and admixed particles was packed by tapping, the packing fraction with modified admixed particles was higher than that with raw admixed particles. This implied that the adequate adhesive force of admixed particles is different by the applied compression force value. [ABSTRACT FROM AUTHOR]

In this study surface-modified nanofibrillated cellulose (NFC) was used at low levels (0.5 to1.5 wt%) as a reinforcement in a polyvinyl alcohol (PVA) matrix. The modified-NFC-PVA composite films prepared using the solution casting technique showed improved mechanical performance. Birch pulp cellulose was initially modified by allylation using a solvent-free, dry modification method followed by subsequent epoxidation of the allyl groups and finally grinding the pulp to yield epoxy-NFC. In order to obtain optimal mechanical performance, epoxy-NFC with different degrees of substitution was evaluated in the reinforcement of PVA. The addition of 1 wt% epoxy-NFC (degree of substitution, DS 0.07) enhanced the modulus, strength, and strain of pure PVA film by 307, 139 and 23 %, respectively, thus producing the best performing film. The results demonstrate the favourable effect of chemically functionalized NFC on the mechanical properties of polyvinyl alcohol compared to unmodified NFC as reinforcement. In order to improve industrial and economic feasibility, the manufacture of the composite was also done in situ by grinding cellulose directly in PVA to produce the new biocomposite in a one-step process. [ABSTRACT FROM AUTHOR]

The rigid core of intracellular tau filaments from Alzheimer's disease (AD), Pick's disease (PiD), and Corticobasal disease (CBD) brains has been shown to differ in their cryo-EM atomic structure. Despite providing critical information on the intimate arrangement of a fraction of htau molecule within the fibrillar scaffold, the cryo-EM studies neither yield a complete picture of tau fibrillar assemblies structure nor contribute insights into the surfaces that define their interactions with numerous cellular components. Here, using proteomic approaches such as proteolysis and molecular covalent painting, we mapped the exposed amino acid stretches at the surface and those constituting the fibrillar core of in vitro-assembled fibrils of human htau containing one N-terminal domain and three (1N3R) or four (1N4R) C-terminal microtubule-binding repeat domains as a result of alternative splicing. Using limited proteolysis, we identified the proteolytic fragments composing the molecular "bar-code" for each type of fibril. Our results are in agreement with structural data reported for filamentous tau from AD, PiD, and CBD cases predigested with the protease pronase. Finally, we report two amino acid stretches, exposed to the solvent in 1N4R not in 1N3R htau, which distinguish the surfaces of these two kinds of fibrils. Our findings open new perspectives for the design of highly specific ligands with diagnostic and therapeutic potential., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Nowadays, metal oxide nanoparticles (NPs) have been applied in various fields of nanotechnology including catalysis of chemical reactions, drug delivery, water treatment, textile industries, polymer composites, adhesives, and coatings. The greatest challenge in relation to metal oxide NPs is high tendency to aggregation. Chemical surface modification of metal oxide NPs has gained widely interest to control of dispersion and aggregation of NPs. Silane modifiers are one of the most important bifunctional modifiers that are frequently used for surface treatment of metal oxide NPs. In this review paper, we first focus on the synthesis, surface thermodynamic properties, surface modification techniques, and kinetic of silanization reaction of metal oxide NPs. Then, the recent development in using silane modifiers for treatment of metal oxide NPs in various applications were investigated. It was found that the unmodified NPs have high surface energy and are thermodynamically unstable. The thermodynamic properties of NPs including G m s , H m s , and S m s increase with decreasing the particle size. Aggregation phenomena is the simple way to reduce the excess surface energy of NPs that leads to an increase in particle size. Therefore, the chemical surface modification of NPs using silane modifiers can be used as an effective method for the prevention of NPs agglomeration and improvement of NPs stability. Unlabelled Image • A general overview of the synthesis techniques of metal oxide nanoparticles. • Study of surface thermodynamic properties of nanoparticles. • Investigation of kinetic of silanization reaction. • Improvement of the surface properties of metal oxide nanoparticles by using silane modifiers. • A glimpse of potential application of silane-modified metal oxide nanoparticles. [ABSTRACT FROM AUTHOR]

Heavy metal adsorption from aqueous solution onto modified biochar derived from date seed biomass was investigated. Modification methods included pre-treatment of the biomass prior to pyrolysis using NaOH and HCl (labelled as DSB-PB and DSB-PA respectively) and post–treatment of the biochar pyrolyzed at 550 °C for 3 h with NaOH and HCl (labelled as DSB-BW and DSB-AW respectively). Modified biochars were compared to unmodified one in terms of their surface chemistry, morphology, metal uptake, and adsorption kinetic behaviour. Scanning electron microscopy images show that acid and base treatment enhanced the biochar porous structure. Fourier-transform infrared spectroscopy revealed that acid treatment had enriched the functional groups such as C C, C O, C O, and phenolic groups on the biochar surface which further facilitated metal ions adsorption. Alkali treatment had less significant impact on the biochar surface functional groups. Modification improved the adsorption capacity for all metals. Most notably, DSB-PA biochar showed the highest adsorption capacities of 0.911, 0.705, and 0.692 mmol g−1 for Pb2+, Cu2+, and Ni2+ respectively. Compared to the unmodified biochar, the adsorption capacities of DSB-PA for Pb2+, Cu2+, and Ni2+ increased by 27%, 66% and 98%, respectively. Sips model adequately described the adsorption isotherms indicating heterogeneous adsorption systems. Adsorption rates of metal ions onto the DSB-PA were fast with almost 94% of the total amount of metals adsorbed within the first hour compared to 3–6 h for unmodified biochar. Pre-treatment of biochar with HCl is an economical method to produce an effective low-cost adsorbent with low environmental impact. [ABSTRACT FROM AUTHOR]

A manufacturing process for the site-selective modification of structured (bio)material surfaces with two different polymers/biomolecules is presented. In the first step, a chemical surface contrast is created (e.g., a gold-on-silicon contrast obtained by colloidal lithography), and is combined with two orthogonal surface reactions for polymer/biomolecule immobilization. To demonstrate this, an antimicrobial SMAMP polymer and a protein-repellent polyzwitterion were site-selectively surface-immobilized on the gold-silicon structures. By varying the structure spacing and the surface architecture, structure-property relationships for the interaction of these bifunctional polymer surfaces with bacteria and proteins were obtained (studied by fluorescence microscopy, atomic force microscopy, surface plasmon resonance spectroscopy, and antimicrobial assays). At 1 μm spacing, a fully antimicrobially active bifunctional material was obtained, which also near-quantitatively reduced protein adhesion. As the process is generally applicable to polymers/biomolecules with aliphatic CH-groups, it is an interesting platform technology for site-selectively functionalized bifunctional (Bio)MEMS.

Contact active surfaces are an innovative tool for developing antibacterial products. Here, the microfibrillated cellulose (MFC) surface was modified with the β-lactam antibiotic benzyl penicillin in aqueous medium to prepare antimicrobial films. Penicillin was grafted on the MFC surface using a suspension of these nanofilaments or directly on films. Films prepared from the penicillin-modified MFC were characterized by Fourier transform infrared spectroscopy, contact angle measurements, elemental analysis, and X-ray photoelectron spectroscopy and tested for antibacterial activity against the Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Penicillin-grafted MFC films exhibited successful killing effect on Gram-positive bacteria with 3.5-log reduction whereas bacteriostatic efficiency was found in penicillin-grafted MFC suspension. The zone of inhibition test and leaching dynamic assay demonstrated that penicillin was not diffused into the surrounding media, thus proving that the films were indeed contact active. Thus, penicillin can be chemically bound to the modified substrate surface to produce promising nonleaching antimicrobial systems.