Construction of Pt@BiFeO3 Xerogel-Supported O-g-C3N4 Heterojunction System for Enhanced Visible-Light Activity towards Photocatalytic Degradation of Rhodamine B.

Synthetic organic pigments from the direct discharge of textile effluents are considered as colossal global concern and attract the attention of scholars. The efficient construction of heterojunction systems involving precious metal co-catalysis is an effective strategy for obtaining highly efficient photocatalytic materials. Herein, we report the construction of a Pt-doped BiFeO3/O-g-C3N4 (Pt@BFO/O-CN) S-scheme heterojunction system for photocatalytic degradation of aqueous rhodamine B (RhB) under visible-light irradiation. The photocatalytic performances of Pt@BFO/O-CN and BFO/O-CN composites and pristine BiFeO3 and O-g-C3N4 were compared, and the photocatalytic process of the Pt@BFO/O-CN system was optimized. The results exhibit that the S-scheme Pt@BFO/O-CN heterojunction has superior photocatalytic performance compared to its fellow catalysts, which is due to the asymmetric nature of the as-constructed heterojunction. The as-constructed Pt@BFO/O-CN heterojunction reveals high performance in photocatalytic degradation of RhB with a degradation efficiency of 100% achieved after 50 min of visible-light irradiation. The photodegradation fitted well with pseudo-first-order kinetics proceeding with a rate constant of 4.63 × 10-2 min-1. The radical trapping test reveals that h+ and •O2- take the leading role in the reaction, while the stability test reveals a 98% efficiency after the fourth cycle. As established from various interpretations, the considerably enhanced photocatalytic performance of the heterojunction system can be attributed to the promoted charge carrier separation and transfer of photoexcited carriers, as well as the strong photo-redox ability established. Hence, the S-scheme Pt@BFO/O-CN heterojunction is a good candidate in the treatment of industrial wastewater for the mineralization of organic micropollutants, which pose a grievous threat to the environment.

Phytosynthesis of Silver Nanoparticles Using Leonurus cardiaca L. Extracts.

The present work describes, for the first time in the literature, the phytosynthesis of silver nanoparticles using Leonurus cardiaca L. extracts. The influence of the extraction method (classical temperature extraction and microwave extraction), as well as of the extract concentration on the characteristics of the nanoparticles, was studied using analytical methods, such as UV-Vis spectrometry, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. Experimental data suggest that use of lower extract concentration leads to smaller dimensions nanoparticles, the same effect using the extract obtained by microwave-assisted extraction. The smallest recorded crystallite sizes (by X-ray diffraction) were under 3 nm. The antioxidant properties (determined by the DPPH assay) and the antimicrobial potential (determined against Gram-negative and Gram-positive strains) are enhanced by the phytosynthesis process (as demonstrated by the comparison of the nanoparticles' properties with the parent extracts). The present work could also represent an important step in obtaining nanoparticles with enhanced properties and controlled morphologies, but also offers information on the phytosynthesis of metallic nanoparticles using low extract concentrations.

Synthesis of Ruthenium-Promoted ZnO/SBA-15 Composites for Enhanced Photocatalytic Degradation of Methylene Blue Dye.

Synthetic organic pigments like xanthene and azo dyes from the direct discharge of textile effluents are considered colossal global issues and attract the concern of scholars. Photocatalysis continues to be a very valuable pollution control method for industrial wastewater. Incorporations of metal oxide catalysts such as zinc oxide (ZnO) on mesoporous Santa Barbara Armophous-15 (SBA-15) support to improve catalyst thermo-mechanical stability have been comprehensively reported. However, charge separation efficiency and light absorption of ZnO/SBA-15 continue to be limiting its photocatalytic activity. Herein, we report a successful preparation of Ruthenium-induced ZnO/SBA-15 composite via conventional incipient wetness impregnation technique with the aim of boosting the photocatalytic activity of the incorporated ZnO. Physicochemical properties of the SBA-15 support, ZnO/SBA-15, and Ru-ZnO/SBA-15 composites were characterized by X-ray diffraction (XRD), N2 physisorption isotherms at 77 K, Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDS), and transmission electron microscopy (TEM). The characterization outcomes exhibited that ZnO and ruthenium species have been successfully embedded into SBA-15 support, andtheSBA-15 support maintains its structured hexagonal mesoscopic ordering in both ZnO/SBA-15 and Ru-ZnO/SBA-15 composites. The photocatalytic activity of the composite was assessed through photo-assisted mineralization of aqueous MB solution, and the process was optimized for initial dye concentration and catalyst dosage. 50 mg catalyst exhibited significant degradation efficiency of 97.96% after 120 min, surpassing the efficiencies of 77% and 81% displayed by 10 and 30 mg of the as-synthesized catalyst. The photodegradation rate was found to decrease with an increase in the initial dye concentration. The superior photocatalytic activity of Ru-ZnO/SBA-15 over the binary ZnO/SBA-15 may be attributed to the slower recombination rate of photogenerated charges on the ZnO surface with the addition of ruthenium.

Ecotoxicity of o-Chlorobenzylidene Malononitrile (CBM) and Toxicological Risk Assessment for SCLP Biological Cultures (Saccharomyces sp., Chlorella sp., Lactobacillus sp., Paramecium sp.).

Toxic substances used as chemical weapons present a number of particularities that affect the surrounding environment, having a wide range of action by disrupting the ecological balance: they may infect soil or air, or form aerosols through smoke or toxic fog. Such substances can have a long duration of action, from minutes to weeks, which is why they are used in military attacks. This study evaluated the toxicological character of o-chlorobenzyliden malonitrile (CBM) in order to study the toxicity limit of this substance using microbiological cultures of Saccharomyces sp., Chlorella sp., Lactobacillus sp. and Paramecium sp., which were used to determine their rate of growth in the presence of different concentrations of o-chlorobenzyliden malonitrile and their ability to respond to this toxic stimulus.

A Modified Sol-Gel Synthesis of Anatase {001}-TiO2/Au Hybrid Nanocomposites for Enhanced Photodegradation of Organic Contaminants.

A sol-gel synthesis technique was employed for the preparation of anatase phase {001}-TiO2/Au hybrid nanocomposites (NCs). The scalable, schematic, and cost-efficient method was successfully modified using HF and NH4OH capping agents. The photocatalytic activity of the as-synthesized {001}-TiO2/Au NCs were tested over 2-cycle degradation of methylene blue (MB) dye and pharmaceutical active compounds (PhACs) of ibuprofen and naproxen under direct sunlight illumination at 35 °C and 44,000 lx. Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), fast Fourier transform (FFT), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed for the characterization of the as-prepared sample. The characterization results from the TEM, XPS, and XRD studies established both the distribution of Au colloids on the surface of TiO2 material, and the presence of the highly crystalline structure of anatase {001}-TiO2/Au NCs. Photodegradation results from the visible light irradiation of MB indicate an enhanced photocatalytic performance of Au/TiO2 NCs over TiO2. The results from the photocatalytic activity test performed under direct sunlight exposure exhibited promising photodegradation efficiencies. In the first cycle, the sol-gel synthesized material exhibited relatively better efficiencies (91%) with the MB dye and ibuprofen, while the highest degradation efficiency for the second cycle was 79% for the MB dye. Pseudo first-order photodegradation rates from the first cycle were determined to be comparatively slower than those from the second degradation cycle.

Poly(N-vinylpyrrolidone)-Laponite XLG Nanocomposite Hydrogels: Characterization, Properties and Comparison with Divinyl Monomer-Crosslinked Hydrogels.

The present work investigates, for the first time, the synthesis and properties of some nanocomposite (NC) hydrogels obtained by the aqueous solution free radical polymerization of N-vinylpyrrolidone (NVP) in the presence of Laponite XLG (XLG) as a crosslinker, in comparison with the corresponding hydrogels prepared by using two conventional crosslinking divinyl monomers: N,N'-methylenebisacrylamide (MBA) and tri(ethylene glycol) divinyl ether (DVE). The structure and properties of the hydrogels were studied by FTIR, TEM, XRD, SEM, swelling and rheological and compressive mechanical measurements. The results showed that DVE and XLG are much better crosslinking agents for the synthesis of PNVP hydrogels than MBA, leading to larger gel fractions and more homogeneous network hydrogels. The hydrogels crosslinked by either DVE or XLG displayed comparable viscoelastic and compressive mechanical properties under the experimental conditions employed. The properties of the XLG-crosslinked hydrogels steadily improved as the clay content increased. The addition of XLG as a second crosslinker together with a divinyl monomer strongly enhanced the material properties in comparison with the hydrogels crosslinked by only one of the crosslinkers involved. The FTIR analyses suggested that the crosslinking of the NC hydrogels was the result of two different interactions occurring between the clay platelets and the PNVP chains. Laponite XLG displayed a uniform distribution within the NC hydrogels, the clay being mostly exfoliated. However, a small number of platelet agglomerations were still present. The PNVP hydrogels described here may find applications for water purification and in the biomedical field as drug delivery systems or wound dressings.

Phytosynthesis of Biological Active Silver Nanoparticles Using Echinacea purpurea L. Extracts.

With their phytoconstituents acting as reducing and capping agents, natural extracts can be considered a viable alternative for the obtaining of metallic nanoparticles. The properties of phytosynthesized nanoparticles are dependent upon size and morphology, which, in turn, can be tailored by adjusting different parameters of the phytosynthesis process (such as the extracts' composition). In the present study, we aimed to evaluate, for the first time in the literature, the influence of the extraction method and extract concentration on the morphological and biological properties (antioxidant and antibacterial activity) of silver nanoparticles phytosynthesized using Echinacea pupurea L. extracts. The obtained results revealed that the use of the low-concentration Echinacea hydro-alcoholic extract obtained via classical temperature extraction led to the development of nanoparticles with the smallest dimensions (less than 10 nm), compared with the use of extracts obtained with higher concentrations and the extract obtained via the microwave method. The developed nanomaterials exhibited enhanced antioxidant effects (determined via the DPPH assay) and antimicrobial properties (against Escherichia coli and Candida albicans), compared with the parent extracts.

Biocompatible and Antimicrobial Cellulose Acetate-Collagen Films Containing MWCNTs Decorated with TiO2 Nanoparticles for Potential Biomedical Applications.

This research focuses on the synthesis of multi-walled carbon nanotubes (MWCNTs) decorated with TiO2 nanoparticles (NPs) and incorporated in cellulose acetate-collagen film in order to obtain a new biomaterial with potential biomedical applications and improved antimicrobial activity. The successful decoration of the MWCNTs with TiO2 NPs was confirmed by several structural and morphological analysis, such as Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction and transmission electron microscopy. The obtained nanocomposites were further incorporated into cellulose acetate-collagen films, at different concentrations and absorption kinetics, antimicrobial activity and in vitro biocompatibility of the obtained films was investigated. The antimicrobial tests sustained that the presence of the nanocomposites into the polymeric matrix is an important aspect in increasing and maintaining the antimicrobial activity of the polymeric wound dressings over time. The biocompatibility and cytotoxicity of the obtained films was evaluated using cellular viability/proliferation assay and fluorescent microscopy which revealed the ability of the obtained materials as potential wound dressing biomaterial.

Effects of Siliceous Natural Nanomaterials Applied in Combination with Foliar Fertilizers on Physiology, Yield and Fruit Quality of the Apricot and Peach Trees.

Siliceous natural nanomaterials (SNNMs), i.e., diatomaceous earth and natural zeolites, have a nanoporous structure with large active surfaces that adsorb cations or polarized molecules. Such nanoporous feature determines the effects related to SNNM utilization as low-risk plant protectants and soil improvers. This work used SNNMs from Romanian quarries as carriers for foliar fertilizers applied to stone-fruit trees, apricot and peach. We determined the effects of SNNMs on the physiology, yield and fruit quality of the treated stone-fruit trees. SNNM application determined impacts specific to the formation of particle films on leaves: reduced leaf temperature (up to 4.5 °C) and enhanced water use efficiency (up to 30%). Foliar fertilizers' effects on yield are amplified by their application with SNNMs. Yield is increased up to 8.1% by the utilization of SNNMs with foliar fertilizers, compared to applying foliar fertilizer alone. Diatomaceous earth and natural zeolites promote the accumulation of polyphenols in apricot and peach fruits. The combined application of SNNMs and foliar fertilizer enhance the performance of peach and apricot trees.

Novel Chemical Architectures Based on Beta-Cyclodextrin Derivatives Covalently Attached on Polymer Spheres.

This study presents the synthesis and characterization of polymer derivatives of beta-cyclodextrin (BCD), obtained by chemical grafting onto spherical polymer particles (200 nm) presenting oxirane functional groups at their surface. The polymer spheres were synthesized by emulsion polymerization of styrene (ST) and hydroxyethyl methacrylate (HEMA), followed by the grafting on the surface of glycidyl methacrylate (GMA) by seeded emulsion polymerization. The BCD-polymer derivatives were obtained using two BCD derivatives with hydroxylic (BCD-OH) and amino groups (BCD-NH2). The degree of polymer covalent functionalization using the BCD-OH and BCD-NH2 derivatives were determined to be 4.27 and 19.19 weight %, respectively. The adsorption properties of the materials were evaluated using bisphenol A as a target molecule. The best fit for the adsorption kinetics was Lagergren's model (both for Qe value and for R2) together with Weber's intraparticle diffusion model in the case of ST-HEMA-GMA-BCD-NH2. The isothermal adsorption evaluation indicated that both systems follow a Langmuir type behavior and afforded a Qmax value of 148.37 mg g-1 and 37.09 mg g-1 for ST-HEMA-GMA-BCD-NH2 and ST-HEMA-GMA-BCD-OH, respectively. The BCD-modified polymers display a degradation temperature of over 400 °C which can be attributed to the existence of hydrogen bonds and BCD thermal degradation pathway in the presence of the polymers.

Hybrid Materials Based on Multi-Walled Carbon Nanotubes and Nanoparticles with Antimicrobial Properties.

In this study, multi-walled carbon nanotubes (MWCNTs) were decorated with different types of nanoparticles (NPs) in order to obtain hybrid materials with improved antimicrobial activity. Structural and morphological analysis, such as Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy and the Brunauer-Emmett-Teller technique were used in order to investigate the decoration of the nanotubes with NPs. Analysis of the decorated nanotubes showed a narrow size distribution of NPs, 7-13 nm for the nanotubes decorated with zinc oxide (ZnO) NPs, 15-33 nm for the nanotubes decorated with silver (Ag) NPs and 20-35 nm for the nanotubes decorated with hydroxyapatite (HAp) NPs, respectively. The dispersion in water of the obtained nanomaterials was improved for all the decorated MWCNTs, as revealed by the relative absorbance variation in time of the water-dispersed nanomaterials. The obtained nanomaterials showed a good antimicrobial activity; however, the presence of the NPs on the surface of MWCNTs improved the nanocomposites' activity. The presence of ZnO and Ag nanoparticles enhanced the antimicrobial properties of the material, in clinically relevant microbial strains. Our data proves that such composite nanomaterials are efficient antimicrobial agents, suitable for the therapy of severe infection and biofilms.

Preparation and Characterization of Silica Nanoparticles and of Silica-Gentamicin Nanostructured Solution Obtained by Microwave-Assisted Synthesis.

In this research work, silica nanoparticles and silica-gentamicin nanostructured solution were synthesized by using the microwave-assisted synthesis, in basic medium, using two silane precursors (tetraethylorthosilicate and octyltriethoxysilane) and the antibiotic (gentamicin sulfate). The prepared materials were characterized through Fourier transform infrared (FTIR) spectroscopy, TGA analysis, transmission electron microscopy (TEM), and atomic force microscopy (AFM) to investigate the morphology and structure. Antimicrobial studies of the silica-gentamicin nanostructured solution versus silica nanoparticles were performed against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. FTIR spectra showed that the gentamicin has been loaded to the silica nanoparticles. AFM analysis showed that the morphology of the silica-gentamicin nanostructured solution has changed, and agglomerations of particles are present at the surface. Antimicrobial testing, performed using the diffusion method through spot inoculation, indicates that the silica-gentamicin nanostructured solution exhibited activity against the resistant strain. The obtained silica-gentamicin solution can be used as biochemical agent for the prevention and treatment of microorganisms which are deposited on different surfaces (e.g., glass, plastic, ceramic).

In Vitro and In Vivo Evaluation of Silver Nanoparticles Phytosynthesized Using Raphanus sativus L. Waste Extracts.

The aim of the current paper is the development of phytosynthesized silver nanoparticles mediated by Raphanus sativus L. extracts obtained through two extraction methods (temperature and microwave) and to test their potential application for controlling apple crops pathogens. The phytosynthesized materials were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. All the materials were evaluated in terms of antioxidant and in vitro antimicrobial activity (against bacteria, molds, and yeast: Escherichia coli ATCC 8738, Staphylococcus aureus ATTC 25923, Pseudomonas aeruginosa ATCC 9027, Salmonella typhimurium ATCC 14028, Candida albicans ATCC 10231, Venturia inaequalis, Podosphaera leucotricha, Fusarium oxysporum ATCC 48112, Penicillium hirsutum ATCC 52323, and Aspergillus niger ATCC 15475). Considering the results obtained in the in vitro assays, formulations based on nanoparticles phytosynthesized using Raphanus sativus L. waste extracts (RS1N) were evaluated as potential antifungal agents for horticultural crops protection, against Venturia inaequalis and Podosphaera leucotricha through in vivo assays. For the DPPH assay, the inhibition (%) varied between 37.06% (for RS1N at 0.8 mg/mL concentration) and 83.72% (for RS1N at 7.2 mg/mL concentration) compared to 19.97% (for RS2N at 0.8 mg/mL) and only 28.91% (for RS2N at 7.2 mg/mL). Similar results were obtained for RS3N (85.42% inhibition at 7.2 mg/mL) compared with RS4N (21.76% inhibition at 7.2 mg/mL). Regarding the ABTS assay, the highest scavenger activity values were recorded for samples RS1N (91.43% at 1.6 mg/mL) and RS3N (96.62% at 1.6 mg/mL).

Model Systems for Evidencing the Mediator Role of Riboflavin in the UVA Cross-Linking Treatment of Keratoconus.

Riboflavin under UVA radiation generates reactive oxygen species (ROS) that can induce various changes in biological systems. Under controlled conditions, these processes can be used in some treatments for ocular or dermal diseases. For instance, corneal cross-linking (CXL) treatment of keratoconus involves UVA irradiation combined with riboflavin aiming to induce the formation of new collagen fibrils in cornea. To reduce the damaging effect of ROS formed in the presence of riboflavin and UVA, the CXL treatment is performed with the addition of polysaccharides (dextran). Hyaluronic acid is a polysaccharide that can be found in the aqueous layer of the tear film. In many cases, keratoconus patients also present dry eye syndrome that can be reduced by the application of topical solutions containing hyaluronic acid. This study presents physico-chemical evidence on the effect of riboflavin on collagen fibril formation revealed by the following methods: differential scanning microcalorimetry, rheology, and STEM images. The collagen used was extracted from calf skin that contains type I collagen similar to that found in the eye. Spin trapping experiments on collagen/hyaluronic acid/riboflavin solutions evidenced the formation of ROS species by electron paramagnetic resonance measurements.

Adsorption of Sb (III) on Oxidized Exfoliated Graphite Nanoplatelets.

In this work, Sb (III) adsorption on oxidized exfoliated graphite nanoplatelets (ox-xGnP) was evaluated for the first time, to the best of our knowledge. The ox-xGnP were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), Brunauer⁻Emmet⁻Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray spectroscopy (EDX), and Zeta potential analysis. The adsorption parameters, such as pH and contact time, were optimized, and the best adsorption capacity obtained was 8.91 mg g-1 at pH = 7.0, 1.0 mg ox-xGnP/100 mL solution, T = 293 K, 1.0 mg L-1, Sb (III), 25 min contact time. The best correlation of the kinetic data was described by a pseudo-first-order kinetic model, with R² = 0.999. The adsorption isotherms of Sb (III) onto ox-xGnP were best described by the Langmuir isotherm model. The thermodynamic parameters showed that the adsorption process was exothermic and spontaneous.

Morphological and Tribological Properties of PMMA/Halloysite Nanocomposites.

From an environmental and cost-effective perspective, a number of research challenges can be found for electronics, household, but especially in the automotive polymer parts industry. Reducing synthesis steps, parts coating and painting, or other solvent-assisted processes, have been identified as major constrains for the existing technologies. Therefore, simple polymer processing routes (mixing, extrusion, injection moulding) were used for obtaining PMMA/HNT nanocomposites. By these techniques, an automotive-grade polymethylmethacrylate (PMMA) was modified with halloysite nanotubes (HNT) and an eco-friendly additive N,N'-ethylenebis(stearamide) (EBS) to improve nanomechanical properties involved in scratch resistance, mechanical properties (balance between tensile strength and impact resistance) without diminishing other properties. The relationship between morphological/structural (XRD, TEM, FTIR) and tribological (friction) properties of PMMA nanocomposites were investigated. A synergistic effect was found between HNT and EBS in the PMMA matrix. The synergy was attained by the phase distribution resulted from the selective interaction between partners and favourable processing conditions. Modification of HNT with EBS improved the dispersion of nanoparticles in the polymer matrix by increasing their interfacial compatibility through hydrogen bonding established by amide groups with aluminol groups. The increased interfacial adhesion further improved the nanocomposite scratch resistance. The PMMA/HNT-EBS nanocomposite had a lower coefficient of friction and lower scratch penetration depth than PMMA/HNT nanocomposite.

The Effect of Different Coupling Agents on Nano-ZnO Materials Obtained via the Sol-Gel Process.

Hybrid nanomaterials based on zinc oxide were synthesized via the sol-gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300-500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

Novel Hydrogel-Advanced Modified Clay Nanocomposites as Possible Vehicles for Drug Delivery and Controlled Release.

Present study refers to the synthesis of new advanced materials based on poly(methacrylic acid) (PMAA) with previously reported own advanced modified clays by edge covalent bonding. This will create the premises to obtain nanocomposite hydrogels with combined hydrophilic-hydrophobic behavior absolutely necessary for co-delivery of polar/nonpolar substances. For the synthesis, N,N'-methylenebisacrylamide was used as cross-linker and ammonium persulphate as initiator. As a consequence of the inclusion of clay into the polymer matrix and the intercalation of PMAA between the layers as well as the presence of hydrophobic interactions occurred between partners, the final hydrogel nanocomposites possessed greater swelling degrees, slower de-swelling process and enhanced mechanical properties depending on the clay type in comparison with pure hydrogel. In vitro MTS ([3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt]) colorimetric assay showed that direct exposure with PMMA-clay-based constructs did not affect cell viability and proliferation in time (24 and 48 h) on either normal or adenocarcinoma cell lines.

Medium Chain-Length Polyhydroxyalkanoate Copolymer Modified by Bacterial Cellulose for Medical Devices.

Medium chain-length polyhydroxyalkanoates (mPHAs) are flexible elastomeric biopolymers with valuable properties for biomedical applications like artificial arteries and other medical implants. However, an environmentally friendly and high productivity process together with the tuning of the mechanical and biological properties of mPHAs are mandatory for this purpose. Here, for the first time, a melt processing technique was applied for the preparation of bionanocomposites starting from poly(3-hydroxyoctanoate) (PHO) and bacterial cellulose nanofibers (BC). The incorporation of only 3 wt % BC in PHO improved its thermal stability with 25 °C and reinforced it, increasing the Young's modulus with 76% and the tensile strength with 44%. The percolation threshold calculated with the aspect ratio of the fibers after melt processing was very low and close to 3 wt %. We showed that this bionanocomposite is able to preserve the ductile behavior during storage, no important aging being noted between 3 h and one month after compression-molding. Moreover, this study is the first to investigate the melt processability of PHO nanocomposite for tube extrusion. In addition, biocompatibility study showed no proinflammatory immune response and better cell adhesion for PHO/BC nanocomposite with 3 wt % BC and demonstrated the high feasibility of this bionanocomposite for in vivo application of tissue-engineered blood vessels.

The Influence of New Hydrophobic Silica Nanoparticles on the Surface Properties of the Films Obtained from Bilayer Hybrids.

Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol-gel process using hexadecyltrimethoxysilane (C16TMS) and tetramethoxysilane (TMOS) (1:4 molar ratio) as precursors. After coating, silica nanoparticles (SiO2 NPs) functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; and methoxydimethyloctylsilane, DMeC8MS) were added, assuring the microscale roughness on the glass surface. Influences of the functionalized SiO2 NPs and surface morphology on the hydrophobicity of the hybrid films were discussed. The successful functionalization of SiO2 NPs with hydrophobic alkyl groups were confirmed by Fourier transform infrared spectroscopy (FTIR). The thermal stability of hydrophobic SiO2 NPs showed that the degradation of the alkyl groups takes place in the 200-400 °C range. Bilayer coating with C16TMS/TMOS and SiO2 NPs modified with alkoxysilane substituted with C8 alkyl chain (SiO2 NP-C8) has micro/nano structure. Hydrophobicity of functionalized SiO2 NPs-C8 and its higher degree of nanometer-scale roughness gave rise to ultra-hydrophobicity performance for bilayer coating C16TMS/TMOS + SiO2 NPs-C8 (145°), compared to other similar hybrid structures. Our synthesis method for the functionalization of SiO2 NPs is useful for the modification of surface polarity and roughness.