Combining high energy ball milling and liquid crystal templating method to prepare magnetic ordered mesoporous silica. A physico-chemical investigation.

The physico-chemical investigation of superparamagnetic MCM41 like materials prepared by the novel combination of high energy ball milling and a liquid crystal templating method is presented. Structural, morphological, textural, thermal, and preliminary magnetic characterization demonstrated the successful combination of the two synthesis techniques, avoiding the problems associated with the current methods used for the preparation of magnetic ordered mesoporous silica. MCM41 like materials with high specific surface area values (625-720 m2 g-1) and high mesopore volumes in the range 1-0.7 cm3 g-1 were obtained. The ordered mesoporous structure and accessible pores were maintained after the inclusion of increasing amounts of the magnetic component in the silica structure. All the samples showed superparamagnetic behaviour.

Physico-Chemical Investigation and Antimicrobial Efficacy of Ozonated Oils: The Case Study of Commercial Ozonated Olive and Sunflower Seed Refined Oils.

Drug resistance represents one of the great plagues of our time worldwide. This largely limits the treatment of common infections and requires the development of new antibiotics or other alternative approaches. Noteworthy, the indiscriminate use of antibiotics is mostly responsible for the selection of mutations that confer drug resistance to microbes. In this regard, recently, ozone has been raising interest for its unique biological properties when dissolved in natural oils. Ozonated oils have been reported to act in a non-specific way on microorganisms hindering the acquisition of advantageous mutations that result in resistance. Here, we focused on the antimicrobial effect of two commercial olive (OOO) and sunflower seeds (OSO) oils. Nuclear magnetic resonance spectroscopy and thermal analysis showed the change in the chemical composition of the oils after ozonation treatment. Different ozonated oil concentrations were then used to evaluate their antimicrobial profile against Candida albicans, Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli by agar diffusion and broth dilution methods. Cytotoxicity was also evaluated in keratinocytes and epithelial cells. Overall, our results revealed that both OOO and OSO showed a potent microbicidal effect, especially against C. albicans (IC50 = OOO: 0.3 mg/mL and OSO: 0.2 mg/mL) and E. faecalis (IC50 = OOO: 0.4 mg/mL and OSO: 2.8 mg/mL) albeit exerting a certain effect also against S. aureus and E. coli. Moreover, both OOO and OSO do not yield any relevant cytotoxic effect at the active concentrations in both cell lines. This indicates that the ozonated oils studied are not toxic for mammalian cells despite exerting a potent antimicrobial effect on specific microorganisms. Therefore, OOO and OSO may be considered to integrate standard therapies in the treatment of common infections, likely overcoming drug resistance issues.

Green Preparation of Antimicrobial 1D-Coordination Polymers: [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞ by Ultrasonication of Zn(II) Salts and 4,4'-Bipyridine.

We report on the green preparation of one-dimensional metal coordination polymers by sonochemical approach. The spacer ligand 4,4'-bipyridine was ultrasonicated with chloride or acetate zinc salts to obtain [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞, respectively. Benign solvents such as ethanol and water were selected as reaction media, and the synthesis took place in a few minutes-a very short time compared to conventional methods where some days' synthesis is required. X-ray powder diffraction, Fourier transform infrared spectroscopy, thermal analysis (thermogravimetric and differential scanning calorimetry), and CHN techniques investigated the influence of using different reaction solvents on the chemical, structural, and thermal properties of the final products. The 1D [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞ polymers, in agreement with the structures reported in the literature, were obtained in the form of nanocrystals with an average crystal size around 100 nm. As a proof of concept, a set of Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae), and three yeast strains (Candida albicans, Candida krusei, Candida glabrata) were tested to evaluate the antimicrobial activity of the coordination polymers, following the Kirby-Bauer procedure and microplate dilution method. Thus, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimal biofilm inhibitory concentration (MBIC) were evaluated. Except for Candida krusei, the compounds showed an appreciable antimicrobial and antibiofilm activity against these strains grown in the liquid medium.

Dysprosium Chlorocyanoanilate-Based 2D-Layered Coordination Polymers.

A series of two-dimensional (2D)-layered coordination polymers (CPs) based on the heterosubstituted anilate ligand ClCNAn2- derived from 3-chloro-6-cyano-2,5-dihydroxybenzoquinone and DyIII are reported. By changes in the synthetic methods (layering technique, solvothermal or conventional one-pot reactions) and conditions (solvent, concentration, etc.), different types of 2D extended networks could be prepared and structurally characterized. Compounds 1 and 1', two polymorphs with the formula [Dy2(ClCNAn)3(DMSO)6]n·(H2O)x [x = 7 (1), 0 (1')], were prepared by a conventional one-pot reaction and recrystallized at different concentrations. Compound 2, formulated as [Dy2(ClCNAn)3(DMF)6]n, was prepared by a layering technique, while compound 3, formulated as {(Me2NH2)2[Dy2(ClCNAn)4(H2O)2]·(DMF)2·(H2O)5}n, was obtained by a solvothermal method. Compounds 1 and 2 are neutral 2D CPs of the ClCNAn2- ligand and DyIII ions, while 3 presents 2D anionic layers of [Dy2(ClCNAn)4(H2O)2]2- alternating with cationic layers of Me2NH2+ ions. These compounds show very diverse networks, with compound 1 forming 2D (8,3) and (4,3) topology with eight- and four-membered rings with square cavities, 1' and 2, respectively, a 2D (6,3) topology with six-membered rings (a rectangular cavity for 1' and a regular hexagonal cavity for 2), and 3 a 2D (4,4) topology with distorted square cavities. In this respect, 1 and 1' represent the first examples of polymorphism in the family of anilate-based CPs. Thermal analysis measurements (differential scanning calorimetry and thermogravimetry) show an exothermic polymorphic transformation from the kinetically stable 1' phase to the thermodynamically stable phase 1. The magnetic behavior of 1-3 very likely indicates depopulation of the mJ levels, while the presence of weak antiferromagnetic coupling between the DyIII centers mediated by the anilate bridge cannot be excluded.

Microemulsions: The Renaissance of Ferrite Nanoparticle Synthesis.

Ferrite nanoparticles (NPs) are of special interest for a wide range of applications. Microemulsions represent the Renaissance of ferrite NP preparation offering a series of advantages with respect to other methods due the possibility to confine reactions into nanosized reactors. They allow the preparation in mild synthesis conditions of a wide variety of nanostructured ferrites with controlled composition, particle size and shape. This review wants to give a comprehensive overview of the microemulsion performance in the ferrite NP synthesis. Firstly, a general section on microemulsion properties is presented. The basics of NP formation mechanism, with a first-rate emphasis in the influence of microemulsion properties and dynamics on the control of NP size and shape, are addressed. A summary of the synthesis procedure evolution by both direct and reverse microemulsions over a selection of ferrite NPs is also provided in the review. Finally, the perspectives on microemulsion systems for ferrite NP preparation are quickly revised.

Synthesis and thermodynamics of Ag-Cu nanoparticles.

Metallic silver, copper, and Ag-Cu nanoparticles (NPs) have been produced by a chemical reduction method. The obtained nanoparticles were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). A side-segregated configuration was observed for the one-pot synthesized Ag-Cu NPs, and the melting temperature depression of about 14 °C was found by differential scanning calorimetry (DSC). A comparison between the new experimental data, the literature data on Ag-Cu bimetallic NPs and the corresponding theoretical values obtained from the Ag-Cu nano-sized phase diagram was done, whereas the melting behaviour of Ag and Cu metal nanoparticles was discussed in the framework of the liquid layer model (LLM).

Drug silica nanocomposite: preparation, characterization and skin permeation studies.

The aim of this work was to evaluate silica nanocomposites as topical drug delivery systems for the model drug, caffeine. Preparation, characterization, and skin permeation properties of caffeine-silica nanocomposites are described. Caffeine was loaded into the nanocomposites by grinding the drug with mesoporous silica in a ball mill up to 10 h and the efficiency of the process was studied by XRPD. Formulations were characterized by several methods that include FTIR, XRPD, SEM and TEM. The successful loading of caffeine was demonstrated by XRPD and FTIR. Morphology was studied by SEM that showed particle size reduction while TEM demonstrated formation of both core-shell and multilayered caffeine-silica structures. Solid-state NMR spectra excluded chemical interactions between caffeine and silica matrix, thus confirming that no solid state reactions occurred during the grinding process. Influence of drug inclusion in silica nanocomposite on the in vitro caffeine diffusion into and through the skin was investigated in comparison with a caffeine gel formulation (reference), using newborn pig skin and vertical Franz diffusion cells. Results from the in vitro skin permeation experiments showed that inclusion into the nanocomposite reduced and delayed caffeine permeation from the silica nanocomposite in comparison with the reference, independently from the amount of the tested formulation.

Centella asiatica extract-SiO2 nanocomposite: More than a drug-delivery system for skin protection from oxidative damage.

An innovative nanotechnology-based approach was used for the preparation of Centella asiatica (C. asiatica) extract-SiO2 nanocomposites, specifically tailored for skin protection from oxidative damage. Different amounts of C. asiatica glycolic extract (1.0, 3.0, 5.0, and 10.0 wt %) and fumed silica were used to prepare the nanocomposites by means of ball milling method. The influence of both composition of the starting mixture and milling time on the final products was evaluated by different techniques such as X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, and nitrogen sorption analysis. Results confirmed the integrity of the natural extract after the milling process, and its successful loading in the silica matrix. No cytotoxicity was observed for the obtained nanocomposites, which showed high in-vitro ability to scavenge 2,2-diphenyl-1-picrylhydrazyl and to protect human keratinocytes from damages induced with hydrogen peroxide.

Calcium carbonate as sorbent for lead removal from wastewaters.

Low-cost and largely available industrial by-products such as calcite (CaCO3) have been considered as sorbents to remediate wastewaters from toxic elements, such as lead, in compliance with the European circular economy strategy. To date few articles are reporting results on lead sorption at the calcite-water solution interface by X-ray photoelectron spectroscopy (XPS) and this investigation aims to clarifying the mechanism of the interaction of Pb2+ model solutions over a wide concentration range, from 0.1 µM to 80 mM, with commercial calcite. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM, EDX) and XPS analysis indicate that when CaCO3 particles are soaked in Pb2+ 0.1 mM and 1 mM solutions, hexagonal platelets of hydrocerussite [(PbCO3)2 Pb(OH)2] precipitate on its surface. When the concentration of Pb2+ is equal or higher than 40 mM, prismatic acicula of cerussite [PbCO3] precipitate. Solution analysis by atomic emission spectroscopy (ICP-AES) and ICP-mass spectrometry (ICP-MS) indicate that Pb2+ removal efficiency is nearly 100%; when the initial Pb2+ concentration was equal to 0.1 µM it was below the limit of detection (LOD) and the efficiency could not be determined. The sorption capacity (qe) increases linearly with increasing initial Pb2+ concentration up to a value of 1680 (20) mg/g when the initial Pb2+concentration is 80 mM. These findings suggest that heterogeneous nucleation and surface co-precipitation occur and calcite can be well considered a very promising sorbent for Pb2+ removal from wastewaters within a wide initial concentration range.

Effect of Manual Grinding on Diclofenac Acid Nanocrystals: A Chemico-Physical Investigation.

X-ray Powder Diffraction, Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimeter were used to study the effect of the manual grinding in an agate mortar of the diclofenac acid polymorphs HD1 and HD2. In particular, we have tried to highlight how the HD2 form is more sensitive than the HD1 to the grinding process to achieve a nanometric crystal size. HD1 shows no change, while in the case of the HD2, changes in the molecular conformation and the formation of a new metastable form of the polymorph are observed after grinding.

A New One-Pot Way to Prepare Enzyme-Containing Coordination Polymers by Sonochemistry.

Enzyme-containing Coordination Polymers (CPs) were prepared by a one-pot sonochemical method, mixing Glucose Oxidase (GOx) enzyme, 4,4'-bipyridine as spacer ligand, and chloride zinc salt. The reaction took place in a very short time (a few minutes) with a minimum use of solvents compared to conventional methods. The obtained composite material, named GOx-[Zn(4,4'-bipy)Cl2]∞, resulted from embedding the GOx molecules into uniformly sized [Zn(4,4'-bipy)Cl2] nanocrystals. The structural and thermal characterization, confirmed that the adopted strategy allows the preparation of hybrid bio-nanomaterials in a very fast, facile and eco-friendly method, by simply synthesising the [Zn(4,4'-bipy)Cl2] nanocrystals in the presence of the enzyme.

Alternative Silica Sources in the Synthesis of Ordered Mesoporous Silica.

In this work, the influence of the use of alternative inexpensive silica sources on the structural, morphological and textural properties of MCM-41 like mesoporous materials to be used for biomedical applications has been investigated. The Liquid Crystal Template Method has been used to prepare the ordered mesoporous structured materials according to a novel composition starting from fumed silica or granular silica gel as alternative silica sources. The obtained materials have been characterized by X-ray Powder Diffraction, Transmission and Scanning Electron Microscopy, and nitrogen sorption, which showed for both samples the formation of the ordered hexagonal pore arrangement typical of a MCM-41 material. However, when using fumed silica, higher long-range hexagonal pore ordering as well as higher surface area have been obtained (1030 vs. 763 m²/g). For comparison, the features of a commercial silica mesostructured MCM-41 type have been investigated as well. Again, the silica fumed based sample has showed higher long-range hexagonal pore ordering, higher surface area and wall thickness. Preliminary stability studies on the fumed silica based material showed a decrease in the pore ordering at the end of the third year after the synthesis.

High Energy Ball Milling and Liquid Crystal Template Method: A Successful Combination for the Preparation of Magnetic Nano-Platforms.

In this study, we present the preparation of superparamagnetic ordered mesoporous silica (SOMS) for biomedical applications by the combination of high energy ball milling (HEBM) and the liquid crystal template method (LCT) to produce a material comprised of room temperature superparamagnetic Fe3O4 nanoparticles in a MCM-41 like mesostructured silica. In a typical synthesis, a mixture of Fe2O3 and silica was sealed in a stainless-steel vial with steel balls. Ball milling experiments were performed in a vibratory mill apparatus. The milling process produced nanocomposites with an average size ranging from ∼100-200 nm, where the Fe3O4 nanoparticles (4.8 nm size) are homogeneously dispersed into the amorphous SiO2 matrix. The obtained nanocomposite has been used for the preparation of the SOMS through the LCT method. Structural, morphological and textural characterization were performed using X-ray powder diffraction, transmission electron microscopy and nitrogen sorption analysis. Field dependence of magnetization was investigated and showed superparamagnetic behaviour at 300 K with a value of saturation magnetization (Ms) that is of interest for biomedical applications.

Nanocrystals as Tool to Enhance Stigmasterol Oral Bioavailability.

Phytosterols are sterols naturally occurring in plant cells and well known for their cholesterollowering activity, as witnessed by the large number of food supplements based on these functional ingredients available on the market. However, the marked hydrophobic character of phytosterols makes their solubility in biological fluids extremely low, with disadvantageous consequences on the bioavailability and therapeutic efficacy. In this work, we explore the effect of particle size reduction on the water solubility of stigmasterol, one of the most abundant phytosterols, through the formulation of nanocystals. A robust, top-down production process was employed to prepare stigmasterol nanocrystals, subsequently characterized by thermal and spectroscopic techniques. When formulated as nanocrystals, the solubility of stigmasterol in water and in simulated gastro-intestinal fluids was boosted compared to the raw material. The increased solubility of stigmasterol nanocrystals makes such formulation a promising candidate for the development of medicinal/nutraceutical products with enhanced bioavailability.

Morpholine- and Thiomorpholine-Based Amidodithiophosphonato Nickel Complexes: Synthesis, Characterization, P-N Cleavage, Antibacterial Activity and Silica Nano-Dispersion.

The reactivity of thiomorpholinium P-(4-methoxyphenyl)-N-thiomorpholin-amidodithiophosphonate (S-MorH+2)(S-Mor-adtp-) and morpholinium P-(4-methoxyphenyl)-N-morpholin-amidodithiophosphonate (O-MorH+2)(O-Mor-adtp-) towards nickel (II) dichloride hexahydrated is presented and the hydrolysis of the relevant metal complexes investigated. The hydrolytic products (S-MorH+2)2 [Ni(dtp)2]²- and (O-MorH+2)2[Ni(dtp)2]²- were characterized by means of FT-IR, 1H, and 31P NMR and XRD and the experimented P-N cleavage investigated and elucidated by means of DFT calculations. The antimicrobial activity of the neutral nickel complex [Ni(S-Mor-adtp)2] was tested against a set of Gram-positive and Gram-negative bacteria alongside with its nanodispersion in a silica matrix. The complex [Ni(S-Mor-adtp)2] did not show antibacterial activity, whilst the nano-dispersed sample [Ni(S-Mor-adtp)2]_SiO2 demonstrated inhibition to growth of Staphylococcus aureus. The nanocomposites were fully characterized by means of XRPD, TGA, SEM and dinitrogen sorption techniques.

Exploring the Effect of Iron Metal-Organic Framework Particles in Polylactic Acid Membranes for the Azeotropic Separation of Organic/Organic Mixtures by Pervaporation.

A microporous carboxylate metal-organic framework MIL-100 Fe was prepared as submicron particles by microwave-assisted hydrothermal synthesis (Fe-MOF-MW). This product was explored, for the first time, for the preparation of polylactic acid (PLA) mixed matrix membranes. The produced MOF was characterised by powder X-ray diffraction (PXRD), environmental scanning electron microscopy (ESEM) as well as by thermogravimetric analysis (TGA) and nitrogen adsorption/desorption. The effect of different Fe-MOF-MW concentrations (0.1 and 0.5 wt%) on the membrane properties and performance were evaluated. These membranes were used in the pervaporation process for the separation of methanol/methyl tert-butyl-ether mixtures at the azeotropic point. The influence of the feed temperature and vacuum pressure on the membrane performance was evaluated and the results were compared with PLA pristine membranes. Moreover, the produced membranes have been characterised in terms of morphology, MOF dispersion in the polymeric membrane matrix, wettability, thickness, mechanical resistance and swelling propensity. The presence of Fe-MOF-MW was found to have a beneficial effect in improving the selectivity of mixed matrix membranes towards methanol at both concentrations. The highest selectivity was obtained for the PLA membranes embedded with 0.5 wt% of Fe-MOF-MW and tested at the temperature of 25 °C and vacuum pressure of 0.09 mbar.

Formation of metallic silver and copper in non-aqueous media by ultrasonic radiation.

Concentrated suspensions of silver and copper salts in silicone oil were heated to 200 °C and irradiated with ultrasonic energy for different time durations. Characterization of the products was done using X-ray powder diffraction. In most cases, metallic Ag or Cu were obtained, together with their oxide forms Ag2O and Cu2O. The salts, used as precursors, do not dissolve in silicone oil but rather form a heterogeneous system, and we assume that local heating, caused by the acoustic cavitation, enhanced their thermal decomposition and the formation of metallic particles. It was found that the presence of silver particles enhances the formation of metallic copper. This phenomenon was observed in the experiment with the acetate salts mixture.

The effect of diethylene glycol monoethyl ether on skin penetration ability of diclofenac acid nanosuspensions.

The poor ability of many drugs to cross skin layers is the main limiting factor for the exploitation of the transdermal route for drug delivery. As a consequence, several approaches have been proposed to overcome the skin barrier, such as the inclusion of penetration enhancers in the topically applied drug solutions and emulsions. In this work, the penetration enhancer diethylene glycol monoethyl ether was included in novel diclofenac acid nanocrystal formulations, developed using the wet media milling technique and Poloxamer 188 as stabilizer. The nanosuspensions were characterized by different techniques such as scanning electron microscopy, differential scanning calorimetry, X-ray powder diffractometry, Fourier-transform infrared spectroscopy and photon correlation spectroscopy. The influence of diethylene glycol monoethyl ether on (trans)dermal delivery of diclofenac nanosuspensions was evaluated by in vitro studies using Franz diffusion cells and pig skin. RESULTS: demonstrated that the presence of diethylene glycol monoethyl ether influences the Poloxamer 188 ability to stabilize the nanocrystals during the milling process, leading to larger particles as compared to penetration enhancer-free nanosuspensions. As previously reported, the in vitro permeation studies indicate the nanosizing as a key factor in the dermal penetration of topically applied diclofenac. Surprisingly enough, the inclusion of increasing amounts of the penetration enhancer in the formulation decreased the diclofenac accumulation in the stratum corneum, while showing no significant effect on the drug delivered to the epidermis. Overall, the present results exclude a synergistic effect of the nanosizing approach and the addition of diethylene glycol monoethyl ether in regard to the skin penetration of diclofenac applied as a nanosuspension.

Combination of grape extract-silver nanoparticles and liposomes: A totally green approach.

In the present work, silver nanoparticles were prepared using a totally green procedure combining silver nitrate and an extract of grape pomace as a green source. Additionally, nanoparticles were stabilized using phospholipid and water and/or a mixture of water and propylene glycol (PG). To the best of our knowledge, grape-silver nanoparticle stabilized liposomes or PG-liposomes were formulated, for the first time, combining the residual products of wine-made industry, silver nitrate and phospholipids, avoiding the addition of hazardous substances to human health and the environment, in an easy, scalable and reproducible method. The structure and morphology of grape-silver nanoparticle stabilized vesicles were evaluated by transmission electron microscopy (TEM), UV-vis spectroscopy and photon correlation spectroscopy. Samples were designed as possible carrier for skin protection because of their double function: the grape extract acts as antioxidant and the colloidal silver as antimicrobial agent, which might be helpful in eliminating dangerous free radicals and many pathogenic microorganisms. Obtained nanoparticles were small in size and their combination with phospholipids did not hamper the vesicle formation, which were multilamellar and sized ~100nm. TEM images shows a heterogeneous distribution of nanoparticles, which were located both in the intervesicular medium and in the vesicular structure. Further, grape-silver nanoparticles, when stabilized by liposomes, were able to inhibit the proliferation of both Staphylococcus aureus and Pseudomonas aeruginosa and provided a great protection of keratinocytes and fibroblasts against oxidative stress avoiding their damage and death.