Ultrasound-Assisted Synthesis of Luminescent Micro- and Nanocrystalline Eu-Based MOFs as Luminescent Probes for Heavy Metal Ions

The luminescent coarse-, micro- and nanocrystalline europium(III) terephthalate tetrahydrate (Eu2bdc3·4H2O) metal-organic frameworks were synthesized by the ultrasound-assisted wet-chemical method. Electron micrographs show that the europium(III) terephthalate microparticles are 7 μm long leaf-like plates. According to the dynamic light scattering technique, the average size of the Eu2bdc3·4H2O nanoparticles is equal to about 8 ± 2 nm. Thereby, the reported Eu2bdc3·4H2O nanoparticles are the smallest nanosized rare-earth-based MOF crystals, to the best of our knowledge. The synthesized materials demonstrate red emission due to the 5D0–7FJ transitions of Eu3+ upon 250 nm excitation into 1ππ* state of the terephthalate ion. Size reduction results in broadened emission bands, an increase in the non-radiative rate constants and a decrease in both the quantum efficiency of the 5D0 level and Eu3+ and the luminescence quantum yields. Cu2+, Cr3+, and Fe3+ ions efficiently and selectively quench the luminescence of nanocrystalline europium(III) terephthalate, which makes it a prospective material for luminescent probes to monitor these ions in waste and drinking water.

Kinetics of the Cationic bio-reduction involved in the biosynthesis of silver nanoparticles from Leea Coccinea Leaves

The resistance of microorganisms to conventional antimicrobials is one of the most serious health problems that affect not only the human, but also animals and plants, making the search for antimicrobial active ingredients a priority of global research. Green synthesis of antimicrobial silver nanoparticles (AgNPs) is a simple, cost-effective, rapid, reproducible, and environment friendly alternative for which numerous plant species have been reported for this purpose. Previous studies have shown the potential of Leea coccinea leaves in to the biosynthesis of antimicrobial silver nanoparticles. The current research aimed to study the kinetics of the reaction of synthesis of AgNPs by cationic bio-reduction from this botanical bioresource. A technology for the synthesis of AgNPs was established and the influence of operational parameters such as the bio-reduction conditions and the kinetics of the reaction were studied. AgNPs were characterized at different times by UV-VIS spectroscopic method, scanning electron microscopy, determination of particle size, and Z potential through Dynamic Light Scattering technique (DLS). Addition of tensoactive substances was evaluated for the stabilization of the suspension of nanoparticles. The results showed that spherical AgNPs smaller than 100 nm were obtained, which were visually identified by the formation of a dark brown complex with maximum absorption at 470 nm. Kinetic studies demonstrated the influence of the initial plant material on speed and performance, making evident a complex phenomenology with the possible occurrence of parallel reactions, which points to the possible reaction of different reducing compounds contained in this natural source. Addition of surface agents, such as SDS (0,5 %) or maltose (0,5 %), improved the stabilization in the aqueous medium, suggesting the continuation of studies to develop pharmaceuticals formulations based on AgNPs.

Preparation and Characterization of Curcumin Nanoemulsion in Olive Oil-Tween 80 System using Wet Ball Milling Method

Nanoemulsion has been developed as a drug delivery system which increases bioavailability and effectiveness of curcumin. Many methods and formulations have been applied in order to fabricate the most efficient nanoemulsion system to deliver curcumin. Wet ball milling is a simple technique to grind solids like powder to produce nano emulsion. On the other hand, a combination of olive oil and curcumin in Mediterranian Diet shows a promising anticancer activity. This research aims to elaborate the preparation and characterization of curcumin nanoemulsion in olive oil-Tween 80 system with wet ball milling method. It is expected that the procedure yields a combination of curcumin and olive oil in nanoemulsion system with simple preparation. This research uses curcumin as active compound, olive oil as solvent for curcumin, Tween 80 as stabilizer, and water as dispersing agent. Particle size and polydispersity index are determined using Dynamic Light Scattering technique. The results show that the best milling time is 8 hours to produce nanoemulsion that has diameter of 303 nm and polidispersity index of 0.29. Nanoemulsion system is stable for 60 days storage at 4 oC and 25 oC. The maximum curcumin mass that can be loaded in the system while maintaining particle size in nanoemulsion range is 300 mg.

Preparation and of PVA-based compositions with embedded silver, copper and zinc oxide nanoparticles and assessment of their antibacterial properties

A series of poly(vinyl alcohol) (PVA) based liquid compositions with addition of zinc oxide, silver and copper nanoparticles has been prepared. The compositions also contained other consistency-forming organic components. The physico-chemical properties of the products have been determined. Their pH and density have been assessed. Also, the size of nanoparticles has been defined with using a dynamic light scattering technique. The compositions were subjected to XRD, FT-IR and microscopic analysis as well. Thanks to the incorporation of both metal oxide and metallic nanoparticles, it was possible to enrich the products with antibacterial properties. Their inhibiting properties in the growth of microorganisms have been confirmed against both Gram-negative and Gram-positive strains such as E. coli, S. aureus and P. aeruginosa. Thanks to the ability for solidification, the compositions may be applied on a bacterially contaminated surface, and after destroying the microorganisms and its solidification, it may be peeled off along with the dead bacterial film.

Preparation of Titanium Oxide-Based Nanoparticles Modified with D-(+)-Mannose and Investigation of their Properties As A Potential Drug Carrier

Titanium oxide nanoparticles modified with D-(+)-mannose were obtained. In the process of their formation, they were conjugated with an active substance (tadalafil). The physicochemical properties of the obtained products were assessed, and the size and electrokinetic potential were determined using a dynamic light scattering technique. X-ray diffractometry was applied in order to define the crystalline properties, and Fourier-transform infrared spectroscopy was used to confirm the formation of the desired products. It was possible to obtain TiO2 coated with D-(+)-mannose. The average size of nanoparticles was between 230 and 268 nm. The release of the active substance from the product over a time period of three hours was assessed against the reference material, which was not modified by D-(+)-mannose. The results indicate that covering titanium oxide nanoparticles with the modifying substance favours a slower rate of release for the active substance, which is the desired effect from a pharmacological point of view. The releasing of active substance from modified products was even 68% slower than that from the reference product. These modified titanium oxides are promising materials that may have found an application as drug carriers. Graphic Abstract

Synthesis and Characterization of Amphiphilic Diblock Copolymer by Reverse Iodine Transfer Polymerization (RITP)

Iodine transfer radical homo- and diblock copolymerization of N-[3-(dimethylamino)propyl] methacrylamide (DMAPMA) with methyl methacrylate (MMA) were carried out in the presence of iodine I2 and 2,2′-azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively. Using reverse iodine transfer polymerization (RITP) method based on the in situ generation of transfer agents using molecular iodine I2. The homopolymer and copolymer were characterized by FT-IR and 1H NMR. The self-assembly behaviours of diblock copolymer in water are studied by viscosity and tensiometry techniques. The water-soluble fraction of P(DMAPMA-b-MMA) block copolymer formed micelles which were investigated at 25°C in water at 0.2 mg.mL−1 concentration using a tensiometry device. Dynamic light scattering technique (DLS) was performed over a wide range of concentration to determine hydrodynamic size of the aggregates.

Kinetic Study of Peroxidase-Catalyzed Oxidation of 2-Hydroxyanthracene and 9-Phenanthrol in Presence of Biosurfactant Escin

The kinetics of fungal peroxidase-catalyzed 2-hydroxyanthracene and 9-phenanthrol oxidation was investigated in presence of biosurfactant escin at pH 5.5 and 25 °C. The kinetic measurements were performed using the fluorimetric method and the critical micelle concentration (CMC) of escin was determined using the dynamic light scattering technique. Inactivation of peroxidase was observed in absence of biosurfactant escin. It was shown that escin, used in concentrations lower than CMC, decreases or completely stops the peroxidase inactivation and increases the conversion of 2-hydroxyanthracene as well as of 9-phenanthrol. The environmentally friendly method of peroxidase-catalyzed 2-hydroxyanthracene and 9-phenanthrol oxidation in presence of biosurfactant Escin has an advantage over traditional decontamination methods due to their less environmental impact.

As(V) Adsorption Kinetics of Humic Acid-Coated Magnetite Particles

The discharge of arsenic (As) ions into water is a serious issue which needs to be curbed effectively due to the hazards of As exposure. Hence, a simple, cheap and effective removal procedure is required in order to meet water quality standards. In this research, magnetite (Fe3O4) particles coated with humic acid were investigated for its efficacy in adsorbing As. The particles were synthesised by varying the temperature (70, 80 and 90°C) and concentration of humic acid (1%, 2% and 3%) to study the corresponding changes in terms of size, structure and As adsorption performance. The phase and size were characterised with X-ray Diffraction and Dynamic Light Scattering technique, respectively. The performance of the synthesised particles in removing As (V) was quantitatively analysed using the colorimetric method with the assistance of a double-beam Ultraviolet-Visible Spectrophotometry. XRD analysis confirms the formation of magnetite while samples coated with 2% and 3% humic acid exhibited less crystallised structures. From the DLS analysis, Fe3O4 was found to have an average size of 2238nm while humic acid coated-Fe3O4 had increased particle sizes of between 2400nm to 3712nm. All the synthesised magnetite particles were able to remove certain percentages of As (V) from water. The highest adsorption capacity obtained was 1.984 mg/g and the lowest was 1.376 mg/g for a contact times of 40 minutes and 20 minutes, respectively.