This article presents the influence of low frequency, high intensity ultrasonic irradiation on the characteristics (average size, polydispersity index) of ethyl cellulose nanocapsules encapsulating a photochromic dye. Photochromic nanocapsules were prepared by the emulsion-solvent evaporation method. The acoustic densities entering the system were systematically studied with respect to their abilities to modify and reduce the average sizes and polydispersity indexes of the nanocapsules. Scanning electron microscope, confocal laser microscope, and dynamic light scattering were utilised to characterise the structure, shape, size, and polydispersity of ethyl cellulose photochromic nanocapsules. We were able to tailor the size of the photochromic nanocapsules simply by varying the acoustic densities entering the system. At an acoustic density of 1.5 W/mL and 60 s of continuous irradiation, we were able to prepare an almost monodispersed population of the nanocapsules with an average size of 193 nm.
COBISS.SI-ID: 20690198
This study presents an optical chemical sensing system based on an SiO2 sensor layer for continuous determination of biogenic amines (BAs), such as isopentylamine, propylamine and putrescine. For this purpose, the indicator dye ETH4001 was chosen and immobilized in different sol-gel sensor layers, which were prepared by various combinations of hydrophilic tetraethoxysilane and hydrophobic sol-gel precursors propyl-trimethoxysilane, and 3,3,3-trifluoropropyltrimethoxysilane. The preparation of the starting sol-gel solution containing the indicator ETH4001 was carried out via the acid-catalyzed process and at a constant molar ratio R = 7 in all cases. The sensing system was optimized according to spectral properties, dynamic range, sensitivity, response and regeneration time and sensor layer aging time.
COBISS.SI-ID: 20229910
We report about the fluorometric method for the determination of glutathione (GSH) in dietary supplements. The fluorometric assay is based on the use of functionalized silica particles (SiO2-SH) in combination with o-phthaldialdehyde (OPA). The fluorescence excitation and emission wavelengths were located at 340?nm and 430?nm. The relative fluorescence intensity was linear in the concentration range between 1.0?×?10-7?mol/L and 1.0?×?10-5?mol/L (M) with the detection limit of 3.4?×?10-7?M. The fluorescent silica particle-based sensor was successfully employed for the determination of GSH in dietary supplements with excellent recoveries. The proposed sensor may pave a new way for fluorescence sensing of other substances in food samples.
COBISS.SI-ID: 21872150
In this study, we developed hexagon silver nanoparticles (AgNPs) prepared by the polyol method in ethylene glycol media using aminopropyltrimethoxysilane (APTMS) as a capping agent for the first time. The presence of the primary amine group makes APTMS a great candidate as a capping agent for the synthesis of silver nanostructures, but it has not been used for this purpose until now. The synthesized silver nanostructures were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and ultraviolet-visible spectroscopy. The molar ratio of APTMS to AgNO3 varied from 0.5 to 6.8, which resulted in an average diameter of the obtained nanoparticles from 50 to 100 nm. The optimum morphology of hexagonally shaped AgNPs was obtained at a molar ratio of 2.2. The prepared AgNPs were evaluated for their antibacterial and antifungal properties. Antimicrobial tests showed that a cotton textile coated with colloidal amino functionalized AgNPs has excellent antimicrobial properties as an inhibitor of growth against the gram-positive bacteria Staphylococcus aureus, gram-negative bacteria, Escherichia coli and fungus Candida albicans, and therefore showing potential for real applications.
COBISS.SI-ID: 22385686
In this work, mono-dispersed mercapto-functionalized silica (SiO2@SH) particles with a narrow particle size distribution of around 420 ± 10 nm were prepared by the sol–gel method for the adsorption of aqueous dissolved lead ions (Pb2+) from model wastewater. Dispersive X-ray Spectroscopy (EDXS) indicated strong signals of Si and S, implying successful mercapto (SH) functionalization of the silica (SiO2) surfaces. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the occurrences of Si–O–Si and SH vibrations within the samples and, thus come to a conclusion about the formations of the mercapto-functionalized samples. The EXAFS/XANES (Extended X-ray Absorption Fine Structure/Xray Absorption Near Edge Structure) analysis indicated complete Pb2+ complexation with two SH groups of the prepared SiO2@SH samples. The results for Pb2+ adsorptions from model wastewater showed affinity of around 55 % and the obtained value of the maximum amount of adsorbed Pb2+ ions on the surface of the SiO2@SH particles was 10.82 mg/g under studied conditions. Adsorptions results were fitted with the Langmuir and Freundlich isotherm models and the pseudo-first and pseudo-second kinetic models were evaluated.
COBISS.SI-ID: 20042774