Journal of Particle Science and Technology
Volume:7 Issue: 1, Autumn 2021

Voriconazole is an approved antifungal agent belonging to the triazole family. It is generally used for treating aggressive fungal infections such as invasive candidiasis or aspergillosis, as well as certain fungal infections, in immunocompromised patients. Voriconazole has an oral bioavailability of 96%, and patients can receive the medication either by oral or parenteral routes. To fabricate a topical ocular voriconazole delivery system, we prepared voriconazole-loaded chitosan nanoparticles by ionic gelation of chitosan with the addition of sodium tripolyphosphate (TPP). Three chitosan polymers with different molecular weights were tested by varying chitosan and TPP concentrations, and the produced nanoparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and x-ray powder diffraction (XRD). The obtained data was presented into a Box-Behnken design, which showed a set of optimum parameters that would yield an optimized formulation with the most favourable properties. Subsequently, the optimized formulation was synthesized, and the voriconazole release from this formulation was monitored over 48 hr. Results showed the drug-loaded nanoparticles have high drug loading, show no burst effect, and sustain drug release for up to 48 hr. Therefore, this formulation is a potentially efficient ocular delivery system for voriconazole.

Particulate emission from a high density of vehicles has become a subject of interest and great concern for the assessment of local air quality within the Ilorin metropolis, Nigeria. This study aims to determine possible heavy metal pollution from vehicular emission along the major transport pool within the Ilorin metropolis. Deposition gauges were placed on a pole above human breathing height at 1.5 m at selected major roundabouts within the Ilorin metropolis. Gauges were planted for one month (April 27th to May 30th, 2020) during the Covid-19 lockdown and one month (January 15th to February 14th, 2021) after the Covid-19 lockdown. The collected samples were rinsed with deionized water, filtered, and dried in a desiccator. The dried samples were characterized using Energy-dispersive X-ray fluorescence (EDXRF). Twenty-one heavy metals were detected from all sampling locations. The total sum concentrations of the heavy metals recorded during and after the Covid-19 lockdown were 1018.58785 and 1359.15479 mg.m-3, respectively. The averaged measured concentration of most of the heavy metals sampled along selected major roundabouts within the Ilorin metropolis during and after Covid-19 lockdown exceeded the permissible emission limit. The Deposition Flux (DF) of the measured heavy metals ranged from 4.53 to 8.91 g.m-2.month-1 during the lockdown and from 6.23 to 29.55 g.m-2.month-1 after the lockdown. The enrichment factor and concentration ratio were also determined. The results of both indicated that heavy metal pollutions originated from multiple similar anthropogenic sources, and photochemical degradation was active in all the sampling locations. This study suggested the need to shift from a fossil fuel economy to a hydrogen economy to mitigate heavy metal pollutions from vehicular emissions to the barest minimum.

Methylene blue is an organic pollutant found in industrial effluents that is very toxic to humans and the environment. This study used 8-hydroxyquinoline-modified bentonite adsorbent to remove methylene blue from aqueous solutions. In the present work, different doses of modified bentonite were used as a new adsorbent for the removal of methylene blue. The effects of contact time, pH, adsorbent dose, and initial methylene blue concentration were recorded. Then, the adsorption data were described with Langmuir and Freundlich adsorption isotherms. The highest percentage of methylene blue adsorption was observed at pH = 7.5. The optimum amount of adsorbent was 0.1 g.L-1 and after 120 minutes, the process reached an equilibrium state. The adsorption of methylene blue increased following an increase in the pH of the solution. It was also observed that the contact time significantly affected the rate of methylene blue adsorption. The experimental data fit much better in the Freundlich (R2 = 0.999) model than the Langmuir (R2 = 0.992) model. So, 8-hydroxyquinoline-modified bentonite has the potential to be utilized for the cost-effective removal of methylene blue from aqueous solutions.

Polymers have good dynamic mechanical properties and high damping capacity due to their viscoelastic nature, especially in the glass transition range, and are considered a good damper with a loss factor greater than 0.3 and a peak temperature range of at least 60-80ºC. Two of the best ways to expand the damping range are fabricating the core/shell latex particles with a specific morphology and using interpenetrating polymer networks in the core and shell sections. The aim of this study is to synthesize and investigate the dynamic-mechanical properties of interpenetrating polymer networks with core/shell morphology. A set of multilayer core/shell/shell latex particles with styrene-acrylic monomers were synthesized by varying the initiator (thermal initiator and redox initiator) via semi-continuous emulsion polymerization. In this study, synthesized particles were characterized with fourier transform infrared (FT-IR) spectroscopy, the morphology was determined by transfer electron microscopy (TEM), and the size and size distribution were investigated via dynamic laser scattering (DLS), which represent nano-scale particles with narrow distribution. The damping properties of the formed films were studied by dynamic mechanical analysis (DMA). The factors affecting the formation of poly(styrene/methyl methacrylate/butyl acrylate)-based core/shell particles, including the type of initiator and layer mass ratio, were discussed. The results showed that the IPN core/shell latex particles with a thermal initiator exhibited the best damping properties, with a broad effective damping range (tanδ > 0.3). The influence of the layer mass ratio on damping was also explored in this work.

This study considers the radial behavior of a coated microbubble after a shell rupture using the Marmottant model. The surface tension of the encapsulated microbubble should equal the free bubble in the rupture state of the Marmottant model. Despite the assumption that the bubble is considered free in the third state, dilatational interfacial viscosity is constant in the equation in this model. This paper assumes that dilatational interfacial viscosity decreases gradually after shell rupture until it becomes zero. The decrease of dilatational interfacial viscosity caused by the shell rupture significantly affects radial behavior and the nonlinear response of the encapsulated microbubble, such as subharmonic response. Because the subharmonic response is extensively used in ultrasound imaging, the effect of a decrease in dilatational interfacial viscosity on the subharmonic threshold needs to be investigated. In figures showing the radius versus time and the frequency response of the coated microbubble, it is observed that at high excitation pressure, the proposed model is more nonlinear than the Marmottant model, resulting in a lower subharmonic threshold.

Tautomers can be defined as isomers of single molecules existing in solutions or cells. Tautomers have the ability to interchange due to numerous spontaneous arrangements of chemical bonds, unlike chirality, whose molecules represent mirror images of enantiomers of one another. Tautomerization of the carmustine mechanism as a potential anti-cancer medication was examined using the DFT method. Two conformational tautomers were identified in the structure of carmustine, and the structure of both tautomers was shown to consider the contribution of atom changes to carmustine conformation. It was possible to obtain the relative energies B3LYP/6-311G++ (d,p), Aug-cc-pVDZ, and 6-311++g(2d,2p) basis sets. Calculations of the highest occupied molecular orbital (HOMO), the lowest unoccupied orbital (LUMO), and bandgap energies of structures were performed while also obtaining the electronics parameters, electrophilicity, electronegativity, softness, and hardness in order to determine the compounds’ reactivity within the biological medium. Based on the results, the carmustine structure and both tautomer conformations showed stability, but T1 had greater stability than T2.