A synergistic effect on flame retardancy, thermal stability, and mechanical properties was found when sepiolite was incorporated into a linear low-density polyethylene (LLDPE)/magnesium hydroxide (MH) composite. Different amounts of sepiolite (up to a maximum concentration of 15 phr) were added to a standard LLDPE/MH formulation, and vinyltriethoxysilane was used as a compatibilizer as well as a crosslinking agent. The thermal stability and the oxidation induction time increased with increasing sepiolite content in the LLDPE composites. Limiting oxygen index (LOI) results indicated an increase in LOI with the addition of sepiolite, and an LOI value of 36.5% was observed with 15 phr sepiolite in the LLDPE/MH formulation. The addition of sepiolite increased the gel content and tensile strength of all samples and lowered the elongation at break. The heat deflection, Vicat softening temperature, and hardness were also improved by the incorporation of sepiolite. This synergistic behavior of sepiolite with MH could be used in halogen-free, flame-retardant LLDPE formulations.
Gold nanoparticle-porphyrin assemblies were formed by binding functionalized porphyrins to gold nanoparticles (Au-NPs). Spectroscopic properties of hybrids and binding strength of porphyrins to Au-NPs were observed based on number and type of linker moieties using fluorescence spectroscopy. Binding appears to be dependent on number rather than type of linker moieties present on the porphyrin molecules, as tetraaminophenyl porphyrin shows the highest binding among the molecules we studied and causes agglomeration of nanoparticles due to presence of four linker groups. The inner filter effects of Au-NPs are considerably high due to their high extinction coefficient and cause large errors in the evaluation of quenching efficiencies. We have described a very simple method to calculate the inner filter effects of Au-NPs by first loading them with porphyrins and then replacing them with nonfluorescent ligands. The difference in the fluorescence of unbound porphyrins in the presence and absence of Au-NPs describes their inner filter effects.
The aim of present study was to enhance topical permeation of clotrimazole gel preparation by using various permeability enhancers such as coconut oil, pistachio oil and sodium lauryl sulphate (SLS). Clotrimazole gel preparations were prepared and optimized by using three factor, five level central composite design. A second-order polynomial equation was generated in order to estimate the effect of independent variables i.e. coconut oil (X 1 ), pistachio oil (X 2 ) and sodium lauryl sulphate (X 3 ) at various dependent variables i.e. flux (Y 1 ), lag time (Y 2 ), diffusion coefficient (Y 3 ), permeability coefficient (Y 4 ), and input rate (Y 5 ) of clotrimazole gel formulations. Ex vivo skin permeation study was performed through rat skin by using modified Franz diffusion cell system. Optimized formulation F8 exhibited highest flux 2.17 µg/cm 2 /min, permeability coefficient 0.0019 cm/min and input rate 1.543 µg/cm 2 /min, along with moderate lag time 77.27 min and diffusion coefficient 0.063 cm 2 /min, which is further supported by anti-fungal activity that exhibited more prominent zone of inhibition against Candida albicans, Aspergillus niger and Mucor. Thus, it can be concluded that permeation of clotrimazole gel was enhanced by various combination of coconut oil, pistachio oil and sodium lauryl sulphate but optimized formulation F8 containing 0.4 ml pistachio oil, 0.8 ml coconut oil and 0.04 g of SLS exhibited more pronounced and promising effect through rat skin.
Over the past few years, considerable attention has been focused on carrageenan based bionanocomposites due to their multifaceted properties like biodegradability, biocompatibility, and nontoxicity. Moreover, these composites can be tailored according to the desired purpose by using different nanofillers. The role of ferromagnetic nanoparticles in drug delivery is also discussed here in detail. Moreover, this article also presents a short review of recent research on the different types of the carrageenan based bionanocomposites and applications.
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