Intracellular Trafficking of Fluorescent Nanodiamonds and Regulation of Their Cellular Toxicity

In this paper, cellular management of fluorescent nanodiamonds (FNDs) has been studied for better understanding in the design for potential applications of FNDs in biomedicine. The FNDs have shown to be photostable probes for bioimaging and thus are well-suited, for example, long-term tracking purposes. The FNDs also exhibit good biocompatibility and, in general, low toxicity for cell labeling. To demonstrate the underlying mechanism of cells coping the low but potentially toxic effects by nondegradable FNDs, we have studied their temporal intracellular trafficking. The FNDs were observed to be localized as distinct populations inside cells in early endosomes, lysosomes, and in proximity to the plasma membrane. The localization of FNDs in early endosomes suggests the internalization of FNDs, and lysosomal localization, in turn, can be interpreted as a prestate for exocytosis via lysosomal degradation pathway. The endocytosis and exocytosis appear to be occurring simultaneously in our observations. The mechanism of continuous endocytosis and exocytosis of FNDs could be necessary for cells to maintain normal proliferation. Furthermore, 120 h cell growth assay was performed to verify the long-term biocompatibility of FNDs for cellular studies

One-Pot Synthesis of Menthol from Citral over Ni/H-β-38 Extrudates Containing Bentonite Clay Binder in Batch and Continuous Reactors

Optimization of bifunctional Ni catalysts was performed to enhance the catalytic performance in the one-pot synthesis of commercially valuable menthol from citral. The effect of nickel precursors (nitrate, chloride, acetate, and sulfate) and the addition of bentonite clay was investigated in citral transformations in a batch reactor at 70 °C and 10 bar hydrogen, demonstrating higher activity for the Ni-H-β-38-bentonite composite derived from a nickel nitrate precursor, which can be attributed to a higher surface area, optimal Brønsted to Lewis acidity and metal particle size, as well as the egg-shell distribution of Ni particles. H-β-38 impregnated with nickel nitrate, followed by calcination and reduction, was shaped with bentonite as a binder to give extrudates for exploring the citral transformations in the trickle-bed reactor at 50–70 °C and 10 bar hydrogen. The highest selectivity to the desired menthols of 45% was obtained with 70% stereoselectivity to the menthol isomer at 70 °C. The apparent activation energy for citral transformations to menthols of 18.6 kJ/mol indicated the presence of mass transfer limitations. Catalytic activity was linked with the physical-chemical properties, which were characterized by transmission electron microscopy, X-ray diffraction, temperature-programmed reduction, Fourier transform infrared spectroscopy with pyridine, N2 physisorption, and inductively coupled plasma–optical emission spectrometry methods

Controlled Dissolution of Griseofulvin Solid Dispersions from Electrosprayed Enteric Polymer Micromatrix Particles: Physicochemical Characterization and <i>in Vitro</i> Evaluation

The oral bio­avail­ability of a poorly water-soluble drug is often inadequate for the desired therapeutic effect. The bio­avail­ability can be improved by enhancing the physico­chemical properties of the drug (e.g., dissolution rate, permeation across the gastro­intestinal tract). Other approach include shielding the drug from the gastric metabolism and targeted drug release to obtain optimal drug absorption. In this study, a poorly water-soluble model drug, griseo­fulvin, was encapsulated as disordered solid dispersions into Eudragit L 100-55 enteric polymer micro­matrix particles, which were produced by electro­spraying. Similar micro­matrix particles were also produced with griseo­fulvin-loaded thermally oxidized mesoporous silicon (TOPSi) nanoparticles dispersed to the polymer micro­matrices. The <i>in vitro</i> drug dissolution at pH 1.2 and 6.8, and permeation at pH 7.4 across Caco-2/HT29 cell monolayers from the micro­matrix particles, were investigated. The micro­matrix particles were found to be gastro-resistant, while at pH 6.8 the griseo­fulvin was released very rapidly in a fast-dissolving form. Compared to free griseo­fulvin, the permeability of encapsulated griseo­fulvin across the intestinal cell monolayers was greatly improved, particularly for the TOPSi-doped micro­matrix particles. The griseo­fulvin solid dispersions were stable during storage for 6 months at accelerated conditions. Overall, the method developed here could prove to be a useful oral drug delivery solution for improving the bio­avail­ability of poorly water-soluble or otherwise problematic drugs

Extraction of Lipids from <i>Chlorella</i> Alga by Supercritical Hexane and Demonstration of Their Subsequent Catalytic Hydrodeoxygenation

Extraction of lipids from <i>Chlorella</i> algae with supercritical hexane resulted in the high lipids yield of approximately 10% obtained at optimum conditions in terms of extraction time and agitation compared to the total content of lipids being 12%. Furthermore, an easiness of hexane recovery may be considered as economically and ecologically attractive. For the first time, in the current work catalytic hydrodeoxygenation (HDO) of <i>Chlorella</i> algal lipids was studied over 5 wt % Ni/SiO₂ at 300 °C and under 30 bar total pressure in H₂. The conversion of lipids was about 15% as the catalyst was totally deactivated after 60 min. The transformation of lipids proceeded mostly via hydrogenation and hydrogenolysis with formation of free fatty acid (FFA). Lower activity might be attributed to deactivation of catalysts caused by chlorophylls and carotenoids. Even though the conversion is low, future studies in HDO of lipids extracted from other algae species having higher lipid content could be proposed. A coke resistant catalyst might be considered to improve catalytic activity