Introduction: The Caco-2 adenocarcinoma cell line has been used extensively for the past couple of decades in nutrient and drug transport studies as an adequate in vitro model of the intestinal mucosa. However, due to the over-expression of tight junction protein complexes, Caco-2 monolayers fail to provide a reliable estimation in terms of in vivo paracellular permeability of small hydrophilic compounds. To address this issue, we co-cultured Caco-2 and HT29-MTX (mucus-secreting cell-line) to ensure a tunable model and emulate the intestinal transport of two classes of nanoparticles.

Methods: We exposed Caco-2/HT29-MTX of different seeding ratios, cultured on Transwell® systems, to non-cytotoxic concentration levels (20 μg/mL) of Si/SiO₂ quantum dots and iron oxide (α-Fe₂O₃) nanoparticles. Transepithelial electric resistance was measured before and after exposure, and monolayer permeability (P_eff) was assessed via the paracellular marker Lucifer Yellow. At regular intervals during the 3-hour transport study, samples were collected from the basolateral compartments for nanoparticle detection and quantitative testing. Cell morphology characterization was done by phalloidin-FITC/DAPI labelling, and Alcian Blue/eosin staining was performed on insert cross-sections in order to compare the intestinal models and evaluate the production of mucins.

Results: Morphological alterations of the Caco-2/HT29-MTX (7:3 ratio) co-cultures were observed at the end of the transport study compared to the controls. The nanoparticle suspensions tested did not diffuse across the intestinal model and were not detected in the receiving compartments, due to their tendency to precipitate at the monolayer surface level and form visible aggregates. Our preliminary results indicated the need for further nanoparticle functionalization in order to appropriately assess intestinal absorption in vitro. The intestinal models used in this study have been shown to adequately screen for prospective candidate carrier-type materials and gauge the transport dynamics of nanoparticles.

Acknowledgements: This work was supported by the project no. 77/2018 NANO-BIO-INT.

Synthesis of nanostructured materials is not straightforward that involve the complicated use of surfactant templates. Currently, only non-renewable resources that are hazardous and toxic are used to produce the surfactant templates in the industries. This study presents an environmentally friendly and efficient route for the synthesis of nanostructured of both silica and hematite using rice starch as a promising biomaterials template. The rice starch-templated synthesis yield both hematite and silica with nano-sized and high surface area. In particular, the nanostructured silica showed a pseudo-spherical morphology with nano-sized from 13 to 22 nm, amorphous structure and surface area of 538.74 m²•g⁻¹. On the other hand, the nanostructured hematite showed an oval-shaped morphology with nano-sized from 24 to 48 nm, rhombohedral structure, and surface area of 20.04 m²•g⁻¹. Interestingly, both synthesized silica and hematite showed capability as good nano-catalysts. More importantly, the used of rice starch-template a greener approach in the synthesis of nanomaterials have been successfully outlined.

In the present work, SBA-15 aluminosilicate materials were modified for their use as catalysts in the valeric acid esterification. Firstly, Al-SBA-15 material were functionalised by ball milling with several niobium loadings (0.25-1 wt.%) and, eventualy, by incipient wetness impregnation with several F^- loadings, using ammonium fluoride as salt precursor. The catalyst herein synthesised were characterised by XRD, N2 porosimetry and DRIFT among others with a special emphasis to the acidic properties, which were evaluated by titration using pyridine and 2,6-dimethylpyridine. The prepared materials shown form moderate to high catalytic activities in the microwave-assisted transformation of valeric acid to ethyl valerate via esterification. Unexpectedly, the incorporation of niobic acid nanoparticles on the aluminosicates lead to a decrease in the conversion without finding any trend related with the metal loading. On the contrary, the incorporation of fluoride anions either on Al-SBA-15 or on Nb1%/Al-SBA-15 leads to a linear increase in valeric acid conversion with the F^- content. The increase on valeric acid conversion has been the same independently if the modification with fluoride anions has been performed over Al-SBA-15 or Nb1%/Al-SBA-15. Thus, it can be concluded that F^- modified mesoporous aluminosilicates are efficient catalyst for the transformation of valeric acid into alkyl valerate esters as renewable fuels.

Graphene oxide (GO), the oxidized form of graphene, shows unique properties such as strong mechanical strength, high electrical and thermal conductivity, amphiphilicity and surface functionalization capability that make it very attractive in various fields ranging from medicine to optoelectronic devices and solar cells. However, its insolubility in non-polar and polar aprotic solvents hinders some applications. To solve this issue, novel functionalization strategies are pursued. In this regard, the current study deals with the preparation and characterization of hexamethylene diisocyanate (HDI)-functionalized GO. Different reactions conditions were tested to optimize the functionalization degree (FD), and detailed characterizations were conducted via elemental analysis, Fourier-transformed infrared (FT-IR) and Raman spectroscopies to confirm the success of the functionalization reaction. The morphology of HDI-GO was investigated by transmission electron microscopy (TEM), which revealed an increase in the flake thickness with increasing FD. The HDI-GO showed a more hydrophobic nature than pristine GO and could be suspended in polar aprotic solvents such as N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO) as well as in some low polar/non-polar solvents like tetrahydrofuran (THF), chloroform and toluene; further, the dispersibility improved upon increasing FD. Thermogravimetric analysis (TGA) results confirmed that the covalent attachment of HDI greatly improves the thermal stability of GO, ascribed to the crosslinking between adjacent sheets, which is interesting for a variety of applications including long-term electronics and electrothermal devices. The HDI-GO could further react with other organic molecules or polymers via the remaining oxygen groups, which makes them ideal candidates as nanofillers for high-performance GO-based polymer nanocomposites.

Nowadays the development of nanoscale power sources with a long battery life is required for novel nanoelectronic devices, such as wireless sensors, biomedical implants, smart cards and others. Lithiated metal oxides (Li-Me-O) are widely used in Lithium-ion batteries (LIBs). Depending on the type of metal Li-Me-O can be applied as cathode, anode or electrolyte materials. Atomic layer deposition (ALD) is an excellent method for synthesis of a different type of thin films LIBs materials due to its precision control over thickness, purity, and uniformity over large areas. In this study, Li-Sn-O and Li-Al-O thin films were synthesized by ALD as the anodes and solid-state electrolyte materials for thin films power sources. It was shown that prepared thin film anodes demonstrate exceptional cyclability at a fast discharge rate. Specific capacity decrease at the increase of discharge rate up to 40 times is less than 20 %. The present work reports results of films investigation with the use of spectral ellipsometry, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry.

This research was supported by the Russian Science Foundation grant (project No 18-73-10015).