Janos B. Nagy

PEG-templated mesoporous silica nanoparticles exclusively target cancer cells

Mesoporous silica nanoparticles (MSNs) have been proposed as DNA and drug delivery carriers, as well as efficient tools for fluorescent cell tracking. The major limitation is that MSNs enter cells regardless of a target-specific functionalization. Here we show that non functionalized MSNs, synthesized using a PEG surfactant-based interfacial synthesis procedure, do not enter cells, while a highly specific, receptor mediated, cellular internalization of folic acid (FOL) grafted MSNs (MSN-FOL), occurs exclusively in folate receptor (FR) expressing cells. Neither the classical clathrin pathway nor macropinocytosis is involved in the MSN endocytic process, while fluorescent MSNs (MSN-FITC) enter cells through aspecific, caveolae-mediated, endocytosis. Moreover, internalized particles seem to be mostly exocytosed from cells within 96 h. Finally, cisplatin (Cp) loaded MSN-FOL were tested on cancerous FR-positive (HeLa) or normal FR-negative (HEK293) cells. A strong growth arrest was observed only in HeLa cells treated with MSN-FOL-Cp. The results presented here show that our mesoporous nanoparticles do not enter cells unless opportunely functionalized, suggesting that they could represent a promising vehicle for drug targeting applications.

Formation of MFI crystalline zeosilites from fluoride-containing silicate gels

Abstract Silicalite-1 samples are readily prepared at 170°C from F− containing gels of composition a HF-b NaF-cNaCI-d TPABr-e TPAOH-10 SiO2-330 H2O with a + b = 1 (constant F− content) and d + e = 1.25 (constant TPA content). Large crystals of ca. 450 μm were found in some of the systems. The rate of length increase was proportional to the pH of the initial gels. For pH ≤ 2, no crystallization occurred. The aspect ratio (length width) of the crystals was found to increase as with crystal growth. Some 2 F/u.c. are incorporated into the products.

From hydrophobic to hydrophilic polyvinylidenefluoride (PVDF) membranes by gaining new insight into material's properties

This work provides an easy and versatile strategy to manufacture novel polyvinylidenefluoride (PVDF) membranes by solution casting and phase separation techniques displaying tailored physicochemical and microstructural features depending on the opportune combination of functionalization by blending chemical additives (multiwalled carbon nanotubes, MWCNTs) and manufacturing procedure. The systematic study of the effect of (i) polymer concentration, (ii) use of pore forming additives (LiCl), and (iii) type and concentration of MWCNTs, on the PVDF crystalline composition and membrane microstructure, highlights the strong relationships of these parameters with the wettability, fouling and transport attributes of the formed membranes. The results provide the key to discriminate membrane preparation conditions favoring hydrophilic, low fouling, and highly selective PVDF–MWCNTs membranes, for water-treatment applications in pressure-driven membrane operations, from conditions favoring the formation of hydrophobic and waterproof membranes, to be used in the membrane contactors field. Also, they open exciting perspectives for a more effective development of PVDF-based nanostructured membranes for advanced separations based on a comprehensive investigation and understanding of materials properties.

Evaluation and comparison of the ammonia adsorption capacity of titanosilicates ETS-4 and ETS-10 and aluminotitanosilicates ETAS-4 and ETAS-10

Due to the well-known adsorption properties of titanosilicates (ETS-4 and ETS-10) and aluminotitanosilicates (ETAS-4 and ETAS-10), it was considered particularly interesting to investigate their efficiency in adsorbing ammonia from a gaseous phase. Prior to testing their adsorption capacity, materials thus synthesized have been analyzed by appropriate characterization techniques. Afterward, the adsorption capacity of microporous materials toward ammonia has been evaluated by measuring the corresponding adsorption isotherms through batch experiments. Experimental measurements were best fitted by a linear constant relationship. From the experimental results, high adsorption capacity values were found for all microporous materials in correspondence of high gaseous ammonia concentration values. In particular, ETAS-10 attained the maximum value of adsorption potential, equal to 7.647xa0mg of NH3 per g of material. This was likely due to the presence of the acid site linked to the Al atom in its structure with respect to the ETS structure. In addition to that the greater pore size characterizing the phase 10 compared to phase 4 might have entailed a more selective sorption of ammonia molecule. Overall, both titanosilicates and aluminotitanosilicates showed a great adsorption potential toward ammonia. However, materials achieved their maximum capacity at high pollutant loading.

Kinetic and thermodynamic effects during the adsorption of heavy metals on ETS-4 and ETS-10 microporous materials

ETS-10 and ETS-4 microporous materials were synthesized in presence of tetralkylammonium (TAA) ions from gels of molar composition w Na2O–0.10 TAABr–1 SiO2–z TiO2–0.6 KF–1.28 w HCl–39.5 H2O with TAAxa0=xa0tetramethyl-, tetraethyl-, tetrapropyl- and tetrabutyl-ammonium in hydrothermal conditions at 190xa0°C. The TAA ions enter the microporous channel of ETS-10, while they cannot penetrate the void spaces of ETS-4. The ETS-10 microcrystals are all cubic, while the ETS-4 crystals are laminar and irregular. The microporous volume of ETS-10 is equal to 0.11–0.13xa0cm3xa0g−1, the microporous volume of ETS-4 is very small, 0.002–0.008xa0cm3xa0g−1. The ion exchange of Cs+, Cd++, Pb++ and Hg++ ions using their corresponding nitrates show kinetic effects, i.e. the efficiency of ion exchange is higher at 1 than 2xa0h, the thermodynamic equilibrium. For ETS-10, partially dehydrated cations intervene in the ion exchange, while for ETS-4 well dehydrated ions can only penetrate the available pores.

Physico-chemical characterisation of zirconium-based self-bonded ETS-4 pellets

This paper reports a study of ETS-4 based self-bonded pellets, with several amounts of Zr moles in initial gel. The following gel composition is used: xNa2O–0.6KF–1.28xHCl–yZrO2–0.2TiO2–1.49SiO2–39.5H2O with 0.5xa0≤xa0xxa0≤xa02.5 and 0.015xa0≤xa0yxa0≤xa00.12. The characterisation of obtained samples is carried out by XRD, thermal analysis, EDX and SEM. The results point out the possibility to synthesise ETS-4 zeotype with Zr in self-bonded pellets form. The importance of the amount and composition of the amorphous phase is underlined as binder of the ETS-4 crystals. Its amount is bigger at the outer face of the pellets, showing that the crystallisation occurred from the inner to the external face. Zirconium replaces titanium in the structure and its presence reinforces the mechanical resistance of the pellets.

The role of carbon nanotubes and cobalt in the synthesis of pellets of titanium silicates

In the present work self-bonded pellets of Engelhard Titaniun Silicates, ETS-4 and ETS-10, containing cobalt and carbon nanotubes, were synthesized by hydrothermal synthesis at 190u2009°C, from gels of the initial composition x–Na2O–0.2TiO2–0.6KF–(1.28xu2009−u20092y)HCl–2yHNO3–1.49SiO2–yCoO–39.5H2O, with x equal to 0.8; 1; 1.5; 2.5 mol and y equal to 0.015; 0.03; 0.06; 0.1. To the initial gels were then added different weight percentages of carbon nanotubes compared to the dry gel. The obtained pellets were characterized by X-ray diffraction analysis, thermal analysis (TG, DTG, DSC), tests of mechanical resistance to compression and nuclear magnetic resonance.