Mesoporous amine functionalized SiO2 supported Cu nanocatalyst and a kinetic-mechanistic degradation study of azo dyes

Mesoporous Fe3O4/SiO2/poly(2-carboxyethyl acrylate) composite polymer particles for pH-responsive loading and targeted release of bioactive molecules

pH-responsive polymer microspheres undergoing reversible changes in their surface properties have been proved useful for drug delivery to targeted sites. This paper is aimed at preparing pH-responsive polymer-modified magnetic mesoporous SiO2 particles. First, mesoporous magnetic (Fe3O4) core-particles are prepared using a one-pot solvothermal method. Then, magnetic Fe3O4 particles are covered with a C[double bond, length as m-dash]C functional mesoporous SiO2 layer before seeded emulsion polymerization of 2-carboxyethyl acrylate (2-CEA). The composite polymer particles are named Fe3O4/SiO2/P(2-CEA). The average diameters of the Fe3O4 core and Fe3O4/SiO2/P(2-CEA) composite polymer particles are 414 and 595 nm, respectively. The mesoporous (pore diameter = 3.41 nm) structure of Fe3O4/SiO2/P(2-CEA) composite polymer particles is confirmed from Brunauer-Emmett-Teller (BET) surface analysis. The synthesized Fe3O4/SiO2/P(2-CEA) composite polymer exhibited pH-dependent changes in volume and surface charge density due to deprotonation of the carboxyl group under alkaline pH conditions. The change in the surface properties of Fe3O4/SiO2/P(2-CEA) composite polymer particles following pH change is confirmed from the pH-dependent sorption of cationic methylene blue (MB) and anionic methyl orange (MO) dye molecules. The opening of the pH-responsive P(2-CEA) gate valve at pH 10.0 allowed the release of loaded vancomycin up to 99% after 165 min and p-acetamido phenol (p-AP) up to 46% after 225 min. Comparatively, the amount of release is lower at pH 8.0 but still suitable for drug delivery applications. These results suggested that the mesoporous Fe3O4/SiO2 composite seed acted as a microcapsule, while P(2-CEA) functioned as a gate valve across the porous channel. The prepared composite polymer can therefore be useful for treating intestine/colon cancer, where the pH is comparatively alkaline.

Transformation of used aluminium foil food container into AlOOH nanoflakes with high catalytic activity in anionic azo dye reduction

Synthesis of aluminium-based nanomaterials from aluminium-waste has received huge attention in current scientific research. Herein, an attempt was made to convert aluminium foil food container into aluminium oxyhydroxide (AlOOH) nanoparticles by a precipitation method. X-ray diffraction (XRD), spectroscopic and electron microscopic studies were employed to characterize impure AlOOH (containing sodium chloride, NaCl) and pure AlOOH samples. The band gap (E_g) of AlOOH nanoparticles was found to be 4.5 eV. The catalytic potential of AlOOH samples was evaluated using reduction of methyl orange (MO) and Eriochrome black T (EBT) dyes. Impure AlOOH nanoparticles could reduce 99.8% of MO and EBT dye within 4 min and 3 min respectively. Effect of the AlOOH dosage and NaBH₄ concentration on catalytic reduction was determined. Used aluminium foil food container-derived AlOOH nanoparticles will become a low-cost and sustainable catalyst in the catalytic treatment of azo dye contaminated waters.

Silica-Supported Assemblage of CuII Ions with Carbon Dots for Self-Boosting and Glutathione-Induced ROS Generation

The present work introduces coordinative binding of CuII ions with both amino-functionalized silica nanoparticles (SNs) and green-emitting carbon dots (CDs) as the pregrequisite for the CuII-assisted self-assembly of the CDs at the surface of the SNs. The produced composite SNs exhibit stable in time stimuli-responsive green fluorescence derived from the CuII-assisted assemblage of CDs. The fluorescence response of the composite SNs is sensitive to the complex formation with glutathione (GSH), enabling them to detect it with the lower limit of detection of 0.15 μM. The spin-trap-facilitated electron spin resonance technique indicated that the composite SNs are capable of self-boosting generation of ROS due to CuII→CuI reduction by carbon in low oxidation states as a part of the CDs. The intensity of the ESR signals is enhanced under the heating to 38 °C. The intensity is suppressed at the GSH concentration of 0.35 mM but is enhanced at 1.0 mM of glutathione, while it is suppressed once more at the highest intracellular concentration level of GSH (10 mM). These tendencies reveal the concentrations optimal for the scavenger or reductive potential of GSH. Flow cytometry and fluorescence and confocal microscopy methods revealed efficient cell internalization of SNs-NH2-CuII-CDs comparable with that of “free” CDs.

Impact of mesoporous SiO2 support for Ni/polypyrrole nanocomposite particles on their capacitive performance

The inclusion of mesoporous H2N-SiO2 support in H2N-SiO2/Ni/PPy nanocomposite particles improved their electrochemical performance, suitable for energy storage devices.