Search

Physiological stimulus-specific cargo release from nanoparticle carriers is a holy grail of drug delivery research. While the majority of such work is carried out in vitro with cell lines, widespread use of common mammalian model systems – mice and rats – is difficult due to the associated cost and regulatory restrictions. Here we use the inexpensive, easily reared, excellent genetic model system Drosophila melanogaster to test pH responsive cargo release from widely used mesoporous silica nanoparticles (MSNs) coated with pH sensitive polydopamine (PDA) and polyethylene glycol (PEG) polymers. We synthesized 650 ± 75 nm diameter PDA or PEG coated mesoporous silica nanoparticles loaded with a fluorescent dye and fed to individual adult flies. Subsequently, the passage of the particles were monitored through the fly gut. As in mammals, the fly intestine has multiple pH specific zones that are easily accessible for imaging and also genetic, biochemical or physiological manipulations. We observed that both the species of MSNs ruptured around the acidic (pH < 4.0) middle midgut of the flies. PEG coated particles showed sharper specificity of release in the acidic middle midgut of flies than the PDA coated ones and had less tendency to clump together. Our results clearly show that the Drosophila gut can be used as a model to test pH responsive biocompatible materials in vivo. Our work paves the way for greater use of Drosophila as an in vivo complete systemic model in drug delivery and smart materials research. It also suggests that such specific delivery of chemical/biological cargo can be exploited to study basic biology of the gut cells and their communication with other organs.

The effect of different buffers on in vitro release of PEG coated mesoporous silica nanoparticles is discussed in this work. We prepared Rhodamine loaded and PEG coated mesoporous silica nanoparticles (PEG coated RhB@MSNs) of ~ 650 nm size and studied their release behaviour for 5 hours in various buffer solutions (both Na+ and K+ versions) prepared by standard procedure. We observed that Rhodamine release was highest in the citrate buffer. A comparison of different buffer effects on the in vitro release reveals that it is crucial to choose the right buffer for determining the loaded cargo release in each pH zone (acidic, neutral and basic). Clearly, choosing the wrong combination of buffers for different pH zones would result in completely different interpretation of the release behaviour.

Very high surface area, self-assembled, highly crystalline mesoporous SrTiO3 (STO) thin films were developed for photoelectrochemical water splitting. Much improved performance of these mesoporous films compared to planar STO thin films and any other form of STO such as single crystal samples and nanostructures was demonstrated. The high performance resulted from very large surface area films and optimization of carrier concentration.

An original synthesis approach to prepare Cu 3 (BTC) 2 (BTC = benzene tricarboxylic acid) encapsulated Keggin phosphotungstic acid (HPW) [HPW/Cu 3 (BTC) 2 ] involving mixing of reagents at room temperature, quenching in liquid nitrogen and freeze drying has resulted in the formation of nanocrystals. The catalytic properties of the as-synthesized nanocrystalline materials were assessed using a model esterification reaction of acetic acid with 1-propanol. HPW/Cu 3 (BTC) 2 catalyst is partially dissolved in presence of acetic acid. In the esterification reaction the molar ratio of acetic acid to 1-propanol is critical. At high molar ratio of acetic acid to 1-propanol (1:2) leaching of Cu 2+ and HPW was observed. However, at low molar ratio of acetic acid to 1-propanol (1:40) leaching of Cu 2+ and HPW could be prevented and the catalyst was stable. Nanosized HPW/Cu 3 (BTC) 2 showed higher catalytic activity compared to micron-size Cu 3 (BTC) 2 (HKUST-1), ultrastable Y zeolite and micron-sized HPW/Cu 3 (BTC) 2 catalysts. The stability of the nanosized MOF catalyst in acidic reaction medium after esterification reaction was investigated by powder X-ray diffraction (PXRD), scanning electron microscope (SEM) and N 2 adsorption.

Low energy permanent magnetic fields (0.5T) applied in hydrodynamically turbulent conditions are observed to enhance self-assembly of materials with magnetically frustrated spin systems (spin-glass, spin-ice or spin–liquid). This effect is demonstrated for the crystallization of vanadium oxide nano-scrolls, manganese oxide nano-tubes and HKUST-1 type Cu3(BTC)2.3H2O Metal-Organic Framework. Crystallization of these spin systems involves spin coupling and alignment of initially isolated paramagnetic metal ions, respectively V(IV), Mn(IV) and Cu(II) into molecular precursor units that self-assemble to the final material. The electromagnetic and hydrodynamic forces applied during magnetohydrodynamic precursor treatment induce a long lived state of collective spin order by the resonant coupling of magnetic field and turbulent structured flow. This altered magnetic alignment in the molecular precursor units consequently assist the self-assembly process resulting in optimised morphology. The presented experimental setup enables precise control over the magnetohydrodynamic conditions during synthesis, essential for elucidation the detailed mechanism. ispartof: Advanced Materials vol:26 issue:30 pages:5173-5178 ispartof: location:Germany status: published

A new concept of luminescent host-guest materials was developed by introduction of Eu3+ into COK-16, a HKUST-1 type hybrid metal-organic framework (MOF) with cation exchange properties. In Eu@COK-16, the luminescent ion resides in the pore system of the MOF. The luminescent properties of Eu@COK-16 have been studied based on excitation and emission, allowing analysis of intramolecular energy-transfer processes from the COK-16 host to the exchanged Eu3+ ions. Both, the framework trimesate (BTC) and encapsulated [PW12O40] 3- ions contribute to energy transfer. Since the antenna molecules (BTC) are part of the framework structure and [PW12O40]3- ions only partly occupy one of the three types of cavities in the structure, a large fraction of the pore volume in this host sensitized luminescent MOF remains available for catalysis applications or adsorption of additional sensitizing molecules. The material structure was determined from a combination of elemental analysis, XAS, XRD, electron and luminescence spectroscopy. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: The accepted version of this article will be made freely available in the Chemical Sciences Article Repository after a 12 month embargo period history: Received 26 March 2014; Accepted 9 May 2014; Accepted Manuscript published 9 May 2014; Advance Article published 30 May 2014; Version of Record published 19 August 2014 ispartof: Dalton Transactions vol:43 issue:36 pages:13480-13484 ispartof: location:England status: published

The solvent dependent solubility of HKUST-1 metal–organic framework (MOF) with encapsulated Keggin 12-tungstophosphoric acid (HPW@Cu3(BTC)2) was exploited to liberate homogeneous heteropolyacid catalyst in a reaction medium and to recover the catalyst by encapsulation in the MOF upon addition of hexane. The application of the new Keggin type heteropolyacid catalyst recovery concept was demonstrated in the esterification of acetic acid with 1-propanol and salicylic acid with ethanol.

Cu-3(BTC)(2) with an incorporated Keggin polyoxometalate was demonstrated to be stable under steaming conditions up to 483 K, while the isostructural HKUST-1 degrades and transforms into [Cu2OH(BTC)(H2O)](n)center dot 2nH(2)O from 343 K onwards. ispartof: Chemical Communications vol:47 issue:28 pages:8037-8039 ispartof: location:England status: published