Compressed antisolvent process for polymer coating of drug-loaded aerogel nanoparticles

 Nerea Murillo-Cremaes, Pascal Subra-Paternault*, Javier Saurina, Anna Roig*, Concepción Domingo*

 Colloid and Polymer Science (2014) DOI 10.1007/s00396-014-3260-6, published on-line June 2014

The overall objective of the present work was to modulate the release behavior of drug-impregnated silica particles from almost instantaneous release to a more sustained delivery, prolonged during several hours. Triflusal was chosen as a model drug of the low biodisponibility type. The process is based in the coating with Eudragit® RL 100 polymer of aerogel-like silica particles. Materials were processed in compressed CO2 by using the batch and semicontinuous antisolvent coating methods. Triflusal release from Eudragit-coated aerogel particles was compared with the dissolution profiles recorded for pristine triflusal and for triflusal impregnated into polymer or non-coated aerogel particles. The release profiles were determined by high-performance liquid chromatography. Eudragit-coated materials presented an intermediate drug-release rate between this obtained for the infused polymer and that of the impregnated aerogel particles. Diffusion-governed mechanisms were found for the studied aerogel-like systems after fitting the release data to both Korsmeyer-Peppas and Baker-Lonsdale equations. The major advantage of the compressed CO2 antisolvent approach was the ability to physically coat very fine particles. Moreover, the stability of the studied drug in water increased after coating.

Rapid synthesis of water-dispersible superparamagnetic iron oxide
nanoparticles by a microwave-assisted route for safe labeling of
endothelial progenitor cells

Elisa Carenza, Verónica Barceló, Anna Morancho, Joan Montaner, Anna Rosell*, Anna Roig*

Acta-Biomaterialia 10 (2014) pp. 3775-3785) DOI: 10.1016/j.actbio.2014.04.01

Highly crystalline citrate coated iron oxide superparamagnetic nanoparticles readily dispersible in water were fabricated by an extremely fast microwave-assisted route, the uptake of magnetic nanoparticles by endothelial cells is further investigated. Nanoparticles form large aggregates when added to complete endothelial cell media. The size of aggregates was controlled by adjusting the ionic strength of the media. The internalization of nanoparticles into endothelial cells was then investigated by transmission electron microscopy, magnetometry and chemical analysis together with cell viability assays. Interestingly, a seven-fold more efficient uptake was found for systems with larger nanoparticle aggregates which also showed significantly higher magnetic resonance imaging effectiveness without compromising cell viability and functionality. We are thus presenting an example of a straightforward microwave synthesis of citrate-coated iron oxide nanoparticles for safe endothelial progenitor cell labeling and good magnetic resonance cell imaging with potential application in magnetic cell guiding and in vivo cell tracking.

Elisa Carenza defended her PhD Thesis on the 11th of July,  the jury formed by

Origami magnetic cellulose: controlled magnetic fraction and patterning of flexible bacterial cellulose

Muling Zeng, Anna Laromaine,* Wenqian Feng, Pavel A. Levkin and Anna Roig*

Journal of Materials Chemistry C, (2014)  DOI: 10.1039/c4tc00787e

Cellulose of microbial origin is becoming a commodity structural material with promise in a myriad of potential applications. The range of applications can be further enlarged by nanocomposites that provide additional functional properties to the bacterial cellulose. Here, bacterial cellulose films nanocomposited with iron oxide nanoparticles are fabricated by microwave-assisted thermal decomposition within only 5 min and without the need for any post-synthetic treatment. Control over the magnetic fraction (from 4 to 40 wt%) is achieved either by employing undried cellulose, cellulose films dried by different methods, or by adjusting the initial iron precursor concentration. Structural, magnetic, and mechanical characterization of the materials is included. All films react easily to an external magnetic field, present a superparamagnetic behavior at room temperature, and are flexible enough to be bent and folded into complex origami shapes. Finally, preliminary results on a strategy to selectively pattern bacterial cellulose with nanoparticles are presented that pave the way to new uses of functional bacterial cellulose.

Multiferroic Iron Oxide Thin Films at Room Temperature
Martí Gich ,* Ignasi Fina , Alessio Morelli , Florencio Sánchez , Marin Alexe ,
Jaume Gàzquez , Josep Fontcuberta , and Anna Roig

Advanced Materials Volume 26, Issue 27, pages 4645–4652, July 16, 2014, DOI: 10.1002/adma.201400990

Multiferroic behaviour at room temperature is demonstrated in ε-Fe₂O₃. The simple composition of this new ferromagnetic ferroelectric oxide and the discovery of a robust path for its thin film growth by using suitable seed layers may boost the exploitation of ε-Fe₂O₃ in novel devices.

Enhanced stability of superparamagnetic iron oxide nanoparticles in biological media using a pH adjusted-BSA adsorption protocol
Si-Ming Yu • Anna Laromaine* • Anna Roig*
J Nanopart Res (2014) 16:2484, DOI 10.1007/s11051-014-2484-1

SPIONs were  synthesized by  a facile, rapid  and cost  effective  microwave  assisted  method. Then,  a modified pH  adjusted-BSA  adsorption  protocol and an  addition of excess  trisodium citrate dihydrate (Na₃Cit) were used to enhance their stability in the media. The BSA adsorption protocol showed great efficiency in stabilizing the dispersed state of both SPIONs in the tested media, while the addition of excess Na₃Cit showed limit effect. The formed BSA layer on SPIONs could be imaged by negative staining TEM, and revealed by Cryo-TEM, FTIR, DLS and the zeta potential measurements. Results indicated that BSA forms a monolayer of a thickness of about 3 ± 1 nm and BSA interacts with SPIONs coating rather than by replacing them and interacting directly with the SPIONs surface. This synthetic method and stabilization protocol offer a general methodology to obtain SPIONs with a variety of surfactants, stable in different biological media in few minutes.