Developing microcapsule membranes for the encapsulation of active ingredients of varying molecular weights

Over the last 5 years our research group has developed a range of microcapsule and particle designs adapted to the characteristics of the ingredient to be encapsulated. In this presentation, I will give examples of core-shell particles for use in electrophoretic display applications and semi-permeable and impermeable microcapsule shells for the encapsulation of large and small molecular weight species. I will first focus on our ability to use environment-responsive polymers to manage the permeability of the polymer shells built around emulsion droplets precursors and the potential to use membrane emulsification techniques to enable the manufacture of such emulsions on multi-litre scales. Subsequently, I will introduce a recently developed method for the preparation of metal-coated emulsion droplets for the long-term retention of small, volatile encapsulated species. I will indicate the key aspects of the synthesis method for such metal shells and demonstrate our ability to control the thickness of the shell deposited on the surface of the droplets and exemplify the release properties of these microcapsule

Controlled adsorption of metallic nanoparticles on polymeric microcapsules with a view to growing secondary continuous metal films

Small, volatile actives cannot be micro-encapsulated efficiently over the lifetime of a product using current encapsulation techniques. This is due to the inherent porosity of the polymeric membranes which are used as the capsule shell material. We have developed a method for preventing undesired loss of encapsulated actives which prevents loss of the core into ethanol over 90 days +. Oil core microcapsules are produced using oil-in-water emulsification followed by co-solvent extraction to precipitate a polymeric shell around the oil core. Metallic catalytic nanoparticles are then physically adsorbed onto the microcapsules and used to catalyse the growth of a continuous secondary metallic film via electroless deposition. It is important to have good control over the primary nanoparticle adsorption density which requires a good control over and understanding of the original nanoparticle (NP) synthesis. In this work we use Quartz crystal microbalance (QCM) and transmission electron microscopy (TEM) to demonstrate the ability to control NP adsorption densities by varying several parameters such as concentration of polymeric stabiliser used in the original NP dispersion synthesis and NP dispersion concentration. We show that NP films form in seconds and demonstrate good adsorption energies. We also discuss/explain the semi regular hexagonal packing of the NP cores we observe under TEM. Please click Additional Files below to see the full abstract

A Facile Method for Generating Worm-like Micelles with Controlled Lengths and Narrow Polydispersity

This work shows that highly uniform worm micelles formed by polymerisation induced self-assembly can be obtained via simple postsynthesis sonication. Importantly, this straightforward and versatile strategy yields exceptionally monodisperse worms with tunable aspect ratios ranging from 7.2 to 17.6 by simply changing the sonication time

Directed assembly of yeast cells into living yeastosomes by microbubble templating

We report the fabrication of yeastosomes - novel multicellular assemblies, which consist of a spherical monolayer of living yeast cells held together by colloid interactions. Our method is based on templating of microbubbles with cells coated with cationic polyelectrolyte and the layer-by-layer technique. We show the mechanism of formation of yeastosomes which involves a gradual dissolution of the air-cores and their infusion with water. We demonstrate that the cells remain viable in the yeastosome structures. Yeastosomes and similar structures may find applications in the development of novel symbiotic bio-structures, artificial multicellular organisms and in tissue engineering. The unusual structure of these multicellular assemblies resembles the primitive forms of multicellular species, like Volvox, and other algae and could be regarded as one possible stage of the evolutionary development of multicellularity. © 2010 The Royal Society of Chemistry

Specific ligation to double-stranded RNA for analysis of cellular RNA::RNA interactions

Double-stranded RNA (dsRNA) is formed in cells as intra- and intermolecular RNA interactions and is involved in a range of biological processes including RNA metabolism, RNA interference and translation control mediated by natural antisense RNA and microRNA. Despite this breadth of activities, few molecular tools are available to analyse dsRNA as native hybrids. We describe a two-step ligation method for enzymatic joining of dsRNA adaptors to any dsRNA molecule in its duplex form without a need for prior sequence or termini information. The method is specific for dsRNA and can ligate various adaptors to label, map or amplify dsRNA sequences. When combined with reverse transcription–polymerase chain reaction, the method is sensitive and can detect low nanomolar concentrations of dsRNA in total RNA. As examples, we mapped dsRNA/single-stranded RNA junctions within Escherichia coli hok mRNA and the human immunodeficiency virus TAR element using RNA from bacteria and mammalian cells

Reelin Controls Progenitor Cell Migration in the Healthy and Pathological Adult Mouse Brain

Understanding the signals that control migration of neural progenitor cells in the adult brain may provide new therapeutic opportunities. Reelin is best known for its role in regulating cell migration during brain development, but we now demonstrate a novel function for reelin in the injured adult brain. First, we show that Reelin is upregulated around lesions. Second, experimentally increasing Reelin expression levels in healthy mouse brain leads to a change in the migratory behavior of subventricular zone-derived progenitors, triggering them to leave the rostral migratory stream (RMS) to which they are normally restricted during their migration to the olfactory bulb. Third, we reveal that Reelin increases endogenous progenitor cell dispersal in periventricular structures independently of any chemoattraction but via cell detachment and chemokinetic action, and thereby potentiates spontaneous cell recruitment to demyelination lesions in the corpus callosum. Conversely, animals lacking Reelin signaling exhibit reduced endogenous progenitor recruitment at the lesion site. Altogether, these results demonstrate that beyond its known role during brain development, Reelin is a key player in post-lesional cell migration in the adult brain. Finally our findings provide proof of concept that allowing progenitors to escape from the RMS is a potential therapeutic approach to promote myelin repair

Poly(dimethylsiloxane)-Stabilized Polymer Particles from Radical Dispersion Polymerization in Nonpolar Solvent: Influence of Stabilizer Properties and Monomer Type

Particles used in electrophoretic display applications (EPD) must possess a number of specific properties ranging from stability in a nonaqueous solvent, high reflectivity, low polydispersity, and high charge density to name but a few. The manufacture of such particles is best carried out in the solvent of choice for the EPD. This opens up new interests in the study of nonaqueous dispersion polymerization methods, which deliver polymer particles suspended in low dielectric constant solvents. We explore in this article the use of a poly(dimethylsiloxane) macromonomer for the stabilization of poly(methyl methacrylate) polymer particles in dodecane, a typical solvent of choice for EPDs. The use of this stabilizer is significant for this method as it is directly soluble in the reaction medium as opposed to traditionally used poly(12-hydroxystearic acid)-based stabilizers. Additionally, the present study serves as a baseline for subsequent work, where nonaqueous dispersion polymerization will be used to create polymer particles encapsulating liquid droplets and solid pigment particles. In this article, the influence of the macromonomer molecular weight and concentration on the properties of the synthesized particles is studied. In addition, we investigate the possibility of synthesizing polymer particles from other monomers both as a comonomer for methyl methacrylate and as the only monomer in the process. The influence of macromonomer concentration is also studied throughout all experiments

Suppression of grasshopper sound production by nitric oxide-releasing neurons of the central complex

The central complex of acridid grasshoppers integrates sensory information pertinent to reproduction-related acoustic communication. Activation of nitric oxide (NO)/cyclic GMP-signaling by injection of NO donors into the central complex of restrained Chorthippus biguttulus females suppresses muscarine-stimulated sound production. In contrast, sound production is released by aminoguanidine (AG)-mediated inhibition of nitric oxide synthase (NOS) in the central body, suggesting a basal release of NO that suppresses singing in this situation. Using anti-citrulline immunocytochemistry to detect recent NO production, subtypes of columnar neurons with somata located in the pars intercerebralis and tangential neurons with somata in the ventro-median protocerebrum were distinctly labeled. Their arborizations in the central body upper division overlap with expression patterns for NOS and with the site of injection where NO donors suppress sound production. Systemic application of AG increases the responsiveness of unrestrained females to male calling songs. Identical treatment with the NOS inhibitor that increased male song-stimulated sound production in females induced a marked reduction of citrulline accumulation in central complex columnar and tangential neurons. We conclude that behavioral situations that are unfavorable for sound production (like being restrained) activate NOS-expressing central body neurons to release NO and elevate the behavioral threshold for sound production in female grasshoppers

Long non-coding RNAs and cancer: a new frontier of translational research?

Author manuscriptTiling array and novel sequencing technologies have made available the transcription profile of the entire human genome. However, the extent of transcription and the function of genetic elements that occur outside of protein-coding genes, particularly those involved in disease, are still a matter of debate. In this review, we focus on long non-coding RNAs (lncRNAs) that are involved in cancer. We define lncRNAs and present a cancer-oriented list of lncRNAs, list some tools (for example, public databases) that classify lncRNAs or that scan genome spans of interest to find whether known lncRNAs reside there, and describe some of the functions of lncRNAs and the possible genetic mechanisms that underlie lncRNA expression changes in cancer, as well as current and potential future applications of lncRNA research in the treatment of cancer.RS is supported as a fellow of the TALENTS Programme (7th R&D Framework Programme, Specific Programme: PEOPLE—Marie Curie Actions—COFUND). MIA is supported as a PhD fellow of the FCT (Fundação para a Ciência e Tecnologia), Portugal. GAC is supported as a fellow by The University of Texas MD Anderson Cancer Center Research Trust, as a research scholar by The University of Texas System Regents, and by the Chronic Lymphocytic Leukemia Global Research Foundation. Work in GAC’s laboratory is supported in part by the NIH/ NCI (CA135444); a Department of Defense Breast Cancer Idea Award; Developmental Research Awards from the Breast Cancer, Ovarian Cancer, Brain Cancer, Multiple Myeloma and Leukemia Specialized Programs of Research Excellence (SPORE) grants from the National Institutes of Health; a 2009 Seena Magowitz–Pancreatic Cancer Action Network AACR Pilot Grant; the Laura and John Arnold Foundation and the RGK Foundation