Electrospun pH-sensitive core–shell polymer nanocomposites fabricated using a tri-axial process

A modified tri-axial electrospinning process was developed for the generation of a new type of pH-sensitive polymer/lipid nanocomposite. The systems produced are able to promote both dissolution and permeation of a model poorly water-soluble drug. First, we show that it is possible to run a tri-axial process with only one of the three fluids being electrospinnable. Using an electrospinnable middle fluid of Eudragit S100 (ES100) with pure ethanol as the outer solvent and an unspinnable lecithin-diclofenac sodium (PL–DS) core solution, nanofibers with linear morphology and clear core/shell structures can be fabricated continuously and smoothly. X-ray diffraction proved that these nanofibers are structural nanocomposites with the drug present in an amorphous state. In vitro dissolution tests demonstrated that the formulations could preclude release in acidic conditions, and that the drug was released from the fibers in two successive steps at neutral pH. The first step is the dissolution of the shell ES100 and the conversion of the core PL–DS into sub-micron sized particles. This frees some DS into solution, and later the remaining DS is gradually released from the PL–DS particles through diffusion. Ex vivo permeation results showed that the composite nanofibers give a more than twofold uplift in the amount of DS passing through the colonic membrane as compared to pure DS; 74% of the transmitted drug was in the form of PL–DS particles. The new tri-axial electrospinning process developed in this work provides a platform to fabricate structural nanomaterials, and the core–shell polymer-PL nanocomposites we have produced have significant potential applications for oral colon-targeted drug delivery.

Managing the core executive

In the build up to general elections there is invariably a wealth of discourse on constitutional and transitional issues and even on the efficiency and cost-effectiveness of the civil service, but rarely is there any debate on the manner in which politicians manage the government machine. This article seeks to address this deficiency. It examines the operational factors common to the core executive, assesses the problems usually associated with the government as an organization and reviews alternative solutions. Finally, it offers managerially oriented advice, reasoning that it is the role of policy analysts to prescribe and that it is irresponsible to ignore this function. it is clearly emphasized that management solutions are not synonymous with business solutions. The article draws on universal principles of management, seeking to avoid normative suggestions and concentrating instead on practical considerations. Those considerations include personnel selection, collective responsibility, leadership style, organizational structure and team mentality. The conclusion is that strong managerially based leadership should not be dismissed as incompatible with the political constraints placed upon Prime Ministers but rather it should e the predominant impulse.