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.

Orizzonte Cina: le sfide dell’urbanizzazione al 2020

A metà marzo 2014 il governo cinese ha reso pubblico un documento di indirizzo per le politiche urbane che potrebbe determinare una correzione di rotta nell’attuale processo di rapida urbanizzazione che il paese attraversa ormai da qualche decennio. Si tratta del National New-Type Urbanization Plan – Guojia Xinxing Chengzhenhua Guihua 2014-2020 (SCPRC, 2014), ovvero il primo piano nazionale per un nuovo modello people-centred di urbanizzazione del paese. Compito di questo saggio breve è quello di riflettere sulle sfide future del processo di urbanizzazione cinese che tale documento lascia intravedere, alla luce di una serie di nodi irrisolti del processo non finito di opening-up della società cinese al modello capitalista occidentale.