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Yue Zhang,1 Rui Zhang,1 Upulitha Eranka Illangakoon,1,2 Anthony Henry Harker,3 Christopher Thrasivoulou,4 Maryam Parhizkar,1,2 Mohan Edirisinghe,1 CJ Luo1 1Department of Mechanical Engineering, University College London, London WC1E 7JE, UK; 2UCL School of Pharmacy, University College London, London WC1N 1AX, UK; 3Department of Physics & Astronomy, University College London, London WC1E 6BT, UK; 4Cell & Developmental Biology, Division of Biosciences, University College London, London WC1E 6BT, UKCorrespondence: CJ Luo Tel +44 20 7679 3942Email chaojie.luo@ucl.ac.ukHypothesis: Developing oral formulations to enable effective release of poorly water-soluble drugs like progesterone is a major challenge in pharmaceutics. Coaxial electrospray can generate drug-loaded nanoparticles of strategic compositions and configurations to enhance physiological dissolution and bioavailability of poorly water-soluble drug progesterone.Experiments: Six formulations comprising nanoparticles encapsulating progesterone in different poly(lactide-co-glycolide) (PLGA) matrix configurations and compositions were fabricated and characterized in terms of morphology, molecular crystallinity, drug encapsulation efficiency and release behavior.Findings: A protocol of fabrication conditions to achieve 100% drug encapsulation efficiency in nanoparticles was developed. Scanning electron microscopy shows smooth and spherical morphology of 472.1± 54.8 to 588.0± 92.1 nm in diameter. Multiphoton Airyscan super-resolution confocal microscopy revealed core-shell nanoparticle configuration. Fourier transform infrared spectroscopy confirmed presence of PLGA and progesterone in all formulations. Diffractometry indicated amorphous state of the encapsulated drug. UV-vis spectroscopy showed drug release increased with hydrophilic copolymer glycolide ratio while core-shell formulations with progesterone co-dissolved in PLGA core exhibited enhanced release over five hours at 79.9± 1.4% and 70.7± 3.5% for LA:GA 50:50 and 75:25 in comparison with pure progesterone without polymer matrix in the core at 67.0± 1.7% and 57.5± 2.8%, respectively. Computational modeling showed good agreement with the experimental drug release behavior in vitro.Keywords: core-shell nanoparticles, oral formulations, bioavailability, drug delivery, poorly water-soluble drugs, progesterone, poly, lactide-co-glycolide, PLGA, copolymer, coaxial electrospray

There is a critical clinical need for small-diameter bypass grafts, with applications involved in the coronary artery and lower limb. Commercially available materials give rise to unfavorable responses when in contact with blood and subjected to low-flow hemodynamics and, thus, are nonideal as small-diameter bypass grafts. Optimizing the mechanical properties to match both the native artery and the graft surfaces has received keen attention. Endothelialization of bypass grafts is considered a protective mechanism where the biochemicals produced from endothelial cells exert a range of favorable responses, including antithrombotic, noninflammatory responses and inhibition of intimal hyperplasia. In situ endothelialization is most desirable. Nanotechnology approaches facilitate all aspects of endothelialization, including endothelial progenitor cell mobilization, migration, adhesion, proliferation and differentiation. 'Surface nanoarchitecturing mechanisms', which mimic the natural extracellular matrix to optimize endothelial progenitor cell interaction and controlled delivery of various factors in the form of nanoparticles, which can be combined with gene therapy, are of keen interest. This article discusses the development of bypass grafts, focusing on the optimization of the biological properties of mechanically suitable grafts.

A polysilane with a C-to-Si ratio of 6.0 was pyrolysed to produce an amorphous matrix (source powder), which was heated further to obtain different products. These polysilane-derived samples were studied using X-ray diffraction, Raman spectroscopy, solid-state magic-angle-spinning nuclear magnetic resonance and transmission electron microscopy. The source powder is a hydrogenated matrix composed of free carbon, random SiC4 sites and trace SiCO species. Pyrolysis of the source powder leads to the nucleation and growth of SiC and progressive organization of free carbon. SiC forms at 1100°C and fast growth appears at 1700°C accompanied by obvious weight loss. SiC decomposition also occurs at high temperatures, which leads to the formation of relatively well-organized carbon. The structural evolution is discussed and compared with the literature.

Solid freeforming is a genus of manufacturing processes in which three-dimensional objects are assembled by point, line or planar addition of material. Confining surfaces, such as mould or die walls, are absent. The shape is built by adding rather than subtracting material. Solid freeforming has come to be computer controlled over the past two decades in parallel with the expansion of the data handling capacity of personal computers. It can be used for rapid prototyping but also offers mass production pathways in which individuation is possible. It is of particular interest for the creation, inter alia, of prosthetics that can be individually built from modified X-ray computed tomographic data. Some routes offer the additional capability to control, from the computer, not just the shape but also the composition throughout a component. Thus, three-dimensional functional gradients in multiphase ordered composites become possible. The concept of 'design' now embraces the integration of the spatial va...

A novel computer-controlled method of depositing ceramic droplets, according to a pre-determined architecture is described. A 21 vol% alumina suspension flowing through a nozzle was subjected to electrostatic atomization in the cone-jet mode at different applied voltages. By using a point-like ground electrode the resulting spray was focused and printed on a substrate placed between the nozzle and the ground electrode. The substrate was moved with the aid of a 2-axis computer controlled stepper motor driven system which enabled the forming of different ceramic architectures. As an example, the word CERAMIC was printed. At an applied voltage of 10 kV, droplet relics in the print were in the size range 30–60 µm.

Silicon carbide (SiC) coatings and films have been prepared for the first time by electrostatic atomization of a solution of a polymeric precursor and deposition on to alumina and zirconia substrates. The deposits were heated to 1300 degreesC prior to their examination by X-ray energy-dispersive spectra and selected-area diffraction in scanning and transmission electron microscopes. The results show that these coatings and films are crystalline and probably consist of co-existing alpha -SiC and beta -SiC phases.

A new method that can be used for the synthesis of SiC-Si3N4 composites using a single polymeric precursor is described. A co-polysilane-cyclodisilazane precursor was prepared and characterized. Subsequently, it was heated to 1650oC to form SiC and Si3N4 simultaneously. The ceramic products have been characterized using X-ray diffraction and secondary-ion mass spectrometry.

A mechanically-ground doped ceria powder with 10 mol% SmO1.5 was incorporated by high shear mixing into a polystyrene-based organic vehicle. At 45 vol.% solids loading, the suspension could be subjected to elongational flow processes and was prepared in thin film form by tubular film blowing; the manufacturing process used to make thermoplastic polymer film. This provides a potential route for the manufacture of ceramic electrolyte plates for solid oxide fuel cells for which doped ceria is a candidate material. After sintering, film thickness down to 50 μm could be achieved with relative densities >95%. The main problem with this route is in retaining flatness of films of less than 100 μm in thickness during sintering; a problem which exists whatever the particle assembly route.

Several polymer processing techniques, such as extrusion, injection molding, vacuum forming, blow molding and film blowing can be used to mass produce complex shape components from engineering ceramic powders with a high degree of dimensional accuracy and good process control. In these processes the ceramic powder is dispersed in one or several additive(s), usually polymeric. These additives are only useful as the vehicle of the forming process and therefore have to be removed subsequently whilst retaining the architecture of the ceramic particle assembly which is densified by the conventional process of sintering. The removal of the additives, usually referred to as the debinding stage, is carried out usually by slow heating (thermolysis) to about 400°C. This is a crucial and a difficult stage as many unforgiving strength-limiting defects could appear during thermolysis. Defects which occur during thermolysis are difficult to prevent because these can be caused by several factors. Several variab...

In many ceramic processing routes organic additions are made which are later removed from the particle assembly before firing. These include residues from the manufacture of chemically derived powders, pressing aids or lubricants used in compaction processes, dispersants and binders added to casting suspensions, and organic vehicles which convey ceramic particles in plastic forming processes such as injection moulding. In many cases, large organic molecules are required to move in the pore structure of ultrafine powder assemblies so that a range of flow regimes, e.g. Knudsen, intermediate, molecular, and viscous, have to be considered. The quantitative evaluation of gas flow in such systems is used to evaluate the pressure that develops during ceramic processing and the viability of heating schedules. This review describes the procedures that can be used for the determination of transport coefficients in such systems and highlights the ways in which simplification can be achieved by judicious appr...

A Polypropylene based organic vehicle was used to injection mould commercial Purity aluminium powder. The test bars produced were heated, according to near optimum temperature-time schedules, in both static air and flowing nitrogen to remove the organic vehicle. Heating was interrupted at different temperatures to measure shrinkage and strength of the test bars. Shrinkage caused by the removal of organic vehicle increases the volume percentage of aluminium in the test bars and this results in an increase in their strength but the packing efficiency attained is well below the maximum value.

(2005). A fresh beginning. Advances in Applied Ceramics: Vol. 104, Cellular ceramics, pp. 1-1.