Design and fabrication of novel polymeric biodegradable stents for small caliber blood vessels by computer-aided wet-spinning.

Biodegradable stents have emerged as one of the most promising approaches in obstructive cardiovascular disease treatment due to their potential in providing mechanical support while it is needed and then leaving behind only the healed natural vessel. The aim of this study was to develop polymeric biodegradable stents for application in small caliber blood vessels. Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBHHx), a renewable microbial aliphatic polyester, and poly(ε-caprolactone), a synthetic polyester approved by the US Food and Drug Administration for different biomedical applications, were investigated as suitable polymers for stent development. A novel manufacturing approach based on computer-aided wet-spinning of a polymeric solution was developed to fabricate polymeric stents. By tuning the fabrication parameters, it was possible to develop stents with different morphological characteristics (e.g. pore size and wall thickness). Thermal analysis results suggested that material processing did not cause changes in the molecular structure of the polymers. PHBHHx stents demonstrated great radial elasticity while PCL stents showed higher axial and radial mechanical strength. The developed stents resulted able to sustain proliferation of human umbilical vein endothelial cells within two weeks of in vitro culture and they showed excellent results in terms of thromboresistivity when in contact with human blood.

Study on the impregnation of archaeological waterlogged wood with consolidation treatments using synchrotron radiation microtomography.

In favourable conditions of low temperature and low oxygen concentration, archaeological waterlogged wooden artefacts, such as shipwrecks, can survive with a good state of preservation. Nevertheless, anaerobic bacteria can considerably degrade waterlogged wooden objects with a significant loss in polysaccharidic components. Due to these decay processes, wood porosity and water content increase under ageing. In such conditions, the conservation treatments of archaeological wooden artefacts often involve the replacement of water with substances which fill the cavities and help to prevent collapse and stress during drying. The treatments are very often expensive and technically difficult, and their effectiveness very much depends on the chemical and physical characteristics of the substances used for impregnation. Also important are the degree of cavity-filling, penetration depth and distribution in the structure of the wood. In this study, the distribution in wood cavities of some mixtures based on polyethylene glycols and colophony, used for the conservation of waterlogged archaeological wood, was investigated using synchrotron radiation X-ray computed microtomography (SR-microCT). This non-destructive imaging technique was useful for the study of the degraded waterlogged wood and enabled us to visualise the morphology of the wood and the distribution of the materials used in the wood treatments. The study has shown how deposition is strictly related to the dimension of the wooden cavities. The work is currently proceeding with the comparison of synchrotron observations with the data of the solutions viscosity and with those of the properties imparted to the wood by the treatments.