Recently, interest has focused on hepatocytes’ implantation to provide end stage liver failure patients with a temporary support until spontaneous recovery or a suitable donor becomes available. To avoid cell damage and use of an immunosuppressive treatment, hepatic cells could be implanted after encapsulation in a porous biomaterial of bead or capsule shape. The aim of this study was to compare the production and the physical properties of the beads, together with some hepatic cell functions, resulting from the use of different material combinations for cell microencapsulation: alginate alone or combined with type I collagen with or without poly-L-lysine and alginate coatings. Collagen and poly-L-lysine increased the bead mechanical resistance but lowered the mass transfer kinetics of vitamin B12. Proliferation of encapsulated HepG2/C3A cells was shown to be improved in alginate-collagen beads. Finally, when the beads were subcutaneously implanted in mice, the inflammatory response was reduced in the case of alginate mixed with collagen. This in vitro and in vivo study clearly outlines, based on a systematic comparison, the necessity of compromising between material physical properties (mechanical stability and porosity) and cell behavior (viability, proliferation, functionalities) to define optima hepatic cell microencapsulation conditions before implantation.
New approaches of packaging of integrated circuits show the need of flexible and cheap materials. Polymers offer possibilities regarding the flexibility and mass production opportunities in terms of roll to roll production for foil technology based substrates, as well the use of injection molding for more complex three-dimensional housings, circuits, electronics and even sensor actor arrays (2,3,4,5). A new manufacturing strategy to produce pre-structured wafer substrates which can be used for electroplating processes without the need of photolithography is developed. Important process steps are injection molding, sputter deposition, electroplating, chemical mechanical polishing and micro end milling. These manufacturing processes are not in the need of clean room technology and abstain from any lithography processes. Therefore this idea can be interesting for low cost production systems which exclude expensive clean room technology and expensive substrate materials without functionalized properties
Electroplating is a common process in micro technologies and in large scale application to create e.g. corrosion protected surfaces (1). New technologies as three dimensional printing and vacuum casting enable new methods to create surfaces. This provides the opportunity to merge micro structures [e.g. conductors] with macro structures [e.g. curvature].The created textures might be implemented in an electroplating based pattern transfer process. The results indicate the possibility of creating functional planar and three dimensional structures using the described technology.
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