| Biocompatible Materials » Project survey » Main projects » Time and functionally programmed surfaces | ||
| Background and description The project involves the development and characterization of model surfaces and surface modification methods, which do not necessarily have to be applicable to currently existing implant materials and devices. Rather the model surfaces should identify the key characteristics of an optimal surface or coating, which would then be further developed for actual implant devices. Model surfaces types include porous surfaces, viscoelastic surfaces, biologically active surfaces, and dynamic surfaces whose biological function varies over time. This project has been running both at Linköping University and Chalmers University of Technology and is an extension of activities from the SSF Biomaterials Consortium. Each university contributed to this project with one additional student funded from another related research program. Scientific results 
Porous surface models: Systematically varying microgrooved/pillared surfaces
microfabricated in silicon wafers, as well as porous titanium surfaces
created by sodium hydroxide etching or electrochemical oxidization have
been prepared and tested for the influence of porous layer properties on
cell and tissue responses. Different cell types exhibit different attachment,
morphology and growth on porous, micropillared surfaces and the response is
mainly due to the influence of reduced area available for cell attachment.
A new cell-force sensor was realized as a result of this project
(see Cell-force sensor).
Viscoelastic and biofunctional coatings: Thin blood plasma or fibrin clots have been generated and covalently bound at metal implant surfaces and represent extracellular matrix (ECM)-like materials. Animal experiments with ECM-like layers on titanium show no difference in inflammatory behaviour or new bone formation at the implant surface in a rabbit bone model (see Optimal surface topography...) compared to non-coated implants. Multilayer natural polymer films: Preparation of multilayer plasma protein films on silicon have led to the possibility to prepare coatings with different physical and bio-functional properties in successive layers. Different types of polysaccharide coatings have also been generated and studied for their protein adsorption properties. Surface bound actin, IgG, IgM, and complement: Interactions between surface bound biofunctional molecules and blood cells have been studied. Actin surfaces displayed weak protein binding and complement activation in whole human plasma. IgG and IgM surfaces show that platelets strongly amplify reactions previously attributed to neutrophils only. Different surface immobilized plasma proteins gave rise to differential interleukin-1 and TNF-α expressions in in vitro monocyte cell culture. Such data help us to understand how to design complex interfaces to be used in a variety of applications. Thin films of degradable polymers: Different compositions and molecular weights of PLGA (poly-lactic/poly-glycolic acid) biodegradable films, which can eventually be used for drug delivery at the implant surface, have been formed on flat titanium samples as well as on screw shaped titanium dental implants. The process of generating thin films by various methods has been evaluated. |
