Projekt mikro- i nanotribologicznych badań chondrocytów

Według aktualnej informacji autorów w badaniach naukowych prowadzonych obecnie w Polsce i na świecie brakuje zarówno eksperymentalnych, jak też analityczno-numerycznych badań tribologicznych parametrów związanych z tarciem, zużyciem-uszkodzeniem i smarowaniem komórek chrząstki stawowej podczas ich opływu oraz odżywiania cieczami biologicznymi. Hydrodynamiczne smarowanie komórki (chondrocytu) odbywa się poprzez jej opływ super cienką warstewką płynu biologicznego, natomiast odżywianie następuje poprzez cząsteczki cieczy biologicznej lub farmakologicznej, kontaktującej się z chondrocytem. Proponowane w projekcie badania obejmują: wyznaczanie prędkości przepływów cieczy o własnościach nienewtonowskich w supercienkich warstwach granicznych w skali mikro i nano, obliczanie ciśnienia hydrodynamicznego i naprężeń, znajdowanie mikro- lub nanosił tarcia, a także współczynników tarcia.

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Tissue engineering is one of the most quickly developing domains of applied biotechnology. A new method of research on this science can be solved only during cooperation of biologists, mechanics, tribologists, orthopaedics, and clinicians. In the authors’ opinion, at present, scientific researchers in Poland and in the world have a lack of experimental and numerical tribological investigations connected with friction, wear, and the lubrication of cartilage joint cells during the biological fluid flow around the chondrocytes (cartilage cells). In this paper, the authors present the comparisons between lubricating flows in liquid thin layers occurring in micro-bearings for a journal diameter not greater than 1 mm and with the velocity distributions existing in liquid micro-layers flowing around the cartilage cells in bioreactors and in gaps of human joints. Presented research contains the following: determination of non-Newtonian fluid velocities in the micro- and nano-level in very thin boundary layers near the cartilage cells, hydrodynamic pressure and stress calculations, the determination of micro- and nano-friction forces to obtain proper friction coefficients. The existing shear rates during the flow have an influence on the apparent viscosity in the thin layer near the cells. In the ultra thin boundary layer, the viscosity changes also additionally in the gap height direction. Taking into account the newest theoretical models in the field of micro- and nano- mechanics for the fluid flow in ultra thin boundary layer around the cells, the authors indicate that the analytical and numerical determination of the influence of genetic code, growth possibility and cell regeneration on the fluid dynamic apparent viscosity is very necessary. For such numerical calculations, the values of measurements performed in the Atomic Force Microscope are desired to obtain the values at the micro- and nano level. Simultaneously, it is very important to perform the measurements of values of material coefficients, i.e. fluid pseudo-viscosity, describing the physical relations between stresses and shear-rate tensor coefficients for non-Newtonian biological fluid. Such measurements are possible only by using the AFM microscope and new mathematical programs. Moreover, the measurements of cell surface roughness and friction forces at the nano level during the lubrication are possible only by using the atomic force microscope. Many illness causing changes of human hip and knee joints are connected mainly with the decreasing of the synovial fluid dynamic viscosity. Hence, the research has a practical meaning, because the lack of knowledge in the field of tribological parameters of synovial fluid and the human joint cartilage cells leads to the improper therapy and thus to the mechanical reconstruction of the whole human hip or knee joint.