Modelowanie komputerowe i analityczne bioinspirowanego, standardowego układu fizyki powierzchni, w zakresie tarcia i smarowania, na wybranym przykładzie

Abstract

This thesis presents a description of friction and lubrication mechanisms when applied to natural system of articular cartilage. The presented model of facilitated lubrication of articular cartilage explains a multiscale phenomenon during application of an external quasi-normal load to the surfaces. The model is applied to explain degeneration of articular cartilage surface as well as synovial fluid in terms of its composition. Molecular dynamics simulations as well as analytical description are employed to describe these phenomena. Presented work is divided into 7 chapters. First chapter describes the theory behind friction and lubrication. The chapter consists of 5 subsections essential for understanding all occurrences in the system. First one introduces friction and lubrication phenomenon. The basics of Soft Matter Physics as well as physiology of articular cartilage are presented in terms of their connection to friction/lubrication mechanism. Finally, the key factors of hydration repulsion and Grotthuss mechanism are discussed. Second chapter presents the theory of molecular dynamics simulation and its several varieties: full-atom, coarse grained and steered molecular dynamics. Third section depicts a facilitated lubrication mechanism. The model is delivered by applying dispersive kinetics as a description of PLs concentration fields. Then by modification of model variables one can discuss a physical explanation. Finally, MNET dynamics is used to describe dynamics of proton channels as interplay between overcrowding of protons and confinement of a channel. Fourth part presents on hyaluronic acid and phospholipids interactions. The literature study provides a first step towards understanding processes occurring in normal and abnormal synovial fluid. Results of microelectrophoresis on HA/PL complexes are presented in terms of cross-linking mechanism as well as proton transport. Finally, molecular dynamics simulations of HA:PL complexes are presented for different pHs and PLs concentrations. The results are rationalized in terms of Rouse model. Fifth chapter presents steered molecular dynamics study on micelles’ interactions and their impact on overall process. Sixth part presents recapitulation of all works published for this thesis and a connection between them. The last chapter summarizes and addresses a future application of presented studies.