Estudo morfológico e das propriedades elásticas de plaquetas humanas por microscopia de força atômica

Abstract

The platelets have a major rule in processes like hemostasis and thrombosis. They go through drastic changes in their structure in such events, which includes alterations in shape from a circular outline to a completely amorphous profile. Therefore, this cellular restructuration is strongly linked to citoesqueleton rearrangement, affecting the whole structure localizes under the plasmatic membrane, which is responsible for cell's shape, malleability and deformability. In this view, looking into elastic properties of activated platelets' bodies is a promising source of deeper knowledge about the function of these cells in animal organisms. Nowadays, Atomic Force Microscopy (AFM) is the most suitable technique for this task. Because of its ability of touching a surface with forces around picoNewtons (10-¹² N), the AFM can be straightly used as a nanoindenter. In this work, two AFM subtechniques were applied to study healthy activated human platelets, which were: Force Plot and Force Volume. The former generates a graphic called force curve that is obtaneid when the sample is indented only once on a single point. The second procedure joins several force curves extracted over a surface area in an image known as force volume image. The data provided by these procedures were worked out through a model based on Hertz theory for Young's modules calculation for a surface indented with a conic indenter. Finally, the platelets' mechanical properties were determined not only locally, but throughout the cell body.