0000000000266007
AUTHOR
Stefan Ecke
Dynamic studies on living cells with an atomic force fluorescence microscope
Analysis of the reaction of bone structure to mechanical stimulation is a key issue in understanding the origins of osteoporosis and mechanical adaptation of living bone to external forces. This is thought to be regulated on a cellular level. We have investigated quantitative mechanical stimulation of single bone cells and their immediate intracellular calcium responses using a combination of an atomic force microscope (AFM) and a fluorescence microscope, developed in our laboratory. The force stimulation system can apply quantified forces in the pico- and nano-newton regime on exactly defined positions of a cell. We present here the first measurements using this system on the mechanically …
Microsphere tensiometry to measure advancing and receding contact angles on individual particles
In this paper, a method to measure the advancing and receding contact angles on individual colloidal spheres is described. For this purpose, the microspheres were attached to atomic force microscope cantilevers. Then the distance to which the microsphere jumps into its equilibrium position at the air-liquid interface of a drop or an air bubble was measured. From these distances the contact angles were calculated. To test the method, experiments were done with silanized silica spheres (4.1 μm in diameter). From the experiments with drops, an advancing contact angle of 101 ± 4° was determined. A receding contact angle of 101 ± 2° was calculated from the jump-in distance into a bubble. Both ex…