Abstract
Cell biology has greatly assisted biologists in further understanding the biological mechanisms, which in turn are critical for researchers. Atomic Force Microscopy (AFM) is able to provide information regarding shape, height, surface roughness, volume, force, and elasticity as a platform for the multi-parameter analysis of cell functions. In this dissertation, we used AFM-based technology to study two different kinds of cells – sperms and astrocytes – to obtain information on morphological changes, force measurement, and cellular mechanics. First, we used AFM to measure the motility of a mouse sperm. Eukaryotic flagellum is responsible for the motile organelles that cause the migration of a mammalian sperm. The results showed that at a distance of about 18.5 μm from its head-tail junction, a lashing force of 0.96 ± 0.20 nN was measured. Its corresponding lashing torque was 1.77 ± 0.37 × 10-14 N•m. Our results reasonably concluded that the axonemal motility was linear dependent on the flagellum length of the sperm, and our developed measurement system could consistently determine the lashing force and torque of a sperm which might contribute to further studies concerning the mechanism of sperm transport and fertilization. Second, we used a combination of Astigmatic Detection Microscopy (ADM) and AFM techniques to study the pathogen-host interaction for astrocyte apoptosis triggered by Toxocara canis (T. canis) larval excretory/secretory antigen (Tc E/S), without tedious procedures and only relying on shape, surface structure, and height information. The variation in the pathology of a cell’s morphological changes was investigated with ADM and AFM analyses and then confirmed by Western Blotting. The results showed that the round cells increased as the concentration of Tc E/S antigen and incubated time increased, a similar trend. In addition, the mean height of apoptotic cells was approximately twice that of untreated normal cells, which meant there was correlation between the Tc E/S antigen treatment and cell height. For each cleaved caspase-3 in the cells co-cultured with Tc E/S antigen and incubated for 9 h, the corresponding intensities increased about 34-fold (34.4 ± 1.8) compared with those of the control cells. This method can provide researchers a perspective of understanding the limited information on the mechanism of astroglial injury and death during a T. canis larval invasion in a brain infection. Today, AFM is increasingly used in biological, biophysical and even biomedical research. As AFM instrumentation continues to develop, AFM measurements have boosted our understanding of various biological systems while revealing the promising potential in answering some unsolved questions in biology and in the establishment of novel biophysically analytical method.