Quantitative atomic force microscopy and light microscopy of hydrogels and cells

Abstract

Quantitative biology is an interdisciplinary subject that combines biology, mathematics and physics. Intimate collaboration on a global scale between these disciplines results in a wide variety of tools and innovation in either fields.

This work was performed in collaboration with several research groups and combined interdisciplinary knowledge and experience with main focus to develop mathematical tools for biological data analysis, image processing and quantification of mechanical properties of biomaterials.

Mechanical properties of chitosan-alginate multilayers coated hydrogel were studied using Atomic Force Microscopy in a Paper I of this study. Detailed data analysis and quantification were performed using finite element modeling approach. Young’s modulus has been estimated using Hertz model. Obtained results demonstrate the importance of analyzing substrate and layers materials separately with different fitting and material properties.

Extracellular and intracellular cell responses to pathogens, such as Lipopolysaccharides (LPS) and Sendai virus were studied using Total Internal Force Microscopy and Confocal Microscopy. In Paper II it has been shown that LPS induces clustering of Toll-like receptor 4 (TLR4) into CD14 positive punctate structures on in the plasma membrane. Confirming the hypothesis that TLR4 is preparing for endocytosis and further signaling. In paper III of current study it was reported for the first time that the activation and subcellular relocation of ULK1 is regulated by viral infection. Paramyxovirus Sendai virus (SV) triggers formation of LC3-containing autophagosomes through the ULK1 complex, a key initiator in the autophagic cascade. Concomitantly, viral infection triggered a striking relocation of ULK1 to mitochondrial perinuclear structures.

Techniques described in this study are but a few of biophysical techniques widely used in biomedical research to study the structure and functions of biomolecules. Biophysical approaches and computational modeling described above making a big impact on our understanding of cell biology and mechanical properties of cells and hydrogels.