Nanomechanics of biomaterials using atomic force microscope

Abstract

Understanding mechanical properties of biological elements such as cells proteins and deoxyribonucleic acid DNA is very important in order to understand their function Various techniques such as nanoindentation Optical Tweezers OT Magnetic Tweezers MT and Atomic Force Microscope AFM are widely used for studying the mechanical properties of biomaterials AFM has been used previously for imaging of cells bacteria and proteins as well as for protein protein interaction antigen antibody interaction ligand receptor interaction and protein drug interaction Protein drug interaction is very well studied using fluorescence Ultraviolet Visible UV Vis absorption and circular dichroism techniques We have studied interaction of Chloramphenicol with titin I27 protein using Fluorescence and AFM It has been found out from the fluorescence study that the drug binds to the protein resulting in the formation of protein drug complex Alteration in mechanical properties of proteins at different drug concentrations is studied using AFM AFM data shows that the drug binds to the protein at 40 181 M of drug concentration thereby resulting in an increment of unfolding force by 25 pN and decrease in persistence length Therefore the drug is mechanically stabilizing the protein However chemical stability of the protein is checked by equilibrium denaturation experiment The denaturation experiment shows the increase in free energy of stabilization for the protein drug complex with respect to protein only Therefore the drug stabilizes the protein mechanically and chemically In another study mechanical properties of mouse embryonic stem cells mESCs is also studied Previously it was shown that loss of clathrin heavy chain results in loss of clathrin mediated endocytosis CME and thereby shows loss of pluripotency However the mechanical properties on loss of clathrin heavy chain was not known The results shows that the mESCs lacking clathrin shows greater cellular stiffness in comparison to wild type cells Also treatment of mESCs with