Executive Summary : | The proposed integration of a multi-probe Near field scanning Optical Microscope (NsOM) with an Optical Tweezer (OT) aims to perform micromanipulation and force spectroscopy on biological cells, multicellular nerve and muscle fibers. The goal is to study cell stretching on human red blood cells (RBC) in different cell health conditions and single nerve and muscle cells and multicellular bundles of the fruit fly insect. The NsOM will enable Plasmonic Tweezing (PT) on the NsOM for simultaneous near field OT and imaging, assisted by local plasmonic field enhancement. This allows for the design and fabrication of Au coated nanostructures of different shapes through laser etching, which will be tested for suitability for single biomolecule studies. Far field tweezer-based cell stretching results in larger optomechanical stress on the cell, making the nonlinear regimes of the strain response accessible. Weaker forces created through lower power, with trapping through plasmonic field enhancement at the trap site, can selectively stretch the outer cell membrane with minimal perturbation of the underlying cytoskeleton. The work on fruit fly nerve and muscle cells will explore differences in elastic and shear moduli between wild type and genetically modified species. The plasmonic structures of different shapes/patterns will be tested for their biocompatibility and effectiveness in PT. The results on RBC stretching in both strong and weak force regimes can help understand the physics of membrane stiffening and provide insights into cell pathology. The work with insect cells can also provide insights into the differences in cell tension between modified and wild type species. |