Development of the next generation of sicm for live cell imaging

The cell surface is a complex arrangement of many molecules and this arrangement changes in time for the cell to perform specific functions and in response to stimuli. At present we can only resolve the molecular structure on frozen cells, so dynamics cannot be followed or we can follow just one component on the surface of live cells by the use of labelling. One method that has been developed to probe live cells at sufficient resolution to determine proteins on the surface is based on a scanned nanopipette. This controlled just above the soft cell surface so that it never touches and can be rastered over the surface to determine the topography. We aim to build on this method so that it can image more complex cell surfaces faster and can also locally apply reagents to identfy the features that we detect. This will be done with sufficient resolution to detect indvidual protein complexes on the cell surface, their organization and how this changes with time. This will allow many new details of how the cell works at the nanoscale to be observed for the first time and opening up many new types of experiments

Our previous published work shows that scanning ion conductance microscopy, using a nanopipette, can be used for non-contact imaging of live cells under physiological buffer and to follow changes in time. Our recent work has shown that SICM can now be performed at sufficient resolution on specialized live cells to image individual protein complexes in the plasma membrane and to follow their reorganization in time. We have also shown that it is possible to pull fine double barrel pipettes and use these for controlled delivery on surfaces. We aim to build on these advances to develop the next generation of SICM using recent advances in digital signal processing, using Field Gated Programmable arrays, which allow fast parallel signal processing and the implementation of complex control algorithms.. We will improve the distance control algorithm and speed of imaging and develop control software that allows us to deliver reagents to the cell surface from defined distances with the dosage controlled by voltage pulses. This will allow us to image live cells of increased complexity at high resolution, follow real-time dynamics on the cell surface and use antibody binding to identify specific high resolution topographic features on the cell surface. This new generation of SICM will open up a wide range of new biological and biomedical studies of the cell membrane