Supervisors: Dr David McGloin and Prof Kees Weijer
This project will involve conducting research in the development and applications of high strength optical tweezers to perform force measurements on highly motile cells and to explore applications in rheology. This will entail training in the principles and use of optical tweezers, surface modification methodology, data analysis and essential cell biology.
High strength photonic tweezers represent a powerful tool to access biological forces outside the normal range of optical tweezers. They may be used to perform force measurements on highly motile cells and to study tissue dynamics, as well as to explore application in rheology. The project aim to produce a suitable tool to exert nanoNewton forces and to carry out biologically relevant experiments.
A first research study carried out in collaboration with Erik Schaeffer’s group at the University of Tuebingen has lead to the synthesis of novel photonically structured probes for optical trapping. These probes are made of a silica coated core-shell structure in titanium dioxide. Through a morphological characterisation carried out by the use of a Scanning Electron Microscope (SEM), we demonstrated that the synthesis of the probes can be reproduced, making them suitable for experiments. The optical trap stiffness characterisation showed that nanoNewton forces can be achieved, and their use in biological experiments is currently under exploration.
In addition to the development of nanoNewton probes, we have implemented a prototype Total Internal Reflection Fluorescence (TIRF) Microscope with Integrated Photonic Tweezers, or TIR-PH, which combines the advantages of high resolution microscopy with the possibility of locally manipulate the sample with optical tweezers. The system has been used for preliminary studies on Dictyostelium with knock-In of the fluorophore GFP into the myosin II heavy chain gene to stimulate the myosin contraction by the application of a pulling force with the optical tweezers, while imaging the myosin with the TIRF microscope. The high resolution of the TIRF system has been proved, and we are currently working in enabling the interaction with the optical tweezers. Other experiments have been carried out with Drosophila S2 cells (see Figure 2), where the actin network in the cellular cortex has been imaged while optically moving silica beads phagocyted by the cells.
Journal and Conference Papers and Posters
[August 2016] Improved antireflection coated microspheres for biological applications of optical tweezers. Poster presented at SPIE Optics and Photonics, San Diego, USA, 30th August 2016.
[August 2016] Improved antireflection coated microspheres for biological applications of optical tweezers. Poster presented at the Biophotonic approaches: From molecules to living systems conference, Dundee, Scotland, 23rd August 2016.
[August 2016] Optical manipulation of cells junctions in chick embryos. Poster presented at the Biophotonic approaches: From molecules to living systems conference, Dundee, Scotland, 23rd August 2016.
[November 2015] High Strength Photonics Tweezers. Presentation at the 43rd Scottish Microscopy Group Symposium, Dundee, Scotland.
[October 2016] Optical Tweezers : Methods and Protocols. Chapter 6. Custom-Made Microspheres for Optical Tweezers by Anita Jannasch, Mohammad K. Abdosamadi, Avin Ramaiya, Suman De, Valentina Ferro, Aaron Sonnberger, Erik Schäffer.