Quantum limited sensing of motor molecule dynamics

Speaker: Larnii Booth
Affiliation: University of Queensland

Abstract:

Motor molecules are a type of biological molecule that take chemical energy and convert it to mechanical work. They perform the manual functions in a cell which are crucial for any living organism, but their dynamics are poorly understood as they are extremely hard to detect because of their size (typically smaller than 50nm) and their speed (>100Hz), making direct optical imaging of single molecules impossible. Even though they have been observed by attaching labels to biomolecules, it has been shown that these labels can severely impede the normal function of biological molecules.   

For these reasons, unlabelled biosensing has been developed. Unlabelled biosensors have used plasmonics and optical micro resonators to detect molecular dynamics, however, they use high intensities which are known to damage biological samples, preventing the observation of healthy molecular motor for an extended period of time. Quantum limited sensing has been demonstrated as a solution to this, as it allows the sensor to operate at much lower intensities, however, current implementations with nanofibres do not have the resolution to resolve motor molecule dynamics. In my talk, I will first present a novel way to model optical radiation of bio-molecules using the interactive dipole model for a better prediction of the signal of unlabelled biosensors. I will also show how to combine the advantages of optical resonantors sensor with quantum limited detection using a photonic crystal cavity device. Photonic crystal cavities possess highly confined electric field, offering a high resolution required to observe molecular motors. Design and fabrication of this new type of sensor will be presented which can potentially allow detection of motor molecule dynamics at optical intensities below the damage threshold for biological samples.