Acknowledgements

The authors would like to acknowledge the Macquarie University Faculty of Science and Engineering Microscope Facility (MQFoSEMF) for access to its instrumentation and staff. This work was supported by the Australian Research Council (ARC) through the Centre of Excellence for Nanoscale BioPhotonics (CE140100003). H. Liu and K. Peng are supported by International Macquarie University Research Excellence Scholarships (iMQRES) for graduate study.