Leo Velleman

Plasmonic nanoparticle assembly at liquid-liquid interfaces

The three most significant challenges facing biosensing are inaccuracy, insensitivity, and low-throughput detection. One technique that is capable of facing these challenges is Surface Enhanced Raman Scattering (SERS) which has demonstrated potential for extreme sensitivity (single molecule detection) and rapid, multiple-analyte detection within complex mixtures. Early stage diagnosis of disease requires the detection of trace amounts of analyte in multi-component biological samples (blood, urine, saliva). It is therefore particularly important for sensors to reach the single-molecule detection limit. Further, the ability to analyse biological samples without separation or other treatment steps is a crucial advantage of SERS.

My approach involves the electrotuneable self-assembly of plasmonic nanoparticles at a liquid-liquid interface for SERS detection, overcoming the severe limitations of current sensors (sensitivity, specificity and speed). The positioning of nanoparticles at the interface is electrochemically controlled in a precise manner to maximise the Raman signal. Additionally I am investigating shaped nanoparticles, such as stars and ellipsoids, to exploit the enormous Raman enhancements observed at sharp metallic tips and push the sensitivity towards single-molecule detection limits. Due to the versatility of this system it can be adapted to any disease or virus where the related biomarker is known.

Mini bio

• Postdoctoral Research Associate, Department of Chemistry, Imperial College London. Supervisor: Dr Joshua Edel
• Postdoctoral Research Associate, Institute for Frontier Materials, Deakin University. Supervisor: Prof Lingxue Kong
• Postdoctoral Research Associate, School of Chemical and Physical Sciences, Flinders University. Supervisors: Prof Joe Shapter, Prof Justin Gooding
• PhD in Chemistry, School of Chemical and Physical Sciences, Flinders University. Supervisors: Prof Joe Shapter, Dr Dusan Losic
• BSc in Nanotechnology (Honours), Flinders University

Selected Publications

• L. Velleman, J.G. Shapter, D. Losic. Book chapter: Gold nanotube membranes. Encyclopedia of membrane science and technology. John Wiley & Sons, Inc. (2013)
• L. Velleman, J-L. Bruneel, F. Guillaume, D. Losic, J.G. Shapter. Raman spectroscopy probing of self-assembled monolayers inside the pores of gold nanotube membranes. Physical Chemistry Chemical Physics, 13 (2011) 19587 - 19593.
• L. Velleman, C.J. Shearer, A.V. Ellis, D. Losic, N.H. Voelcker, J.G. Shapter, Fabrication of self-supporting porous silicon membranes and tuning transport properties by surface functionalisation. Nanoscale, 2 (2010) 1756 - 1761.