Novel Optical Nanotweezers for Biology and Medicine: Towards Rapid Isolation and Analysis of Nanoscale Extracellular Vesicles

April 2, 2021

 Justus Ndukaife
Department of Electrical Engineering
Vanderbilt University
Friday, April 2 at 4:00 pm via Zoom



One-half of the 2018 Nobel Prize in Physics was awarded for Optical Tweezers and their application in biological systems. Optical tweezers have emerged as a powerful tool for the non-invasive trapping and manipulation of colloidal particles and biological cells. However, the stable trapping of nanometer-scale biological objects such as proteins, DNA, extracellular vesicles, and virions has been met with challenges due to the diffraction limit of light. Attempts to substantially increase the laser power to generate enough optical trapping potential for trapping such small biological objects, unfortunately, results in photo-toxicity and thermal stress, which damages the integrity of the biological specimens. An optical nanotweezer approach that can stably trap nanoscale biological objects without exposing them to high light intensity or heat which may physically alter or destroy detectable bioactivity is of paramount importance for fundamental life science research and translational biomedical applications. In this talk, I will introduce a new kind of optically controlled nanotweezers termed Opto-Thermo-Electrohydrodynamic Tweezers (OTET) that enables the stable trapping and dynamic manipulation of sub-10 nm biomolecules at locations that are several microns away from the high-intensity laser focus, where they experience both negligible photothermal heating and light intensity. The OTET platform employs a finite array of plasmonic nanoholes illuminated with light in conjunction with an applied alternating current electric field to create the spatially varying electrohydrodynamic potential that can rapidly trap sub-10 nm biomolecules at femtomolar concentrations on-demand. I will show the sorting of extracellular vesicles sub-populations based on size using OTET. This novel non-invasive optical nanotweezer is expected to open new horizons in life science and medicine including the liquid biopsy analysis of extracellular vesicles with single particle sensitivity for early cancer detection.

(Keywords: optical nanotweezer, plasmonics, biomolecules, liquid biopsy)


Justus Ndukaife is an assistant professor of electrical engineering at Vanderbilt University, USA. He received a Ph.D. in Electrical Engineering from Purdue University, USA in 2017. Ndukaife’s interdisciplinary research is focused on nanophotonics including plasmonics and resonant dielectric cavities for applications in life science, quantum science and nano-assembly. He has made major contributions in the field optical nanotweezers. Very recently, Ndukaife invented a new optical nanotweezer approach termed: “opto-thermo-electrohydrodynamic tweezer (OTET)” that enables the trapping of sub-10 nm size biological molecules at tunable trapping locations several microns away from the high-intensity focus to prevent the issue of photo-induced damage usually encountered when trying to trap such minuscule objects using the conventional optical tweezer technology that was recognized with one-half of the 2018 Physics Nobel Prize. Ndukaife’s research works have been published in the top peer-reviewed journals including Nature Nanotechnology, Science, ACS Nano, and Nano Letters, and he is an inventor of six US patents relating to optical nanotweezers. In recognition of his scientific contributions, Ndukaife received an International Rising Stars of Light award for the year 2020. His global iCANX talk on Optical Nanotweezeers research attracted more than 260,000 viewers world-wide. His other honors include the Year 2017 Prize in Physics by the Dimitris N. Chorafas Foundation, the Purdue College of Engineering Outstanding Research Award, NSBE Golden Torch Award, Best Paper Award at the ASME conference, Carnegie African Diaspora Fellowship Award, and Vanderbilt Provost Research Studios Award.