|Wednesday, May 26|
Frontiers in Nanophotonics: Enabling Technology for Next-Generation Biosensors
* Hatice Altug, Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland
Emerging healthcare needs and initiatives, including global health crisis, personalized medicine, point-of-care applications are demanding breakthrough advancements in bioanalytical and diagnostics tools. Biosensors play an essential role in disease diagnostics, but current devices are lacking precision, affordability, and portability. Furthermore, they require long detection times, sophisticated infrastructure, and trained personnel, which limit their broader applicability. In our laboratory, we address these challenges by developing next-generation nanophotonic biosensors, bioimaging, and spectroscopy technologies. The expertise of our lab covers a variety of techniques, including nanophotonics, nanofabrication, microfluidics, surface chemistry, and data science. In particular, we exploit nanoplasmonics and metasurfaces, which can confine light below the fundamental diffraction limit and generate strong electromagnetic fields at nanometric volumes for achieving high device performance. We develop new nanofabrication methods for high-throughput and low-cost manufacturing of nanophotonic biochips. We integrate our sensors with micro/nanofluidic systems for efficient analyte trapping, sample manipulation, and automation. We also use smart data science tools with hyperspectral and bioimaging for aided signal processing. In this talk, I will present some of our recent effort in these directions using gold as the main nanoplasmonic material [1-8]. For example, I will introduce ultra-sensitive Mid-IR biosensors based on surface-enhanced infrared spectroscopy for chemical-specific detection of molecules, large-area chemical imaging, and real-time monitoring of protein conformations in aqueous environment. I will describe our effort to develop ultra-compact, portable, rapid, and low-cost microarrays and their use for early disease diagnostics in real-world settings. I will also highlight our label-free optofluidic biosensors that can perform one-of-a-kind measurements on live cells down to the single-cell level, and provide their overall prospects in biomedical and clinical applications.  Oh and Altug. Nature Communications Vol. 9, p. 5263 (2018).  John-Herpin et al. Advanced Materials, 2006054 (2021).  Beluskin et al. Small Vol. 16, 1906108 (2020).  Rodrigo et al. Nature Communications Vol. 9, p. 2160 (2018).  John-Herpin et al. ACS Photonics Vol. 5, p.4117-4124 (2018).  Etezadi et al. ACS Sensors Vol. 3, p. 1109-1117 (2018).  Li et al. Small Vol. 14, 1870119 (2018).  Soler et al. ACS Sensors Vol. 3, p. 2286-2295 (2018).
SERS optophysiology of metabolites near or inside cells
* Jean-François Masson , Université de Montréal, Canada
Surface enhanced Raman scattering (SERS) optophysiology is a Raman method using nanofibers decorated with a dense and well dispersed array of Au NP for the measurement of neurotransmitters and other metabolites in proximity of cells. Using a pulled nanofiber (tip diameter below 1 um) and polymer assembly of Au NPs on the tip creates a highly sensitive SERS sensor that can be accurately positioned in space with a micromanipulator. The nanosensors are thus highly compatible with current physiology experiments also relying on similar nanosensors based on electrochemistry and electrophysiology. The SERS spectra are associated to single molecule measurements and were identified with a barcoding data processing method, processed with TensorFlow. This machine-learning driven data processing significantly improved the positive assignment rates for a series of neurotransmitters and metabolites, allowing for complex measurements of the brain's neurochemistry or associating differences in cellular metabolism of healthy and cancer cells. Specifically, this presentation will show our efforts in the development and the optical properties of SERS nanofibers, the construction of a SERS optophysiology microscope and the applications of the technique in cultured brain neurons and a series of healthy vs. cancer cell experiments. Of particular interest, the measurement of complex molecular gradients will be demonstrated close to cells.