AUTHOR=Emilsson Gustav , Röder Evelyn , Malekian Bita , Xiong Kunli , Manzi John , Tsai Feng-Ching , Cho Nam-Joon , Bally Marta , Dahlin Andreas TITLE=Nanoplasmonic Sensor Detects Preferential Binding of IRSp53 to Negative Membrane Curvature JOURNAL=Frontiers in Chemistry VOLUME=7 YEAR=2019 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00001 DOI=10.3389/fchem.2019.00001 ISSN=2296-2646 ABSTRACT=

Biosensors based on plasmonic nanostructures are widely used in various applications and benefit from numerous operational advantages. One type of application where nanostructured sensors provide unique value in comparison with, for instance, conventional surface plasmon resonance, is investigations of the influence of nanoscale geometry on biomolecular binding events. In this study, we show that plasmonic “nanowells” conformally coated with a continuous lipid bilayer can be used to detect the preferential binding of the insulin receptor tyrosine kinase substrate protein (IRSp53) I-BAR domain to regions of negative surface curvature, i.e., the interior of the nanowells. Two different sensor architectures with and without an additional niobium oxide layer are compared for this purpose. In both cases, curvature preferential binding of IRSp53 (at around 0.025 nm−1 and higher) can be detected qualitatively. The high refractive index niobium oxide influences the near field distribution and makes the signature for bilayer formation less clear, but the contrast for accumulation at regions of negative curvature is slightly higher. This work shows the first example of analyzing preferential binding of an average-sized and biologically important protein to negative membrane curvature in a label-free manner and in real-time, illustrating a unique application for nanoplasmonic sensors.