Molecular spectroscopies with spectrally selective metasurfaces

• Applicant: Dr. Andreas Tittl
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics ; Biomaterials
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 423258739

Optical spectroscopy approaches in the mid-infrared provide unique information about complex biological systems by detecting the characteristic absorption bands associated with the constituent molecules. Previously, resonant metallic antennas were utilized to focus mid-IR light into nanometer-sized volumes, enabling the study of thin membrane systems and low amounts of molecules. However, the performance of such metal-based systems is severely limited by Ohmic losses and the static nature of antenna materials, especially when investigating the interactions of multiple biological components.In the proposed project, I will develop novel all-dielectric metasurface concepts for surface-enhanced absorption spectroscopy and utilize them to resolve the dynamics of complex biological processes such as those associated with cellular communication. Specifically, I will design metasurfaces with high resonance quality factors (Q > 100) and strong electromagnetic near-field enhancements to amplify and detect the characteristic absorption signatures of biochemical molecules. In contrast to the broad resonances of metal-based antennas, such all-dielectric metasurfaces provide spectral selectivity, enabling the precise retrieval of fingerprint information at multiple specific target wavelengths with unprecedented sensitivity and over a wide spectral operating range. I will first utilize this technology to investigate the kinetics of cellular membrane disruption by the cytolytic protein perforin-1, which is a crucial process underlying the functions of white blood cells and the innate immune system. In addition, I will implement reconfigurable high-Q metasurfaces in spectroscopic imaging experiments, allowing me to track the spatial distribution of multiple molecular species in a biological system simultaneously. These experiments will provide previously unavailable insights into cellular communication processes by revealing both the amount and the spatial distribution of secreted signaling molecules in medically relevant systems such as lymphoma cancer cells. State-of-the-art design and nanofabrication methods will be used to carry out the proposed research, including full-wave electromagnetic simulations, high-resolution electron-beam lithography, and advanced microfluidic techniques for real-time in-situ investigations of biological systems. The research will be supported by the strong nanophotonic and sensor experience of the host group of Prof. Maier as well as by the excellent infrastructure of LMU Munich related to nanotechnology and cellular biology. The proposed project overcomes fundamental limitations of current techniques and will establish a pioneering direction for surface-enhanced detection. By leveraging newly developed metasurface concepts and sensing techniques, it launches a versatile sensor platform capable of answering fundamental questions in any biochemical system where access to spatially resolved molecular information is crucial.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: FTIR-Spektrometer inkl. Mikroskop
• Instrumentation Group: 1830 Fourier-Transform-IR-Spektrometer