Biochemical sensing and spectroscopy
Metasurface-driven sensing of biomolecules, biomimetic membrane processes, and energy conversion dynamics.
Resolving and understanding the dynamic interactions of biomolecules in complex biochemical samples is one of the major challenges of medical diagnostics, biophysics, and biology in general. For many applications, compact sensor systems are highly desirable, because they enable the retrieval of actionable biochemical information directly at the point-of-need, for example in the field or in a patient's home.
Our BIC-driven metasurfaces feature extremely narrow resonances and strong signal enhancements, making them ideal for detecting biomolecules, analyzing biomimetic membrane processes, and monitoring energy conversion dynamics with exceptional sensitivity and in compact footprints (Adv. Mater. 2023). Furthermore, the ultra-sharp resonances enable spectrally selective and label-free detection by measuring the characteristic molecular fingerprints of different analytes, enabling effective molecular differentiation and quantification. By integrating these metasurfaces with microfluidic systems, we enhance their capability for in-situ and real-time measurements of dynamic biochemical reactions (Adv. Opt. Mater. 2022). Below are some of our recent results on biochemical sensing, spectroscopy, and energy conversion.
We utilized scattering-type scanning near-field optical microscopy (s-SNOM) for non-destructive, label-free mid-infrared (MIR) imaging and spectroscopy of photoswitchable liposomes, achieving sub-diffraction limit resolution and dynamic tracking down to 50 ms. We demonstrated the ability to observe photoinduced changes in both shape and MIR spectral signatures of individual vesicles, revealing abrupt change dynamics in the photoisomerization process. Our findings underscore the potential of this method for studying the complex dynamics of unlabeled nanoscale soft matter and broader applications in nanomedicine and material science. arXiv:2406.02513 (2024-06).
Resolving dynamic processes in thin (~ 10 nm) biomimetic lipid membranes is extremely challenging. We combined pixelated "spectrometer-on-a-chip" metasurfaces with machine learning to resolve and classify the photoswitching dynamics of the membrane lipids in their native liquid environment ACS Nano 18, 11644-11654 (2024).
We developed a new metasurface design based on crescent-shaped meta-units. We were able to show that it supports higher-order resonances, which provide with improved field confinement and thus biomolecular sensitivity, especially when used with the aqueous analytes common in biomedical diagnostics Adv. Funct. Mat. 31, 2104652 (2021).
Ultra-sharp BIC-driven resonances can be used to resolve small analyte-induced spectral shifts at visible wavelengths. We demonstrated that the combination of hyperspectral imaging and metasurface-based sensing could deliver sensitivies down to a few molecules per square micrometer Nature Photonics 13, 390-396 (2019).
The paper that launched our metasurface-driven biospectroscopy efforts. We demonstrated a pixelated metasurface concept, where each pixel has a well-defined resonance wavelength in the mid-infrared. This "spectrometer-on-a-chip" approach enabled us to accurately identify different biomolecules in a miniaturized sensor platform Science 360, 1105-1109 (2018).
The sensitivity and strong surface-confinement of our metasurfaces also allows them to effectively enhance and probe catalytic processes.
We developed a multi-band nanophotonic-electrochemical platform that enables the simultaneous in-situ characterization of multiple adsorbed species during electrochemical reactions. We demonstrated the platform by monitoring two distinct adsorption configurations of CO on platinum during the electrochemical reduction of CO2, highlighting its capabilities for indentifying molecular species with low surface coverage or short lifetimes ACS Photonics 11, 714-722 (2024).
The spectroscopic detection of many relevant components of eletrochemical reactions, such as short-lived intermediaries, remains a challenge. We developed a new platform based on platinum nano-slot metasurfaces to dramatically increases the sensitivity of surface-enhanced infrared absorption spectroscopy (SEIRAS), allowing us to resolve low-concentration species involved in electrocatalytic reactions, crucial for developing sustainable energy technologies like green hydrogen production and carbon dioxide reductions Adv. Funct. Mat. 33, 2300411 (2023).
We developed a ultrathin photocatalytic platform that overcomes limitations of traditional thin-film catalysts. By combining loss-engineered titanium oxide with the concept of optical bound states in the continuum, we were able to demonstrate enhanced light absorption and broad spectral tunability. The ability to achieve critical light-matter coupling in the metasurface signifcantly boosted catalytic rates, with far-reaching implications not only for photocatalysis, but also for photovoltaics and photodetectors ACS Nano 16, 13057-13068 (2022).
Take a look at the full list of publications here.