This project has received funding from the European Union’s Horizon 2020 research and innovation programme H2020-MSCA-IF-2019 under grant agreement No 892667
04/2023: We are looking for posdocs! Are you interested in joining this exciting project? Check the Ideal program at IMDEA nanoscience and contact us to apply. You can find further details under the research projects tab: https://idealcofund-project.eu
12/2022: We are looking for PhD students! Check out the project TweeTERS within the Ideal cofund for PhD: https://idealcofund-project.eu/phd/
Synthetic supramolecular systems consist of an ensemble of molecules held together by non-covalent interactions. Among such forces, hydrogen bonds are particularly relevant in fundamental biological and chemical processes. There has been extensive research on the nature of H-bonding on several supramolecular systems like host-guest pairs, supramolecular polymers or molecular machines. From the fundamental point of view, understanding non-covalent interactions is paramount to disentangle the chemistry of biological systems. One of the main challenges in the field nowadays is the investigation of single-molecule events under non-equilibrium conditions, since the data obtained in bulk experiments in equilibrium cannot describe the singularities of, for example, the functionality of individual molecular motors. To this end, optical trapping (OT) experiments have been successfully implemented to determine the mechanical properties and operational dynamics of synthetic supramolecular systems in the single-molecule regime and under aqueous environments. This is achieved by exerting calibrated forces (1-100 pN) on systems immobilized between optically trapped particles and measuring the corresponding displacements (1-10 nm) in real time. For example, characteristic H-bond strength have been determined in situ for single host-guest pairs as well as real-time shuttling events of individual molecular shuttles using optical trapping. Despite the essential information that optical force microscopy experiments provide, there is still a lack of quantitative chemical information. Raman spectroscopy is one of the most powerful tools in analytical chemistry since it can access the vibrational spectrum of solids, organic and inorganic molecules in a non-invasive way, from which the specific composition of a sample can be determined, as well as the conformation and interaction between species, including covalent and non-covalent bonds. In addition, it is suitable for working under aqueous environments, where other vibrational spectroscopies such as IR fail due to the high absorption of water in the IR wavelengths. Consequently, Raman is an ideal tool to provide complementary chemical characterization in OT experiments, particularly in biologically relevant aqueous environments. However, due to the small scattering cross-sections of the Raman process, nearfield approaches using metallic nanoantennas have to be used to access the Raman spectrum of a single molecule. In tip-enhanced Raman spectroscopy (TERS) the excitation light is coupled to the apex of nanometric metallic tip, resulting in a highly enhanced and confined nearfield around the tip apex. The Raman signal from molecules within the nearfield is enhanced by several orders of magnitude (107-1010) with respect to the farfield signal, boosting the sensitivity of the process to the single-molecule limit. By combining state-of-the-art technologies in the fields of OT and nearfield Raman spectroscopy, the main objective of TweeTERS is to create a hybrid tool that can disentangle the relation between mechanical, conformational and chemical properties of individual synthetic supramolecular systems and the non-covalent interactions governing their behavior, with single-molecule sensitivity and spatial resolution in the range of 5-10nm. On the one hand, we will be able to follow in real-time the formation and breaking of individual non-covalent interactions both kinetically and chemically tackling open questions in the field of supramolecular chemistry from a completely new approach. On the other hand, this unique novel instrument will merge two state-of-art single molecule techniques, resulting in a versatile setup with applicability far beyond a single research field and topic pushing the limits of current technology in the single molecule regime.
