Coupling optical tweezers with tip-enhanced Raman spectroscopy for the investigation of individual supramolecular systems

Place: conference room, IMDEA Nanociencia.

Abstract:

Quantitative information on the dynamics and mechanistic principles behind supramolecular systems can be investigated in the single-molecule regime by measuring the nanometer displacements resulting from the application of picoNewton forces in optical trapping (OT) experiments. For example, the mechanical strength of non-covalent interactions can be quantified when studying the reversible breaking/formation of hydrogen bonds on individual host-guest systems or the switching of a macrocycle between binding stations in a molecular shuttle.[1]-[3] However, the fundamental chemical mechanisms behind the obtained real-time operational kinetics are not accessible with OT experiments and fundamental questions about the physicochemical processes underlying real-operation remain unanswered. Tip-enhanced Raman spectroscopy (TERS) is a powerful nearfield-based technique providing chemical characterization with single molecule sensitivity and few-nm spatial resolution. The combination of OT-optical force microscopy with TERS would give access to the underlying physicochemical processes triggering specific shuttling events in molecular motors and other types of supramolecular systems.

In this perspective talk I will introduce a hybrid setup being developed at IMDEA nanociencia that merges OT for single-molecule optical force microscopy experiments with TERS. We aim 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 in situ and under physiologically relevant working conditions.

References

[1] Naranjo, T., Lemishko, K. M., de Lorenzo, S., Somoza, Á., Ritort, F., Pérez, E. M., & Ibarra, B. Dynamics of individual molecular shuttles under mechanical force. Nature Communications (2018), 9(1), 1–7.

[2] Naranjo, T., Cerrón, F., Nieto-Ortega, B., Latorre, A., Somoza, Á., Ibarra, B., & Pérez, E. M. Mechanical measurement of hydrogen bonded host-guest systems under non-equilibrium, near-physiological conditions. Chemical Science (2017), 8(9), 6037–6041.

[3] T. Nicolás, N. Martín Sabanés, R.Bocanegra, D. Astumian, E. Pérez & B. Ibarra Transition-path times of individual molecular shuttles under mechanical equilibrium show symmetry. Chem (2025)