Unraveling Chemical-Structural Properties of Soft Materials Down to the Single-Molecule Level

The introduction of photothermal infrared nanospectroscopy (AFM-IR) has revolutionized the field of nano-chemical analysis in a wide-open range of fields, including biological, material and polymers in soft matter sciences. Here, we will present an overview of our latest development and application of AFM-IR in combination with advanced spectroscopic analysis and chemometrics, as a real breakthrough for the analysis of heterogeneous soft mater down to the single molecule level.<br/>To illustrate our path towards single-molecule AFM-IR, we first show the achievement of single protein molecule detection of infrared absorption spectra and maps by introducing off-resonance, low power, and short pulse ORS-nanoIR. [1] This approach enables the accurate single-molecule determination of the secondary structure of protein their assemblies in the amide band I region. We will then showcase the application of this unprecedented single molecule sensitivity to: i) unravel molecular structure and interactions of protein and organic molecules [2]; ii) origin of chirality in click chemistry polymers [3]; iii) detect nano-plastics in drinking water [4]. Finally, we illustrate the application of this sensitivity to probe the surface and structural properties of functional materials, such as functional protein self-assemblies artificial model membranes [5-6].<br/>Overall, our aim is to expand the capabilities of analytical nanoscience to shed light on the structure-activity relationship of biomolecules and functional materials design.<br/><br/>References:<br/>[1] Ruggeri, Nature Comm., 2020.<br/>[2] Ruggeri, Nature Comm., 2021.<br/>[3] Li, in preparation, 2024.<br/>[4] Vitali, in preparation, 2024.<br/>[5] Marchesi, Advanced Functional Materials, 2020.<br/>[6] Otzen,…, Ruggeri, Small Methods, 2021.