Metasurface engineering of transient photothermal responses for vibrational imaging at living interfaces
Chemical transformations at biological interfaces are central to cellular function, yet the weak vibrational signals associated with subtle molecular changes limit their spatially resolved observation. Here, we present metasurface-driven mid-infrared photothermal imaging (MetaMIP), which uses resonantly engineered metasurfaces to amplify molecular temperature modulation while retaining rapid thermal recovery. Visible-light detection converts this response into submicrometre maps of individual nanoparticles and biological cells. In living cells, MetaMIP resolves spatially distinct chemical changes during enzymatic lipid conversion across the cell membrane. These results demonstrate the potential of engineered photothermal interfaces for mapping chemical composition and tracking its evolution during reactions.