Optothermal Ice–Water Interface Management for Cross-Scale Enrichment and Molecular Sensing

Precise and scalable enrichment of dispersed analytes is vital for biosensing, environmental monitoring, and nanomaterial processing. However, current methods often lack versatility and spatial resolution. Here, we introduce optothermal ice-water interface management (OIIM), a universal, label-free approach for cross-scale enrichment and sensing. By optically guiding a movable ice-water interface, OIIM creates a tunable and controllable nanovessel that actively drives analytes, from angstrom-scale dyes to micrometer-scale particles, into confined regions. This versatile approach efficiently enriches diverse targets, including nucleotides, proteins, and synthetic nanomaterials. Molecular dynamics simulations and fluorescence imaging have been investigated to elucidate the solute-interface interactions and the enhanced interfacial trapping underlie the observed enrichment behavior. Furthermore, OIIM supports multisite enrichment, spatial consolidation, and the formation of femtoliter-scale microreactors for accelerated enzyme-cascade reactions. Notably, OIIM offers unique capabilities for enriching and analyzing ultrashort nucleic acids that elude conventional purification methods, establishing a flexible, molecular-level optothermal strategy within ice.