Real-time controlling a single DNA in hotspot for back-and-forth programmable site-specified SERS characterizations in solution

Abstract Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for single-molecule studies. However, it is challenging to characterize biomacromolecules with conformational complexity in solutions, concerning its credibility, sensitivity, repeatability, and accuracy, due to the limited molecular control of existing single-molecule SERS platforms. Here, we integrate dual-trap optical tweezers and nanoparticle-deposited nanostages with a typical Raman spectro-microscope to correlate single-molecule manipulations and molecular site-specified SERS characterizations. A single drug-bound DNA is stretched at sub-nanometer precision, while its specified site is placed into an inter-particle hotspot under spatial and temporal control. It allows back-and-forth translocations of the single drug-bound DNA through hotspot in a programmable manner, generating the real-time SERS readouts correlative to the specified DNA sites for re-examining the same single molecule multiple times. Hence, it utilizes the extra molecular controllability to minimize errors in direct single-molecule spatial SERS characterizations of biomacromolecules in solutions, providing implications for molecular interactions, encryption, and sequencing.