Infrared nanospectroscopic mapping of DNA molecules on mica surface

TL;DR

This paper demonstrates a novel IR-AFM nanospectroscopy method for mapping DNA molecules on mica, enabling detailed structural analysis at the nanoscale, which could advance nucleoprotein complex research.

Contribution

It introduces a new methodological approach for IR-AFM mapping of DNA on mica surfaces, expanding nanoscale spectroscopic capabilities for nucleic acid studies.

Findings

IR-AFM maps reveal nanoscale DNA morphologies

Distinct IR spectra correspond to different DNA depositions

Method shows potential for nucleoprotein complex analysis

Abstract

Significant efforts have been done in last two decades to develop nanoscale spectroscopy techniques owning to their great potential for single-molecule structural detection and in addition, to resolve open questions in heterogeneous biological systems, such as protein-DNA complexes. Applying AFM-IR technique has become a powerful leverage for obtaining simultaneous absorption spectra with a nanoscale spatial resolution for studied proteins, however the IR-AFM investigation of DNA molecules on surface, as a benchmark for a nucleoprotein complexes nanocharacterization, has remained elusive. Herein, we demonstrate methodological approach for acquisition of IR-AFM mapping modalities with corresponding absorption spectra based on two different DNA deposition protocols on spermidine and Ni2+ pretreated mica surface. The nanoscale IR absorbance of distinctly formed DNA morphologies on mica are demonstrated through series of IR-AFM absorption maps with corresponding IR spectrum. Our results thus demonstrate the sensitivity of IR-AFM nanospectroscopy for a nucleic acid research with an open potential to be employed in further investigation of nucleoprotein complexes.