DNA on stage: Showcasing oligonucleotides at surfaces and interfaces with second harmonic and vibrational sum frequency generation

The field of nonlinear optics continues to expand and surprise. The ability to study DNA with nonlinear optics has opened the door to understand, on a molecular level and without the use of external labels, the physical and chemical properties of DNA single and double strands at surfaces and interfaces. In this Perspective, we survey how nonlinear optical probes access the electronic, vibrational, electrostatic, and chiral signatures of interfacial DNA in its native state. We also show how this exciting new field is directly applicable to tracking and understanding molecular recognition in DNA oligonucleotides and aptamers.