Macroscopic liquid crystal response to isolated DNA helices

Area of Science:

• Biophysics
• Materials Science
• Molecular Biology

Background:

• Liquid crystals (LC) are materials with properties between those of conventional liquids and solid crystals.
• DNA, a molecule carrying genetic instructions, exists in single-stranded (ssDNA) and double-stranded (dsDNA) forms, with dsDNA possessing a characteristic helical structure.

Purpose of the Study:

• To investigate the orientational response of nematic liquid crystals (LC) to isolated DNA molecules.
• To determine if LC can provide a macroscopic optical signal in response to single DNA molecules.

Main Methods:

• Nematic liquid crystals were exposed to isolated single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) molecules immobilized on a surface.
• The orientation of the LC was observed optically to detect responses to the DNA molecules.

Main Results:

• Single-stranded DNA (ssDNA) induced LC alignment parallel to the DNA extension direction.
• Double-stranded DNA (dsDNA) caused LC alignment at an oblique angle, a response attributed to the DNA's chiral helix.
• The study observed a macroscopic, optically visible response to a single molecule of extended dsDNA due to LC orientational correlations.

Conclusions:

• The chiral structure of double-stranded DNA (dsDNA) can be detected through its effect on liquid crystal (LC) orientation.
• Liquid crystals offer a sensitive platform for the optical detection of single DNA molecules, leveraging intrinsic signal amplification.