Solvent‐free Liquid Crystals and Liquids from DNA

Abstract

As DNA exhibits persistent structures with dimensions that exceed the range of their intermolecular forces, solid-state DNA undergoes thermal degradation at elevated temperatures. Therefore, the realization of solvent-free DNA fluids, including liquid crystals and liquids, still remains a significant challenge. To address this intriguing issue, we demonstrate that combining DNA with suitable cationic surfactants, followed by dehydration, can be a simple generic scheme for producing these solvent-free DNA fluid systems. In the anhydrous smectic liquid crystalline phase, DNA sublayers are intercalated between aliphatic hydrocarbon sublayers. The lengths of the DNA and surfactant are found to be extremely important in tuning the physical properties of the fluids. Stable liquid-crystalline and liquid phases are obtained in the -20 °C to 200 °C temperature range without thermal degradation of the DNA. Thus, a new type of DNA-based soft biomaterial has been achieved, which will promote the study and application of DNA in a much broader context.

Nematic DNA Thermotropic Liquid Crystals with Photoresponsive Mechanical Properties

“…Although most investigations of DNA LCs are currently limited to aqueous solutions, research examining anhydrous DNA thermotropic liquid crystals (TLCs) is gaining momentum owing to its relevance in DNA‐based optoelectronic applications . Recently, for example, a new class of smectic DNA TLCs has been generated by electrostatic complexation of single stranded (ss) oligonucleotides with surfactants containing two flexible alkyl chains . Based on this type of DNA TLCs, an electrochromic device that exhibits a clock function and a ceiling temperature indicator was fabricated .…”

“…Here we report a new class of DNA TLC materials exhibiting nematic mesophases whose mechanical behaviors can be controlled conveniently by irradiation with light. Since DNA TLCs exhibit remarkable mechanical properties, we reasoned that modulation of these characteristics by the means of light‐irradiation would add an unprecedented level of control over this type of material. Nematic DNA TLCs were prepared by electrostatic complexation of double‐ and single‐stranded oligonucleotides with cationic surfactants containing two aliphatic chains and one aromatic azobenzene moiety (AZO) followed by dehydration.…”

Liquefaction of Biopolymers: Solvent-free Liquids and Liquid Crystals from Nucleic Acids and Proteins

“…16,21 Instead of PEG residues, we employed ammonium surfactants substituted with aliphatic alkyl chains yielding either DNA–surfactant liquids or mesophases. For the analysis of the DNA LCs, polarized optical microscopy (POM) can be used revealing the characteristic focal-conic textures of lamellar structures (Figure 2a,b).…”

“…(e) Phase-transition temperatures of DNA–surfactant complexes from crystalline (Cr) to liquid crystalline (LC) to isotropic liquid. Adapted with permission from ref (16). Copyright 2015 John Wiley & Sons, Inc.…”

“…14−17 We will briefly outline design, preparation, and application of solvent-free liquids ranging from nucleic acids 14−16 to proteins 17−19 to whole viruses 20,21 that have become accessible employing this simple and general protocol. In addition, this protocol has yielded access to solvent-free liquid crystals (LCs) 21−24 introducing ordering and fluidity by ionic self-assembly while retaining biological function 25 for biocatalysis, 26 bioelectronics, 27,28 and potentially biomedicine.…”