title: Propagation of chirality in mixtures of natural and enantiomeric DNA oligomers.
abstract: Concentrated solutions of ultrashort duplex-forming DNA oligomers may develop various forms of liquid crystal ordering among which is the chiral nematic phase, characterized by a macroscopic helical precession of molecular orientation. The specifics of how chirality propagates from the molecular to the mesoscale is still unclear, both in general and in the case of DNA-based liquid crystals. We have here investigated the onset of nematic ordering and its chiral character in mixtures of natural D-DNA oligomers forming right-handed duplex helices and of mirror symmetric (L-DNA) molecules, forming left-handed helices. Since the nematic ordering of DNA duplexes is mediated by their end-to-end aggregation into linear columns, by controlling the terminals of both enantiomers we could study the propagation of chirality in solutions where the D and L species form mixtures of homochiral columns, and in solutions of heterochiral columns. The two systems behave in markedly different fashion. By adopting a simple model based on nearest-neighbor interactions, we account for the different observed dependence of the chirality of these two systems on the enantiomeric ratio.
authors.affiliation: Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, MI, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Rossi
authors.forename: Giuliano
authors.initials: G
authors.lastname: Zanchetta
authors.forename: Sven
authors.initials: S
authors.lastname: Klussmann
authors.forename: Noel A
authors.initials: NA
authors.lastname: Clark
authors.forename: Tommaso
authors.initials: T
authors.lastname: Bellini
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D003855:Deoxyribose / Q000737:chemistry; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D009841:Oligonucleotides; D003855:Deoxyribose; D004247:DNA