SENSING BIOLOGICAL EFFECTORS THROUGH THE RESPONSE OF BRIDGED NUCLEIC-ACIDS AND POLYNUCLEOTIDES FIXED IN LIQUID-CRYSTALLINE DISPERSIONS

The formation of three-dimensional structures of double-stranded nucle ic acid and polynucleotide molecules, fixed in the structure of liquid -crystalline dispersions and bridged by polymeric chelate complexes is described. The bridging elements consist of alternating daunomycin mo lecules and copper ions. It is shown that these bridges between nuclei c acid molecules stabilize cholesteric structures of the DNA liquid-cr ystalline dispersion. The formation of polymeric chelate bridges is ac companied by a remarkable increase of the intense circular dichroism ( CD) band characteristic of the DNA-daunomycin cholesterics. These brid ges are destabilized by a number of biologically relevant compounds an d macromolecules, such as ascorbic acid, homocarnosine, bovine serum a lbumin and lysozyme. The dramatic change in the optical activity of th e liquid-crystalline dispersions upon addition of these compounds make s them easily detectable. The sensitivity of the method, in the range of analyte concentration 10(-4) - 10(-8) M, depends on the nature of t he compound being tested. The response of bridged DNA structures to bi ological effecters observed here foresees their further development as biosensor devices for detecting the presence of biologically and phar macologically relevant compounds. (C) 1998 Elsevier Science S.A. All r ights reserved.