METHOD FOR DETECTING A BIOLOGICALLY ACTIVE SUBSTANCE IN A LIQUID TO BE ANALYSED AND DEVICE FOR REALISING THE SAME

摘要

The present invention may be used for rapidly and easily detecting with a high precision and sensitivity the presence and concentration of any biologically active substance capable of interacting with linear dual-chain DNA molecules, wherein said detection can be carried out in any liquid including biological fluids. The present method essentially comprises preparing a lyotropic liquid-crystal cholesteric dispersion of DNA from linear dual-chain DNA molecules. This dispersion is prepared in a saline aqueous solution of a polymer which is neutral relative to the DNA immediately before mixing said dispersion to the liquid undergoing analysis and containing the substance to be detected. The liquid for analysis is further prepared by mixing the above-mentioned polymer under conditions that do not alter the optical properties of the lyotropic liquid-crystal cholesteric dispersion of DNA. A probe is then obtained from the mixture of the prepared liquid with the liquid-crystal dispersion of DNA, wherein a circular polarisation light is sent through said probe and an optic signal is recorded at two wavelengths. One wavelength is located in the absorption spectrum of the DNA, while the other is located in the absorption spectrum of the biologically active substance. The method further comprises calculating the ratio between the signals and using the value of this ratio to determine the concentration of the biologically active substance according to a calibration line. The device of the present invention comprises a selector (2) having an electrodynamic actuator (22) of the point-to-point type and at least one optical member (26, 27, 28) which is mounted on the shaft (35) of the motor (33) of said actuator (22).