Cooperation of several research institutes of Russian Academy of Sciences resulted in creation of a new high-precision sensor for detecting substances, hazardous and toxic for DNA.

Accurate and fast detection of potential toxins is extremely important for human health and environment. A close eye should be kept on chemical substances, which are able to interact with DNA, because killing effects of mutagens and carcinogens can be detected years after the exposure to these substances. Combination of nanotechnologies with biotechnologies can result in a new solution to the problem.

An elegant idea of the Russian researchers is using nano-sized constructions of DNA molecules, which change their optical properties, when interacting with toxic compounds. In their turn, changes in optical properties can be detected with a unique sensor, which was developed by the Russian scientists. Authors of the technique claim that new generations of their sensors will be smaller in size and cheaper than the prototype, because they target structural elements of nano-sized constructions, which are nanosensors themselves.

The prototype of a new bio-sensor system has successfully passed first tests and can find application in various medical institutions, where direct detections of substances, toxic for DNA, are performed in liquids. DNA molecules, immobilized in optically transparent, isotropic and chemically neutral gels and showing anomalous optical activity, are used as integral biosensors. As a registering devices scientists suggest using a portable single-wave dichrometer, which converts optical signal of circular dichroism.

Micro-sized DNA constructions (about 0.5 micrometer in diameter) are made from double-stranded DNA molecules by means of “nano-bridges” (chelate links, consisting of alternating molecules of daunomycin, an antracyclic antibiotic, and copper ions Cu²⁺) between neighboring molecules, immobilized in a spatial structure of lyotropic cholesteric liquid-crystal dispersion. Particles of this dispersion are immobilized in advance on a synthetic polymer matrix, which is a result of three-dimensional radical polymerization of bis-micromonoper of polyethylene oxide. Parameters of three-dimension structure of polyethylene oxide provide strong fixation of DNA molecular constructions without breaking their spatial organization and reactive capability for long period of time under room temperature conditions.

Formation of DNA nano-structures is accompanied by anomalous optical activity in the absorption region of daunomycin chromophores, which is about 520 nanometers. Presence and concentration of biologically active substances in sample liquid, which diffuses into hydro-gel, can be detected via values of biosensor signal change, registered by a dichrometer in a abovementioned wavelength of visible light range. New detector can also be used for measuring diffusion rates for various liquids in gel nano-biomaterials.

Source: Science & Technologies

Kizilova Anna