The development of DNA-nanosensors

based on piezoelectric resonators

R.F.Fakhrullin, S.S.Kharintsev, O.A.Konovalova, M.Kh.Salakhov, V.G.Vinter

Kazan State University

Kremlevskaya str., 16, Kazan, 420008, Russia

red@ksu.ru

 

DNA-nanosensors were obtained by immobilization of DNA molecules on the surface of a piezoelectric crystalline oscillator. Immobilization occurred through a consistent self-assembly of nanolayers, so that, contrary to what happens in the already existing DNA-nanosensors, the native structure of DNA was preserved and the nanosensor device was re-usable after careful washing of the device after each test. First a precursor layer made up of polylysine for immobilization of DNA molecules was produced, which was in the form of a strong nanofilm very stable to water flushing but easily removable by alcohol. Silver electrodes were employed. A study of the immobilization rate of native DNA molecules on the polylysine nanomembranes showed that the formation of a DNA molecules layer occurred rather quickly. A strongly immobilized layer of DNA molecules was formed within 2 hours of incubation, and such layer resisted repeated washing with water without any change in resonator oscillations frequency. The nanosensor so obtained was employed to determine the amount of antibodies to DNA in the blood serum of patients suffering from systemic lupus erythematosus and of healthy donors. Changes in the oscillation frequency of the nanosensor were used to test the presence of antibodies. The oscillation frequency dropped sharply in the presence of antibodies, and this was explained with the increase in the electrode mass as a result of the attachment of antibodies to DNA. The high sensitivity and expressivity of such piezoelectric sensor allowed to ascertain the presence of antibodies within a mass difference of 1 ng. This corresponds to the molecular mass of individual macromolecules. The stability of the nanomembrane obtained overcomes the mechanical stability of supramolecular structures which are widely employed in nonlinear optical devices, in microelectronics and in supramolecular chemistry.The nanosensors so developed can be of use for a wide number of applications other than the determination in blood serum of antibodies to ascertain the systemic lupus erythematosus illness.