Yu.A. Tarantov

Fixation of DNA directly on optical waveguide surfaces for molecular probe biosensor development

Abstract Covalent attachment of DNA molecules to the surface of silicon nitride without an intermediate polymer layer is described. It is shown that the silicon nitride has a sorption capacity no less than 200 pg/mm2, hybridization efficiency being close to 100%. The expected value of refractive index changes in the molecular layer under hybridization is estimated as sufficient for the operation of two kinds of waveguide-containing transducers.

Physical and chemical processes in ISFETs with chalcogenide membranes

Abstract Chemical and physical properties of thin chalcogenide films (As 2 Se 3 :Cu) in ISFETs and EIS sysems have been investigated. Chemical sensitivity, selectivity and response time of a pCu-ISFET with chalcogenide membrane are similar to those of a conventional pCu-selective chalcogenide glass electrode (Yu. G. Vlasov and E.A. Bychkov, Ion-selective Electrode Rev., 9 (1987) 5–93). Investigation of the dependences of physical properties of chalcogenide films on the copper content of the films and on the pCu of electrolyte solutions revealed: (i) the spatial distribution of electrical charges in chalcogenide films and their optical constants (refractive index and absorption coefficient) depend strongly on the copper concentration in the film; (ii) the electrical and optical properties of chalcogenide films change drastically during the first exposure to an electrolyte solution containing copper ions; (iii) these changes can be unambiguously described as the formation of the two-layer structure of the chalcogenide film, electrical and optical properties of the outer layer (approximately 100 nm thick) corresponding to the properties of the films with lower copper concentration as compared to the inner part of the film. It is concluded that the formation of a modified surface layer characterised by high mobilities of species in it allows the ion-exchange mechanism of chalcogenide membrane/electrolyte solution interface potential generation to be realised.

Langmuir-Blodgett film based membrane for DNA-probe biosensor

Abstract Covalent attachment of DNA to diacetylene film produced on the surface of oxidized silicon by the Langmuir-Blodgett technique has been studied. Coupling of phage M13 DNA with polymer film was carried out by the carbodiimide method and by the formation of linker structures. Sorption capacity and hybridization efficiency determined using the radioactive label 32P were about 10–20 pg mm−2 and near 100%, respectively.

Optical and thermal sensitivity of pH-ISFET with Ta2O5 membrane

Abstract The effects of light and temperature upon a PH-ISFET with a Ta 2 O 5 membrane have been investigated. It is shown that long-term drain-current relaxation in the ISFET after switching the light on and off is related to the charge generation-neutralization processes in the Ta 2 O 5 layer. The thermal coefficient of the ISFET is determined and its dependence on the channel width to length ratio has been established and compared with conventional MOSFET theory.

COPPER-SELECTIVE FIELD-EFFECT TRANSISTOR (ISFET) WITH CHALCOGENIDE MEMBRANE

ABSTRACT pCu-ISPET is developed, the thin film of chalcogenide glass As2Se3 containing copper having been used as copper-sensitive membrane. The ellipsometry and C-V curves in EIS-system were applied to study in situ the membrane surface properties in contact with the electrolyte solution. The experimental data obtained confirm the modified surface layer model of pCu-ISFET operation.