FG Nanobiotechnologie
Refine
Year of publication
- 2017 (4) (remove)
Document Type
- Scientific journal article peer-reviewed (4) (remove)
Language
- English (4)
Keywords
- Affinity (1)
- Chemical sensor (1)
- Chemotransistor (1)
- Conducting polymer (1)
- Conductometric sensor (1)
- Fish freshness (1)
- Sensor arrays (1)
- electrochemical polymerization (1)
- nitrogen heterocycle (1)
- polymer film (1)
Institute
Recently reported concept of electrical control of sensor affinity was applied for formation of a virtual sensor array based on the single sensing element. Affinity properties of this element were modulated by electrically controlled conversion of chemosensitive material between its different redox states possessing different affinity. The sensor was realized on the basis of electrochemical chemotransistor in which a low temperature ionic liquid containing chloride was used to connect the chemosensitive material to the Ag/AgCl reference electrode. The concept of virtual array was proved by its application for monitoring of fish headspace. Using three characteristics of the sensor response measured at three different redox states of the same sensor material, we have obtained signals from a virtual sensor array consisting of nine chemosensitive elements. The sensor displays systematic changes of its nine signals during fish degradation and allows us to make quantitative analysis of its freshness defined as the after the catch. The level of detection is far below the level of organoleptic detection.
The amino-substituted coumarin derivative of Tröger’s base (CTB) was electrochemically polymerized on the surface of gold electrodes. The obtained polymer films were characterized by SEM, Raman spectroscopy, cyclic voltammetry and in-situ conductometry. Spectroscopic analysis indicates that the polymerization of CTB takes place via oxidation of the aniline fragment of CTB molecule, similar to the polymerization of aniline. The similarity of the polymer backbone to that of the polyaniline is also confirmed by the influence of potential on the film’s conductivity, however the conductivity of the new material is in principle lower than that of polyaniline. SEM shows that the polymer forms a thin layer with a thickness of ~ 100 nm. Possible applications of the new material as an artificial receptor for aromatic analytes containing carboxy-group are proposed.
An approach for visualization of patterned monomolecular layers in surface plasmon microscopy (SPM) is suggested. The development of hidden image in SPM is achieved by referencing of images obtained in the presence of electrolytes with a high molar refraction of either anions or cations. A formation of diffuse layer near the charged surface areas leads to the redistribution of ions. The ratio of SPM images allows one to visualize this redistribution and to distinguish surface areas with different properties. The approach is unobtrusive and robust; it can be used with most SPR imaging instruments.
Surface plasmon resonance, being widely used in bioanalytics and biotechnology, is influenced by the electrical potential of the resonant gold layer. To evaluate the mechanism of this effect, we have studied it in solutions of various inorganic electrolytes. The magnitude of the effect decreases according to the series: KBr>KCl>KF>NaClO4. The data were treated by using different models of the interface. A quantitative description was obtained for the model, which takes into account the local dielectric function of gold being affected by the free electron charge, diffuse ionic layer near the gold/water interface, and specific adsorption of halides to the gold surface with partial charge transfer. Taking into account that most biological experiments are performed in chloride-containing solutions, detailed analysis of the model at these conditions was performed. The results indicate that the chloride adsorption is the main mechanism for the influence of potential on the surface plasmon resonance. The dependencies of surface concentration and residual charge of chloride on the applied potential were determined.