ИСТИНА

Metabolism of neurotransmitters is one of the most important processes in human body. Any serious disruptions of this equilibrium signals about beginning of neurodegenerative dementias or neuroendocrine tumors.1 Thus, significant deviations in the direction of increasing or decreasing concentrations of neurotransmitters, namely, dopamine (DA), indicate violations of the functioning of the body.2 A promising approach is the creation of highly sensitive and selective optical sensor systems. Surface enhanced Raman spectroscopy (SERS) opens up new possibilities towards lowering detection limits of analytes to pico- and femtomolar concentrations.3 An optimum tuning of chemical properties of the nanostructured substrates may lead to their higher affinities toward certain classes of analytes. We propose a quite simple and effective solution of key problems of DA detection usually associated with either improper positions of analyte absorption regions, often found in the UV-range (230 – 270 nm), far above the energy of silver (ca. 420 nm) and gold (ca. 520 nm) plasmonic bands, or a low binding ability of analyte molecules to the surface of SERS substrates.4 These restrictions usually do not allow SERS to be effectively applied as a highly sensitive tool for the detection of the above-mentioned analytes. A novel approach has been developed to build up advanced SERS planar sensors with a nanostructured silver layer coated with a thin layer of optically transparent chitosan gel.5 A chemical modification of the polymer with Cu(II) and different special triazole derivatives revealed that such a sensor benefits of from absorbing and preconcentrating of DA, followed by their selective binding of the analysed molecules into complexes. This novel indicator system allows sensitive determination of DA up to 10–10 mol/L without any tedious sample pretreatment steps in small volumes of biological samples for reliable diagnostics of neurodegenerative dementias or neuroendocrine tumors.