Evgeniia M. Khairullina

Non-enzymatic sensors based on in situ laser-induced synthesis of copper-gold and gold nano-sized microstructures

The synthesis of conductive gold and copper-gold microstructures with high developed surface based on the method of laser-induced metal deposition from solution was developed. The topology and crystallization phase of these structures were observed by means of scanning electron microscopy and X-ray diffraction, respectively. The electrochemical properties of the synthesized materials were investigated using cyclic voltamperometry and amperometry. According to the obtained results, it was found out that copper-gold microstructures demonstrate a linear dependence of Faraday current vs. concentration from 0.025 to 5µM for D-glucose and from 0.025 to 10µM for hydrogen peroxide. In turn, gold deposit exhibits a linear dependence of Faraday current vs. concentration from 0.025 to 50µM for D-glucose and from 0.025 to 1µM for hydrogen peroxide. Moreover, the synthesized materials reveal low detection limits (0.025µM) with respect to the aforementioned analytes, which is quite promising for their potential application in design and fabrication of new non-enzymatic biosensors.

Influence of surfactants on laser-induced copper deposition from solution

The influence of surfactants on the result of laser induced copper deposition from solution on the dielectric surface was studied. The dependences of the topology of the copper structures on the hydrophilic—lipophilic balance of non-ionogenic surfactants was found. The surface tension at the gas phase—solution interface was measured. The best results of laser deposition are obtained by the use of non-ionogenic surfactants with low values of hydrophilic—lipophilic balance.

In situ laser-induced codeposition of copper and different metals for fabrication of microcomposite sensor-active materials

We report one-step in situ laser-induced synthesis of the conductive copper microstructures doped with iron, zinc, nickel, and cobalt with highly developed surface area. It was observed that the presence of chlorides of the aforementioned metals in the solutions used in our experiments increases the deposition rate and the amount of copper in the resulting deposits; it also leads to the deposit miniaturization. The laser deposition from solutions containing cobalt (II) chloride of concentration more than 0.003 M results in fabrication of copper microelectrode with better electrochemical properties than those deposited from solutions containing chlorides of other metals of the same concentration. Moreover, copper microelectrode doped with cobalt has demonstrated good reproducibility and long-run stability as well as sensitivity and selectivity towards determination of hydrogen peroxide (limit of detection-0.2 μM) and d-glucose (limit of detection-2.2 μM). Thus, in this article we have shown the opportunity to manufacture two-phase microcomposite materials with good electrical conductivity and electrochemical characteristics using in situ laser-induced metal deposition technique. These materials might be quite useful in development of new perspective sensors for non-enzymatic detection of such important analytes as hydrogen peroxide and glucose.

Catalytic activity of copper nanostructures produced by laser-induced deposition technique

The method of laser-induced metal deposition from solution was applied in the continuous in situ laser generation of metal copper catalysts for model organic synthesis reactions. The gas phase products producing during laser-induced copper deposition were analyzed by mass spectrometry whereas solutions used for the copper deposition were investigated before and after laser irradiation using chromato-mass spectrometry and NMR spectroscopy. It was found out that the catalysis of the studied organic reactions by metal catalysts generated during laser deposition process occurs only upon laser irradiation of the reaction mixture.

Non-enzymatic glucose and hydrogen peroxide sensors based on metal structures produced by laser-induced deposition from solution

The method of laser-induced metal deposition was applied to synthesize nano- and microstructured metal electrodes for non-enzymatic glucose and hydrogen peroxide sensing. These electrodes were characterized by SEM, EDX, SIMS, XRD and EIS. Copper electrodes have a linear dependence of the current-concentration in the range of 10-100 μmol/L for hydrogen peroxide and 0.6-3.0 mmol/L for D-glucose.

Laser-induce co-deposition of copper with cobalt as signal amplification method for biochemical microbiosensors

The influence of cobalt (II) chloride on laser-induced copper deposition was studied. Copper deposition experiments in aqueous solutions containing various concentrations of cobalt (II) chloride upon 532 laser irradiation were performed. The influence of additives on the deposition rate, the topology, electrochemical properties of the deposited microstructures was investigated. Sensory activity of these structures towards hydrogen peroxide and glucose was studied.

A new approach to obtain nanostructured nickel deposits on the surface of dielectrics by direct laser writing

Nanostructured nickel deposits can be applied in hydrogenation reactions catalysis and electrochemical systems development. Laser-induced liquid-phase metal deposition allows creating microscaled nickel structures with a developed surface. In this paper a possibility of abandoning technologically imperfect plating solutions containing various reducing agents such as hypophosphite, boron hydride is shown. Deposition was conducted from solutions only containing nickel salt and various organic ligands which allow avoiding phosphorus and boron codeposition. Influence of ligand nature, ligand concentration and solution pH on laser deposition results was studied. Obtained deposits were researched using SEM, EDX, XRD methods.

Laser-induced copper deposition with weak reducing agents

The study showed that organic alcohols with 1,2,3,5,6 hydroxyl groups can be used as reducing agents for laser-induced copper deposition from solutions (LCLD).Multiatomic alcohols, sorbitol, xylitol, and glycerol, are shown to be effective reducing agents for performing LCLD at glass-ceramic surfaces. High-conductivity copper tracks with good topology were synthesized.