N. O. Ronzhin

Designing a reusable system based on nanodiamonds for biochemical determination of urea

A reusable system including urease covalently bound to the surface of modified nanodiamonds (MNDs) has been developed for the multiple determination of urea. The immobilized enzyme exhibits functional activity and catalyzes the hydrolysis of urea to yield ammonia. The presence of ammonia is confirmed by the formation of a colored product after the addition of chemical reagents. It was shown that the MNDs-urease complex can function in a wide range of temperatures and pH as well as in deionized water. The complex provides a linear yield of the product at low analyte concentrations and allows the multiple determination of urea in vitro.

Detonation Nanodiamonds as a New Tool for Phenol Detection in Aqueous Medium

This paper demonstrates the effectiveness of using detonation nanodiamonds (DNDs) for detecting phenol in aqueous medium. The study has shown that the catalytic effect of DNDs in the oxidative azo coupling reaction (phenol-4-aminoantipyrine-hydrogen peroxide) is produced by trace amounts of iron and copper ions adsorbed on the surface of nanoparticles. The effectiveness of DNDs as a catalyst is determined by the amounts of these adsorbates and can be enhanced by a factor of two by additional adsorption of these ions onto the nanoparticles. A rise in the temperature of the DND-catalyzed azo coupling reaction leads to a considerable (4.5-fold) increase in the reaction product yield. DNDs used to detect phenol in aqueous medium enable a linear increase in the yield of the product of the azo coupling reaction at concentrations of the analyte of between 0.05 and 10 μg/ml. The study demonstrates that DNDs can be reused to detect phenol in water samples.

Creation of Bifunctional Indicating Complex Based on Nanodiamonds and Extracellular Oxidases of Luminous Fungus Neonothopanus nambi

A bifunctional indicating complex was created by immobilization of extracellular oxidases (glucose oxidase and peroxidases) of luminous fungus Neonothopanus nambi onto modified nanodiamonds (MNDs) synthesized by detonation. It was found that the enzymes firmly adsorb onto MND particles and exhibit their catalytic activity. Model in vitro experiments showed that the created MND–enzymes complex is suitable for repeated use for analyte (glucose and phenol) testing and retains its activity after storage at 4°C in deionized water for 1 month. The data obtained offer the prospects for developing a new class of reusable multifunctional indicating and diagnostic test systems on the basis of MNDs and higher fungal enzymes for medical and ecological analytics.

Extracellular Peroxidase Activity and Light Emission of the Mycelium of the Basidiomycete Neonothopanus nambi in the Presence of β-Glucosidase

A comparative evaluation of the level of extracellular peroxidase activity and light-emission intensity of the mycelium of the luminescent basidiomycete Neonothopanus nambi in the presence of β-glucosidase was performed. The enzyme activity damages the hyphae of the fungus leading to osmotic imbalance, partial degradation of the mycelium, and release of extracellular peroxidases into the incubation medium. The presence of β-glucosidase reduces the time necessary to reach the maximum luminescence. Putative biochemical mechanisms that underlie the stimulation of reactive oxygen species formation (first and foremost, of hydrogen peroxide) in the N. nambi mycelium in the presence of β-glucosidase are proposed.

Nanodiamonds as an effective adsorbent for immobilization of extracellular peroxidases from luminous fungus Neonothopanus nambi to construct a phenol detection system

Abstract Modified nanodiamonds (MNDs) produced by detonation synthesis can be used as an effective adsorbent to immobilize extracellular peroxidases of the luminous basidiomycete Neonothopanus nambi. The enzymes are firmly immobilized on MND particles and exhibit catalytic activity. The indicator system (the MND–enzyme complex) reused many times retains its ability to catalyze reaction of co-oxidation of phenol and 4-aminoantipirine in the presence of hydrogen peroxide and remains functionally active during long-term storage (for 1 month or longer) in aqueous suspensions at 4 °C. MNDs and enzymes of higher fungi can be effectively used to construct new reusable indicator systems for analytical applications such as monitoring contamination of aquatic environments by phenolic compounds.

On the applicability of nanodiamonds produced by detonation synthesis for phenol testing in aqueous media

It was found that the catalytic effect of modified nanodiamonds (MND) in the H2O2–4-aminoantipyrine–phenol oxidative azo coupling reaction is due to microimpurities of iron and copper ions on the surface of nanoparticles. The efficiency of MND as a catalyst is determined by the amount of surface impurities of these ions and can be doubled by their additional adsorption on nanoparticles. Using MND for phenol indication ensures a linear yield of the colored product of the azo coupling reaction over an analyte concentration range of 0.05–10 μg/mL. The possibility of reusing MND for phenol testing in aqueous samples was demonstrated.

Reusable biochemical diagnosis systems based on nanodiamonds

55 Physicochemical properties of nanodiamonds of detonation synthesis [1] allow them to be considered as a new material of biotechnological purposes with prospects of application in biology and medicine [2–4]. One of the areas of application of nanodiamonds is the construction on their basis of new tools for biochemii cal indication (including reusable systems), expanding the arsenal of methods of medical diagnostics. Spee cialists working in this field may be interested in modd ified nanodiamonds (MNDs) of detonation synthesis, forming free dispersion systems and adapted for bioo medical research [5, 6]. The chemically polymorphic active surface of MNDs, exhibiting a high colloidal stability in dispersive media [7, 8], makes it possible to predict the possibility of their use to design the systems of biochemical diagnostics of the components of bioo logical fluids [9]. We have experimentally demonstrated that MNDs can be used as a basis for designing reusable diagnostic test systems using the model systems for determinaa tion of cholesterol and glucose as an example. In the study we used the modified nanodiamonds RUDDM 00125 (d 50 = 49.6 nm), produced at OOO ReallDzerzhinsk (Dzerzhinsk, Russia) by the known technology [6]. Experiments were performed with MND hydrosols with the concentration of nanopartii cles of 1 wt%, which were prepared by adding deionn ized (DI) water (MilliiQ system, Millipore, United States) to an MND powder aliquot. In the study we used the following reagents: 44amii noantipyrine (11phenyll2,33dimethyll44aminopyraa zolone) (44AAP) and Dglucose of analytical grade (Reakhim, Russia), phenol (Fluka, Germany), and cholesterol standard (Vital Diagnostics, St. Peterss burg, Russia). The working solutions of reagents were prepared in situ in DI water. To create the indicator systems, we used the enzyme solutions from the reagent kits Cholesteroll Vital (Vital Diagnostics, St. Petersburg, Russia) and Glucose LS (ProDia International, Germany), which are commonly used to determine the concentration of total cholesterol and glucose in blood serum and plasma. For our experiments, the enzyme solutions were preliminarily dialyzed against 10 mM phosphate buffer (pH 7.0) by ultrafiltration (the Amicon system, United States) through a membrane with a 300kDa exclusion limit. The principle of operation of biochemical indicaa tion systems created on the basis of MNDs and enzymes is that the analyte is transformed in a chain of successive biochemical reactions catalyzed by enzymes Е1→Е2→…→Еn, immobilized on nanoparr ticles, to products Р1→Р2→…→Рn, the last of which (Pn) is colored and can be easily detected by spectral …