Surface nanogrooving of carbon microtubes

New micro/nanocomposite with peroxidase-like activity in construction of oxidases-based amperometric biosensors for ethanol and glucose analysis

Development of artificial enzymes, including nanozymes as an alternative for non-stable and expensive natural enzymes, is a booming field of modern Biosensorics and Biofuel Technology. In this study, we describe fabrication and characterization of sensitive biosensors for the detection of ethanol and glucose based on new micro/nanocomposite electrodes with peroxidase-like activity (nanozyme) coupled with microbial oxidases: alcohol oxidase (AOX) and glucose oxidase (GOX). The nanozyme was synthesized by modification of carbon microfibers (CF) by hemin (H) and gold (Au) nanoparticles. The formation of gold nanoparticles on the surface of hemin-modified carbon microfibers has been confirmed by the UV-Vis and X-ray spectroscopy as well by the SEM analysis. Compared to hemin-only modified electrodes, the resulting micro/nanocomposite CF-H-Au electrodes exhibit a higher specific catalytic activity and a better affinity for H₂O₂ in solution. The H₂O₂-sensitive CF-H-Au-modified electrodes showed a higher sensitivity (1.3-2.6-fold) compared with the nearest carbon-derived analogs and were used for the construction of highly sensitive ethanol and glucose biosensors. To eliminate diffusion limitation for substrates, AOX or GOX were fixed on the CF-H-Au-modified electrodes using a highly porous Nafion membrane. The main biosensors' characteristics have been investigated. The developed biosensors were tested for ethanol and glucose analysis in the real samples of both grape must and wine. The results are in good agreement with the results obtained using enzymatic kits as reference approaches.

On the Investigation of Microstructured Charcoal as an ANFO Blasting Enhancer

In this study, we examined the influence of microstructured charcoal (MC) when added to ammonium nitrate fuel oil (ANFO) samples. We performed a study that investigated ANFOs structure, crystallinity, and morphology by utilizing infrared spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. MC characteristics were probed by Raman spectroscopy and SEM analysis. SEM analysis indicated how fuel oil (FO) covered ammonium nitrate prill. Moreover, the surface of the MC was covered by specific microfibers and microtubes. The disordered graphitic structure of the MC was also confirmed by Raman spectroscopy. Simulation of blasting properties revealed that the addition of MC should decrease blasting parameters like heat explosion, detonation pressure, and detonation temperature. However, the obtained differences are negligible in comparison with the regular ANFO. All analyses indicated that MC was a good candidate as an additive to ANFO.

Microporous carbon fibers as electroconductive immobilization matrixes: Effect of their structure on operational parameters of laccase-based amperometric biosensor

In this study, we describe the fabrication of sensitive biosensor for the detection of phenolic substrates using laccase immobilized onto two types of microporous carbon fibers (CFs). The main characteristics of microporous CFs used for preparation of biosensors are given. Two CFs were characterized by different specific surface area, CFA (<1 m²·g^-1) and CFB (1448 m²·g^-1), but with comparable size of the micropores estimated by positron annihilation lifetime spectroscopy. The structural analysis was shown that CFA is formed by thin interwoven fibers forming a highly porous structure, as well as CFB - by granular formations with uneven edges that shape a cellulose membrane of lower porosity. The results of amperometric analysis revealed that the laccase-bound CFs possesses better electrochemical behavior for laccase than non-modified rod carbon electrodes (control). Using chronoamperometric analysis, the operational parameters of the CFs-modified bioelectrodes were compared to control bioelectrodes. The bioelectrodes based on CFs have demonstrated 2.4-2.7 folds enhanced maximal current at substrate saturation (I_max) values, 1.2-1.4 folds increased sensitivity and twice wide linearity compared with control bioelectrodes. The sensitivity of the developed CFs-based bioelectrodes was improved compared with the laccase-bound electrodes, described in literature. The developed biosensor was tested for catechol analysis in the real communal wastewater sample.