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The use of Boron Doped Diamond Electrode for Determination of 5-hydroxyindoleacetic Acid
Hrdlička, Vojtěch ; Navrátil, Tomáš
A new method for voltammetric determination of clinical biomarker 5-hydroxyindoleacetic\nacid (HIAA) at the boron-doped diamond electrode (BDDE) was developed. Anodically and\ncathodically pretreated BDDEs were tested in the pH ranges from 1 to 12, pre-treatment at\n+2.0V/60 s, and pH 3 was found to be the optimum.\nThe optimum square wave voltammetry (SWV) parameters were: f = 12 Hz, amplitude 60\nmV, and potential step 4 mV. SWV concentration dependency was constructed in the range\nfrom 0.1 to 100 μmol L−1, limits of determination and detection were 0.3 and 0.1 μmol L−1,\nrespectively. HIAA oxidation electrode process at BDDE was diffusion-controlled, as\nuncovered by cyclic voltammetry. Interestingly, HIAA peak potential was constant in various\nranges of pH, indicating a non-Nernstian behavior at the BDDE, in contrast to a previously\npublished electrooxidation mechanism consisting of a coupled H+/e− transfer.
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Comparison of the Covalent Laccase Immobilization at Amino- and Carboxylfunctionalized Mesoporous Silica, Glassy Carbon, and Graphite Powders using Different Coupling Agents for Optimal Biosensor Preparation
Tvorynska, Sofiia ; Barek, J. ; Josypčuk, Bohdan
In order to find the most suitable immobilization protocol, a comparison of three strategies\nbased on the application of –NH2 and –COOH functionalized supports with the different\nactivation agents (glutaraldehyde and carbodiimide) have been conducted for the covalent\nenzyme (laccase) attachment. Two kinds of the supports, namely mesoporous silica (SBA−15,\nMCM−41) and carbonaceous (glassy carbon, graphite) powders, have been used. It was found\nthat a biosensor consisted of tubular detector of silver solid amalgam as a working electrode\nand the enzymatic mini-reactor with laccase covalently attached to glutaraldehyde activated\n–NH2 functionalized MCM−41 shows the best results regarding sensitivity and stability for\ndopamine detection.
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Construction and application of the amperometric uric acid biosensors based on the covalent immobilization of uricase by different strategies
Tvorynska, Sofiia ; Barek, J. ; Josypčuk, Bohdan
In this work, a promising combination of a biosensor based on the\nenzymatic mini-reactor with the detection principle of four-electron\nreduction of the consumed oxygen at highly negative potential has\nbeen developed for uric acid determination using flow injection\nanalysis. The construction of the biosensor provides a spatial\nsegregation of the biorecognition (uricase-based mini-reactor) and\ndetection (tubular detector of silver solid amalgam (TD-p-AgSA))\nparts. To find out the most appropriate enzyme immobilization\nprotocol, three different strategies of the covalent attachment for\nuricase from Bacillus fastidiosus have been compared. It was found\nthat the biosensor with the mini-reactor based on the covalent\nattachment of uricase via glutaraldehyde to -NH2 functionalized\nmesoporous silica powder MCM-41 showed extremely high stability\n(>1 year) and reusability (at least 600 measurements) The biosensor's\npractical applicability was confirmed by successful determination\nof uric acid in human urine.
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3D printed materials for the electrochemical determination of biologically active compounds
Choińska, Marta Katarzyna ; Navrátil, Tomáš ; Hrdlička, Vojtěch
3D printing materials are relatively novel materials in electrochemistry,\nused for manufacturing of electrochemical cells, electrodes\netc. They have been widely used mainly for tailored, fast, inexpensive,\nand easy preparation of various equipment for analyses of\nbiologically active compounds. Various medicinal products and illicit\ndrugs belong to this broad group of analytes which need to be\nmonitored because of the possibility of (un)intentional overdose or\nrecreational consumption, which can cause serious side effects or\neven death. Due to this risk, we decided to focus our research on the\ndevelopment of new, sensitive, selective, and easily customizable 3D\nprinted sensors for the determination of some commonly used\nantidepressants, analgesics, and illicit drugs.
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