CC BY
9
ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
AZERBAIJAN CHEMICAL JOURNAL No 4 2020
65
UDC 544.344; 577.1.08
PHYSICO-CHEMICAL FEATURES OF CATALASE BIOMIMETIC SENSORS N.N.Malikova, N.I.Ali-zade, T.M.Nagiev
M.Nagiev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
Received 17.03.2020 Accepted 20.05.2020
The physicochemical features of biomimetic sensor have been studied, using various materials as a transducer. It is shown that biomimetic sensor prepared on the basis of a smart material and semiconductors had a number of technological advantages. It was found that among the selected various materials, the biomimetic sensor prepared from the smart material TPhPFe3+OH/Al2O3 and the semiconductor Si proved to be the most effective. The developed biomimetic sensor is differed by high activity, sensitivity, stability and reproducibility with the possibility of expanding the range of detectable trace concentration of H2O2 in aqueous solutions to 10-6 mass %.
Keywords: biomimetic sensor, catalase, iron tetraphenylporphyrin, semiconductors, smart material. doi.org/10.32737/0005-2531-2020-4-65-68 Introduction
The development of highly sensitive, express and accurate biosensors and their mimetic analogues is of great interest in various types of diagnostics. Biosensors are successfully used to control environmental pollution in medical diagnostics, in industry for the production of a wide class of products and etc. Enzyme biosensors take the leading position in this area due to the high specificity of the enzyme to the substrate. Enzyme biosensors take the leading position in this area due to the high specificity of the enzyme to the substrate. At enzymes adsorption of solid surfaces (metals, ceramics, polymers), they, as a rule, retain their structure and catalytic activity. The enzyme in the ampere-metric biosensor mode exhibits electrocatalytic activity, that is, accelerates the process of electrons exchange between the substrate and electrode. This allows to measure directly in the sample of a multicomponent composition.
In this regard, the topic of work is certainly actual. In the work proposed biomimetic sensors used as the active material iron tetra-phenylporphyrin was deposited on various electrodes. The use of these materials has increased the sensitivity of the biomimetic sensor. With the help of the developed biomimetic sensor, the possibility of determining the trace concentrations of hydrogen peroxide in aqueous and in aqueous-alcohol solutions was shown.
Fig.1. Infographics.
A promising direction in the field of modern biotechnology is the creation of highly sensitive biosensors and their mimetics, in which enzymes are used as working materials (bioselectors). In [1, 2] studies in this direction were carried out.
In the present work, potentiometric studies of the catalase activity of biomimetic sensors prepared from different electrodes and smart biomimetic catalyst TPhPFe3+OH/Al2O3 were carried out.
Materials and Methods
Studies were performed in an electrochemical cell, which for clarity, is presented in the form of infographics (Figure 1).
The catalase activity of biomimetic sensors was determined by a potentiometric method.
The experimental setup, to carry out these studies, consisted of the electrode part, the cell, and the B7-21A universal voltmeter. The electrode part of the installation consists of a reference electrode (Ag/AgCl/Cl-) and a bio-mimetic sensor prepared by us. As background solution served as bidistilled water.
Potentiometric studies were carried out as follows: in the cell filled with a certain amount of bidistilled water, the e.m.f of (E) element was determined and then, adding different concentrations of H2O2 of solution, determined the changes in e.m.f. of system.
All measurements were performed with continuous stirring with a magnetic stirrer.
Results and Discussions
As you know, one of the main indicators of sensors is their sensitivity to the lowest concentrations of substances determined by them -the threshold of sensitivity.
Metals
Pb-electrode
Initially, our studies were devoted to potentiometric measurements of low concentrations of H2O2 in an aqueous solution for a Pb-electrode. For this, solutions with low concentrations of H2O2 were prepared - 10-6 and 10-8 mass % (Figure 2).
In Figure 2 are given experimental data on the catalase activity of a biomimetic sensor when determining trace concentrations of H2O2 in an aqueous solution. When H2O2 is added to the system, there is a sharp change in the values of
AE, B -0,5 --0,4 -
1 o x, min
Fig.2. Change e.m.f. systems depending on time at low concentrations of H2O2 for TPhPFe (III)/ Al2Os/Pb electrode: 1 - 10-6, 2 - 10-8 mass %.
the electrochemical potential and it makes up (0.15 mV) for both concentrations (curves 1 and 2). Starting from 1 minute, the value of the electrochemical potential continues to change until the practical decomposition of H2O2. This is evidenced by the fact that the value of the pH solution by the end of the experiment is 6.8, meaning that the background solution had the same value.
As a result of the research, it was found that a Pb-electrode with TPhPFe3+OH/AhO3 allows detecting trace concentrations of hydrogen peroxide in an aqueous solution in an amount of 10-8 mass % [3].
Al-electrode
It was interesting for us to conduct experiments with another metal, namely with aluminum, on the surface of which TPhPFe3+OH/ Al2O3 was applied. Under identical conditions carried out with TPhPFe3+OH/AhO3//Pb biomimetic electrode, the Al electrode was investigated.
In Figure 3 experimental data on catalase activity TPhPFe3+OH/Al2O3//Al biomimetic sensor when determining trace concentrations of H2O2 in aqueous solution are shown.
As is seen the background solution for 10 mass % (curve 1), Al-electrode without imitator (curve 2) and 10-4 mass.% (curve 3) H2O is (0.58), (0.55) and (0.383 mV) respectively.
-6
Fig.3. Change e.m.f systems depending on time at low concentrations of H2O2 for TPhPFe3+OH/Al2O3//Al biomimetic sensor CH2O2 = 10-6 mass %. t = 220C. 1 - Al+Ag paste+TPhPFe3+OH/Al2O3 (10-6), 2 - Al -without imitator (10-4), 3 - Al+Ag paste+ TPhPFe3+OH/Al2O3 (10-4 mass %).
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When H2O2 is added to the system, there is a change in the values of the electrochemical potential, which is (0.588) for 10-6 mass %, (0.407 mV) for 10-4 mass % (curves 1 and 3, Figure 3). The sensitivity threshold of TPhPFe3+OH/ M2O3 //Al of the biomimetic sensor was 10-6 mass %.
Semiconductors
Our further studies were continued with the use of semiconductors, which have received wide practical application in bioelectronics, primarily silicon, germanium and tellurium (Si, Ge, Te).
Te-electrode
First, we conducted our studies with the semiconductor Te (Figure 4). As can be seen from Figure 4, curve 1, on 10-4mass % H2O2 addeing to the system, a jump in the electrochemical potential is observed, then a new surface layer is formed at the sensor-solution interface and the potential value stabilizes. In the presence of 10-6 mass % H2O2 in the reaction system, a low sensitivity of TPhPFe3+OH/ Al2O3//Te biomimetic sensor curve 2 is observed. In the study of the cata-lase biomimetic sensor, it was found that a Te-electrode with TPhPFe3+OH can detect trace concentrations of H2O2 in an aqueous solution in an amounts of 10-4, 10-6 mass % [6].
Ge-electrode
Our research was related to the search for an effective semiconductor for the preparation of a biomimetic sensor. These were the main objectives of our research. In the framework of solving this problem, we used the most com-
Fig.4. Change emf systems depending on time at low concentrations of H2O2 for TPhPFe3+OH/Al2O3//Te biomimetic sensor: 1 - Сн2о2=10-4, 2 - Сн2о2=10-6 mass %.
mon semiconductor element in electronics - Ge. However, when using Ge as a substrate, it was found that when H2O2 is added to the system, Ge dissolves. Therefore, studies using Ge have been discontinued.
Si-electrode
In the next series of experiments for the preparation of a biomimetic sensor we nave chosen the simplest one among of semiconductors which are widely used in bioelectronics -silicon.
The results of the experiments carried out at various concentrations of H2O2 are shown in Figure 5. From Figure 5 it is clearly seen that the presence of hydrogen peroxide in the system leads to a change in the value of ДЕ, and an increase in the concentration of H2O2 from 10-6 to 1 mass % increases the jump in the electrochemical potential (curves 1-4).
Considering curves 1-4, it is not difficult to notice that in a few seconds, after adding H2O2, all curves reach their maximum.
Then the electrochemical potential in the biomimetic sensor/H2O2//Ag/AgCl/Cl- system continues to change until the practical decomposition of H2O2.
When using a 1% aqueous solution of H2O2 to study the biomimetic sensor for cata-lase activity (curve 1), at the 3rd second observed the maximum e.m.f. value systems was (-0.461).
Fig.5. Change emf systems depending on time at low H2O2 concentrations for TPhPFe(III)/Al2O3//Si biomimetic sensor. t = 220С. The number of TPhPFe3+OH = 0,025 mg. 1 - Сн2о2 = 1, 2 - Сн2о2= 0.5, 3 - Сно = 10-6 , 4 - Сно, = 10-4 mass %.
Experimental data related to the determination of the high sensitivity of the developed biomimetic sensor for determining trace amounts of H2O2 in aqueous solution are shown in Figure 5, curves 3, 4. Curve 3 (10-6 % concentration of H2O2) and curve 4 (10-4% concentration of H2O2) after a few seconds (2-5 seconds) reaches a maximum value of AE and continues to change
As a result, potentiometric studies of the catalase activity of a biomimetic sensor prepared from a Si electrode and a smart biomimetic catalyst TPhPFe3+OH/Al2O3 were carried out. The developed biomimetic sensor allows detecting trace concentrations of H2O2 in an aqueous solution at a sensitivity threshold of 10-6 mass % [4, 5, 7].
Conclusions
The synthesized TPhPFe3+OH/AhO3//Pb and TPhPFe3+OH/Al2O3//Al biomimetic sensors had high sensitivity, the threshold of sensitivity to trace H2O2 concentrations was 10-8 and 10-6 mass % respectively.
Developed on the basis of smart biomimetic material (tetraphenylporphyrin iron) and semiconductor - Si, the biomimetic sensor is characterized by long stability, high sensitivity and reproducibility, with the possibility of expanding the range of trace concentrations of H2O2 in aqueous solutions.
For a long time, the synthesized biomimetic sensors did not lose their activity both under the influence of an oxidizing agent and its intermediates.
References
1. Nagiev T.M. Coherent Synchronized Oxidation by Hydrogen Peroxide. Amsterdam: Elsevier, 2007. 325 p.
2. Nagiev T.M. Biomimetic Based Application. Preface IX. Chapter 4. Croatia. INTECH. 2011. P.105.
3. Malikova N.N., Ali-zadeh N.I., Nagiev T.M. Cata-lase-biomimetic sensor on base of electrochemical electrode TPhPFe(III)/Al2O3/Pb Nature Inspires, Chemistry Engineers. 2nd International Conference on Bioinspired and Biobased Chemistry & Materials. October 15-17 2014, Nice, France. P. 348 SMART-TECH-OR 208.
4. Malikova N.N., Ali-zadeh N.I., Nagiev T.M. Cata-lase-biomimetic sensor on base of electrochemical electrode TPhPFe(III)/Al2O3/Pb and TPhPFe(III)/ Al2Os/Si. J. Chemis. Chemical Eng. (USA). www.da-vidpublishing.com V. 9. Number 1. January 2015. P. 67-70.
5. Malikova N.N., Ali-zadeh N.I., Nagiev T.M. Cata-lase biomimetic sensor on base of silicon electrode TPhPFe3+/Al2Os//Si. 34th Int. Conf. Solution Chem. 2015. 30th August-3rd September. Prague. Czech Republic P 41.
6. Melikova N.N., Ali-zade N.I., Nagiev T.M. Issle-dovanie katalaznoi aktivnosti bio-mimeticheskikh sensorov. Chemical Problems. 2018. № 3(16). P. 437-443.
7. Malikova N.N., Qli-zada N.Í., Nagiyev T.M. Bio-mimetik elektrodun hazirlanma üsulu. Azarb. Respub. Patenti. № I 2018 0017. 02.05.2018.
KATALAZ BÍOMÍMETÍK SENSORLARIN FÍZÍKÍ-KImYOVÍ XÜSUSiYYOTLORl
N.N.Malikova, N.LOH-zada, T.M.Nagiyev
Transdüser kimi, müxtalif materiallardan istifada edilan biomimetik sensorlarin fiki-kimyavi xüsusiyyatlari öyranilmiijdir Smart material va yanmkegiricilardan hazirlanmi§ biomimetik sensorlar bir sira texnoioji üstünlüklara malik oldugu göstarilmiijdir Müxtalif istifada olunan materiallardan an effektiv smart material - TPhPFe3+OH/Al2O3 va Si-yanmkegirici biomimetik sensor müayyan edilmi§dir. i§lanib-hazirlanmi§ biomimetik sensor yüksak aktivliyi, hassasligi, stabilliyi va takrar istifadasi ila H2O2-in sulu mahlulda tayini diapazonun geni§ imkani ila xarakteriza olunur (10-6 küt.% qadar).
Agar sözlzr: biomimetik sensor, katalaz, damir tetrafenilporfirin, yarimkegiricihr, smart material.
ФИЗИКО-ХИМИЧЕСКИЕ ОСОБЕННОСТИ КАТАЛАЗНЫХ БИОМИМЕТИЧЕСКИХ СЕНСОРОВ
Н.Н.Меликова, Н.И.Али-заде, Т.М.Нагиев
Изучены физико-химические особенности биомиметических сенсоров, в качестве трансдьюсера которых использованы различные материалы. Показано, что биомиметические сенсоры, приготовленные на основе смарт материала и полупроводников, имели ряд технологических преимуществ. Установлено, что из использованных различных материалов наиболее эффективным оказался биомиметический сенсор, приготовленный из смарт материала - TPhPFe3+OH/Al2O3 и полупроводника Si. Разработанный биомиметический сенсор характеризуется высокими, активностью, чувствительностью, устойчивостью и воспроизводимостью с возможностью расширения диапазона определяемых следовых концентраций Н2О2 в водном растворе до 10-6 масс %.
Ключевые слова: биомиметический сенсор, каталазный, тетрафенилпорфирин железа, полупроводники, смарт материал.
