Send Orders for Reprints to
[email protected] Current Analytical Chemistry, 2016, 12, 37-42
37
Electrochemical Biosensors for Direct Determination of Organophosphorus Pesticides: A Review Margarita Stoytcheva*1, Velizar Gochev2 and Zdravka Velkova3 1
Engineering Institute, Autonomous University of Baja California, Mexicali, Mexico; 2Plovdiv University “P. Hilendarskii”, Plovdiv, Bulgaria; 3Medical University of Plovdiv, Plovdiv, Bulgaria Abstract: An overview on the progress in the organophosphorus hydrolase based electrochemical sensors design and application for direct organophosphorus pesticides quantification is presented in this work. The key analytical performances of the enzyme and of the bacterial potentiometric and amperometric organophosphorus hydrolase based sensors, as well as their advantages and deficiencies are commented in detail.
Keywords: Electrochemical biosensors, organophosphorus hydrolase, organophosphorus pesticides. 1. INTRODUCTION The organophosphorus pesticides (OPs) are a large group of synthetic compounds, including esters, amides, or thiol derivatives of phosphoric, phosphonic, phosphorothioic, or phosphonothioic acids [1-4]. Their action is associated with the irreversible acetylcholinesterase inhibition they cause, which results in nerve function disruption in both insects and human beings [3-6]. To avoid intoxications, the international and national legislations establish the maximum residue levels of OPs in or on food, feed, and water. According to the European water quality standards and regulations [7], the limit value of each pesticide in drinking water for human consumption does not exceed 0.1 μg L-1, while that of the total pesticides is fixed at 0.5 μg L-1. The drinking water health advisory levels of some selected OPs set by the US EPA, as an example are: diazinon 3 μg L-1, parathion-methyl 2 μg L-1, disulfoton 1 μg L-1, fenamiphos 2 μg L-1, etc. The OPs analysis is currently performed applying various chromatographic techniques, which are extensively commented and comprehensively reviewed in the literature [814]. The involved procedures which have to be carried out by qualified analysts consist of sampling, extraction, cleanup of the extract, and compound determination. The stage of the sample pretreatment especially is complex, timeconsuming, and costly. The chromatographic analysis itself is performed off-site, and off-line, using robust and expensive laboratory equipment. In this context, the application of the electrochemical biosensors-based methods, which are economical and simple to perform, as well as suitable for in situ and on line determinations, is considered as a high-potential innovative strategy for OPs quantification.
*Address correspondence to this author at the Autonomous University of Baja California, Engineering Institute, 21280 Mexicali, México; Tel: +52 686 5664150; Fax: +52 686 5664150; E-mail:
[email protected]
The common electrochemical biosensors based approach for OPs determination comprises the quantification, using electroanalytical techniques, of the cholinesterases inhibition that the OPs provoke, as function of their concentration. The method is attractive, because of its high sensitivity. Nevertheless, it is not direct and selective. The other shortcomings of the technique are associated with the irreversible enzyme inhibition, involving procedures for enzyme reactivation/ regeneration, and the need of substrate addition and incubation [15, 16]. The reviews commenting on the performances of the enzyme-inhibition based electrochemical sensors for OPs determination are abundant [17-27]. In contrast, only few works address the possibility of direct, selective, rapid, and simple determination of OPs based on the substitution of the inhibition receptor by a catalytic receptor enzyme such as the organophosphorus hydrolase (OPH), in combination with electrochemical detection. Thus, the objective of this review is to demonstrate the potential of the OPH (enzyme and bacterial)-based electrochemical sensors for OPs determination. 2. ENZYME (OPH) - BASED ELECTROCHEMICAL SENSORS FOR DIRECT OPs DETERMINATION 2.1. Principle of the Determination The organophosphorus hydrolase (OPH, also known as aryldialkylphosphatase, phosphotriesterase, or paraoxon hydrolase EC 3.1.8.1) exhibits substrate specificity toward a number of organophosphorus pesticides: paraoxon, parathion, methyl parathion, coumaphos, malathion, fenitrothion, acephate, demethon-S, diazinon, chlorpyrifos, etc. [28-31]. The enzyme catalyses, at different extend, the hydrolysis of P-O, P-S, P-F, and P-CN bonds, according to the following reaction [31, 32]: X
R
P R'
17-/16 $58.00+.00
X Z +
OPH H2O pH=810
© 2016 Bentham Science Publishers
R
P R'
OH+ ZH
38 Current Analytical Chemistry, 2016, Vol. 12, No. 1
X is oxygen or sulfur, R is an alcoxy group (methoxy to butoxy), R’ is an alkoxy or phenyl group, and Z is a phenoxy group, a thiol moiety, a cyanide or a fluorine group. OPH displays a maximum activity in the pH range 8-10 and at a temperature of 50oC. The hydrolysis provokes a pH change and electroactive products generation. Therefore, the OPs quantification could be performed applying potentiometric or amperometric sensors, correspondingly. For convenience, the analytical determinations are performed at ambient temperature. 2.2. Potentiometric Enzyme (OPH) - Based Sensors for Direct OPs Determination The principle of the potentiometry is well known. It is based on the measurement of the potential difference between two electrodes: the indicator electrode and the reference electrode. The potential of the reference electrode is fixed, while the potential of the indicator electrode varies with analyte concentration, as mathematically described by the Nernst equation. Because of the exponential character of this relationship, the dynamic concentration range of the determinations is large (3-4 decades), but the accuracy and the precision of the method are low. The commonly used indicator electrode for the direct OPs determination is a pH-electrode, which is modified through the formation of an OPH layer [32-34]. The enzyme immobilization is performed by the cross linking method, using bovine serum albumin and glutaraldehyde. The analysis is carried out at 20oC in a HEPES buffer solution (1 mM, pH 8.5) containing also 100 mM NaCl and 50 mM CoCl2 . The limit of detection (LOD) for paraoxon, ethyl parathion, methyl parathion, and diazinon is found to be 2 mol L-1, i.e. higher than the LOD achieved by applying acetylcholinesterase inhibition-based sensors [34]. Another drawback which limits the application of the developed biosensors is the long response time (2-3 min). The useful operating concentration range is extended up to 0.4 mmol L-1 for paraoxon and parathion. The precision of the paraoxon (RSD=4.23, n=9) and parathion (RSD=3.54, n=7) determinations is very satisfactory. Lihong et al. [35] demonstrate, using a mathematical model, that the response behavior of the OPH-pH electrodes could be controlled and optimized by designing an enzyme electrode with appropriate Thiele modulus value, and by selecting the correct buffer concentration. 2.3. Amperometric Enzyme (OPH) - Based Sensors for Direct OPs Determination The amperometric determinations are based on the monitoring of the current produced by an indicator electrode at a fixed electrode potential. The analytical signal is directly proportional to the concentration of the present electroactive specie. The application of an appropriate potential, kept constant, renders the determination selective. The other advantages of the amperometric detections over the potentiometric are the high sensitivity and precision of the analysis, the linear calibration plot, and the fast sensors’ response.
Stoytcheva et al.
The application of OPH-based amperometric sensors is limited to the phenyl-substituted OPs with electroactive leaving groups, such as paraoxon, parathion, methyl parathion, etc. The processes involved are: OPH-catalyzed hydrolysis of the OP, and amperometric anodic detection of the enzymatically released p-nitrophenol (PNP), according to the following reactions: X O2N
OP(R)2+ H2O
O2N
OH PNP
-e-
OH-
OPH O2N
O HO
OH +
(R)2P(X)OH
NO2 H
The PNP oxidation current is directly proportional to the OPs concentration. As reported in the literature, the conventional OPHmodified electrodes are screen-printed thick film carbon-, and carbon paste electrodes [32, 36]. The immobilization procedure includes the application of Nafion on carbon ink [32], and Nafion on carbon paste [32, 36]. Significant improvement of the OPH based carbon paste sensor’s performances in terms of stability, sensitivity, LOD, and selectivity is achieved by the use of enzyme-coated nylon net, saturated with mineral or silicon oil [37]. The reported data demonstrate for the first time how the response of the OPH based sensor for OPs determination could be affected by the organic environment. The amperometric detection of the released PNP is usually carried out at high anodic potential (E0.80 V/Ag,AgCl). However, the generation of PNP oxidation products (phenoxy radicals) provokes the formation of an insulating polymeric film which, due to electrode fouling, inhibits the subsequent phenols oxidation [34, 38-45]. The described effects alter the precision of the OPs analysis. A simple approach to overcome this drawback is suggested by Stoytcheva et al. [46]. It is based on the application of pulsed amperometric detection. Thus, the produced PNP upon the OPH-catalyzed hydrolysis of OPs is detected at a potential of +1.1 V/Ag, AgCl, while the in situ electrode cleaning and reactivation are ensured by applying a cleaning potential of +1.4 V/Ag, AgCl. The modern strategy applied for the improvement of the analytical performances of the OPH based amperometric sensors relies on the biosensors’ interface functionalization using nanomaterials. Data reported in the literature demonstrate that, due to the electrocatalytic properties of the nanostructures, electrode potential lowering is achieved, and the electrode fouling is avoided, while the large surface to volume ratio, structural robustness, and biocompatibility of the nanomaterials favor biosensors’ sensitivity and stability enhancement [47-56]. The carbon nanotubes (CNT) are the typical nanomaterials used in electrochemical biosensors. They are suitable for transducers modification, because they combine chemical inertness and mechanical strength and stiffness with high
Electrochemical Biosensors for Direct Determination of OPs
Current Analytical Chemistry, 2016, Vol. 12, No. 1
electron transfer rate properties [57-59]. Both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are used for OPH immobilization. Two drawbacks of the single-walled carbon nanotubes: high cost and low dispersibility favor the multi-walled carbon nanotubes (MWCNTs) application, in spite of the high surface area and low electrical percolation thresholds of the SWCNTs. Also, the irregular SWCNTs layer thickness formed onto the electrode surface causes considerable response variations. Nonetheless, the activity of the OPH covalently immobilized on SWNTs is conserved better compared with the case of OPH conjugated to MWNTs, as shown by Pedrosa et al. [60], because of the formation of SWNTs network and more uniform OPH layer. SWNT based OPH sensor exhibits a dynamic concentration range of 0.5-8.5 µmol L-1 for paraoxon determination at a detection limit of 0.01 µg mL-1. The operational and solution storage stability of the sensor based on covalently immobilized enzyme on SWNTs was found to be extended to 7 months at only 25% signal loss. As it was shown earlier the CNT surface modification can improve the sensitivity of the phenolic compounds determination, produced upon OPH catalyzed hydrolysis of OPs and the stability of the sensor as well. The investigations have proved that the electrodes modified with SWCNTs or MWNTs prepared by chemical vapor deposition exhibit sensitivity enhancement compared to the modified with arc discharge prepared MWNTs, probably due to the
higher electrochemical reactivity caused by the higher density of the edge-plane-like defects [61]. The various aspects of the CNT synthesis by chemical vapor deposition (CVD) and by arc discharge (ARC) are comprehensively addressed in a number of review articles [62-66]. The OPH-based sensors preparation using commercially available SWCNT, MWNT-CVD, and MWCNT-ARC was performed by consecutively casting onto the surface of the glassy-carbon electrode of dispersions of CNT in Nafion, and of OPH solution in Nafion [61]. The operational sequence is illustrated in Fig. (1). The mesoporous carbons and carbon black (MC/CB) are the other promising carbonaceous materials, which are successfully used for the construction of OPH-based electrochemical sensors for OPs determination with improved sensitivity [67]. The biosensor fabrication was performed likewise demonstrated in Fig. (1). The first layer included mesoporous carbon and carbon black. The second layer was composed of OPH and Nafion. Paraoxon detection, as an example, was achieved in the nanomolar range reaching a LOD of 0.12 µmol L-1. This result was attributed to the properties of the selected nanomaterials, such as well-ordered nanopores, several edgeplane-like defective sites, and high surface area. The LOD attained by applying the reported OPH based amperometric sensors for OPs determination are presented in Table 1.
Nafion+PBS+CNT sonication OPH solution/Nafion dispersion Nafion/PBS/CNT
casting OPH/Nafion
casting Solvent evaporation GCE
CNT/Nafion
Solvent evaporation
GCE
CNT/Nafion GCE
Fig. (1). OPH-based sensor preparation using CNT for the electrode surface modification. Table 1.
39
LOD attained by applying OPH based amperometric sensors for OPs determination. Analyte
Electrode/Matrix
LOD, µmol L-1
References
Paraoxon
Screen printed carbon
0.09
32
Methyl parathion
Sreen printed carbon
0.07
32
Paraoxon
Carbon paste
0.90
36
Methyl parathion
Carbon paste
0.40
36
Paraoxon
Carbon paste
0.02
37
Parathion
Carbon paste
0.015
37
Paraoxon
SWCNT
0.01
60
Paraoxon
SWCNT
0.15
61
Methyl parathion
SWCNT
0.80
61
Paraoxon
MC/CB
0.12
67
40 Current Analytical Chemistry, 2016, Vol. 12, No. 1
Table 2.
Stoytcheva et al.
LOD of some bacterial electrochemical sensors for OPs determination. Bacteria
Analyte
LOD
References
Recombinant E. coli
paraoxon
2.0 µM
[69]
Recombinant E. coli
methyl parathion
2.0 µM
[69]
Recombinant E. coli
diazinon
5.0 µM
[69]
Recombinant Moraxella
methyl parathion
1.0 µM
[16]
Recombinant Moraxella
paraoxon
0.2 µM
[16]
Recombinant Moraxella
paraoxon
0.1 µM
[71]
Recombinant P. putida
paraoxon
55 ppb
[72]
Recombinant P. putida
methyl paraoxon
53 ppb
[72]
Recombinant P. putida
parathion
58 ppb
[72]
Recombinant P. putida
fenitrothion
277 ppb
[73]
Recombinant P. putida
EPN
1.6 ppm
[73]
3. BACTERIAL ELECTROCHEMICAL SENSORS BASED ON OPH FOR DIRECT OPs DETERMINATION Organophosphorus hydrolase is not produced on a large-scale. Pseudomonas diminuta or Flavobacterium sp. are usually used for its isolation only in specialized laboratories [31, 68]. As the procedures for enzyme extraction and purification are time-consuming and expensive, they limit the development of the enzyme OPHbased sensors. For this reason, the bacterial electrochemical sensors such as those including genetically engineered Moraxella sp., Pseudomonas putida or Escherichia coli with surface-expressed OPH became attractive for the direct OPs determination [16, 69, 70]. The detection principle does not differ from the described above. The potentiometric bacterial sensors developed by Mulchandani et al. [69, 70] combine a pHelectrode with immobilized on its surface OPH expressing recombinant E.coli. OPH catalyzes the hydrolysis of the tested OPs paraoxon, ethyl parathion, methyl parathion, and diazinon to cause a pH change, which depends on the substrate concentration. The reported in the literature amperometric bacterial sensor [16] is designed using carbon paste electrode as a transducer and whole cells of genetically engineered Moraxella sp. with surface expressed OPH as a biorecognition element. The analytical signal is the oxidation current of the p-nitrophenol, which is produced upon the OPH-catalyzed hydrolysis of the selected substrates paraoxon and methyl parathion. It is a function of their concentration. Lately, Mulchandani et al. [71] and Lei et al. [72, 73] suggest a microbial sensor, which includes a Clark type electrode and recombinant p-nitrophenol degrading/oxidizing bacteria Pseudomonas putida with surface-expressed OPH. The products of the enzymatic hydrolysis of the chosen sub-
strates paraoxon, parathion, methyl parathion, fenitrothion, and EPN are p-nitrophenol and 3-methyl-4-nitrophenol, correspondingly. The bacterial metabolism involves their oxidation to CO2 with oxygen consumption. The recorded change in the oxygen reduction current is dependent on the substrate concentration. The principle of the OPs determination by applying a hybrid biosensor with co-immobilized OPH and Arthrobacter sp. is similar [74]. The enzymatic hydrolysis of the substrates paraoxon and methyl parathion is followed by the bacterial oxidation of the released products to form CO2 through the intermediates 4-nitrocatechol and 1,2,4-benzenetriol, which are electroactive. The current of their oxidation is recorded and the substrate concentration is correlated to the sensor’s response. The analytical characteristics of the reported bacterial and hybrid sensors for direct OPs determination in terms of stability, reproducibility, accuracy, and response time are very satisfactory. Efforts should be made to improve the LOD of the determinations, which is higher than the achieved by applying other techniques such as chromatography, immunoassays, and acylcholinesterases inhibitionbased sensors, and higher that the OPs admissible concentrations in environmental samples. Some relevant data are reported in Table 2. CONCLUSION The achievements in the development of OPH based electrochemical sensors for OPs analyses are discussed in this review. As the OPs act as enzyme substrates, the determination is direct, and the measurement is simple and rapid. The major drawback is associated with the relatively high detection limit, compared with the attained applying inhibition based electrochemical sensors or chromatographic tech-
Electrochemical Biosensors for Direct Determination of OPs
niques. It is also noteworthy to note that chromatography still remains the method of choice for OPs analysis with regard of the regulatory decisions. Therefore, currently the electrochemical biosensing is considered only as a screening method, suitable for express in situ determinations. The potential of the OPH based electrochemical sensors for OPs analysis especially could be successfully exploited for detoxification processes monitoring. CONFLICT OF INTEREST The authors confirm that this article content has no conflict of interest. ACKNOWLEDGEMENTS
Current Analytical Chemistry, 2016, Vol. 12, No. 1 [18] [19] [20]
[21]
[22] [23]
[24]
M. Stoytcheva gratefully acknowledges CONACyTMexico for the support during her sabbatical leave. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9]
[10] [11]
[12] [13]
[14] [15]
[16]
[17]
Eto, M. Organophosphorus pesticides: organic and biological chemistry. CRS Press, Cleveland, 1974. Hassall, K.A. The chemistry of pesticides. Their metabolism, mode of action and uses in crop protection. Verlag Chemie, Weinheim, Deerfield Beach, Florida, Basel, 1982. Corbett, J.R.; Wright, K.; Baillie, A.C. The biochemical mode of action of pesticides, 2nd ed., Academic press, London, 1984. Gupta, R.C. (Ed.) Toxicology of organophosphate & carbamate compounds, 1st ed., Elsevier Academic Press, London, 2005. Fukuto, R. Mechanism of action of organophosphorus and carbamate insecticides. Environ. Health Perspect., 1990, 87, 245-254. Matsumura, F. Toxicology of insecticides. Plenum Press, New York, 1980. Council Directive 98/83/EC (3 November 1998). Official Journal of the European Communities, 5.12.1998, L330/32 Schlecht, P.C.; O'Connor, P.F., (Eds.) NIOSH manual of analytical methods, 4th ed.; DHHS (NIOSH) Publication 1994, 94-113. Jeannot, R.; Dagnac, T. In: Chromatographic analysis of the environmental. 3rd ed.; Nollet L.; Ed.; CRC Press, Boca Raton, London, New York, 2006; pp. 841-889. Soler, C.; Picó, Y. Recent trends in liquid chromatography-tandem mass spectrometry to determine pesticides and their metabolites in food. Trends Anal. Chem., 2007, 26, 103-115. Petrovic, M.; Farré, M.; López de Alda, M.; Pérez, S.; Postigo, S.; Köck, M.; Radjenovic, J.; Gros, M.; Barceló, D. Recent trends in the liquid chromatography-mass spectrometry analysis of organic contaminants in environmental samples. J. Chromatogr. A, 2010, 1217, 4004-4017. Sharma, D.; Nagpal, A.; Pakade, Y.; Katnoria J. Analytical methods for estimation of organophosphorus pesticide residues in fruits and vegetables: A review. Talanta, 2010, 82, 1077-1089. Le Doux, M. Analytical methods applied to the determination of pesticide residues in foods of animal origin. A review of the past two decades. J. Chromatogr. A, 2011, 1218(8), 1021-1036. Pareja, L.; Fernández-Alba, A.R.; Cesio, V.; Heinzen, H. Analytical methods for pesticide residues in rice. Trends Anal. Chem., 2011, 30(2), 270-291. Mulchandani, P.; Chen, W.; Mulchandani, A. Flow injection amperometric enzyme biosensor for direct determination of organophosphate nerve agents. Environ. Sci. Technol., 2001, 35, 25622565. Mulchandani, P.; Chen, W.; Mulchandani, A.; Wang, J.; Chen, L. Amperometric microbial biosensor for direct determination of organophosphate pesticides using recombinant microorganism with surface expressed organophosphorus hydrolase. Biosens. Bioelectron., 2001, 16(7-8), 433-437. Andreescu, S.; Marty, J.L. Twenty years research in cholinesterase biosensors: from basic research to practical applications. Biomol. Eng., 2006, 23(1), 1-15.
[25] [26]
[27] [28] [29]
[30]
[31] [32]
[33]
[34] [35]
[36] [37]
[38]
[39]
[40]
41
Anzai, J. Use of biosensors for detecting organophosphorus agents. Yakugaku Zasshi, 2006, 126(12), 1301-1308. Jaffrezic-Renault, N. New trends in biosensors for organophosphorus pesticides. Sensors, 2001, 1(2), 60-64. Noguer, T.; Leca, B.; Jeanty, G.; Marty, J.L. Biosensors based on enzyme inhibition: Detection of organophosphorus and carbamate insecticides and dithiocarbamate fungicides. Field Anal. Chem. Technol., 1999, 3(3), 171-178. Prieto-Simón, B.; Campàs, M.; Andreescu, S.; Marty, J.L. Trends in flow-based biosensing systems for pesticide assessment. Sensors, 2006, 6(10), 1161-1186. Rodriguez-Mozaz, S.; Marco, M.P.; Lopez de Alda, M.J.; Barceló, D. Biosensors for environmental applications: future development trends. Pure Appl. Chem., 2004, 76(4), 723-752. Solé, S.; Merkoçi, A.; Alegret, S. Determination of toxic substances based on enzyme inhibition. Part I. Electrochemical biosensors for the determination of pesticides using batch procedures. Crit. Rev. Anal. Chem., 2003, 33(2), 89-126. Solé, S.; Merkoçi, A.; Alegret, S. Determination of toxic substances based on enzyme inhibition. Part II. Electrochemical biosensors for the determination of pesticides using flow systems. Crit. Rev. Anal. Chem., 2003, 33(2), 127-143. Tran-Minh, C. Immobilized enzyme probes for determining inhibitors. Ion-Selective Electrode Rev., 1985, 7, 41-75. Tran-Minh, C.; Pandey, P.C.; Kumaran, S. Studies on acetylcholine sensor and its analytical application based on the inhibition of cholinesterase. Biosens. Bioelectron., 1980, 5(6), 461-471. Turdean, G.; Popescu, I.C.; Oniciu, L. Biocapteurs ampérométriques a cholinestérases pour la détermination des pesticides organophosphorés. Can. J. Chem., 2002, 80, 315-331. Munnecke, D.M. Enzymatic detoxification of waste organophosphate pesticides. J. Agric. Food Chem., 1980, 28, 105-111. Efremenko, E.N.; Sergeeva, S. Organophosphate hydrolase-an enzyme catalyzing degradation of phosphorus-containing toxins and pesticides. Russian Chem. Bul. Int. Edition, 2001, 50(10), 1826-1832. Dumas, D.P.; Wild, J.R.; Raushel, F.M. Diisopropylfluorophosphate hydrolysis by a phosphotriesterase from Pseudomonas diminuta. Biotech. Appl. Biochem., 1989, 11, 235-243. Dumas, D.P.; Caldwell, S.R.; Wild, J.R.; Raushel, F.M. Purification and properties of the phosphotriesterase from Pseudomonas diminuta. J. Biol. Chem., 1989, 33, 19659-19665. Mulchandani, A.; Chen, W.; Mulchandani, P.; Wang, J.; Rogers, K.R. Biosensors for direct determination of organophosphate pesticides. Biosens. Bioelectron., 2001, 16(4-5), 225-230. Mulchandani, P.; Mulchandani, A.; Kaneva, I.; Chen, W. Biosensor for direct determination of organophosphate nerve agents. 1. Potentiometric enzyme electrode. Biosens. Bioelectron., 1999, 14(1), 7785. Mulchandani, A.; Mulchandani, P.; Chen, W. Enzyme biosensor for determination of organophosphates. Field Anal. Chem. Technol., 1998, 2(6), 363-369. Lihong, W.; Lin, Z.; Jinxing, H.; Huanlin, C. Model of a pH-based potentiometric biosensor immobilizing organophosphorus hydrolase. Chem. Eng. Technol. 2006, 29(4), 462-467. Wang, J.; Chen, L.; Mulchandani, A.; Mulchandani, P.; Chen, W. Remote biosensor for in-situ monitoring of organophosphate nerve agents. Electroanalysis, 1999, 11(12), 866-869. Chough, S.H.; Mulchandani, A.; Mulchandani, P.; Chen, W.; Wang, J.; Rogers, K.R. Organophosphorus hydrolase-based amperometric sensor: modulation of sensitivity and substrate selectivity. Electroanalysis, 2002, 14(4), 274-276. Borras, C.; Laredo, T.; Mostany, J.; Scharifker, B.R. Study of the oxidation of solutions of p-chlorophenol and p-nitrophenol on Bidoped PbO2 electrodes by UV-Vis and FTIR in situ spectroscopy. Electrochim. Acta, 2004, 49, 641-648. Ferreira, M.; Varela, H.; Toressi, R.; Tremiliosi-Filho, G. Electrode passivation caused by polymerization of different phenolic compounds. Electrochim. Acta, 2006, 52(2), 434-442. Al Maznai, H.; Conway, B.E. Auto-inhibition effects in anodic oxidation of phenols for electrochemical waste-water purification. J. Serb. Chem. Soc., 2001, 66(11-12), 765-784.
42 Current Analytical Chemistry, 2016, Vol. 12, No. 1 [41]
[42] [43]
[44] [45]
[46]
[47] [48] [49] [50] [51] [52] [53]
[54] [55] [56] [57] [58] [59]
[60]
Stoytcheva et al.
Lupu, S.; Ion, I.; Ion, A.C. Voltammetric determination of phenol at platinum electrodes modified with polypyrrole doped with ferricyanide. Rev. Roumaine Chim., 2009, 54(5), 351-357. Kim, H.J.; Chang, S.C.; Shim, Y.B. -Cyclodextrin modified screen printed graphite electrodes for detection of phenols. Bull. Korean Chem. Soc., 2002, 23(3), 427-431. Arslan, G.; Yazici, B.; Erbil, M. The effect of pH, temperature and concentration on electrooxidation of phenol. J. Hazardous Mater., 2005, 124(1-3), 37-43. Obirai, J.; Bedioui, F.; Nyokong, T. Electro-oxidaton of phenol and its derivatives on poly-Ni(OH)TPhPyPc modified vitreous carbon electrode. J. Electroanal. Chem., 2005, 576(2), 323-332. Dejmkova, H.; Scampicchio, M.; Zima, J.; Barek, J.; Mannino, S. Determination of total phenols in foods by Boron Doped Diamond Electrode. Electroanalysis, 2009, 21, 1014-1018. Stoytcheva, M.; Zlatev, R.; Gochev, V.; Velkova, Z.; Montero, G. Amperometric biosensor precision improvement: application to organophosphorus pesticide determination. Anal. Methods, 2014, 6, 8232-8238. Balasubramanian, K.; Burghard, M. Biosensors based on carbon nanotubes. Anal. Bioanal. Chem., 2006, 385(3), 452-468. Eftekhari, A. Nanostructured materials in electrochemistry. WileyVCH, Weinheim, 2008. Gorton, L. Biosensors and modern biospecific analytical techniques. Elsevier, 2005. Guo, S.; Wang, E. Synthesis and electrochemical applications of gold nanoparticels. Anal. Chim. Acta, 2007, 598(2), 181-192. Kerman, K.; Saito, M.; Yamamura, S.; Takamura, Y.; Tamiya, E. Nanomaterial-based electrochemical biosensors for medical applications. Trends Anal. Chem., 2008, 27(7), 585-592. Kumar, C. Nanomaterials for biosensors. Wiley-VCH, Weinheim, 2007. Luo, X.; Morrin, A.; Killard, A.; Smyth, M. Application of nanoparticles in electrochemical sensors and biosensors. Electroanalysis, 2006, 18(4), 319-326. Merkoçi, A., Alegret, S. Toward nanoanalytical chemistry: case of nanomaterial integration into (bio)sensong systems. Contribut. Sci., 2005, 3(1), 57-66. Merkoçi, A. Biosensing using nanomaterials. Wiley, Hoboken, New Jersey, 2009. Pumera, M.; Sánchez, S.; Ichinose, I.; Tang, J. Electrochemical nanobiosensors. Sensors Actuators B, 2007, 123(2), 1195-1205. Ajayan, P.M. Nanotubes from carbon. Chem. Rev., 1999, 99, 17871799. Tasis, D.; Tagmatarchis, N.; Bianco, A.; Prato, M. Chemistry of carbon nanotubes. Chem. Rev., 2006, 106, 1105-1136. Britto, P.J.; Santhanam, K.S.V.; Rubio, A.; l Alonso, J.A.; Ajayan, P.M. Improved charge transfer at carbon nanotube electrodes. Adv. Mat., 1999, 11(2), 154-157. Pedrosa, V.A.; Paliwal, S.; Balasubramanian, S.; Nepal, D.; Davis, V.; Wild, J.; Ramanculo, E.; Simonian, A. Enhanced stability of enzyme organophosphate hydrolase interfaced on the carbon nanotubes. Coll. Surf. B: Biointerface, 2010, 77, 69-74.
Received: April 05, 2015
[61]
[62] [63]
[64] [65]
[66] [67]
[68] [69]
[70]
[71]
[72]
[73]
[74]
Revised: July 06, 2015
Deo, R.P.; Wang, J.; Block, I.; Mulchandani, A.; Joshic, K.A.; Trojanowicz, M.; Scholz, F.; Chen, W.; Lin, Y. Determination of organophosphate pesticides at a carbon nanotube/organophosphorus hydrolase electrochemical biosensor. Analytica Chimica Acta, 2005, 530, 185-189. Prasek, J.; Drbohlavova, J.; Chomoucka, J.; Hubalek, J.; Jasek, O.; Adam, V.; Kizek, R. Methods for carbon nanotubes synthesisreview. J. Mater. Chem., 2011, 21, 15872-15884. Kumar, M.; Ando, Y. Chemical vapor deposition of carbon nanotubes: A review on growth mechanism and mass Production. J. Nanoscie. Nanotechnol., 2010, 10, 3739-3758. Nessim, G.D. Properties, synthesis, and growth mechanisms of carbon nanotubes with special focus on thermal chemical vapor deposition. Nanoscale, 2010, 2, 1306-1323. Ando, Y.; Zhao, X. Synthesis of carbon nanotubes by arc-discharge method. New Diamond and Frontier Carbon Technology, MYU Tokyo, 2006, 16(3), 123-137. Arora, N.; Sharma, N.N. Arc discharge synthesis of carbon nanotubes: Comprehensive review. Diam. Relat. Mater., 2014, 50, 135150. Lee, J.H.; Park, J.Y.; Min, K.; Cha, H.J.; Choi, S.S.; Yoo, Y.J. A novel organophosphorus hydrolase-based biosensor using mesoporous carbons and carbon black for the detection of organophosphate nerve agents. Biosens. Bioelectron., 2010, 25, 15661570. Brown, K.A. Phosphotriesterases of flavobacterium sp. Soil Biol. Biochem., 1980, 12(2), 105-112. Mulchandani, A.; Mulchandani, P.; Kaneva, I.; Chen, W. Biosensor for direct determination of organophosphate nerve agents using recombinant Escherichia coli with surface-expressed organophosphorus hydrolase. 1. Potentiometric microbial electrode. Anal. Chem., 1998, 70(19), 4140-4145. Mulchandani, A.; Mulchandani, P.; Chauhan, S.; Kaneva, I.; Chen, W. A potentiometric microbial biosensor for direct determination of organophosphate nerve agents. Electroanalysis, 1998, 10(11), 733-737. Mulchandani, P.; Chen, W.; Mulchandani, A. Microbial biosensor for direct determination of nitrophenyl-substituted organophosphate nerve agents using genetically engineered Moraxella sp. Anal. Chim. Acta, 2006, 568(1-2), 217-221. Lei, Y.; Mulchandani, P.; Chen, W.; Mulchandani, A. Direct determination of pnitrophenyl substituent organophosphorus nerve agents using a recombinant Pseudomonas putida JS444-modified Clark oxygen electrode. J. Agric. Food Chem., 2005, 53(3),524527. Lei, Y.; Mulchandani, P.; Chen, W.; Mulchandani, A. Biosensor for direct determination of fenitrothion and EPN using recombinant Pseudomonas putida JS444 with surface expressed organophosphorus hydrolase. 1. Modified Clark oxygen electrode. Sensors, 2006, 6(4), 466-472. Lei, Y.; Mulchandani, P.; Chen, W.; Wang J.; Mulchandani, A. Whole cell-enzyme hybrid amperometric biosensor for direct determination of organophosphorous nerve agents with p-nitrophenyl substituent. Biotechnol. Bioeng., 2004, 85(7), 706-713. Accepted: July 07, 2015
