Determination of Phenolic Compounds Based on the Tyrosinase‐ Single Walled Carbon Nanotubes Sensor

Abstract

An amperometric sensor to phenolic compound was successfully constructed by immobilizing tyrosinase on the SWNTs modified glassy carbon (GC) electrode, which was covered with Nafion film. The sensitivity of the tyrosinaseSWNTs sensor to phenol was 155 mA/mM. The tyrosinase-SWNTs sensor also had good response to catechol, pchlorophenol and m-cresol. Furthermore, benzoic acid could be detected based on the inhibition to tyrosinase activity.Keywords: Tyrosinase, Carbon nanotubes, Modified electrode, Sensors, Phenol Carbon nanotubes (CNTs) [1], attractive nanomaterials with specific electronic, chemical, and mechanical properties, have had many applications in the field of material science, chemistry and physics [2,3]. As electrode materials, CNTs can facilitate electron-transfer between the electroacitve species and electrode, and provide a new avenue for fabricating chemical sensors or biosensors [4,5]. Now, more reports of CNTs-based sensors have been demonstrated [6 -14]. These sensors can be used to detect small molecules and bio-macromolecules, such as H 2 O 2 , NADH, glucose, proteins and DNA etc., based on the electronic properties [6 -9] or the electrochemical properties of the CNTs [10 -14]. Electrochemical sensors of CNTs give high sensitivity and good stability, and the electrochemical sensor has advantages such as simple in making, cheap in application and easy in operating.Tyrosinase is a type (III) copper protein and is widely distributed in microorganisms, plants and animals [15]. It catalyzes the orthohydroxylation of monophenols (monophenolase activity) by O 2 , and can also catalyze the oxidation of o-diphenols to o-quinones (catecholase activity). The mechanism of amperometric biosensor for phenols based on tyrosinase is that the tyrosinase at the surface of the electrode is oxidized by oxygen, and then reduced by phenolic compounds. The phenolic compounds mainly convert into quinones, and the products are electrochemically active, can be reduced on the electrode. The reduction current is proportional to the concentration of phenolic compounds in solution.Detection of phenolic compounds is of great importance due to their presence in a broad range of chemical manufacturing processes and their toxicity. Amperometric sensor is simple, effective and fast. Based on the immobilized tyrosinase, amperometric sensors to detect phenolic compounds have been widely carried out [15 -16] By now, there is no report for the detection of phenolic compounds using CNTs as the enzyme support material. In this paper, tyrosinase-SWNTs modified GC electrode covered with Nafion was fabricated successfully as an amperometric sensor to phenolic compounds. Due to SWNTs having high conductivity, high surface area and facilitation of electron transfer, the sensor gave a high sensitivity as 155 mA/mM, and the detection limit was as low as 2 Â 10 À8 M. The sensor also showed good sensitivity to catechol, p-chlorophenol and m-cresol. Based on the inhibition to tyrosinase activity, the benzoic acid could be detected by...

Amperometric Tyrosinase Biosensor Based on Carbon Nanotube–Titania–Nafion Composite Film

“…The MWCNT -titania -Nafion composite films were used for the immobilization of tyrosine to construct the biosensor. As shown in Figure 1, the biosensor based on the MWCNT -titania -Nafion composite showed higher sensitivity (647 mA/M) and lower detection limit (87 nM) than those (553 mA/M and 110 nM) obtained with the biosensor based on titania -Nafion composite without MWCNT, which is in good agreement with the result obtained with the tyrosinase-SWCNT modified biosensor covered with Nafion [19]. The high sensitivity and low detection limit of the present tyrosinase biosensor based on the MWCNTtitania -Nafion composite film can be attributed to the good electrocatalytic effect towards the reduction of o-quinone and large surface area of MWCNT.…”

“…Therefore, a potential of À 100 mV was selected as an optimum potential for all subsequent experiments. The optimum detection potential of À 100 mV is the same as the tyrosinase biosensor based on Nafion-coated SWCNT-modified electrode [19] but less negative than that observed at the tyrosinase biosensor based on silica -Nafion composite [13], sol -gel ZnO film [15], pure titania film [16] and inorganic -organic hybrid titania [17]]. This less negative operational potential can minimize possible interference.…”

“…CNT has been widely used in electrochemical glucose and ethanol biosensors because of the ability of CNT to promote the electron transfer reactions of hydrogen peroxide and NADH [25]. However, until now, only one paper has been reported on the construction of tyrosinase biosensor based on singlewalled CNT (SWCNT) [19]. The biosensor was constructed by immobilizing tyrosinase on the SWCNT-modified glassy carbon electrode, in which SWCNT was dispersed by N,N'-dimethylformamide (DMF) and the top of the biosensor was covered with Nafion film.…”

Electrochemical sensors based on carbon nanotubes and their use in biomedical research

“…Чувствительность сенсора к фенолу оценивалась на уровне 0,155 А´л/моль. Помимо этого сенсор проявлял чувствительность к пирокатехину, хлорфенолу и крезолу, а бензойная кислота могла быть определена на основе ослабления активности тирозиназы [49].…”

“…гомоцистеин [67], глутатион [34,46], дисульфид глутатиона [46], адреналин [31,32,45], норадреналин [32], морфин [33], тиоцитозин [34], холестерин [37], гидрохинон [44], пирокатехин [44,49], резорцин [44], тирозин [60], дофамин [45,59,63,64], серотонин [59], ацетилхолин [48], хлорфенол [49], амино- [65] и нитрофенолы [68], крезол [49], ксантин [39], гетероауксин [51], тироксин [52], азитромицин [53], метронидазол [54], танин [55], резерпин [56], митоцин [57], симвастин [58], каталазу [42], мочевину [48], NADH [32], углеводы [35,62,66,69,71,72] и многие другие химические соединения. Более того, при помощи этих сенсоров можно анализировать ДНК(по результатам определения гуанина и аденина [61].…”