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Electrochemical L-lactic acid sensor based on immobilized ZnO nanorods with lactate oxidase.

Ibupoto ZH, Shah SM, Khun K, Willander M - Sensors (Basel) (2012)

Bottom Line: The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor.We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10(-4)-1 × 10(0) mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade.The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

View Article: PubMed Central - PubMed

Affiliation: Department of Science and Technology, Campus Norrköping, Linköping University, Norrköping, Sweden. zafar.hussain.ibupoto@liu.se

ABSTRACT
In this work, fabrication of gold coated glass substrate, growth of ZnO nanorods and potentiometric response of lactic acid are explained. The biosensor was developed by immobilizing the lactate oxidase on the ZnO nanorods in combination with glutaraldehyde as a cross linker for lactate oxidase enzyme. The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor. We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10(-4)-1 × 10(0) mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade. In addition, the proposed biosensor showed fast response time less than 10 s, a good selectivity towards l-lactic acid in presence of common interfering substances such as ascorbic acid, urea, glucose, galactose, magnesium ions and calcium ions. The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

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(a) The (FESEM) image of ZnO nanorods grown on gold coated glass substrate using hydrothermal growth method. (b) The (FESEM) image of lactate oxidase immobilized ZnO nanorods.
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f1-sensors-12-02456: (a) The (FESEM) image of ZnO nanorods grown on gold coated glass substrate using hydrothermal growth method. (b) The (FESEM) image of lactate oxidase immobilized ZnO nanorods.

Mentions: The fabrication of ZnO nanorods on gold coated glass substrates was as follows: firstly glass substrates were cleaned with isopropanol in an ultrasonic bath for 15 min, and then washed with deionized water and dried by nitrogen gas. After that glass substrates were fixed into the vacuum chamber of a Satis CR 725 evaporator instrument, for the deposition of thin film of 20 nm of titanium as an adhesive layer, followed by a layer of 100 nm thickness of gold. The growth of ZnO nanorods on these substrates was carried out by using the low temperature growth method (aqueous chemical growth method). The process of growing ZnO nanorods was as follows: first of all the gold coated substrates were washed with deionized water and dried by nitrogen gas, afterwards a homogeneous layer of zinc acetate was deposit on those gold coated substrates using the spin coating technique. The purpose of using the zinc acetate layer was to produce nucleation sites on the surface in order to grow well aligned ZnO nanorods of controlled length. The substrates with seed layer were annealed in an oven for 15 min at 130 °C and then affixed onto the Teflon sample holder and dipped into an equimolar solution of zinc nitrate and hexamethylenetetramine, then kept inside the oven below 100 °C for 5 to 7 h. When the growth time was finished, these substrates were then washed with deionized water and dried by nitrogen gas. The morphological study of grown ZnO nanostructures was carried out by using field emission scanning electron microscopy (FESEM) and we found that well aligned and controlled in length ZnO nanorods were grown on the gold coated substrates, as shown in Figure 1(a).


Electrochemical L-lactic acid sensor based on immobilized ZnO nanorods with lactate oxidase.

Ibupoto ZH, Shah SM, Khun K, Willander M - Sensors (Basel) (2012)

(a) The (FESEM) image of ZnO nanorods grown on gold coated glass substrate using hydrothermal growth method. (b) The (FESEM) image of lactate oxidase immobilized ZnO nanorods.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376621&req=5

f1-sensors-12-02456: (a) The (FESEM) image of ZnO nanorods grown on gold coated glass substrate using hydrothermal growth method. (b) The (FESEM) image of lactate oxidase immobilized ZnO nanorods.
Mentions: The fabrication of ZnO nanorods on gold coated glass substrates was as follows: firstly glass substrates were cleaned with isopropanol in an ultrasonic bath for 15 min, and then washed with deionized water and dried by nitrogen gas. After that glass substrates were fixed into the vacuum chamber of a Satis CR 725 evaporator instrument, for the deposition of thin film of 20 nm of titanium as an adhesive layer, followed by a layer of 100 nm thickness of gold. The growth of ZnO nanorods on these substrates was carried out by using the low temperature growth method (aqueous chemical growth method). The process of growing ZnO nanorods was as follows: first of all the gold coated substrates were washed with deionized water and dried by nitrogen gas, afterwards a homogeneous layer of zinc acetate was deposit on those gold coated substrates using the spin coating technique. The purpose of using the zinc acetate layer was to produce nucleation sites on the surface in order to grow well aligned ZnO nanorods of controlled length. The substrates with seed layer were annealed in an oven for 15 min at 130 °C and then affixed onto the Teflon sample holder and dipped into an equimolar solution of zinc nitrate and hexamethylenetetramine, then kept inside the oven below 100 °C for 5 to 7 h. When the growth time was finished, these substrates were then washed with deionized water and dried by nitrogen gas. The morphological study of grown ZnO nanostructures was carried out by using field emission scanning electron microscopy (FESEM) and we found that well aligned and controlled in length ZnO nanorods were grown on the gold coated substrates, as shown in Figure 1(a).

Bottom Line: The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor.We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10(-4)-1 × 10(0) mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade.The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

View Article: PubMed Central - PubMed

Affiliation: Department of Science and Technology, Campus Norrköping, Linköping University, Norrköping, Sweden. zafar.hussain.ibupoto@liu.se

ABSTRACT
In this work, fabrication of gold coated glass substrate, growth of ZnO nanorods and potentiometric response of lactic acid are explained. The biosensor was developed by immobilizing the lactate oxidase on the ZnO nanorods in combination with glutaraldehyde as a cross linker for lactate oxidase enzyme. The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor. We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10(-4)-1 × 10(0) mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade. In addition, the proposed biosensor showed fast response time less than 10 s, a good selectivity towards l-lactic acid in presence of common interfering substances such as ascorbic acid, urea, glucose, galactose, magnesium ions and calcium ions. The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

Show MeSH