Elsevier

Sensors and Actuators B: Chemical

Volume 206, January 2015, Pages 146-151
Sensors and Actuators B: Chemical

Fabrication of highly sensitive uric acid biosensor based on directly grown ZnO nanosheets on electrode surface

https://doi.org/10.1016/j.snb.2014.09.026Get rights and content

Highlights

  • The ZnO nanosheets were directly synthesized on the electrode surface by solution process.

  • Used successfully for the fabrication of uric acid biosensor.

  • The fabricated biosensor showed high sensitivity in wide-linear range.

  • The biosensors were highly reproducible, selective and stable for favorable determination of uric acid.

Abstract

Here we report the direct synthesis of ZnO nanosheets (ZnO NSs) on the electrode surface by one step low temperature solution process and characterized in detail using various techniques. The directly grown ZnO NSs used for fabrication of uric acid biosensor (Nafion/Uricase/ZnO NSs/Ag/Si) and performance of fabricated has been examined for uric acid detection. This biosensor showed high sensitivity of 129.81 μA cm−2 mM−1 in wide-linear range (0.05–2.0 mM) with high correlation coefficient of R2 = 0.9993. A rapid response time of ∼5 s, low detection limit of 0.019 μM (based on S/N ratio) and lower value of apparent Michaelis–Menten constant (Kmapp) of 0.026 mM was calculated for the fabricated biosensor. The lower value of Kmapp shows a high affinity between the uric acid and uricase immobilized on ZnO NSs. The anti-interference ability, reproducibility and long-term storage stability of biosensor were examined. These results suggests that our fabricated biosensors are highly reproducible, selective and stable for favorable determination of uric acid and can be effectively used for application in real samples with good precision and accuracy.

Introduction

Nanostructures and nanomaterial are of great interest due to their potential applications in numerous fields [1], [2], [3]. Varieties of materials such as zinc oxide, iron oxide, cerium oxide, tin oxide, zirconium oxide, titanium oxide and magnesium oxide, etc. have been extensively evaluated to synthesize different nonstructural forms of these metal oxides. Among them, zinc oxide (ZnO), an environment-friendly semiconductor (band gap of 3.37 eV) is an interesting metal oxide with several scientific and engineering based applications [4], [5], [6], [7]. This is one of unique materials for the fabrication of facile, high performing and low-cost biosensors. Especially, nanostructured ZnO owing to its large specific surface area and high isoelectric point (IEP ∼9.5) makes it appropriate for absorption of low IEPs proteins or enzymes such as uricase (IEP ∼4.64) at physiological pH. Also, it can be efficiently used in various fields such as drug delivery vehicles, photocatalyst, UV light-emitting devices, room temperature UV lasers, chemical and biological sensors, microsensors, decontamination agents, and so on [8], [9], [10], [11], [12], [13], [14], [15], [16], [17].

Attempts have been made to synthesize different ZnO nanostructure with desired zero-, one- and two-dimensional design using various synthetic methods and diverse processing technologies [18], [19], [20], [21]. These nanostructures are usually synthesized at higher temperatures. However, it is well known high-temperature synthesis environment is not well suited for fabrication of nanodevices. Low-temperature fabrication is therefore desirable and important for nanodevices, especially those in which the substrate and nanostructures have different compositions. In addition to the potential applications of one-dimensional nanostructures, two-dimensional nanostructures have been extensively used due to their fascinating and unique properties.

Recently, two-dimensional ZnO nanosheets/nanoplates (ZnO NSs/ZnO NPs) have attracted much attention due to their promising potential applications in different areas ranging from catalysis to electronics [22], [23], [24], [25], [26], [27], [28]. Gupta et al. have reported synthesis of ZnO NSs and used for high-performance flexible direct current power piezoelectric nanogenerators [29]. An enhanced gas sensing properties were reported while using ZnO NSs/ZnO NPs nanostructures due to the high specific surface area [30], [31], [32], [33], [34], [35], [36]. However, growth of these structures on solid support (electrode) is still needed for biosensors fabrication.

In this paper, we report for the first time, fabrication of uric acid biosensors based on ZnO NSs directly grown on electrode surface. The fabricated biosensors showed high and reproducible sensitivity in wide-linear range. A rapid response time, low detection limit and lower value of Kmapp recorded for the fabricated biosensor. The lower value of Kmapp shows a high affinity between the uric acid and uricase immobilized on ZnO NSs. The anti-interference ability, reproducibility and long-term storage stability of biosensor were also examined for effective and favorable determination of uric acid.

Section snippets

Reagents

Zinc nitrate hexahydrate [Zn(NO3)2·6H2O, 99%], hexamethylenetetramine [HMTA; C6H12N4, 99%], uricase (EC 1.7.3.3, from Arthrobacter gloiformis), Nafion (5 wt.% in lower aliphatic alcohol and water mixture), uric acid (UA), ascorbic acid (AA), urea, lactic acid (LA), dopamine (DA), sodium phosphate monobasic anhydrous (NaH2PO4), sodium phosphate dibasic dihydrate (Na2HPO4·2H2O), and sodium chloride (NaCl) were purchased from Sigma–Aldrich and used without further purification. Phosphate buffer

Characterization of ZnO NSs

The morphologies of as-synthesized ZnO NSs were examined by FESEM. The low-resolution FESEM image (Fig. 2a) shows that the nanosheets are grown in large quantity and vertically aligned to the substrate. From high-resolution FESEM image (Fig. 2b) the thickness of NSs were found in the range of 10–15 nm. The cross-sectional image (inset of Fig. 2b) confirms that the NSs are grown vertically with high uniform morphology over a large area. Interestingly, it seems that nanosheets interconnect each

Conclusion

In conclusion, we have directly synthesized ZnO NSs on the electrode surface by one-step low temperature solution process and successfully used for the fabrication of uric acid biosensor. The fabricated biosensor showed high sensitivity of 129.8 μA cm−2 mM−1 in wide-linear range (0.05–2.0 mM), low detection limit of 0.019 μM and ower value of Kmapp of 0.026 mM. Also, a better selectivity was found against electroactive species for the fabricated biosensor. All these results demonstrates that ZnO NSs

Acknowledgements

This work was supported by the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (2012-0001039).

Rafiq Ahmad received his B.Sc. (Honors) in Zoology from Aligarh Muslim University (AMU) and M.Sc. degree in Biotechnology from KIIT Bhubaneswar, India, and Ph.D. in Department of BIN Fusion Technology Chonbuk National University, Republic of Korea. He is now working as a postdoctoral fellow in semiconductor and chemical engineering from Chonbuk National University, South Korea. He is currently engaged in the synthesis of different metal and metal oxide nanomaterials by solution process and

References (43)

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Rafiq Ahmad received his B.Sc. (Honors) in Zoology from Aligarh Muslim University (AMU) and M.Sc. degree in Biotechnology from KIIT Bhubaneswar, India, and Ph.D. in Department of BIN Fusion Technology Chonbuk National University, Republic of Korea. He is now working as a postdoctoral fellow in semiconductor and chemical engineering from Chonbuk National University, South Korea. He is currently engaged in the synthesis of different metal and metal oxide nanomaterials by solution process and development of amperometric, potentiometric and field-effect transistor based chemical, biological and hybrid sensors.

Nirmalya Tripathy received her B.Sc. (Honors) in Botany from OUAT and M.Sc. in Biotechnology from KIIT Bhubaneswar, India, Ph.D. in 2013 from Department of BIN Fusion Technology Chonbuk National University, South Korea. She is now working as a postdoctoral fellow in Department of BIN Fusion Technology, Department of Polymer-Nano Science & Technology and Polymer BIN Research Center from Chonbuk National University, Republic of Korea. Her current researches are synthesis of polymers and different metal and metal oxide nanomaterials by solution process and their application in various fields such as biosensors, chemical sensors, drug delivery system and antibacterial agents etc.

Na Keum Jang received her B.S. degree in Animal Biotechnology and currently pursuing MS degree at the Department of BIN Fusion Technology, Chonbuk National University, Republic of Korea. Her current research interest includes synthesis of polymeric biomaterials for regenerative medicine and sensors applications.

Gilson Khang is BK21 professor in the Department of BIN Fusion Technology, Chonbuk National University, Republic of Korea. He is also the Dept. Head of Department of PolymerNano Sci Tech and Chairman of TERMIS-AP Chapter (Asia-Pacific area). He received his BS and MS degree from Inha University, and PhD from University of Lowa, U.S.A. His main research activities focus on the synthesis of biomaterials and their applications for tissue engineering, regenerative medicine, drug delivery system, biosensors, etc.

Yoon-Bong Hahn is a WCU professor in Department of BIN Fusion Technology, School of Semiconductor and Chemical Engineering, Chonbuk National University, Republic of Korea. He is also the director of National Leading Research Laboratory for Hybrid Green Energy Research. He received his Ph.D. in 1988 from University of Utah, USA. His current research activities focus on the synthesis and characterization of metal and metal oxides nanostructures and their applications for optoelectronic devices, solar cells, chemical and biosensors, etc.

1

These authors contributed equally to this work.

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