A novel glucose biosensor platform based on Ag@AuNPs modified graphene oxide nanocomposite and SERS application Vinod Kumar Gupta a,b,⇑ , Necip Atar c , Mehmet Lütfi Yola d,e , Merve Eryılmaz f , Hilal Torul f , Ug ˘ur Tamer f , _ Ismail Hakkı Boyacı g , Zafer Üstündag ˘ c a Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667, India b Dr. RML Avadh University, Faizabad 224 001, UP, India c Dumlupinar University, Faculty of Arts and Science, Department of Chemistry, Kutahya, Turkey d Sinop University, Faculty of Arts and Science, Department of Chemistry, Sinop, Turkey e Hacettepe University, Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, Turkey f Gazi University, Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, Turkey g Hacettepe University, Faculty of Engineering, Department of Food Engineering, Ankara, Turkey article info Article history: Received 30 April 2013 Accepted 3 June 2013 Available online 13 June 2013 Keywords: Graphene oxide Ag@AuNPs Characterization Glucose biosensor SERS abstract This study represents a novel template demonstration of a glucose biosensor based on mercaptophenyl boronic acid (MBA) terminated Ag@AuNPs/graphene oxide (Ag@AuNPs–GO) nanomaterials. The nano- composites were characterized by transmission electron microscopy (TEM), X-ray photoelectron spec- troscopy (XPS), and X-ray diffraction (XRD) method. The TEM image shows that Ag@AuNPs in the nanocomposite is in the range of diameters of 10–20 nm. The nanocomposite was used for the determi- nation of glucose through the complexation between boronic acid and diol groups of glucose. Thus, a novel glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into MBA termi- nated Ag@AuNPs–GO nanocomposite film (MBA–Ag@AuNPs–GO). The linearity range of glucose was obtained as 2–6 mM with detection limit of 0.33 mM. The developed biosensor was also applied success- fully for the determination of glucose in blood samples. The concentration value of glucose in blood sam- ples was calculated to be 1.97 ± 0.002 mM from measurements repeated for six times. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction Because of the importance of determination of glucose and decreasing of complications in diabetes patients, important re- searches have been performed for clinical purposes [1–8]. Never- theless, many materials such as acetaminophen, uric acid, and ascorbic acid can interfere with the determination of glucose. In addition, a large amount of sample volume is needed for glucose determination. So, the simpler and cheaper methods can be signif- icant in terms of clinical benefit. Surface-enhanced Raman spectroscopy (SERS), which is based on the enhancement of Raman signal on different surfaces, is an important method because it is highly sensitive, time-saving, and widely applicable [9–13]. Several studies about the determination of glucose on SERS were reported [14–16]. For instance, Peltier et al. developed the SERS biosensor based on the zone of electro- magnetic field enhancement [17], and the SERS sensor was de- signed on alkane-thiolate tri(ethylene glycol) monolayer [18]. Dinish et al. developed a SERS substrate with nanostructures fabri- cated on silicon wafer using a deep UV lithography for glucose sensing [19]. Mattei et al. prepared a SERS-active silver surface based on the action of a chemical-etching solution containing the ionic or molecular species [20]. Oh et al. developed a novel SERS substrate of glass nanopillar arrays with nanogap-rich silver nanoislands at wafer level [21]. Cejkova et al. developed copper SERS-active substrates [22]. Costa et al. investigated SERS on cop- per electrodes in 1-n-butyl-3-methylimidazolium tetrafluorobo- rate [23]. In addition, colloidal suspensions of silver and gold nanoparticles were successfully synthesized by laser ablation using water as the solvent, and excellent SERS results were found on Au films [24]. Baniukevic et al. described a magnetic gold nanoparticle in SERS-based sandwich immunoassay for BLV antigen gp51 detec- tion using different specific antibody immobilization methods [25]. Nanocomposites have aroused extensive interest due to ther- mal, chemical, physical, and catalytic properties [26]. Because of the large surface area, graphene/graphene oxide has been an attractive nanomaterial [27]. Hence, there are many reports about composites which integrate graphene oxide or graphene with dif- ferent nanoscaled materials [28]. Among them, metal–graphene nanocomposites are very useful for various engineering 0021-9797/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcis.2013.06.007 ⇑ Corresponding author at: Department of Chemistry, Indian Institute of Tech- nology Roorkee, Roorkee 247 667, India. Fax: +91 1332273560/36. E-mail addresses: vinodfcy@iitr.ernet.in, vinodfcy@gmail.com (V.K. Gupta). Journal of Colloid and Interface Science 406 (2013) 231–237 Contents lists available at SciVerse ScienceDirect Journal of Colloid and Interface Science www.elsevier.com/locate/jcis