Using Of Nanofiber Based Electrodes For Detection Of Organic Molecules

Abstract

The disposable electrodes of the diabetes sensors used in our country are in the case of external dependency due to the necessity of importation. In addition, these types of electrodes are only capable of measuring the glucose in blood, and are using for the measurement of other analytics. Consequently, it has become compulsory to develop electrodes with the characteristics of high sensitivity and selectivity for the determination of ethanol, methanol and glucose levels. Electrospun nanofiber membranes are structurally sound and flexible materials. The membranes are promising candidates for immobilization of enzymes because of their high specific surface area and porous structure. A novel technique for designing amperometric glucose biosensor by electrospinning poly (vinyl alcohol) (PVA) - carbon nanotube (CNT) nanocomposite materials is presented in this study. It was aimed to investigate glucose, ethanol and methanol detection efficiency of five different enzyme electrodes using alcohol oxidase and glucose oxidase enzymes by manipulating the structural design and composition of nano-composite membranes. However, Glucose oxidase-based enzyme electrodes are among the simplest, easy-to-use systems for blood sugar testing and play an important role in the continuous monitoring of glucose. Because of these reasons and due to our limited laboratory conditions, glucose oxidase was selected and immobilized onto the surface of sensor electrodes. The electrodes developed in this study were prepared as: a) Glucose oxidase (GOx) immobilized PVA electrospun electrode; b) Glucose oxidase (GOx) immobilized PVA electrospun electrode containing multi-walled carbon nanotube (MWCNT); c) Glucose oxidase (GOx) immobilized PVA electrospun electrode containing poly(diallyldimethylammonium chloride) (PDDA) functionalized multi-walled carbon nanotube (MWCNT); d) Glucose oxidase (GOx) immobilized PVA electrospun electrode containing poly(diallyldimethylammonium chloride) (PDDA) functionalized single-walled carbon nanotube (SWCNT); e) Interfacially cross-linked PVA electrospun electrode containing poly(diallyldimethylammonium chloride) (PDDA) functionalized multi-walled carbon nanotube (MWCNT). Poly (vinyl alcohol) (PVA)/Glucose oxidase (GOx)/graphene biocomposite membranes were prepared using an electrospinning technique and used for enzyme immobilization. The PVA/GOx membrane’s morphology was examined by scanning electron microscopy (SEM). Average diameter for the neat PVA electrospun nanofibers were observed as 100 nm. Glucose sensing activities of the electrodes were amperometrically measured at an applied voltage of -0.5 V (vs. Ag/AgCl) in 0.1 M phosphate buffer solution (PBS pH 7.4). Amperometric measurements demonstrated that electrospun fibrous enzymatic electrodes glucose detection limits for (c) and (d) sensor electrode was observed as 0.024 mM and the glucose sensitivity were calculated as 65.8 and 42.7 µAmM-1cm-2, respectively. Glucose detection limit and sensitivity of these sensor electrodes are quite satisfying. Glucose detection limits of the fabricated glucose electrodes (a), (b), and (e) were observed as 0.048, 0.048 and 0.12 mM respectively, and calculated glucose sensitivity of these sensor electrodes were 19.4, 25.9, 4.01 µAmM-1cm-2, respectively.

Keywords: Electrospin, nanofiber, nanobiosensor, carbon nanotube