Disposable electrochemical detectors based on nickel nanowires for carbohydrate sensing

Nanowires (NWs) are critically important building blocks of nanotechnology for sensing, biosensing and bioelectronics. However, in order to avoid complex and stiff configurations reported, a simpler and disposable approach is needed. Nickel nanowires (NiNWs) are one of the most promising alternatives because they allow magnetic manipulations through the application of an external magnetic field and they remain to be exploited in analytical field for electrochemical biosensing in real samples. In this work, NiNWs were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), energy-dispersive X-ray spectrometry (EDS) and X-ray photoelectronic spectroscopy (XPS) and then easily used in the construction of disposable detectors on carbon-screen printed electrodes (CSPEs). Fabricated NiNWs using alumina templates were about 330 nm of diameter and 6 μm lengths. XPS revealed that NiNWs based electrodes contained just a 0.9% of Ni with an enhancement of current density of about 65 times in comparison with Ni-bulk electrode under flow conditions. Electrochemically activated NiNWs (at -1.5 V, 600 s under magnetic field of 2×4200 G) gave the best signal-to-noise performance exhibiting fast response time to representative carbohydrate, very good mechanical stability, no memory effect and an extreme resistance to fouling under hydrodynamics conditions allowing an excellent analytical performance on the board of just one disposable single-electrode (RSDs≤7%, n=50). Analytical performance of NiNWs was also excellent in the analysis of selected samples exhibiting very good reliability, precision (RSDs≤2%) and recovery rates (95-115%). NiNWs are becoming a simple and easy-to-use nanotool for fast, reliable and decentralized sensing of carbohydrates; and as a consequence, "disposable nanoanalytics" is approaching.