Towards the development of flexible carbon nanotube-parafilm nanocomposites and their application as bioelectrodes

Soft, flexible and conductive interfaces, which can be used as electrode materials integrated with commercial electronic components and the human body for continuous monitoring of different analytes are in high demand in wearable electronics. In the present work, we explore the development of a functionalized multi-walled carbon nanotube‡Functionalized multi-walled carbon nanotube (f-MWCNT).-parafilm§Parafilm-M (PF). nanocomposite (f-MWCNT-PF) for the fabrication of a flexible electrochemical platform for glucose detection. The f-MWCNT-PF nanocomposite was characterized by transmission electron microscopy, energy dispersive X-ray analysis, Fourier-transform infrared spectroscopy, Raman spectroscopy, and electrochemical techniques. A bioelectrode fabricated by immobilization of glucose oxidase at the f-MWCNT-PF surface was further characterized by atomic force microscopy and tested for glucose. The bioelectrode provides two linear regions of glucose detection: a linear range from 0.08 mM to 3 mM, with a correlation coefficient of 0.982 and a sensitivity of 35.322 μA mM^-1; and a linear range from 5 mM to 25 mM, with a correlation coefficient of 0.964 and a sensitivity of 9.346 μA mM^-1. The proposed method was successfully applied to measure glucose in blood serum samples, differentiating healthy and diabetic persons. Additionally, the lower detection region could be effectively applicable for glucose sensing in sweat or interstitial fluid samples. The flexible, water-repellant sensing platform can be used as a universal platform for analyte detection, demanding waterproof, conductive platforms for biosensing applications, as it is suitable for protein/enzyme immobilization.