Hybrid cellulose nanocrystal/magnetite glucose biosensors

Abstract

There exists a high demand for simple and affordable blood glucose monitoring methods. For this purpose, new generations of biosensors are being developed for possible in vivo or dermal use. We present (non)sulphated cellulose nanocrystal/magnetite thin films to act as dermal and oral glucose biosensors. The biocompatible (N-CNC)-Fe₃O₄ and (S-CNC)-Fe₃O₄ hybrid systems exhibit peroxidase-like activity, indicated by an almost instant color change when in the presence of glucose and ABTS. Both types of biosensors detect glucose concentrations as low as 5 mM (which corresponds to the level of glucose in biological fluids), with (S-CNC)-Fe₃O₄ being 1.5 - 2 times as sensitive as (N-CNC)-Fe₃O₄. Hybrid catalytic activity is more pronounced at room temperature and in acidic environments. The hybrids can therefore be used to determine glucose levels by using sweat and saliva - non-blood bodily secretions which tend to be slightly to moderately acidic and have relatively low glucose levels.

Keywords: Cellulose nanocrystals; Glucose sensor; Magnetite; Non-invasive; Peroxidase-like activity; Physiological human body fluids.