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. 2019 May 31;19(11):2511.
doi: 10.3390/s19112511.

Colorimetric Analysis of Glucose Oxidase-Magnetic Cellulose Nanocrystals (CNCs) for Glucose Detection

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Free PMC article

Colorimetric Analysis of Glucose Oxidase-Magnetic Cellulose Nanocrystals (CNCs) for Glucose Detection

Ying Chuin Yee et al. Sensors (Basel). .
Free PMC article

Abstract

Glucose oxidase (EC 1.1.3.4) sensors that have been developed and widely used for glucose monitoring have generally relied on electrochemical principle. In this study, the potential use of colorimetric method for glucose detection utilizing glucose oxidase-magnetic cellulose nanocrystals (CNCs) is explored. Magnetic cellulose nanocrystals (magnetic CNCs) were fabricated using iron oxide nanoparticles (IONPs) and cellulose nanocrystals (CNCs) via electrostatic self-assembly technique. Glucose oxidase was successfully immobilized on magnetic CNCs using carbodiimide-coupling reaction. About 33% of GOx was successfully attached on magnetic CNCs, and the affinity of GOx-magnetic CNCs to glucose molecules was slightly higher than free enzymes. Furthermore, immobilization does not affect the specificity of GOx-magnetic CNCs towards glucose and can detect glucose from 0.25 mM to 2.5 mM. Apart from that, GOx-magnetic CNCs stored at 4 °C for 4 weeks retained 70% of its initial activity and can be recycled for at least ten consecutive cycles.

Keywords: cellulose nanocrystals; detection; glucose oxidase; immobilization; iron oxide nanoparticles; magnetic cellulose nanocrystals.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
TEM images of (a) CNCs, (b) IONPs, and (c) magnetic CNCs.
Figure 2
Figure 2
FTIR spectra of CNCs, modified CNCs and magnetic CNCs. (Inset showing expanded portion of wavelength 1600–1800 cm−1, where the peak shift is clearly seen).
Figure 3
Figure 3
SDS-PAGE showing the attachment of GOx on magnetic CNCs. (L: ladder; A: magnetic CNCs; B: Free GOx; C: GOx-magnetic CNCs).
Figure 4
Figure 4
Lineweaver–Burk plot of immobilized GOx activity.
Figure 5
Figure 5
Dose-dependent curve of glucose detection using GOx-magnetic CNCs. (Inset A showing reactions (a) without HRP, (b), control and (c) with 25 mM glucose; Inset B showing the linear range of glucose detection).
Figure 6
Figure 6
Specificity test of immobilized GOx using glucose (1.25 mM), maltose (1.25 mM), sucrose (1.25 mM), and fructose (1.25 mM).
Figure 7
Figure 7
(a) Reusability and (b) storage stability of GOx-magnetic CNCs. (Error bar represents the standard error of triplicate data).

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