Amperometric glutamate biosensor based on chitosan enzyme film

• Published in: Electrochimica acta Vol. 51; no. 21; pp. 4528 - 4532
• Main Authors: Zhang, Maogen, Mullens, Conor, Gorski, Waldemar
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-06-2006; Elsevier
• Subjects: Biological and medical sciences; Biosensor; Biosensors; Biotechnology; Chitosan; Enzyme immobilization; Fundamental and applied biological sciences. Psychology; Ionotropic gelation; l-Glutamate oxidase; Methods. Procedures. Technologies; Various methods and equipments; l-Glutamate oxidase; Enzyme immobilization; Ionotropic gelation; Chitosan; Biosensor; Performance evaluation; L-Glutamate oxidase; Enzyme; Glutamate; Enzyme electrode; Electrochemical detector; Ion selective electrode; Oxidoreductases; Immobilized enzyme; Polysaccharide
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2006.01.010

A simple method for enzyme immobilization in electrochemical biosensors for monosodium glutamate (MSG) was developed. The method relied on the precipitation of complexes of polyanionic enzyme
l-glutamate oxidase (GmOx) with polycationic chains of chitosan (CHIT) on the surface of platinum electrode. Such ionotropic gelation allowed the CHIT matrix to retain ∼57% of applied GmOx (0.30–3.0
units). The CHIT
+
GmOx based biosensor displayed a low detection limit of 1.0
×
10
−7
M MSG (S/N
=
3,
E
=
0.400
V), linear range up to 2
×
10
−4
M (
R
2
=
0.991), sensitivity of 85
mA
M
−1
cm
−2, and a short response time (
t
90%
=
2
s). The biosensors maintained ∼80% of the MSG signal even after 11
h of continuous use, which indicated good operational stability. Stability studies revealed that a majority of signal loss was due to a slow transformation of glutamate in a solution into the redox inactive pyroglutamate. After 4 months of storage in water at 4
°C, the CHIT
+
GmOx films retained ∼80–90% of their original activity toward the MSG. The CHIT
+
GmOx films are promising candidates for the development of simple and reliable chromatographic detectors for glutamate.