An amperometric glucose oxidase biosensor based on liposome microreactor-chitosan nanocomposite-modified electrode for determination of trace mercury

A biosensor for trace mercury ions based on glucose oxidase (GOD) immobilized on liposome microreactor and chitosan (CS) nanocomposite through layer-by-layer method is described herein. The GOD liposome microreactors (GLMs) were characterized using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and amperometric methods. The results indicated that GLMs were prepared by encapsulating the enzyme GOD in l-α-phosphatidylcholine liposome resulting in spherical bioreactor with a mean diameter of 5.83 ± 0.75 μm. The encapsulation efficiency and drug loading content of the GLMs were about 53.58 ± 0.91 and 41.15 ± 0.95%, respectively. Cyclic voltammogram (CV) was further utilized to explore relevant electrochemical activity on (CS/GLM)8 nanocomposite-modified glassy carbon electrode (GCE). The biosensor based on the (CS/GLM)8-GCE composite films was applied to detect Hg2+ with a broad linear range from 0.5 to 5.00 μmol/L, and the detection limit was brought down to 0.076 μmol/L. The apparent Michaelis-Menten constant, Km, for the enzymatic reaction was 0.37 mmol/L (S/N = 3). Furthermore, the biosensor showed good stability and reproducibility. Such new biosensor based on encapsulation of GOD within liposome microreactors shows great promise for rapid, simple, and cost-effective analysis of Hg2+ in environmental samples.