Biosensor for luteolin based on silver or gold nanoparticles in ionic liquid and laccase immobilized in chitosan modified with cyanuric chloride

Abstract

Novel and effective biosensors based on Ag or Au nanoparticles dispersed in ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF(6)) and laccase (Lac) from Aspergillus oryzae immobilized in chitosan (Chi) chemically cross-linked with cyanuric chloride (CC) were constructed. This enzyme catalyzes the oxidation of luteolin to the corresponding o-quinone, which is electrochemically reduced back to luteolin at 0.35 V vs. Ag/AgCl. Square-wave voltammetry was used for the electrochemical determination of luteolin at the Lac-nanoparticles-BMI.PF(6) biosensors. The best performance was obtained with 50:20:15:15% (w/w/w/w) as the graphite powder:Chi-CC:Nujol:Ag-BMI.PF(6) or Au-BMI.PF(6) composition (Lac 0.29 units mL(-1)) in 0.1 M acetate buffer solution (pH 4.0) with frequency, pulse amplitude and scan increment at 50 Hz, 100 mV, and 5.0 mV, respectively. Under optimized conditions, the cathodic currents increased linearly for the luteolin concentration range of 0.099-5.825 microM with detection limits of 0.054 +/- 0.004 microM (Ag-BMI.PF(6)) and 0.028 +/- 0.002 microM (Au-BMI.PF(6)). These biosensors demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability (13% decrease in response over 70 days). The recovery study for luteolin in chamomile tea samples gave values of 91.8-104.8%. The influence of Lac immobilized in Chi-CC and nanoparticles-BMI.PF(6) contributes to the excellent performance of the biosensors.

Development of Quercetin Biosensor Through Immobilizing Laccase in a Modified β‐Cyclodextrin Matrix Containing Ag Nanoparticles in Ionic Liquid

“…The enzymatic activity was determined in triplicate by measuring of the absorbance at 420 nm of the product formed from the reaction between 2.8 mL of 0.5 mM ABTS solution and 0.2 mL of Lac in 0.1 M acetate buffer (pH 5.0) at 25 8C [17,25].…”

“…The combination of enzyme immobilization and carbon paste is attractive since it offers versatility, speed, renewability and ease of construction [17,25,26]. Moreover, ionic liquids (ILs) and metal nanoparticles dispersed in ILs have attracted considerable attention as chemical modifiers in constructing high performance biosensors [17 -20, 37 -41].…”

Incorporação de líquidos iônicos e nanopartículas metálicas na construção de sensores eletroquímicos

“…Franzoi e coautores 111 empregaram o LI BMI.PF 6 com nanopartículas de prata ou ouro na construção de biossensores para luteolina. Nestes biossensores foi utilizada a enzima lacase de A. oryzae imobilizada em quitosana reticulada quimicamente com cloreto cianúrico.…”

Improved cathode materials for microbial electrosynthesis

“…Cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) has been widely used to modify graphite electrodes to promote the attachment of enzymes. [30][31][32][33] In addition to providing an overall positive charge, there is the possibility that chlorines that have not reacted with the carbon cloth will react with functional groups on the cell surface, such as amino groups of surfaceexposed proteins, to promote absorption of bacteria onto the electrode surface.…”