Search

A voltammetric biosensor for Ara h 6 (a peanut allergen) detection in food samples was developed. Gold nanoparticle-modified screen-printed carbon electrodes were used to develop a sandwich-type immunoassay using two-monoclonal antibodies. The antibody-antigen interaction was detected through the electrochemical detection of enzymatically deposited silver. The immunosensor presented a linear range between 1 and 100 ng/ml, as well as high precision (inter-day RSD ≤9.8 %) and accuracy (recoveries ≥96.7 %). The detection and quantification limits were 0.27 and 0.88 ng/ml, respectively. It was possible to detect small levels of Ara h 6 in complex food matrices. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The performance of an amperometric biosensor constructed by associating tyrosinase (Tyr) enzyme with the advantages of a 3D gold nanoelectrode ensemble (GNEE) is evaluated in a flow-injection analysis (FIA) system for the analysis of l-dopa. GNEEs were fabricated by electroless deposition of the metal within the pores of polycarbonate track-etched membranes. A simple solvent etching procedure based on the solubility of polycarbonate membranes is adopted for the fabrication of the 3D GNEE. Afterward, enzyme was immobilized onto preformed self-assembled monolayers of cysteamine on the 3D GNEEs (GNEE-Tyr) via cross-linking with glutaraldehyde. The experimental conditions of the FIA system, such as the detection potential (−0.200 V vs. Ag/AgCl) and flow rates (1.0 mL min) were optimized. Analytical responses for l-dopa were obtained in a wide concentration range between 1 × 10 mol L and 1 × 10 mol L. The limit of quantification was found to be 1 × 10 mol L with a resultant % RSD of 7.23% ( n = 5). The limit of detection was found to be 1 × 10 mol L (S/N = 3). The common interfering compounds, namely glucose (10 mmol L), ascorbic acid (10 mmol L), and urea (10 mmol L), were studied. The recovery of l-dopa (1 × 10 mol L) from spiked urine samples was found to be 96%. Therefore, the developed method is adequate to be applied in the clinical analysis. [ABSTRACT FROM AUTHOR]