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A one‐pot strategy for the synthesis of bioactive hydroxytyrosol esters from tyrosol and lipophilic carboxylic acids has been developed via multienzyme cascade immobilized on electroactive melanin lignin nanoparticles. The novel catalyst involved the co‐immobilization of lipase and tyrosinase on the polyphenolic support and was operative in the presence of sustainable 2‐methyltetrahydrofuran as organic reaction solvent. The system did not require the use of extra reducing agents for the selective synthesis of catechols. Optoelectronic and electrochemical studies suggested the role played by melanin lignin nanoparticles in the regeneration of the active site of tyrosinase from unproductive met‐form to reversible deoxy/oxy‐form. This effect improved the overall activity of tyrosinase in the multienzyme cascade favouring the reduction of undesired quinones to corresponding catechols. [ABSTRACT FROM AUTHOR]

In this work, we report on the development of a simple electrochemical immunosensor for the detection of D-dimer protein in human plasma samples. The immunosensor is built by a simple drop-casting procedure of chitosan nanoparticles (CSNPs) as biocompatible support, Protein A (PrA), to facilitate the proper orientation of the antibody sites to epitopes as a capture biomolecule, and the D-dimer antibody onto a carboxyl functionalized multi-walled carbon nanotubes screen printed electrode (MWCNTs-SPE). The CSNPs have been morphologically characterized by Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS) techniques. Successively, the electrochemical properties of the screen-printed working electrode after each modification step have been characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The resulting MWCNTs-CSNPs-PrA-D-dimer Ab immunosensor displays an optimal and promising platform for antibody immobilization and specific D-dimer detection. DPV has been used to investigate the antigen/antibody interaction at different D-dimer concentrations. The proposed voltammetric immunosensor allowed a linear range from 2 to 500 μg L−1 with a LOD of 0.6 μg L−1 and a sensitivity of 1.3 μA L μg−1 cm−2. Good stability and a fast response time (5 s) have been reported. Lastly, the performance of the voltammetric immunosensor has been tested in human plasma samples, showing satisfactory results, thus attesting to the promising feasibility of the proposed platform for detecting D-dimer in physiological samples. [ABSTRACT FROM AUTHOR]