Polyelectrolyte multilayers (PEMs) are now widely used for bioanalytical applications. In this work, a bilayer of poly(diallydimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) is consecutively adsorbed on 3-mercapto-1-propanesulfonic acid modified Au electrode surfaces, forming stable, ultrathin multilayer films. Subsequently, Prussian blue nanoparticles protected by PDDA (denoted as P-PB) and negatively charged glucose oxidase (GOx) are consecutively adsorbed onto the PSS-terminated bilayer. The growth of each of the P-PB/GOx bilayers is followed quantitatively using UV-visible absorption spectroscopy and the electrochemical method. The P-PB nanoparticles can catalyze the electroreduction of hydrogen peroxide formed from enzymatic reaction at lower potential and inhibit the responses of interferents, such as ascorbic acid (AA) and uric acid (UA). Performance of the multilayer films can be tailored by controlling the number of bilayers. Under optimal conditions, a linear range of 0.10 to 11.0 mM and a detection limit of 10 microM were achieved. The glucose biosensor has good stability and reproducibility.

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Stable and sensitive electrochemiluminescence (ECL) detection relies on successful immobilization of quantum dots (QDs) on working electrodes. Herein, we report a new technique to apply double-sided carbon adhesive tape as the working electrode to improve the stability and reproducibility of QD-based ECL emission. CdS QD-modified electrodes were prepared by dropping and drying CdS QD suspension on the carbon adhesive tape supported by indium tin oxide (ITO) glass. The ECL detection was performed with the prepared electrode on a paper-based platform. We tested our system using H(2)O(2) of various concentrations and demonstrated that consistent ECL emission could be obtained. We attribute stable and reproducible ECL emission to the robust attachment of CdS QDs on the carbon adhesive tape. The proposed method could be used to quantify the concentration of dopamine from 1 μM to 10 mM based on the quenching effect of dopamine on ECL emission of CdS QD system using H(2)O(2) as the coreactant. Our approach addressed the problem in the integration of stable QD-based ECL detection with portable paper-based analytical devices. The similar design offers great potential for low-cost electrochemical and ECL analytical instruments.

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A new Zn(ii) based 3D MOF having uncommon sev topology synthesized and used as efficient photocatalyst for the photodegradation of dyes methyl violet and rhodamine B.