Navegando por Palavras-chave "Conjugated Polymers"

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    Filmes Nanoestruturados Mistos De Copolímero Conjugado E Urease Para Biossensores De Ureia
    (Universidade Federal de São Paulo (UNIFESP), 2017-09-21) Barbosa, Camila Gouveia [UNIFESP]; Philadelphi, Laura Oliveira Peres [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The search for new molecular architectures to improve the efficiency of trapped enzymes in ultrathin films has increased the effectiveness of biosensors. In this work, a conjugated copolymer derived from thiophene and fluorene was investigated aiming to analyze its capacity of acting as a matrix for the immobilization of urease. Based on this fact, the copolymer poly[(9,9-dioctylfluorene)-co-thiophene] was synthesized, using the Suzuki’s reaction, and characterized by Infrared spectroscopy, Raman, UV-vis, fluorescence and thermogravimetry. Langmuir films of the polymer were prepared in the air-water interface. Urease was incorporated in the Langmuir monolayers and the properties of the mixed films were investigated in detail by surface pressure-area isotherms, polarization modulationinfrared reflection-adsorption spectroscopy (PM-IRRAS) and Brewster angle microscopy (BAM). The Langmuir films prepared were transferred to solid supports forming Langmuir- Blodgett (LB) films with 1, 3, 5 and 9 layers. These films were then characterized by their transfer rate, fluorescence specrtroscopy, PM-IRRAS and atomic force microscopy, confirming the material transfer and conformational changes in the enzyme structure after the deposition. In the 9-layer-film, the catalytic activity of urease was detected, with reaction rate lower than in the homogeneous environment, which was attributed to conformational restrictions imposed to the enzyme retained in the copolymer. The films were also characterized electrochemically, demonstrating their viability to detect urea. The mixed film prepared with 9 layers was also evaluated as an electrochemical biosensor using the cyclic voltammetry technique, in which a peak due to the electrooxidation of urea was noted at 0.6 V, and the chronoamperometry analysis which allowed the detection of the products formed in the reaction at 0.3 V. The chronoamperometry results showed a linear range of work for the urea concentrations from 1 to 4 mM, which demonstrates the feasibility of this system for urea detection.