Navegando por Palavras-chave "Fluoreno"

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Filmes de Langmuir e Langmuir-Blodgett de polímero conjugado para imobilização da enzima Fitase
    (Universidade Federal de São Paulo (UNIFESP), 2020-03-26) Rodrigues, Rebeca Da Rocha [UNIFESP]; Philadelphi, Laura Oliveira Peres [UNIFESP]; Universidade Federal de São Paulo
    The main objective of this work was to employ the copolymer poly[(9,9- dioctylfluorene)-co-(3-hexylthiophene)] (PDOF-co-3HTh), with possible incorporation of gold nanoparticles to them, as matrices for immobilizing phytase, aiming at the manufacture of a phytic acid biosensor. In view of this, the copolymer and nanoparticles were first synthesized and later characterized by Fourier transform infrared spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), UV-Visible Absorption, Fluorescence, Thermogravimetric Analysis (TGA), Zeta Potential and Dynamic Light Scattering (DLS), in order to determine its structural and electronic properties, thus allowing the use of these compounds in the Langmuir and Langmuir-Blodgett (LB) films. The Langmuir films of the copolymer, pure and mixed (with enzyme and nanoparticles), were prepared and the interaction between the copolymer/enzyme/nanoparticle components could be confirmed by potential isotherms and surface-area pressure (DV-A and π-A, respectively), and also by the techniques of Brewster Angle Microscopy (BAM) and absorption-reflection infrared spectroscopy (PM-IRRAS). These characterizations of the interfacial films were able to prove not only the incorporation of the enzyme from the aqueous subphase to the Langmuir films of the copolymer, with presence or absence of nanoparticles, as well as the maintenance of its secondary structure. In addition, the polymeric films showed a morphology pattern of heterogeneity at the air-water interface due mainly to their folding and entanglement of chains, causing inherent defects in the organization and lateral distribution of the polymer at the air-water interface. Subsequently, the interfacial films were transferred to solid supports as LB films and characterized by PM-IRRAS, UV-Vis and Scanning Electron Microscopy (SEM), which proved not only the enzyme's co-transfer, but also the maintenance of its heterogeneous morphological pattern. The enzymatic activity of the biosensor was analyzed by absorption in UV-Vis, allowing to estimate the values of the Michaelis Menten constant (Km) and enzymatic activity of the system, demonstrating the feasibility in the detection of phytic acid as an enzymatic sensor.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    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.