Navegando por Palavras-chave "Gold Nanoparticle"

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    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.