Study of molecular conformation and activity-related properties of lipase immobilized onto core-shell structured polyacrylic acid-coated magnetic silica nanocomposite particles

Esmaeilnejad Ahranjani, P ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1021/acs.langmuir.5b03614
  3. Publisher: American Chemical Society
  4. Abstract:
  5. A facile approach for the preparation of core-shell structured poly(acrylic acid) (PAA)-coated Fe3O4 cluster@SiO2 nanocomposite particles as the support materials for the lipase immobilization is reported. Low- or high-molecular-weight (1800 and 100 000, respectively) PAA molecules were covalently attached onto the surface of amine-functionalized magnetic silica nanoacomposite particles. The successful preparation of particles were verified by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential measurement, and Fourier-transform infrared (FTIR) techniques. Once lipase is covalently immobilized onto the particles with an average diameter of 210 ± 50 nm, resulting from high binding sites concentrations on the low- and high-molecular-weight PAA-coated particles, high lipase immobilization efficiencies (86.2% and 89.9%, respectively), and loading capacities (786 and 816 mg g-1, respectively) are obtained. Results from circular dichroism (CD) analysis and catalytic activity tests reveal an increase in the β-sheet content of lipase molecules upon immobilization, along with an enhancement in their activities and stabilities. The lipases immobilized onto the low- and high-molecular-weight PAA-coated particles show maximum activities at 55 and 50 °C, respectively, which are ∼28% and ∼15% higher than that of the free lipase at its own optimum temperature (40 °C), respectively. The immobilized lipases exhibit excellent performance at broader temperature and pH ranges and high thermal and storage stabilities, as well as superior reusability. These prepared magnetic nanocomposite particles can be offered as suitable support materials for efficient immobilization of enzymes and improvement of the immobilized enzymes properties
  6. Keywords:
  7. Binding sites ; Catalyst activity ; Coated materials ; Dichroism ; Enzyme immobilization ; Enzymes ; Fourier transform infrared spectroscopy ; High resolution transmission electron microscopy ; Lipases ; Magnetism ; Molecular weight ; Molecules ; Nanocomposites ; Organic acids ; Polyethylenes ; Reusability ; Scanning electron microscopy ; Shells (structures) ; Silica ; Transmission electron microscopy ; X- ray diffraction ; Fourier transform infrared ; High molecular weight ; Magnetic nanocomposite particles ; Molecular conformation ; Nano-composite particle ; Scanning transmission electron microscopy ; Vibrating sample magnetometer ; Zeta potential measurements ; Thermogravimetric analysis
  8. Source: Langmuir ; Volume 32, Issue 13 , 2016 , Pages 3242-3252 ; 07437463 (ISSN)
  9. URL: http://pubs.acs.org/doi/abs/10.1021/acs.langmuir.5b03614