Localisation of alkaline phosphatase in the pore structure of paper

Christopher J. Garvey, Mohidus Samad Khan, Michael P. Weir, Gil Garnier

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We study the bulk pore structure of bioactive paper impregnated with an enzyme, alkaline phosphatase (ALP), retained with a cationic polyacrylamide (CPAM) with synchrotron small-angle x-ray scattering and examine the translational dynamics of water in the porous material using 1H pulsed field gradient NMR. The aim of this study is to understand the perturbation of enzyme kinetics from the bulk behavior through the localization of the enzyme within the pore structure. We interpret the small-angle x-ray scattering data where the range of length scales examined in the scattering experiment corresponds to the packing of the unitary crystallites, or microfibrils, and aggregates of these cellulosic microfibrils. Pulsed field gradient NMR measurement of H2O diffusion in the pores between these aggregates indicates that some of these pores are strongly connected allowing convective mass transport, while others exhibit strongly restricted diffusion. Diffusion is also strongly anisotropic. We conclude that the CPAM retention polymer and the protein coat interior surfaces inside the pores of a particular size and that there is no major modification of the pore structure of paper by the CPAM or the ALP. The transport properties of this porous matrix are discussed in terms of the mechanisms by which sorption of ALP may perturb enzyme kinetics.

Original languageEnglish
Pages (from-to)1293–1304
Number of pages12
JournalColloid and Polymer Science
Issue number8
Publication statusPublished - 1 Aug 2017


  • Cellulose fibres
  • CPAM
  • Enzyme
  • Nanostructure
  • Paper
  • Polymer protein interactions
  • Pore size
  • Pulsed field gradient NMR
  • SAXS

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