Investigation and Characterization of Radiation Grafted Materials for Possible use in Biochemical Applications

Abstract

Copolymer of polyvinyl ' alcohol (PVA) and polyacrylamide (PAAm) was prepared in the presence ofN, N'­ methylene-bisacrylamide (BAAni) as a crosslinking agent for enzyme immobilization. The effect of ionizing radiation on invertase in native and immobilized revealed that the activity of the immobilized enzyme decreases on exposure to total dose more than 4 Mrad (40 kGy). The effect of BAAm concentration on invertase activity showed that the relative activity of the enzyme decreases by the increase in BAAm concentration. For the immobilized enzyme, the maximum activity was obtained after incubation time lhr. The immobilized invertase has the same optimum pH (4.5) as the free one and the suitable reaction temperature for such system is 55°C. Michales-Menten constant K111 of immobilized invertase was calculated to be 2 times that of free one. Radiation induced graft copolymerization of different hydrophobic monomers [styrene (Sty) and vinylacetate (VAc)] individually or in a binary system with maleic anhydride (MAn) has been made to investigate the effect of functional groups on protein adsorption, onto hydrophobic polymeric substrate such as polypropylene (PP). It was found that, as the percent graft increases the protein adsorption decreases for both systems. The effect of introducing hydrophilic polymer [polymaleic anhydride (PMAn)] with the hydrophobic PVAc or PSty on the protein adsorption was also investigated. The influence of grafting percent and chemical treatment of such grafted polymers on the bovine serum albumin (BSA) adsorption was studied. Also, the effect of pH, BSA initial concentration and ionic strength was tested.