Production of flower shaped nanobiocatalysts from plant extracts and investigation of their peroxidase like activities on polymerization reactions

Enzyme catalyzed polymerization reactions have been extensively studied by many polymer research groups and are known to be environmental friendly and easy method for many applications. Many enzymes have active sites containing metal ions, for example peroxidases and superoxide dismutases. Hemoproteins like Horseradish peroxidase (HRP) have been studied to explore radicalic polymerization reactions of some aromatic compounds (phenol, aniline, etc.) and vinyl monomers. These catalysts transfer an electron from hydrogen peroxide to the substrate to generate radicals for the initiation of polymerization. Due to that, many polymeric materials can be successfully synthesized by enzyme catalysts. However; high cost of enzymes, instability in aqueous solutions, denaturations in organic solvents and high temperatures, and inefficiency to be used over and over again of enzymes strictly limit their use in industrial applications. Especially, it is crucial requirement to use enzymes over and over again for commercial purposes. For this reason, it is important to discover new generation catalyst systems indicating similar catalytic activities like enzymes for commercial and scientific applications. Recently, flower shaped hybrid organic-inorganic nano biocatalysts obtained from plant extracts become alternative catalyst systems to overcome these disadvantages. Hybrid organic-inorganic flower shaped nano-biocatalysts are synthesized from metal ions (for example, copper (II) ions, Cu2+) as the inorganic component and plant extracts as the organic component. Obtained these flower shaped nano biocatalysts show enzyme like activities. Although the basic oxidation reactions of these types of hybrid nano biocatalysts have been studied by many research groups, their use in polymerization reactions has not yet been investigated in the literature. In the thesis study, the effects of peroxidase-like activities of flower-shaped nano-biocatalysts obtained from two different plant extracts (green tea and viburnum-opulus extract) and Cu2+ ions were investigated on the polymerization of phenol-derivatives (phenol, guaiacol and salicylic acid). Obtained successful outcomes showed that the synthesized catalysts showed very high catalytic activity upon polymerization of phenol and guaiacol. The polymerization yields and molecular weights of the obtained polymers in the polymerizations carried out with these two monomers were found to be quite high. Due to the solubility problem of salicylic acid in aqueous conditions, polymerization reactions of salycilic acid resulted in very low yields for polymerizations carried out for both catalyst systems. Free HRP enzyme loses its catalytical activities at 60 oC and above temperatures. However, the synthesized catalysts exhibited quite high catalytic acivities even at 60 oC and above reaction temperatures. This outcome provides significant advantages in some reactions requiring high temperatures and is very important to use them for both scientific studies and industrial applications.