Research On The Preparation Of Modified Acrylate Copolymer Nanofibers And Its Application For Enzyme Immobilization

The poly(methl acrylate-acrylic acid) P(MA-AA) has good mechanical properties, chemical stability and flexibility. Their side-chain carboxylic acid termini are widely used in anchoring enzyme. However, this polymer suffer from poor biocompatibility, whereas the biocompatibility is critical to the enzyme stability. Feather peptides(FP) are both biocompatible and hydrophilic. To avoid the unfavorable interactions, we blend feather peptides into the polymer to improve its biocompatibility.Electrospun nanofibrous membranes have recently be investigated as supporting materials for enzyme immobilization, which are expected to offer many advantages, such as:effectively improving the enzyme-loading amounts due to large surface-to-mass ratio, facilitating a rapid separation of enzyme from reaction systems, alleviating the transfer barrier based on nanofiber immobilized enzyme, and hence improving the catalytic efficiency. In this work, P (MA-AA)/feather peptides composite nano-fibrous were fabricated and used as carrier for immobilizing horseradish peroxidase. The activity retention, enzyme loading, the kinetic parameters and the stability of immobilized HRP were investigated. The main research results are as follows:(1) Poly(methl acrylate-acrylic acid) P(MA-AA) was prepared by solution copolymerization. Various the monomer concentration, initiator concentration, reaction temperature, reaction time on the polymerization reaction were studied. The surface chemical structure and molecular weight of polymer was confirmed by FT-IR and GPC, respectively.(2) The P(MA-AA) nanofibrous membranes were prepared by electrospinning. Surface morphologies of the nanofibrous membranes were observed by SEM. In this study, various solution concentration, applied voltage, speed and receiving distance on fiber morphology and average diameter were investigated, the optimum electrospinning parameters are given as P(MA-AA) concentration of 28 wt%, applied voltage of 17 KV, solution flow rate of 0.2 mL/h, needle to collector distance of 15cm. The average diameter of fibers was 517nm under optimum electrospinning conditions.(3) Under the optimum conditions, various feather peptides contents were blend to P(MA-AA) solution with magnetic stirring to form a homogeneous solution. Subsequently, the P(MA-AA)/feather peptides composite nanofibers with different feather peptides contents were prepared by electrospinning technique. The surface morphologies and chemical structure of composite nanofibers were confirmed by SEM and FT-IR, respectively. Influence of the feather peptides contents on the mechanical properties of composite nanofibers was investigated. In order to evaluate the biocompatibility of the nanofibers, water contact angle measurement and BSA adsorption experiment tests were performed. The results showed that with the increase of feather peptides content, the diameter of the fiber decreased gradually, the fracture strength of composite nanofibrous membranes were increased firstly and then decreased, the best mechanical property was appeared as the feather peptides content of 10%, the breaking elongation decreased gradually. The results of measurement show that composite nanofibers perform better hydrophilic property with feather peptides content increased, BSA adsorption capacity decreased gradually. The above experiments show that P(MA-AA)/feather peptides composite nanofibers have excellent biocompatibility.(4) Horseradish peroxidase were fixed onto the P(MA-AA) nanofibers and P(MA-AA)/feather peptides composite nanofibers, respectively. The influence factors of enzyme immobilization, the kinetic parameters and the stability of immobilized HRP were investigated. It was found that, P(MA-AA)/feather peptides composite nanofibers presented higher enzyme loading and activities than immobilized HRP on the surface of P(MA-AA) nanofibers. Compared with soluble HRP, HRP immobilized on P(MA-AA)/FP could retain the activity at a wider range of pH; it also exhibited better storage stabilitiy, thermostability and reuse capability were significantly higher compared with free HRP.