Preparation and properties of cryogel based on poly(hydroxypropyl methacrylate)
Abstract A novel supermacroporous poly(hydroxypropyl methacrylate) (p(HPMA)) cryogel was synthesized by cryogelation method at –16 °C. In this synthesis process, HPMA was used as a monomer, and N,N′-methylenebisacrylamide (MBAAm) was used as cross-linker; the reaction was carried out in the presence of redox initiator pair N,N,N′,N′-tetramethylene diamine (TEMED) and ammonium persulfate (APS). The effect of monomer concentration, cross-linker content, cooling rate, and dioxane co-solvent were determined with respect to the pore structure, mechanical behavior, swelling degree, and porosity of cryogel. The ESEM images indicate that the pore wall structure of cryogels was rough; moreover, small holes were present in the pore walls of cryogels. The result of compression test indicates that cryogels can be compressed by at least 80% without any breakdown. The result of swelling kinetics indicates that cryogels attain swelling equilibrium in 10 s. Furthermore, p(HPMA)-Cu2+ cryogel was prepared by loading Cu2+ ions on functionalized poly(hydroxypropyl methacrylate)-iminodiacetic acid (p(HPMA)-IDA) cryogel. We investigated the adsorption of bovine serum albumin (BSA) on cryogels. The results indicate that compared to Freundlich isotherm, Langmuir isotherm could more suitably describe the adsorption process of BSA on cryogels. Meanwhile, the adsorption capacity of p(HPMA)-Cu2+ cryogel was significantly greater than that of p(HPMA) cryogel. The maximum adsorption capacity of BSA on p(HPMA)-Cu2+ cryogel, which was treated with 1 M Cu2+ ions, was as high as 196.87 mg/g cryogel (equivalent to 20.48 mg/mL cryogel) at 25 °C and pH = 7.8; therefore, the maximum adsorption capacity of BSA on p(HPMA)-Cu2+ cryogel was 4.35 times higher than that of p(HPMA) cryogel. Thus, the adsorption capacity of cryogels was strongly influenced by Cu2+ concentration, moreover, temperature changes clearly affected the adsorption capacity of p(HPMA)-Cu2+cryogel. The adsorption capacity at 25 °C was twice as that at 15 °C. By calculating Gibbs free energy change (∆G) of adsorption, we found that the adsorption process was spontaneous; moreover, adsorption process occurred better at higher temperature.
A dye-affinity cryogel membrane for malate dehydrogenase purification from Saccharomyces cerevisiae
Abstract Cibacron blue F3GA functionalized poly(hydroxyethyl methacrylate) cryogel membranes were prepared and applied for a simple purification of malate dehydrogenase (MDH) from crude extract of Saccharomyces cerevisiae. Swelling tests, scanning electron microscopy, surface area measurements and Fourier transform infrared (FTIR) spectroscopy techniques were used for the characterization of dye-affinity cryogel membranes. Following cell homogenization and extraction, MDH was purified using the dye-affinity cryogel membranes at a high yield of 80.5% with 54-fold purification. Maximum MDH adsorption amount was determined to be 267.7 mg/g of membranes at pH 7.4, 25 °C and a flow rate of 1.0 mL/min. Interestingly, the cryogel membranes were used for several purification runs without any significant decrease in MDH adsorption capacity. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was carried out to assess the purity of the eluted MDH. The obtained results highlight the dye-affinity cryogel membranes as powerful dye affinity adsorbents for MDH purification from S. cerevisiae.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.