Valentín Rodríguez, Celimar

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    Assessment of the stability and biological activity of our model proteins encapsulated in hydrogel membranes
    (2007) Valentín Rodríguez, Celimar; Torres Lugo, Madeline; College of Engineering; López Garriga, Juan; Saliceti Piazza, Lorenzo; Department of Chemical Engineering; López, Gustavo
    Proteins are biological macromolecules which have a unique spatial conformation. This spatial conformation can be affected by extremes in pH, temperature, and organic solvents. Once this 3D spatial conformation is affected the protein’s biological stability and activity can be severely limited. For these reasons, this investigation focuses on the effects of pre-polymeric solution components on the behavior of proteins to be encapsulated by the entrapment technique in anionic, cationic, and neutral hydrogel membranes. Five proteins were utilized in this investigation: equine skeletal muscle myoglobin (MMb), equine heart myoglobin (HMb), bovine hemoglobin (bHb), porcine hemoglobin (pHb), and hen egg white lysozyme (HEWL). Three hydrogel morphologies were examined: methacrylic acid-poly(ethylene glycol) dimethacrylate (n=1000) (MAA:PEGDMA1000), dimethylaminoethyl methacrylate-poly(ethylene glycol) dimethacrylate (n=1000) (DMAEM:PEGDMA1000), and poly(ethylene glycol) (200) monomethyl ether-methacrylate-poly(ethylene glycol) dimethacrylate (n=1000) (PEGMA200:PEGDMA1000). The four hemeproteins were put in contact with different ratios of the pre-polymeric solution components. UV-vis spectroscopy was utilized to monitor displacements in the Soret Bands to determine any changes in biological stability. Optimized morphologies were then synthesized. The Soret bands of the proteins in the pre-polymeric solution were at the expected wavelengths ( = 408 (Mb), 406 (Hb)). Yet, upon polymerization, the Soret bands of the encapsulated proteins in ionic morphologies suffered blue shifts. Soret bands of the metaquo, deoxy, and carboxy states were all blue-shifted. Such phenomenon may be attributed to the breakage of the histidine-iron bond. Examination of the results revealed possible coexistence of metaquo/oxy and carboxy/oxy states within the polymerized membranes. Small displacements of the Soret bands upon changes from deoxy to carboxy states possibly expose higher affinity of CO to the polymer than to the heme group. HEWL crystals were exposed to pre-polymeric solutions of MAA:PEGDMA1000. Microscopy revealed that HEWL crystals were stable in these solutions for several hours. These morphologies will be polymerized in presence of HEWL crystals to investigate if crystals endure the polymerization process.