ABSTRACT
In this paper, carboxymethyl konjac glucomannan (CMKGM) was obtained by carboxyl modification of konjac glucomannan. Then CMKGM and chitosan (CS) were crosslinked and freeze-dried to prepare CMKGM/CS composite sponges with different proportions. The structure and micromorphology of CMKGM/CS sponges were investigated by FTIR spectroscopy and SEM. The SEM results showed that the pore structure of the composite sponge gradually increased with the increase of CMKGM content. To assess the applicability of CMKGM/CS composite sponges as wound dressing, the swelling behavior, water vapor transmission rate (WVTR), biocompatibility (cytotoxicity and hemolysis) were analyzed. The results indicated that CMKGM/CS composite sponges possessed high swelling ratio, proper WVTR and good biocompatibility, which might accelerate tissue regeneration. Meanwhile, in vivo experiments demonstrated that CMKGM/CS composite sponges could effectively heal full-layer wound of skin defects of male ICR mice.
Subject(s)
Bandages , Chitosan/chemistry , Cross-Linking Reagents/chemistry , Mannans/chemistry , Wound Healing , Animals , Cell Death/drug effects , Cell Survival/drug effects , Cells, Cultured , Chitosan/pharmacology , Fibroblasts/cytology , Fibroblasts/drug effects , Hemolysis/drug effects , Humans , Male , Mannans/chemical synthesis , Mannans/pharmacology , Mice, Inbred ICR , Porosity , Rabbits , Spectroscopy, Fourier Transform Infrared , Steam/analysis , Temperature , Thermogravimetry , X-Ray DiffractionABSTRACT
Enzyme immobilization is believed to provide an excellent base for increasing environmental tolerance of enzyme and considerable period of time. In this work, a kind of nonporous silica nanoparticles functionalized with amino group was synthesized to immobilize proline-specific endoprotease (PSEP). PSEP is known to specifically cleave peptides (or esters) at the carboxyl side of proline, thus can prevent the formation of haze and prolong the shelf life of beer. After immobilization, the environmental tolerance (temperature and pH, respectively) was obviously improved, and the immobilized enzyme can retain above 90 % of its original activity after 6 uses. Moreover, the immobilized enzyme can effectively prevent the formation of chill-haze using fresh beer fermentation liquid.
Subject(s)
Aspergillus niger/enzymology , Fungal Proteins/chemistry , Nanoparticles/chemistry , Serine Endopeptidases/chemistry , Silicon Dioxide/chemistry , Enzymes, Immobilized/chemistry , Hydrogen-Ion Concentration , Porosity , Prolyl OligopeptidasesABSTRACT
In this work, novel hybrid microbeads composed of chemically reduced graphene oxide (CRGO) and alginate were fabricated, which could encapsulate enzymes by a simple non-covalent adsorption-entrapment method. Compared with alginate gel beads, the intervention of CRGO in the alginate gel enhanced its mechanical strength, effectively prevented the leakage of enzyme, and greatly enhanced the stability and environmental tolerance. Compared with free enzymes or those on a single carrier, the enzyme encapsulated in these hybrid microbeads can retain its optimum activity within a broad range (temperature 45-60 °C, pH 4-6). Additionally, the microbeads can be easily recycled by simple filtration and filled into a column to achieve a continuous fixed-bed enzyme catalytic reaction.
ABSTRACT
The low butanol concentration of acetone-butanol-ethanol fermentation causes uneconomical product recovery. In this work, the effect of small molecule non-ionic surfactants on butanol fermentation was evaluated, using laboratory stocks of Clostridium acetobutylicum ATCC 824. Non-ionic surfactants substantially increased butanol production when additive amount was higher than 1% (W/W). Butanol concentration reached 16.9 g/L with 5% (W/W) Tween 80 and 100 g/L glucose in a 5 L fermenter. It was found that surfactants micelle solubilization capacity to butanol was very limited, indicating that butanol could hardly enter the surfactants micelle. Butanol production improvement was probably caused by cell surface hydrophobicity change due to surfactants adsorption.
