A convenient and rapid method for detecting d-glucose in honey used smartphone.

Information concerning food composition, including information on its glucose content, is essential for modern food industry due to greater consumer awareness and expectations. In this work, the gene encoding d-glucose dehydrogenase (GDH) from Bacillus Natto was expressed in Escherichia coli BL21(DE3) firstly. Ni-IDA column was used for the purification of GDH. Then, the purified GDH was used to construct a color system with stable and effective measurement of concentration of d-glucose. The smart phone photographing and the software Microsoft Photoshop have been used in the system for determination of the color. The enzymatic analysis system can detect the concentration of d-glucose from 5 mM to 40 mM, and other various sugars has no interference to the system. The system was used to quantitatively detect the concentration of d-glucose in honey. The system can be used for convenient and rapid detection of d-glucose in food, especially for large numbers of samples.

Immobilization of ß-glucosidase by self-catalysis and compared to crosslinking with glutaraldehyde.

Nanoparticles have been successfully used for immobilization of different enzymes. The enzyme immobilized by nanomaterials has promising application in the biotechnological industry. The ß-glucosidase is very important in industrial field. The immobilization of ß-glucosidase by nanomaterials increases its activity and reusability. In this work, the ß-glucosidase was extracted from fruiting bodies of Agrocybe aegirit and was purified by anion exchange. The ß-glucosidase was immobilized by SiO2 nanoparticles (nano-SiO2) crosslink with glutaraldehyde (GA). On the other hand, the ß-glucosidase firstly immobilized by process adsorption and then crosslink with genipin (GP) which was produced by the hydrolysis of geniposide by ß-glucosidase. Then we compared the properties of both immobilized GA-crosslinked ß-glucosidase and GP-crosslinked ß-glucosidase, their immobilization yields were 83.34% and 96.29% respectively. The GA-crosslinked ß-glucosidase and free ß-glucosidase revealed optimal pH at 6.0. The optimal pH of GP-crosslinked ß-glucosidase was ranging between 4.5 and 7.5. The GA-crosslinked ß-glucosidase and GP-crosslinked ß-glucosidase revealed the optimal temperature at 50 °C, 70 °C respectively. For the free ß-glucosidase, the optimal temperature was 55 °C. Furthermore, the GA-crosslinked ß-glucosidase and GP-crosslinked ß-glucosidase were characterized by scanning electron microscope (SEM). The geniposide consumption in the reaction system of GA-crosslinked ß-glucosidase was analyzed by high performance liquid chromatography (HPLC).

The effects of NaCl on enzyme encapsulation by zeolitic imidazolate frameworks-8.

Metal-organic framework (MOF) has generated a lot of research interests for it can be employed as immobilization material for enzyme. There are many small molecules in enzyme solution during the extraction process, such as NaCl. It is important to study the effects of the small molecules on MOFs. Here we report a facile and efficient method to encapsulate (R)-1-phenylethanol dehydrogenase ((R)-PEDH) into zeolitic imidazolate framework-8 (ZIF-8). In this work, the effects of NaCl on shape of ZIF-8 and enzyme encapsulation have been investigated. The scanning electron microscope (SEM) results showed that 0.1 M NaCl affect the morphology of ZIF-8 while the crystal structure was not changed analyzed by X-ray diffraction (XRD), and 0.1 M NaCl consisted in the encapsulation system of (R)-PEDH@ZIF-8 enhanced the activity up to 2.5 folds than no NaCl consisted during prepared (R)-PEDH@ZIF-8. The (R)-PEDH@ZIF-8 (prepared with 0.1 M NaCl) enhanced the storage stability and resist ability against trypsin, and the (R)-PEDH@ZIF-8 has been successfully reused.