Magnetic COFs as satisfied support for lipase immobilization and recovery to effectively achieve the production of biodiesel by great maintenance of enzyme activity.

BACKGROUND: Production of biodiesel from renewable sources such as inedible vegetable oils by enzymatic catalysis has been a hotspot but remains a challenge on the efficient use of an enzyme. COFs (Covalent Organic Frameworks) with large surface area and porosity can be applied as ideal support to avoid aggregation of lipase and methanol. However, the naturally low density limits its application. In this work, we reported a facile synthesis of core-shell magnetic COF composite (Fe3O4@COF-OMe) to immobilize RML (Rhizomucor miehei lipase), to achieve its utilization in biodiesel production. RESULT: This strategy gives extrinsic magnetic property, and the magnetic COFs is much heavier and could disperse in water medium well, facilitating the attachment with the enzyme. The resultant biocomposite exhibited an excellent capacity of RML due to its high surface area and fast response to the external magnetic field, as well as good chemical stability. The core-shell magnetic COF-OMe structure not only achieved highly efficient immobilization and recovery processes but also maintained the activity of lipase to a great extent. RML@Fe3O4@COF-OMe performed well in practical applications, while free lipase did not. The biocomposite successfully achieved the production of biodiesel from Jatropha curcas Oil with a yield of about 70% in the optimized conditions. CONCLUSION: Magnetic COFs (Fe3O4@COF-OMe) for RML immobilization greatly improved catalytic performance in template reaction and biodiesel preparation. The magneticity makes it easily recovered and separated from the system. This first successful attempt of COFs-based immobilized enzyme broadened the prospect of biodiesel production by COFs with some inspiration.

Negative short-term impact of intraoperative biliary lavage in patients with hepatolithiasis.

AIM: To evaluate short-term outcomes following intraoperative biliary lavage for hepatolithiasis. METHODS: A total of 932 patients who were admitted to the West China Medical Center of Sichuan University between January 2010 and January 2014 and underwent bile duct exploration and lithotomy were retrospectively included in our study. The patients were divided into the lavage group and the control group. Related pre-, intra-, and postoperative factors were recorded, analyzed, and compared between the two groups in order to verify the effects of biliary lavage on the short-term outcome of patients with hepatolithiasis. RESULTS: Amongst the patients who were included, 678 patients with hepatolithiasis were included in the lavage group, and the other 254 patients were enrolled in the control group. Data analyses revealed that preoperative baseline and related intraoperative variables were not significantly different. However, patients who underwent intraoperative biliary lavage had prolonged postoperative hospital stays (6.67 d vs 7.82 d, P = 0.024), higher hospitalization fees (RMB 28437.1 vs RMB 32264.2, P = 0.043), higher positive rates of bacterial cultures from blood (13.3% vs 25.8%, P = 0.001) and bile (23.6% vs 40.7%, P = 0.001) samples, and increased usage of advanced antibiotics (26.3% vs 38.2%, P = 0.001). In addition, in the lavage group, more patients had fever (> 37.5 °C, 81.4% vs 91.1%, P = 0.001) and hyperthermia (> 38.5°C, 39.7% vs 54.9%, P = 0.001), and higher white blood cell counts within 7 d after the operation compared to the control group. CONCLUSION: Intraoperative biliary lavage might increase the risk of postoperative infection, while not significantly increasing gallstone removal rate.