Protein modified cellulose nanocrystals on reinforcement and self-driven biodegradation of aliphatic polyester.

Due to the highly environment-dependent biodegradation and uncontrolled degradation period, the long-run feasibility and effectiveness of biodegradable polymers are extensively questioned to solve plastics waste accumulation and pollution problems. This work physically incorporated lipase PS from Burkholderia cepacian on cellulose nanocrystals (CNC) and embedded it in polycaprolactone (PCL) to construct stable and controllable interfacial microenvironment between CNC and PCL for the reinforcement and controllable self-driven biodegradation. The physical adsorption of lipase PS on CNC was studied by monitoring the surface charge and particle size. FT-IR spectra confirmed the successful incorporation of lipase PS and CNC. Compared with CNC, protein-modified CNC had a higher maximum thermal decomposition temperature of 345 °C and lower interfacial tension of 11 mN/m with PCL which provided PCL composites with higher nucleation efficiency and tensile elongation of 1086 % at break. In addition, only 0.67 % embedded lipase PS completely hydrolyzed PCL membranes in <140 h. The post-compression molding at 80-100 °C had negligible influence on the lipase activity, which indicated that CNC could protect the lipase from inactivation in polymer extrusion and compression. This work also highlighted protein-modified CNC as a new technology for polymer reinforcement.

Betulinic Acid Enhances the Viability of Random-Pattern Skin Flaps by Activating Autophagy.

Random-pattern skin flap replantation is commonly used to repair skin defects during plastic and reconstructive surgery. However, flap necrosis due to ischemia and ischemia-reperfusion injury limits clinical applications. Betulinic acid, a plant-derived pentacyclic triterpene, may facilitate flap survival. In the present study, the effects of betulinic acid on flap survival and the underlying mechanisms were assessed. Fifty-four mice with a dorsal random flap model were randomly divided into the control, betulinic acid group, and the betulinic acid + 3-methyladenine group. These groups were treated with dimethyl sulfoxide, betulinic acid, and betulinic acid plus 3-methyladenine, respectively. Flap tissues were acquired on postoperative day 7 to assess angiogenesis, apoptosis, oxidative stress, and autophagy. Betulinic acid promoted survival of the skin flap area, reduced tissue edema, and enhanced the number of microvessels. It also enhanced angiogenesis, attenuated apoptosis, alleviated oxidative stress, and activated autophagy. However, its effects on flap viability and angiogenesis, apoptosis, and oxidative stress were reversed by the autophagy inhibitor 3-methyladenine. Our findings reveal that betulinic acid improves survival of random-pattern skin flaps by promoting angiogenesis, dampening apoptosis, and alleviating oxidative stress, which mediates activation of autophagy.

Trehalose promotes the survival of random-pattern skin flaps by TFEB mediated autophagy enhancement.

Random-pattern skin flaps are commonly used and valuable tools in reconstructive surgery, however, post-operative random skin flap necrosis remains a major and common complication. Previous studies have suggested that activating autophagy, a major pathway for degradation of intracellular waste, may improve flap survival. In this study, we investigated whether trehalose, a novel and potent autophagy activator, improves random skin flap viability. Our results demonstrated that trehalose significantly improves viability, augments blood flow, and decreases tissue edema. Furthermore, we found that trehalose leads to increased angiogenesis, decreased apoptosis, and reduced oxidative stress. Using immunohistochestry and western blot, we demonstrated that trehalose augments autophagy, and that inhibition of autophagy augmentation using 3MA significantly blunted the aforementioned benefits of trehalose therapy. Mechanistically, we showed that trehalose's autophagy augmentation is mediated by activation and nuclear translocation of TFEB, which may be due to inhibition of Akt and activation of the AMPK-SKP2-CARM1 signaling pathway. Altogether, our results established that trehalose is a potent agent capable for significantly increasing random-pattern skin flap survival by augmenting autophagy and subsequently promoting angiogenesis, reducing oxidative stress, and inhibiting cell death.

Preparation of Modified Chitosan Microsphere-Supported Copper Catalysts for the Borylation of α,ß-Unsaturated Compounds.

Chitosan microspheres modified by 2-pyridinecarboxaldehyde were prepared and used in the construction of a heterogeneous catalyst loaded with nano-Cu prepared by a reduction reaction. The chemical structure of the catalyst was investigated by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). Under mild conditions, such as no ligand at room temperature, the catalyst was successfully applied to catalyze the borylation of α,ß-unsaturated receptors in a water-methanol medium, yielding 17%-100% of the corresponding -hydroxy product. Even after repeated use five times, the catalyst still exhibited excellent catalytic activity.