The Amino-Functionalized Graphene Oxide Nanosheet Preparation for Enzyme Covalent Immobilization.

Enzyme immobilization has demonstrated effective means for extending protein stability and shelf life. However, current methods negatively affect the enzyme activity, particularly for application purposes. Herein, the amino functionalized graphene oxide (GO-NH2) was synthesized and used to covalently immobilize lactase. FT-IR, UV-Vis, SEM, TEM and XPS were employed to confirm and characterize the immobilized lactase. At the resulting optimal temperature, the immobilization rate achieved 61% and the immobilized lactase maintained approximately 95% of catalyst activity. Compared with the free lactase, used as a control, the immobilized lactase was significantly more stable within acidic or basic environments, higher temperature conditions and had multiple recycle use characteristics. Furthermore, the immobilized lactase had a preserved 87% activity after storage at 4 °C for 30 days, while the free lactase was almost deactivated after 20 days under the same storage conditions. This work conforms that the amino-functionalized graphene oxide is a potential support material for lactase immobilization and can be extended to use with a variety of enzymes for a number of applications.

ICAM-1 and VCAM-1 expression in rat aortic endothelial cells after single-walled carbon nanotube exposure.

The expanded application of carbon nanotubes and increased annual production has recently sparked public interest concerning associated and potentially adverse exposure effects. As very little is known with regard to the toxicology and underlying mechanism of the phenomena termed "single-walled carbon nanotube (SWCNT) exposure", we conducted an in depth investigation of potential SWCNT effects on cell adhesion molecule gene expression within rat aortic endothelial cells (RAECs). RAEC exposure to SWCNT induced neutrophil adhesion to the endothelial monolayer via increased ICAM-1 and VCAM-1 expression. Due to NF-kappaB's fundamental involvement in the transcriptional regulation of cell adhesion molecules, we studied NF-kappaB/P65 activation in SWCNT treated RAECs, as well as GSH and LDH as determinants of oxidative stress, a condition that influences NF-kappaB activation. Resultant data indicates SWCNT exposure induces oxidative stress, thereby altering ICAM-1 and VCAM-1 expression. SWCNT induced nuclear NF-kB/P65 translocation can be inhibited by N-acetylcysteine, indicating elevated ICAM-1 and VCAM-1 expression is mediated by oxidative stress in RAECs, and may play important inflammatory roles in SWCNT-induced vascular endothelium damage.

Oxidative Damage on Testicles of Male Rats Induced by Micro-nano-scale SiO_2 / 环境与健康杂志

Objective To study the oxidative damage on testis of male rats induced by micro-nano-scale SiO2. Methods Male Wistar rats were exposed to nanometer SiO2(20-40 nm) and micro-meter SiO2(1-10 ?m)by intratracheal injection once two days. The rats were killed after 5 weeks of exposure. Some indicators related to the oxidative damage in the serum and the testis were determined. Results The activity of GSH-Px and SOD in the high dose groups decreased significantly and the MDA levels increased compared to the control group;The MDA levels of nano-silicon dioxide high dose group increased in the serum. Conclusion Nano-silicon dioxide may cause lipid peroxidation in the testis with a tendency of higher toxicity than that of micro-SiO2 at the same exposed level,the detail mechanism needs further discussion.