Methanol extracts from 50 batches of Lycium barbarum (L. barbarum, wolfberry) in China were compared and characterized using high‐performance thin‐layer chromatography coupled with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) bioautography (HPTLC‐DPPH) and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐Q‐TOF‐MS/MS), respectively. Results showed that similar components occupying the major antioxidant activity existed in L. barbarum collected from different origins. However, the average antioxidant capacities of methanol extracts of L. barbarum collected in Ningxia were significantly higher than those of Qinghai, Xinjiang, Inner Mongolia, and Gansu, which may contribute to rational use of L. barbarum in China. Furthermore, the chemical structure of compound with the highest antioxidant capacity was tentatively identified as 2‐O‐β‐d ‐glucopyranosyl‐l ‐ascorbic acid using ESI‐Q‐TOF‐MS/MS analysis, which possessed high potentials to be used as an antioxidant biomarker for the quality control of L. barbarum. Results are helpful for the bioactivity‐based quality control of L. barbarum, and beneficial for the improvement of their performance in functional/health foods area, suggesting that HPTLC‐DPPH bioautography with ESI‐Q‐TOF‐MS/MS could be used as a routine approach for quality control of antioxidant components in L. barbarum. 相似文献
A facile method to fabricate ionic polymer‐metal composite (IPMC) actuators is proposed. A blend of mesoporous graphene (MG) and Nafion is used as the ionic matrix, which is sandwiched by two layers of blend of reduced graphene oxide (rGO) and Nafion as the electrodes. When subjected to an electrical field of 3 V, the IPMC actuator exhibits a blocking force of 10 gf g?1 for 20 s, and the same behavior can be repeatedly played for hundreds of cycles. MG improves the mechanical properties of Nafion‐based IPMC, more importantly, the mesopores in graphene provide additional pathway for the diffusion of cationic clusters and thus enhance the actuation speed. In addition, the surface electrodes of rGO protect the interlamellar liquid from evaporation thus ensure the durability.