Biomimetic Electrochemical Sensor Based on Single-Atom Nickel Laccase Nanoenzyme for Quercetin Detection.

Laccase, a member of the copper oxidase family, has been used as a green catalyst in the environmental and biochemical industries. However, laccase nanoenzymes are limited to materials with copper as the active site, and noncopper laccase nanoenzymes have been scarcely reported. In this study, inspired by the multiple copper active sites of natural laccase and the redox Cu2+/Cu+ electron transfer pathway, a novel nitrogen/nickel single-atom nanoenzyme (N/Ni SAE) with high laccase-like activity was prepared by inducing Ni and dopamine precipitation through a controllable water/ethanol interface reaction. Compared with that of laccase, the laccase activity simulated by N/Ni SAE exhibited excellent stability and reusability. The N/Ni SAE exhibited a higher efficiency toward the degradation of 2,4-dichlorophenol, hydroquinone, bisphenol A, and p-aminobenzene. In addition, a sensitive electrochemical biosensor was constructed by leveraging the laccase-like activity of N/Ni SAE; this sensor offered unique advantages in terms of catalytic activity, selectivity, stability, and repeatability. Its detection ranges for quercetin were 0.01-0.1 and 1.0-100 µM, and the detection limit was 3.4 nM. It was also successfully used for the quantitative detection of quercetin in fruit juices. Therefore, the single-atom biomimetic nanoenzymes prepared in this study promote the development of a new electrochemical strategy for the detection of various bioactive molecules and show great potential for practical applications.

[Value of lower-limb short latency somatosensory evoked potentials in predicting early death in patients with massive cerebral infarction].

OBJECTIVE: To explore the value of lower-limb short latency somatosensory evoked potentials (SLSEP) in predicting early death in patients with massive cerebral infarction. METHODS: Forty-eight patients of massive cerebral infarction were admitted in the Neurological Intensive Care Unit (NICU) between March 2008 and March 2009, and Glasgow-Pittsburgh coma scale (GPCS) and SLSEP were recorded and graded within 24 h after admission. The patients were divided into survival and death groups (including brain death) according to their short-term prognosis. The correlations of SLSEP and GPCS to the mortality were assessed. RESULTS: A significant correlation was found between SLSEP and the mortality in patients with massive cerebral infarction (r=0.484, P<0.001). The positive predictive value of the SLSEP grade 3 to death was 100%, and the patients with malignant middle cerebral artery infarction (mMCAI) appeared to have a 100% mortality. CONCLUSION: SLSEP grade 3 can be a highly specificity in predicting early death in patients with massive cerebral infarction, and it is also of value in determining the timing of surgical intervention of mMCAI.