Rapid and facile preparation of NiFe-layered double hydroxide nanosheets as self-supported electrode for glucose detection in drink sample.

Layered double hydroxides have been widely used for electrochemical glucose detection due to their layered structure with more active sites, but they suffer from lower electrical conductivity and long-time hydrothermal preparation. In this paper, NiFe-layered double hydroxide nanosheets supported on nickel foam (NiFe-LDH NSs/NF) was prepared using an ultrafast and facile method via in-situ corroding foam nickel in FeCl3 solution under room temperature, and the whole synthetic process can be accomplished within several minutes. The as-fabricated NiFe-LDH NSs/NF shows significant catalytic activity in the glucose oxidation, showing its great promise in glucose detection. As a self-supported electrode, NiFe-LDH NSs/NF is favorable for glucose detection, with a sensitivity of 9.79 and 3.29 mA mM-1 cm-2 within the linear range of 0.001 to 1.16 mM and 1.16 to 4.67 mM, respectively. Moreover, NiFe-LDH NSs/NF is also selective and reliable towards glucose detection in drink sample.

[Application of flat-sided culture tubes during prenatal diagnosis].

OBJECTIVE: To assess the value of using flat-sided culture tubes for preparing chromosomes through chorionic villi (CV) and amniotic fluid (AF) cell cultures during prenatal diagnosis. METHODS: From February to March 2020, 157 CV samples and 147 AF samples subjected to prenatal diagnosis at the Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region were selected as the study subjects. For each sample, one flat-sided tube and one flask culture were set up by following the standard protocols. The methods were evaluated by comparing the cell growth, experimental process, quality of chromosome preparation and costs. RESULTS: The success rates for the culturing of CV and AF samples by the flat-sided culture tube method were 97.45% (153/157) and 97.96% (144/147), respectively. By contrast, the success rates for the conventional flask method were 98.72% (155/157) for CV and 98.64% (145/147) for AF samples. No significant difference was found between the two methods (P > 0.05). The average harvest time required by the flat-sided culture tube method was 8.45 days for CV and 9.43 days for AF cultures, whilst the average harvest time for conventional flask method was 9.05 days and 9.54 days, respectively. The flat-sided culture tube method for CV had required significantly shorter average harvest time than the conventional method (P < 0.001). No statistical significant difference was found in the average harvest time for AF by the two methods (P > 0.05). The conventional culturing method had required three containers with two sample transfers. By contrast, the flat-sided culture tube method was carried out in one tube without any sample transfer. The average total amount of medium used was 3.91 mL for each flat-sided culture tube and 6.26 mL for each conventional flask. CONCLUSION: The flat-sided culture tube method can provide a simple, cost-effective and error-reducing procedure for the CV and AF samples culture during prenatal diagnosis.

Engineering porous Co-Mn oxide nanosheets with abundant oxygen vacancy as an efficient oxidase-like mimic for heparin colorimetric sensing.

Defects engineering as an effective strategy was widely utilized to modulate catalytic performance for heterogeneous catalysts through tuning surface electronic surface and creating more active sites. In this work, porous Co-Mn oxide nanosheets with abundant oxygen vacancies (OVs-CMO NSs) were prepared via a simple "one-stone-two-birds" method. OVs were verified by various characterizations and found more favorable for O2 absorption and activation to produce more reactive O2•- radical, resulting in an improved oxidase-like activity in initiating 3,3',5,5'-tetramethylbenzidine (TMB) oxidation, with a lower Km value of 0.00717 mM and a higher Vmax of 2.086 × 10-7 M/s. Since heparin (Hep) shows an inhibition effect on OVs-CMO NSs-TMB chromogenic system due to strong absorption, a colorimetric sensing platform for Hep detection was established. The present colorimetric detection shows high sensitivity, good selectivity and reliability for normal goat serum. This work not only provides a high-performance non-precious metal oxidase mimic prepared by simple surface defect engineering, but also builds a sensitive colorimetric method for Hep detection.