Enzymes usually have poor thermal and operational stability as well as limited reuse cycles, which greatly limit their practical applications. This study reports a novel strategy for enzyme immobilization based on toehold-mediated DNA strand displacement on modified magnetic nanoparticles using alkaline phosphatase (ALP) and horseradish peroxidase (HRP) as different model enzymes. The immobilized enzyme procedure by DNA strand displacement exhibited high reversibility and reproducibility, and the mild, convenient approach achieved successive enzyme immobilization through triggering a toehold-mediated DNA strand displacement reaction. The immobilized HRP exhibited promising thermal stability after 50 min incubation at 50 °C and 60 °C, which were about 6.5- and 9.7-fold greater than the free enzyme, respectively. Notably, the immobilized enzyme exhibited excellent long-term storage stability, and the enzymatic activities were about 34.4- and 24.9-fold greater than free HRP after storage at 4 °C for 68 days and at room temperature for 9 days, respectively. The immobilized enzyme also preserved high performance towards long-term incubation stability, compared to the free enzyme, and excellent reusability, which showed a high degree of activity (more than 73%) after 5 cycles. Thus, the developed strategy exhibited a promising alternative platform with high magnetic responsiveness and significantly enhanced properties for the immobilization of important enzymes and their broad applications.

A vancomycin chiral stationary phase modified open tubular capillary electrochromatography (OT-CEC) column has been prepared using a microwave irradiation method. Compared with the use of conventional heating, the microwave-assisted process improved the efficiency of the synthesis, led to a significant increase in the rate of the reaction, and reduced the preparation time from 12 h to 55 min. Four aromatic racemates were selected as model compounds to evaluate the performance of the vancomycin modified OT-CEC column. Using the optimized conditions, all four of these racemic compounds were successfully separated with a baseline resolution (RS) of more than 1.75. These results demonstrated that the vancomycin modified OT-CEC column prepared using the microwave-assisted process possessed excellent chiral recognition properties towards aromatic racemates, as well as showed good levels of stability and repeatability. This column is therefore suitable for use in chiral separations by CEC.

Two-dimensional gas chromatography using the heart-cutting technique was applied to the analysis of the C5 fraction and extractive distillation solvent. High-resolution separation of the C5 fraction and N-methylpyrrolidone with water was obtained under optimized conditions. The separated components were identified by mass spectroscopy using standard samples. The recoveries of standard compounds were 99.5–100.6%, and the relative standard deviations were all less than 3%. It took only 30 min to finish a determination. Industrial samples from Yanshan Petrochemical Industry Corporation were also analyzed using the method. The experimental results indicate that the method is specific, sensitive and suitable for the determination of the C5 fraction and the extractive distillation solvent. Thus, the method is expected to be widely applicable and will be valuable in industrial applications.

A vancomycin chiral stationary phase modified open tubular capillary electrochromatography (OT-CEC) column has been prepared using a microwave irradiation method. Compared with the use of conventional heating, the microwave-assisted process improved the efficiency of the synthesis, led to a significant increase in the rate of the reaction, and reduced the preparation time from 12 h to 55 min. Four aromatic racemates were selected as model compounds to evaluate the performance of the vancomycin modified OT-CEC column. Using the optimized conditions, all four of these racemic compounds were successfully separated with a baseline resolution (RS) of more than 1.75. These results demonstrated that the vancomycin modified OT-CEC column prepared using the microwave-assisted process possessed excellent chiral recognition properties towards aromatic racemates, as well as showed good levels of stability and repeatability. This column is therefore suitable for use in chiral separations by CEC.

Two-dimensional gas chromatography using the heart-cutting technique was applied to the analysis of the C5 fraction and extractive distillation solvent. High-resolution separation of the C5 fraction and N-methylpyrrolidone with water was obtained under optimized conditions. The separated components were identified by mass spectroscopy using standard samples. The recoveries of standard compounds were 99.5–100.6%, and the relative standard deviations were all less than 3%. It took only 30 min to finish a determination. Industrial samples from Yanshan Petrochemical Industry Corporation were also analyzed using the method. The experimental results indicate that the method is specific, sensitive and suitable for the determination of the C5 fraction and the extractive distillation solvent. Thus, the method is expected to be widely applicable and will be valuable in industrial applications.