Galvanic replacement synthesis of PtPdAu hollow nanorods as peroxidase mimic with high specific activity for colorimetric detection.

Noble metal nanomaterials have been widely demonstrated to possess intrinsic enzyme-like properties and have been increasingly applied in the fields of analysis and biomedicine. However, current exploration of high-activity noble metal nanozymes is still far from adequate. The construction of hollow structures and adjustment of their elemental composition are effective ways to improve the specific activity (SA) of nanozymes. In this study, trimetallic PtPdAu hollow nanorods (HNRs) were developed using a galvanic replacement reaction and Kirkendall effect. The catalytic experiment showed that the PtPdAu HNRs possessed outstanding peroxidase-like performance and their SA value was up to 563.71 U mg-1, which is remarkable among various previously reported nanozymes and higher than that of monometallic or bimetallic counterparts with similar structure and size prepared in this study. Electron paramagnetic resonance (EPR)measurements showed that the PtPdAu HNRs could contribute to the formation of hydroxyl radicals (˙OH) in catalyzing hydrogen peroxide. When using PtPdAu HNRs as a nanozyme in the colorimetric detection of H2O2 and ascorbic acid (AA), the limits of detection were as low as 1.8 µM and 0.068 µM, respectively. This study demonstrates that PtPdAu HNRs are high-activity nanozymes and have the potential to be applied in the field of analysis.

ERK is involved in the regulation of CpG ODN 2395 on the expression levels of anti-lipopolysaccharide factors in Chinese mitten crab, Eriocheir sinensis.

CpG oligodeoxynucleotides (ODN), as an effective adjuvant or immunopotentiator, activate the immune system and induce various immune responses. Recently, it has also been reported that high dose of CpG ODN can lead to immunosuppression. However, the underlying mechanism of CpG ODN-mediated immune response remains largely unknown in invertebrates. In the present study, the role of ERK in regulating expression levels of anti-lipopolysaccharide factors (ALFs) induced by different doses of CpG ODN 2395 was analyzed in Chinese mitten crab, Eriocheir sinensis. The mRNA expression levels of EsALFs (EsALF1, EsALF2 and EsALF3) and EsERK in haemocytes were observed to increase from 6 h to 48 h post low doses of CpG ODN 2395 (0.5 µg and 2.5 µg) stimulation, while they were suppressed after high dose of CpG ODN 2395 (12.5 µg) injection. Meanwhile, the phosphorylation levels of ERK in haemocytes were significantly promoted after low doses of CpG ODN 2395 injection, and a reduce level of ERK phosphorylation was observed after high dose of CpG ODN 2395 injection. Further investigation showed that the expression levels of EsALFs induced by CpG ODN 2395 were markedly down-regulated after knocking down the expression of EsERK. Similarly, the EsALFs mRNA expression were also inhibited post different doses of CpG ODN 2395 stimulation in PD98059 (ERK inhibitor) injection crabs. These results collectively suggest that ERK is involved in regulating the expression level of EsALFs induced by different dose of CpG ODN 2395 in Chinese mitten crab, which contribute to the understanding of the regulation of CpG ODN involving in immune response in crustaceans.

Gas-liquid countercurrent integration process for continuous biodiesel production using a microporous solid base KF/CaO as catalyst.

A continuous-flow integration process was developed for biodiesel production using rapeseed oil as feedstock, based on the countercurrent contact reaction between gas and liquid, separation of glycerol on-line and cyclic utilization of methanol. Orthogonal experimental design and response surface methodology were adopted to optimize technological parameters. A second-order polynomial model for the biodiesel yield was established and validated experimentally. The high determination coefficient (R(2)=98.98%) and the low probability value (Pr<0.0001) proved that the model matched the experimental data, and had a high predictive ability. The optimal technological parameters were: 81.5°C reaction temperature, 51.7cm fill height of catalyst KF/CaO and 105.98kPa system pressure. Under these conditions, the average yield of triplicate experiments was 93.7%, indicating the continuous-flow process has good potential in the manufacture of biodiesel.