Objective To establish a rapid analysis method for cyanide based on a ratiometric fluores-cent probe,providing a quantitative strategy for on-site visual and rapid detection of cyanide.Methods A dual-emission ratiometric fluorescent probe(AuNCs-FL)was constructed by using bovine serum al-bumin(BSA)-stabilized gold nanoclusters(AuNCs,fluorescence emission at 660 nm)as the responsive signal unit and fluorescein(FL,emission at 515 nm)as the internal reference.Results The etching effect of cyanide on AuNCs resulted in fluorescence quenching at 660 nm,while the fluorescence inten-sity of FL at 515 nm remained unchanged,enabling a rapid response analysis of cyanide shift from red to green fluorescence.The developed probe enabled rapid analysis of cyanide within 3 min,with a limit of detection(LOD)of 3.4 mg/L and a visual detection range of 10-100 mg/L.Conclusion The AuNCs-FL fluorescent probe is structurally simple,low-cost,and easy to operate,delivering rapid and accurate results.It also avoids the interference from sulfides encountered in commercial cyanide test kits,making it suitable for the on-site rapid detection of suspected powder samples in cyanide poisoning cases.

OBJECTIVE: To construct the RNA interference(RNAi) lentiviral vector of suppressor of variegation 3-9 homolog 1(Suv39 h1) and verify its interfering efficiency by transfecting it to the bone marrow-derived mesenchymal stem cells(BMSCs). METHODS: The oligonucleotides of RNA plasmid were designed and synthesized according to the gene sequence of Suv39 h1 and short hairpin RNA design principles. Three kinds of LV-Suv39 h1-RNAi recombinant plasmids with different lentivirus knockdown targets(KD1, KD2 and KD3) were constructed. After identification by restriction analysis and sequencing, the packaged lentivirus vectors with the three kinds of Suv39 h1 gene were transfected into rat BMSCs at logarithmic growth stage, and were named KD1, KD2 and KD3 transfection groups. The control group was transfected with the negative control virus. After 72 hours transfection, the transfection efficiency was evaluated, and the relative mRNA levels of Suv39 h1 were determined by quantitative real-time polymerase chain reaction(qPCR). RESULTS: Sequencing analysis demonstrated that three kinds of LV-Suv39 h1-RNAi recombinant plasmids were constructed correctly. The results of transfection efficiency evaluation showed that more than 80.00% green fluorescence was expressed in the BMSCs transfected with the three lentiviral vectors with a multiplicity of infection of 20. These results indicated that lentivirus was successfully constructed and transfection efficiency was high. The results of qPCR showed that the relative expression of Suv39 h1 mRNA in BMSCs of KD1, KD2 and KD3 transfection groups was lower than that in the control group(all P<0.05), and the relative expression of Suv39 h1 mRNA in KD1 and KD3 transfection groups was lower than that in KD2 transfection group(both P<0.05). However, there was no significant difference in the relative expression of Suv39 h1 mRNA between KD1 and KD3 transfection groups(P>0.05). CONCLUSION: The constructed lentiviral vector with low expression of Suv39 h1 was constructed successfully. This vector can be expressed in rat BMSCs, which lays a foundation to study the effect of Suv39 h1 gene in acute myeloid leukemia.

Objective Feasibility of using MNA cell-culture inoculation test to detect and isolate the street rabies virus. Methods Using MNA cell-culture inoculation test, fluorescent antibody test (FAT) and sandwich ELISA with double-antibodies to detect 33 specimens of street rabies virus, 20 specimens of negative canine brains and 4 specimens of healthy mice brains. Results 33 specimens of street rabies virus were positive to the cell-culture inoculation test but the others were negative. The concordances of MNA cell-cultured inoculation test with FAT and sandwich ELISA with double-antibodies were both 100%. Conclusion MNA cell-culture inoculation test appeared to be both highly sensitive and specific in detecting the street rabies virus, and could be used in detection and isolation of the virus.