In order to explore the potential of nanoparticles from ethanol extracts of Euphorbia he-lioscopia L.(ZQNPs)in antibacterial application.In this study,ZQNPs were prepared by the self-assembly method using alcohol extract of Euphorbia helioscopia L.,polylysine and polyethylene glycol 1 000 as raw materials.The morphology and structure of ZQNPs were characterized by transmission electron microscopy,UV-vis spectrophotometer,and Fourier transform infrared spec-troscopy.The growth and biofilm inhibition of ZQNPs against methicillin-resistant Staphylococcus aureus(MRSA)were tested by broth microdilution,crystal violet,and checkerboard assays.The broad-spectrum antibacterial activity and antibacterial activity of ZQNPs against three clinical strains were evaluated by broth microdilution method.Finally,the antibacterial mechanism of ZQNPs was preliminarily explored by morphological observation and soluble protein detection of MRSA.The results showed that ZQNPs were self-assembled and cross-linked multi-faceted spheres with an average diameter of 67 nm.The MIC of ZQNPs against MRSA was 8 mg/L,and the antibacterial effect was much better than that of Euphorbia helioscopia L.mongolicum alcohol extract(MIC＞32 mg/L).The time killing curve again showed that ZQNPS had a good antibacteri-al effect on MRSA(8 mg/L)biofilm inhibition rate of 89％,and the antibacterial effect of ZQNPS combined with cefquinome sulfate showed additive results.The mics of ZQNPs against Gram-posi-tive bacteria(S.aureus)and gram-negative bacteria(E.coli)were 16 mg/L and 8 mg/L,respec-tively.The mics of ZQNPS against E.coli clinical strains were stable between 8 and 16 mg/L.The MIC of Salmonella clinical strains was 32-64 mg/L,and the MIC of S.aureus clinical strains was 8-64 mg/L.Preliminary antibacterial mechanism showed that ZQNPs could destroy the membrane structure of MRSA,lead to the release of intracellular substances,and affect the growth of MRSA.These results indicate that ZQNPs have a good antibacterial effect and have potential application value in antimicrobial therapy.

In order to explore the potential of nanoparticles from ethanol extracts of Euphorbia he-lioscopia L.(ZQNPs)in antibacterial application.In this study,ZQNPs were prepared by the self-assembly method using alcohol extract of Euphorbia helioscopia L.,polylysine and polyethylene glycol 1 000 as raw materials.The morphology and structure of ZQNPs were characterized by transmission electron microscopy,UV-vis spectrophotometer,and Fourier transform infrared spec-troscopy.The growth and biofilm inhibition of ZQNPs against methicillin-resistant Staphylococcus aureus(MRSA)were tested by broth microdilution,crystal violet,and checkerboard assays.The broad-spectrum antibacterial activity and antibacterial activity of ZQNPs against three clinical strains were evaluated by broth microdilution method.Finally,the antibacterial mechanism of ZQNPs was preliminarily explored by morphological observation and soluble protein detection of MRSA.The results showed that ZQNPs were self-assembled and cross-linked multi-faceted spheres with an average diameter of 67 nm.The MIC of ZQNPs against MRSA was 8 mg/L,and the antibacterial effect was much better than that of Euphorbia helioscopia L.mongolicum alcohol extract(MIC＞32 mg/L).The time killing curve again showed that ZQNPS had a good antibacteri-al effect on MRSA(8 mg/L)biofilm inhibition rate of 89％,and the antibacterial effect of ZQNPS combined with cefquinome sulfate showed additive results.The mics of ZQNPs against Gram-posi-tive bacteria(S.aureus)and gram-negative bacteria(E.coli)were 16 mg/L and 8 mg/L,respec-tively.The mics of ZQNPS against E.coli clinical strains were stable between 8 and 16 mg/L.The MIC of Salmonella clinical strains was 32-64 mg/L,and the MIC of S.aureus clinical strains was 8-64 mg/L.Preliminary antibacterial mechanism showed that ZQNPs could destroy the membrane structure of MRSA,lead to the release of intracellular substances,and affect the growth of MRSA.These results indicate that ZQNPs have a good antibacterial effect and have potential application value in antimicrobial therapy.