Study on the Photodynamic Efficiency of Sodium Chlorophyllin from Spirulina

[Objectives] This study was conducted to investigate the photodynamic technology(PDT) of water-soluble sodium chlorophyllin extract from Spirulina and its photodynamic sterilization efficiency on Gram bacteria and photodynamic antitumor effect on rat glioma C6 cells. [Methods]The absorption spectrum and fluorescence spectrum of sodium chlorophyllin were measured by an ultraviolet spectrophotometer and a fluorescence spectrophotometer;the plate count method was used to investigate the photodynamic sterilization efficiency of sodium chlorophyllin on Escherichia coli and Staphylococcus aureus;and the MTT method was used to determine the photodynamic antitumor effect of sodium chlorophyllin on rat glioma cell C6. [Results] The sterilization rates of sodium chlorophyllin with the 100 J/cm^2 photodynamic treatment were 98.96% 1.284 and 100% 0 on S. aureus and E. coli, respectively. The half maximal inhibitory concentration(IC50) of the sodium chlorophyllin photodynamic therapy with 5, 10 and 20 J/cm^2 on C6 were 69.9, 48.21 and 47.56 μg/ml respectively, and the dark toxicity was extremely low at 0 J/cm^2. [Conclusions]The photodynamic treatment mediated by the alcohol-extracted sodium chlorophyllin from Spirulina showed excellent inhibitory effects on bacteria and tumor cells. This study initially reveals its excellent photodynamic performance and provides a reference for its in-depth application in the field of photodynamic therapy.

Flow cytometric assessment of the effects of chlorine, chloramine, and UV on bacteria by using nucleic acid stains and 5-cyano-2,3-ditolyltetrazolium chloride

Flow cytometry （FCM） has been widely used in multi-parametric assessment of cells in various research fields, especially in environmental sciences. This study detected the metabolic activity of Escherichia coli and Staphylococcus aureus by using an FCM method based on 5-cyano-2,3-ditolyltetrazolium chloride （CTC）; the accuracy of this method was enhanced by adding SYTO 9 and 10% R2A broth. The disinfection effects of chlorine, chloramine, and UV were subsequently evaluated by FCM methods. Chlorine demonstrated stronger and faster destructive effects on cytomembrane than chloramine, and nucleic acids decomposed afterwards. The metabolic activity of the bacteria persisted after the cytomembmnewas damaged as detected using CTC. Low-pressure （LP） UV or medium-oressure （MP） UV treatments exerted no significant effects on membrane permeability. The metabolic activityof the bacteria decreased with increasing UV dosage, and MP-UV was a stronger inhibitor of metabolic activity than LP-UV. Furthermore, the membrane of Gram-positive S. aureus was more resistant to chlorine/chloramine than that of Gram-negative E. coil In addition, S. aureus showed higher resistance to UV irradiation than E. coli.

Antibacterial Behavior of Laser-Ablated Copper Nanoparticles

Copper nanoparticles（Cu NPs） have been synthesized by using laser ablation method,using deionized water as main solvent.The formation of Cu NPs is confirmed by UV-visible spectrophotometer（UV-Vis）,atomic force microscopy（AFM） and X-ray diffraction（XRD）.Cu NPs fabricated by laser ablation have diameter in the range from 14 to 55 nm.Structural analysis revealed the face-centered cubic（fcc） crystal structure of Cu NPs.The antibacterial activity of Cu NPs has been evaluated in vitro against strains of Escherichia coli（E.coli） and Staphylococcus aureus（5.aureus）.The fabricated Cu NPs show considerable antibacterial activity against both bacterial strains.The bacterial activity of Cu NPs was found to depend on the microbial species.