Yossi Zafrani

Application of Fluorescent Nanocrystals (q-dots) for the Detection of Pathogenic Bacteria by Flow-Cytometry

Fluorescent semiconductor nanocrystals (q-dots) benefit from practical features such as high fluorescence intensity, broad excitation band and emission diameter dependency. These unique spectroscopic characterizations make q-dots excellent candidates for new fluorescent labels in multi-chromatic analysis, such as Flow-Cytometry (FCM). In this work we shall present new possibilities of multi-labeling and multiplex analysis of pathogenic bacteria, by Flow-Cytometry (FCM) analysis and new specific IgG—q-dots conjugates. We have prepared specific conjugates against B. anthracis spores (q-dots585-IgGαB. anthracis and q-dots655-IgGαB.anthracis). These conjugates enabled us to achieve double staining of B. anthracis spores which improve the FCM analysis specificity versus control Bacillus spores. Moreover, multiplexed analysis of B. anthracis spores and Y. pestis bacteria was achieved by using specific antibodies labeled with different q-dots to obtain: q-dots585-IgGαB. anthracis and q-dots655-IgGαY.pestis, each characterized by its own emission peak as a marker. Specific and sensitive multiplex analysis for both pathogens has been achieved, down to 103 bacteria per ml in the sample.

Studies of the Synthesis of Diethyl Cyclopropylphosphonate and Its Thio and Seleno Analogs

Abstract Two methods for the synthesis of unsubstituted diethyl cyclopropylphosphonate are described. One method is a reaction between cyclopropylmagnesium bromide and diethyl chlorophosphite to give diethyl cyclopropylphosphonite, followed by oxidation with sodium periodate to the corresponding phosphonate. Alternatively, diethyl cyclopropylphosphonite was reacted with elemental sulfur or selenium to give the thio and seleno analogs, respectively. The second method involves exclusive 1,3‐elimination of HBr from diethyl 3‐bromopropylphosphonate. This method can be directed to either the 1,2‐ or the 1,3‐elimination reaction, leading to propenylphosphonate or cyclopropylphosphonate, depending on the solvent used.

Degradation of Sulfur Mustard (HD) on KF/Al2O3: The role of Organic Solvents and Active Species

Solvent effects on the ability of KF/Al2O3 supports to degrade the warfare agent sulfur mustard (HD) were explored. RP-KF/Al2O3 possessing hydroxide ions and ECUF/KF/Al2O3 holding fluoride ions were examined. Reactions on RP-KF/Al2O3 containing 10 wt % of organic solvents were faster than those on ECUF/KF/Al2O3. Additionally, RP-KF/Al2O3 led to elimination products, while ECUF/KF/Al2O3 mainly led to substitution derivatives. Enlarging the solvent amounts to 90 wt % resulted in decreased reaction rates. The significance of solvent identity/amount and active species is discussed.