A Shulga | PubMed Health

PubMed2005

Nanoassemblies designed from semiconductor quantum dots and molecular arrays.

The formation of nanoassemblies of CdSe/ZnS quantum dots (QD) and pyridyl-substituted free-base porphyrin (H(2)P) molecules has been spectroscopically identified by static and time-resolved techniques. The formation of nanoassemblies has been engineered by controlling the type and geometry of the H(2)P molecules. Pyridyl functionalization gives rise to a strong complex formation accompanied by QD photoluminescence (PL) quenching. For some of the systems, this quenching is partly related to fluorescence resonance energy transfer (FRET) from the QD to H(2)P and can be explained according to the Förster model. The quantitative interpretation of PL quenching due to complexation reveals that (i) on average only about (1)/(5) of the H(2)P molecules at a given H(2)P/QD molar ratio are assembled on the QD and (ii) only a limited number of "vacancies" accessible for H(2)P attachment exist on the QD surface.

Journal Article↗

PubMed2001

Biosurfactant-rhamnolipid effects on yeast cells.

AIM: The aim of this work was to study the effect of the novel surfactant PS from Pseudomonas sp. S-17 on Saccharomyces cerevisiae 83-20 yeast cells and to compare it with the effect of the well known surfactant Triton X-100. METHODS AND RESULTS: The effect of surfactants was investigated on the cells during growth, and on the separated cells. The cell-permeabilizing effect of surfactants was studied by following the release of protein and some enzyme activities. The biosurfactant did not affect the culture growth kinetics, and altered the polypeptide profiles of cells and membrane proteins in the same way as Triton X-100. CONCLUSION: Results of this study demonstrate that biosurfactant PS and Triton X-100 have a similar type of action, mainly surface located, and that they do not affect the intracellular structures of yeast cells. SIGNIFICANCE AND IMPACT OF THE STUDY: A novel surfactant PS was isolated from Pseudomonas sp. S-17. A mild effect of PS on yeast cells was demonstrated. The results indicate the ecological safety of the biosurfactant and its potential use in the development of environmentally-benign and efficient cleaning technologies.

Cell Membrane Permeability↗