In vitro effect of DNA topoisomerase inhibitors on Candida albicans.

In this study we investigated the in vitro antifungal activity of 10 DNA topoisomerase inhibitors on the growth of Candida albicans. The EUCAST broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of the compounds for C. albicans. In addition, the effect of the inhibitors on the growth mode of C. albicans was investigated by light microscopy imaging. Of the 10 DNA topoisomerase inhibitors tested, only the anti-cancer drug aclarubicin displayed antifungal activity with a determinable MIC value of 8.4 microg/ml (10.3 microM). Aclarubicin was also active against clinical isolates of C. albicans with MIC values ranging between 0.8 and 7.3 microg/ml (1-9 microM). Vitality assays showed that the action of aclarubicin was fungistatic. Four other DNA topoisomerase inhibitors, daunorubicin, doxorubicin, idarubicin and beta-lapachone, affected the morphology of C. albicans. The first three inhibitors encouraged the fungus to grow predominantly in the yeast form, whereas beta-lapachone caused hyphal proliferation. The results of this study indicate that some DNA topoisomerase inhibitors effect the growth and morphology of C. albicans suggesting a possible role as antifungal agents in the treatment of C. albicans infections.

Noninvasive metabolomic profiling of embryo culture media using Raman and near-infrared spectroscopy correlates with reproductive potential of embryos in women undergoing in vitro fertilization.

OBJECTIVE: To determine if metabolomic profiling of embryo culture media correlates with reproductive potential of individual embryos. DESIGN: Prospective study. SETTING: An academic and a private assisted reproduction program; a university research center. PATIENT(S): Women undergoing assisted reproduction treatment. INTERVENTION(S): Sixty-nine spent media samples from 30 patients with known outcome (0 or 100% sustained implantation rates) were individually collected after embryo transfer on day 3 and were evaluated using Raman and/or near-infrared spectroscopy. The spectra obtained from each instrument were separately analyzed using a wavelength selective genetic algorithm to determine regions predictive of pregnancy outcome. Viability indices reflective of reproductive potential were calculated for each sample. To avoid random correlations, a leave-one-out cross-validation was used. Sensitivity and specificity of predicting viability (described as implantation and delivery) were calculated. MAIN OUTCOME MEASURE(S): Metabolomic profile of culture media and embryo viability. RESULT(S): Viability indices calculated by Raman or near-infrared spectroscopy were higher for embryos that implanted and resulted in a delivery, compared with those that failed to implant. Raman spectroscopy predicted viability of individual embryos with a sensitivity of 86% and a specificity of 76.5%; near-infrared provided a sensitivity of 75% and a specificity of 83.3%. CONCLUSION(S): Rapid, noninvasive metabolomic profiling of human embryo culture media using Raman or near-infrared spectroscopy combined with bioinformatics correlates with pregnancy outcome.

Surface plasmon-quantum dot coupling from arrays of nanoholes.

The coupling of semiconductor quantum dots (QDs) to the surface plasmon (SP) modes of nanohole arrays in a metal film was demonstrated for the first time, showing enhancement in the spontaneous emission by 2 orders of magnitude. The SP-enhanced transmission resonances of the nanohole arrays were tuned around the photoluminescence (PL) peak of polystyrene-b-poly(acrylic acid) (PS-b-PAA)-stabilized cadmium sulfide (CdS) quantum dots (QDs) in contact with the arrays. As a result the overall PL from the SP-QD system was enhanced by 2 orders of magnitude, even after excluding the enhanced transmission of the nanohole array without the QDs. The maximum enhancement occurred when the resonance from the nanohole array matched the QD PL spectrum. Time-resolved PL measurements were used to estimate the relative contribution of different physical mechanisms to the enhanced spontaneous emission. The increased spontaneous emission in the SP-QD system is promising for prospective plasmonic light-emitting devices incorporating QDs.

Enhanced fluorescence from arrays of nanoholes in a gold film.

Arrays of sub-wavelength holes (nanoholes) in gold films were used as a substrate for enhanced fluorescence spectroscopy. Seven arrays of nanoholes with distinct periodicities (distances between the holes) were fabricated. The arrays were then spin-coated with polystyrene films containing different concentrations of the fluorescent dye oxazine 720. The dye was excited via resonant extraordinary transmission of the laser source through the nanoholes. Enhanced fluorescence was observed when the geometric characteristics of the arrays allowed for an enhancement in the transmitted excitation. This enhancement occurred via surface plasmon excitation by the laser and a consequential increase in the local electromagnetic field in a sub-wavelength region at the metal-film interface. It was demonstrated that the sensitivity of the fluorescence measurement (change in signal vs change in dye concentration in the polymer film) is significantly larger at the surface plasmon resonance conditions than that obtained from equivalent films on glass substrates. Enhancement factors for the fluorescence emission were calculated for each array, with a maximum enhancement of close to 2 orders of magnitude as compared to the emission of films on glass. The results presented here indicate that arrays of nanoholes are interesting substrates for the development of fluorescence sensors based on surface plasmon resonance, as they provide a platform that allows both spatial confinement and enhancement of excitation light. Moreover, the collinear characteristics of the present optical setup, due to the resonant extraordinary transmission through the nanohole arrays, are more conducive to miniaturization and chip integration than more traditional experimental geometries.