Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks.

Whispering Gallery Mode (WGM) microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q) factors, WGM resonators can be highly sensitive. A biosensor also needs to be selective, requiring proper functionalization of its surface with the appropriate ligand that will attach the biomolecule of interest.

Differential toxicity of gold-doxorubicin in cancer cells vs. cardiomyocytes as measured by real-time growth assays and fluorescence lifetime imaging microscopy (FLIM).

The kinetics of toxicity of doxorubicin (Dox) and gold nanoparticle-conjugated doxorubicin (Au-Dox) were investigated in cultured B16 melanoma cells and cardiomyocytes using real-time cell-growth imaging. Both bolus exposure and continuous exposure were used. Modeling of the growth curve dynamics suggested patterns of uptake and/or expulsion of the drug that were different for the different cell lines and exposures.

Immobilized phage proteins for specific detection of staphylococci.

Rapid, specific detection of pathogenic bacteria remains a major challenge in infectious disease diagnostics. Bacteriophages can show genus- or even species-level specificity and have been developed for biosensing purposes, but the possibility of using individual phage proteins for detection has not been fully explored. This work exploits the ability of specific phage proteins, the endolysins LysK and Φ11, and the bacteriocin lysostaphin, fixed on silicon wafers to bind staphylococci.

Comparison of cytotoxicity and expression of metal regulatory genes in zebrafish (Danio rerio) liver cells exposed to cadmium sulfate, zinc sulfate and quantum dots.

Recent advances in the ability to manufacture and manipulate materials at the nanometer scale have led to increased production and use of many types of nanoparticles. Quantum dots (QDs) are small, fluorescent nanoparticles composed of a core of semiconductor material (e.g.

Cadmium sulfate and CdTe-quantum dots alter DNA repair in zebrafish (Danio rerio) liver cells.

Increasing use of quantum dots (QDs) makes it necessary to evaluate their toxicological impacts on aquatic organisms, since their contamination of surface water is inevitable. This study compares the genotoxic effects of ionic Cd versus CdTe nanocrystals in zebrafish hepatocytes. After 24h of CdSO4 or CdTe QD exposure, zebrafish liver (ZFL) cells showed a decreased number of viable cells, an accumulation of Cd, an increased formation of reactive oxygen species (ROS), and an induction of DNA strand breaks.

Stability of aminooxy glycosides to glycosidase catalysed hydrolysis.

The stability of the amino(methoxy) beta-glycosidic bond to glycosidase catalysed hydrolysis is reported. Beta-O-benzyl glucose and beta-O-benzyl galactose are substrates hydrolysed by beta-glucosidase and beta-galactosidase from almonds and Escherichia coli, respectively. However their beta-N-benzyl-(O-methoxy)-glucoside and beta-N-benzyl-(O-methoxy)-galactoside derivatives are competitive inhibitors.

InP/ZnS as a safer alternative to CdSe/ZnS core/shell quantum dots: in vitro and in vivo toxicity assessment.

We show that water soluble InP/ZnS core/shell QDs are a safer alternative to CdSe/ZnS QDs for biological applications, by comparing their toxicity in vitro (cell culture) and in vivo (animal model Drosophila). By choosing QDs with comparable physical and chemical properties, we find that cellular uptake and localization are practically identical for these two nanomaterials. Toxicity of CdSe/ZnS QDs appears to be related to the release of poisonous Cd(2+) ions and indeed we show that there is leaching of Cd(2+) ions from the particle core despite the two-layer ZnS shell.

Solubilization and bio-conjugation of quantum dots and bacterial toxicity assays by growth curve and plate count.

Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. QDs have attracted a lot of interest for imaging, diagnostics, and therapy due to their bright, stable fluorescence. QDs can be conjugated to a variety of bio-active molecules for binding to bacteria and mammalian cells.

Comparative cytotoxicity of gold-doxorubicin and InP-doxorubicin conjugates.

Direct comparisons of different types of nanoparticles for drug delivery have seldom been performed. In this study we compare the physical properties and cellular activity of doxorubicin (Dox) conjugates to gold nanoparticles (Au) and InP quantum dots of comparable diameter. Although the Au particles alone are non-toxic and InP is moderately toxic, Au-Dox is more effective than InP-Dox against the Dox-resistant B16 melanoma cell line.

Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation.

Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe.

Antimicrobial activity and cellular toxicity of nanoparticle-polymyxin B conjugates.

We investigate the antimicrobial activity and cytotoxicity to mammalian cells of conjugates of the peptide antibiotic polymyxin B (PMB) to Au nanoparticles and CdTe quantum dots. Au nanoparticles fully covered with PMB are identical in antimicrobial activity to the free drug alone, whereas partially-conjugated Au particles show decreased effectiveness in proportion to the concentration of Au. CdTe-PMB conjugates are more toxic to Escherichia coli than PMB alone, resulting in a flattening of the steep PMB dose-response curve.

Ultrasmall gold-doxorubicin conjugates rapidly kill apoptosis-resistant cancer cells.

Ultrasmall (mean diameter, 2.7 nm) gold nanoparticles conjugated to doxorubicin (Au-Dox) are up to 20-fold more cytotoxic to B16 melanoma cells than the equivalent concentration of doxorubicin alone, and act up to six times more quickly. Ultrasmall Au-Dox enters the cell endocytic vesicles and is also seen free in the cytoplasm and nuclei.

One-pot carbanionic synthesis of P1,P2-diglycosyl, P1,P1,P2-triglycosyl, and P1,P1,P2,P2-tetraribosyl methylenediphosphonates.

Novel lithiated carbanions derived from ethyl glycosyl- and diglycosyl methylphosphonates were used in a direct and convenient synthesis of P1,P2-diglycosyl, P1,P1,P2-triglycosyl, and P1,P1,P2,P2-tetraribosyl methylenediphosphonates involving a one-pot methylidenediphosphonylation of sugars.