Abstract: The invention features methods of quantifying cells in a sample by lysing the cells followed by the measurement of at least one intracellular component. Methods of the invention are especially useful for quantifying small numbers of cells, e.g., over a large surface area or volume compared to the cell size. In a preferred embodiment, methods of the invention are performed using a microfluidic device.

Abstract: The invention features methods of quantifying cells in a sample by lysing the cells followed by the measurement of at least one intracellular component. Methods of the invention are especially useful for quantifying small numbers of cells, e.g., over a large surface area or volume compared to the cell size. In a preferred embodiment, methods of the invention are performed using a microfluidic device.

Abstract: Methods are provided for detecting, separating, isolating and quantifying contaminants in starting materials by separating the contaminant from the starting material using a bead coupled to an affinity moiety and quantum dot-labeling the contaminant. The contaminant is detected by the characteristic emission spectrum of the quantum dot. Also, competitive binding methods are provided wherein the starting material and a control material are contacted with a quantum dot coupled to an affinity moiety capable of binding the contaminant and a competitor complex. A decrease in the intensity of the characteristic emission spectrum of the quantum dot associated with the competitor complex from the starting material as compared to that of the control material is indicative of the presence of the contaminant in the starting material.

Abstract: A method for in situ detection of viable pathogenic bacteria in a selective medium by measuring cathodic peak current of oxygen on cyclic voltammograms during bacterial proliferation with an electrochemical voltammetric analyzer. The rapid oxygen consumption at a time during the growth of bacteria resulted in a sharp decline of the cathodic peak current curves. The detection times (threshold values) obtained from the cathodic peak current curve were inversely related to the concentrations of the pathogenic bacteria in the medium. This method for detection of pathogenic bacteria is more sensitive than nucleic acid-based polymerase chain reaction (PCR) methods and any of antibody-based methods such as enzyme-linked immunosorbent assay (ELISA) technology, electrochemical immunoassays, immunosensors, and it has a sensitivity similar to conventional culture methods and impedimetric methods but is more rapid than both of them.

Abstract: A method for in situ detection of viable pathogenic bacteria in a selective medium by measuring cathodic peak current of oxygen on cyclic voltammograms during bacterial proliferation with an electrochemical voltammetric analyzer. The rapid oxygen consumption at a time during the growth of bacteria resulted in a sharp decline of the cathodic peak current curves. The detection times (threshold values) obtained from the cathodic peak current curve were inversely related to the concentrations of the pathogenic bacteria in the medium. This method for detection of pathogenic bacteria is more sensitive than nucleic acid-based polymerase chain reaction (PCR) methods and any of antibody-based methods such as enzyme-linked immunosorbent assay (ELISA) technology, electrochemical immunoassays, immunosensors, and it has a sensitivity similar to conventional culture methods and impedimetric methods but is more rapid than both of them.