Cellular metabolism is affected by many factors in a cell's environment. Given a sufficiently sensitive method for measuring cellular metabolic rates, it should be possible to detect a wide variety of chemical and physical stimuli. A biosensor has been constructed in which living cells are confined to a flow chamber in which a potentiometric sensor continually measures the rate of production of acidic metabolites. Exploratory studies demonstrate several applications of the device in basic science and technology.

No abstract

A light-addressable potentiometric (silicon) sensor was used in an immunofiltration procedure for the detection of pathogenic bacteria. Yersinia pestis was detected by filtering the cells onto nitrocellulose membranes and then filtering anti-Y. pestis mouse monoclonal antibody and anti-mouse immunoglobulin G-horseradish peroxidase conjugate. For Neisseria meningitidis detection, mouse monoclonal antibody to the major outer membrane protein of this bacterium was coupled directly to horseradish peroxidase. N. meningitidis cell suspensions were filtered onto polycarbonate membranes, and the enzyme conjugate was allowed to react with the filtered bacteria. The presence of both enzyme conjugates was determined potentiometrically with the silicon sensor. The sensitivity of this technique relative to that of an enzyme-linked immunosorbent assay for N. meningitidis was determined. Fewer than 1,000 bacterial cells could be detected with the silicon sensor in a 20-min assay, whereas a 2.5-h enzyme-linked immunosorbent assay with the same antigen and antibody preparations was significantly less sensitive.