AN OPTICAL SUBMICROMETER CALCIUM SENSOR WITH CONDUCTANCE SENSING CAPABILITY

The identification of chemical species and the measurement of their co ncentrations with high (submicrometer) spatial resolution are of consi derable importance in cell biology. In this article we report the firs t successful development of a greater than or equal to 0.1-mu m Ca2+ s ensor based on a pulled micropipet, filled with a conducting porous so l-gel glass which was doped with the fluorescent calcium green 1 Ca2indicator. Such sensors are potentially capable of measuring Ca2+ conc entrations as low as 10(-8) M, in confined volumes, with a three-dimen sional resolution which exceeds similar to 0.1 mu m. A major advantage of the sensor is its capability to be integrated into a multifunction al probe which will measure chemical analyte concentrations and ion co nductance. (C) 1997 Academic Press