Two-Dimensional Microchemical Observation of Mast
Cell Biogenic Amine Release as Monitored by a 128 × 128 Array-Type
Charge-Coupled Device Ion Image Sensor
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Abstract
Available array-type, chemical-sensing
image sensors generally
only provide on/off responses to the sensed chemical and produce qualitative
information. Therefore, there is a need for an array sensor design
that can detect chemical concentration changes to produce quantitative,
event-sensitive information. In this study, a 128 × 128 array-type
image sensor was modified and applied to imaging of biogenic amines
released from stimulated rat mast cells, providing recordable responses
of the time course of their release and diffusion. The imaging tool
was manufactured by an integrated circuit process, including complementary
metal oxide semiconductor and charge-coupled device technology. It
was fitted with an amine-sensitive membrane prepared from plasticized
poly(vinyl chloride) including a hydrophobic anion, which allowed
the sensor to detect amines, such as histamine and serotonin, in Tyrode’s
solution. As mast cells were larger in diameter than the pixel hollows,
some pixels monitored amines released from single cells. The image
from the array responses yielded sequential snapshots at a practical
frame speed that followed amine concentration changes over time, after
mast cell amine release was synchronized by chemical stimulation.
This sensor was shown to be sensitive to amine release at very low
stimulus concentrations and was able to detect localized spots of
high amine release. The entire time course of the amine release was
recorded, including maximum concentration at 4–6 s and signal
disappearance at 30 s after stimulation. With further development,
this sensor will increase opportunities to study a variety of biological
systems, including neuronal chemical processes