Figure 5: Functional testing of the biosensor in Hank’s buffer
containing 5 mM Ca2+ reveals that the signal can be
amplified by increasing the concentration of calcium ions in the
extracellular medium. The p-value for the difference in normalized
fluorescence between PP-Orco and the control is less than 0.01 when the
VUAA1 concentration is 0.125 mM. The corresponding p-values for the
remaining VUAA1 concentrations are below 0.001.
The sensitivity and signal-to-noise ratio of the biosensor was uniformly
higher when it was exposed to 5 mM Ca2+ and the
TRP-like response was noticeable at all concentrations of VUAA1 that
were tested. This observation confirms that the biosensor’s readout can
be titrated by changing the concentration of Ca2 in
the extracellular medium. A statistically significant difference in
normalized fluorescence between PP-Orco and the control is measurable at
concentrations of VUAA1 as low as 0.125 mM. The p-value for this
statistic is less than 0.01, whereas the p-values for the remaining
VUAA1 concentrations are below 0.001.