Due
to its direct effect on biomolecules and cells, electrical
stimulation (ES) is now widely used to regulate cell proliferation,
differentiation, and neurostimulation and is even used in the clinic
for pain relief, treatment of nerve damage, and muscle rehabilitation.
Conventional ES is mostly studied on cell populations, but the heterogeneity
of cancer cells results in the inability to access the response of
individual cells to ES. Therefore, detecting the extracellular pH
change (ΔpHe) after ES at the single-cell level is important
for the application of ES in tumor therapy. In this study, cellular
ΔpHe after periodic impulse electrostimulation (IES) was monitored
in situ by using a polyaniline (PANI)-modified gold microelectrode
array. The PANI sensor had excellent sensitivity (53.68 mV/pH) and
linear correlation coefficient (R2 = 0.999)
over the pH range of 5.55–7.41. The cells showed different
degrees of ΔpHe after the IES with different intervals and stimulation
potential. A shorter pulse interval and a higher stimulation potential
could effectively enhance stimulation and increase cellular ΔpHe.
At 0.5 V potential stimulation, the cellular ΔpHe increased
with decreasing pulse interval. However, if the pulse interval was
long enough, even at a higher potential of 0.7 V, there was no significant
additional ΔpHe due to the insufficient stimulus strength. Based
on the above conclusions, the prepared PANI microelectrode arrays
(MEAs) were capable of stimulating and detecting single cells, which
contributed to the deeper application of ES in tumor therapy.