2.5. Detection performance of PEC biosensor
Under the constructed experimental conditions, the potential of the PEC
biosensor to detect Omicron BA.5 was explored by measuring the PEC
response at various cDNA template concentrations. Figure 6C showed that
over a concentration range from from 0 to 1.0 nM, the photocurrent was
monotonically smaller at higher concentrations of the Omicron BA.5 cDNA
template. Furthermore, a strong correlation was found between the change
in photocurrent (∆I, the difference between photocurrent levels with and
without cDNA) and the logarithm of cDNA template concentration
(Figure 6D). The figure
illustrated the linear regression equation as ΔI = 6.27 log [DNA] +
121.06, which exhibited an R2 value of 0.9991. The
error bars in the figure represented the standard deviation σ calculated
from three independent measurements. According to the 3δ/K method, the
estimated detection limit was 2.93×102zM[41,42]. In this case, the standard deviation
was computed based on six measurements of the background signal. In
contrast to previous DNA detection strategies(Table S3), this PEC
biosensor demonstrated a superior lower detection limit and a broader
linear range.