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.