To evaluate the specificity performance of the proposed PEC platform on CEA sensing, the photocurrent of the fabricated biosensor incubated with different interferents was measured under the same conditions as indicated in Figure 5D. A visibly decreased photocurrent signal with the presence of CEA was obtained and other interfering markers of cancer made no difference on the PEC performance; however, the mixture of CEA, AFP, and H-lgG indicated obvious reduction the same as the presence of CEA, which showed us the proposed sensing platform has excellent specificity for CEA. Here, AFP is linked to cancer.