SERS-based CRISPR/Cas12a assays for protein biomarker prostate-specific antigen detection.

Sensitive and accurate detection of protein biomarkers is crucial for disease diagnosis, especially for early diagnosis. Here, we describe surface-enhanced Raman scattering (SERS)-based CRISPR/Cas12a assays (S-CRISPR) for protein biomarker detection. Firstly, an S-CRISPR-driven enzyme-linked immunosorbent assay (S-CasLISA) was developed utilizing a capture antibody coated on a microplate to recognize the target and a detection antibody labeled with active DNA to trigger the activity of CRISPR/Cas12a. With this assay, we achieved detection of prostate-specific antigen (PSA) as models at the picogram level. The limit of detection (LoD) of S-CasLISA was 0.17 pg mL and in the range of 0.1 pg mL to 10 ng mL. Further, we applied aptamer to S-CRISPR (S-Apt-CRISPR), combining the high sensitivity of SERS with the high selectivity of aptamers, while simplifying the operation process of CRISPR detection of protein biomarkers. The proposed S-Apt-CRISPR also could detect picogram-level PSA and without repeated washing steps. The LoD of S-Apt-CRISPR was 0.35 pg mL and in the range of 0.1 pg mL to 10 ng mL. Both SERS-based CRISPR/Cas12a assays were validated with clinical samples and demonstrated accuracy consistent with the chemiluminescence immunoassay. The introduction of the CRISPR/Cas12a system with SERS has the effect of improving the analytical capabilities of the system, thereby broadening and facilitating its application in the analysis of sensitive and accurate protein biomarkers.