Spatially Segregated Electrochemical Sensor for Simultaneous Detection of Prostate-Specific Antigen and Sarcosine with Boosted Clinical Prediction of Early Prostate Cancer

Accurate early screening for prostate cancer (PCa) is critical to clinical decision-making. Simultaneous detection of the independent biomarkers sarcosine (Sar) and prostate-specific antigen (PSA) can improve screening accuracy for PCa through cross-validation. However, co-immobilizing the two detection units on the sensor surface causes close intermingling, leading to mutual interference between PSA and Sar detection, which severely reduces detection sensitivity. To address this issue, we adopted a spatial segregation strategy that allows Sar and PSA to be detected inside the pores and on the external surface of the metal-organic framework (MOF) sensors, respectively. First of all, we screened various MOFs through density functional theory calculations and adsorption experiments and found that MOF-74(Ni) outperformed other MOFs in adsorbing Sar. The nanozyme riboflavin (Rf) encapsulated within MOF-74 pores enables intracavity detection of small Sar molecules by size-sieving and cascade reaction. Concurrently, the ferrocene-labeled peptides (Pep-Fc), which are specifically cleavable by PSA, were immobilized on the surface to detect the large PSA molecules excluded from the pores. Finally, the MOF-74/Rf@Pep-Fc electrochemical sensor was constructed for spatial segregation detection. A series of results from adsorption kinetics and anti-interference experiments confirmed that this design can effectively eliminate the mutual interference between Sar and PSA. The sensor demonstrates a limit of detection of 0.78 fg/mL for Sar and 0.065 fg/mL for PSA. Clinical validation in serum showed that the sensor achieved 100% PCa predictive accuracy for PSA > 20 ng/mL, and in the 4-20 ng/mL range, simultaneous detection raised accuracy from < 50% to > 85%, highlighting its clinical potential.