Dual electrochemical genosensor for early diagnosis of prostate cancer through lncRNAs detection

The prostate specific antigen (PSA) test is the gold standard for the screening of prostate cancer (PCa), despite its limited clinical specificity. Long noncoding RNAs are released from the tumor tissue to the urine and show great potential for improving specificity in PCa diagnosis. This work reports on a sandwich-type hybridization assay to detect both the urinary biomarker prostate cancer antigen 3 (PCA3) and an endogenous control, the PSA mRNA. Multiple fluorescein-tagged hybridization assistant probes are used to promote the selective capture of this long noncoding RNA, and sensitivity by incorporating multiple redox enzymes per target molecule, after addition of antifluorescein Fab fragment-peroxidase conjugate. This strategy alleviates the problems associated with the low natural abundance of this marker, its large size, and complex secondary structure. The individual genosensors exhibit good sensitivity (2.48 ± 0.01 μA nM^-1 and 6.4 ± 0.3 μA nM^-1 for PCA3 and PSA, respectively), with wide linear ranges (from 25 pM to 10 nM for PCA3 and 1 nM for PSA), and detection limits in the low picomolar range (4.4 pM and 1.5 pM for PCA3 and PSA, respectively). This analytical performance is retained in the dual configuration without significant cross-talk, despite using the same enzyme label. The usefulness of this dual platform was demonstrated by analyzing RNA extracts from the prostate cancer cell line LNCaP and from urine samples of prostate cancer patients.