Time-Resolved Förster Resonance Energy Transfer Nanoassay Based on CdTe Quantum Dots for Sensitive Detection of Prostate Cancer Antigen 3.

Prostate Cancer Antigen 3 (PCA3) is a long noncoding RNA highly expressed in prostate cancer cells, making it a promising biomarker for noninvasive prostate cancer diagnosis. Simple and rapid detection using nanoprobes can potentially overcome the limitations of traditional diagnostic techniques. Here, we designed, characterized, and applied a DNA-strand displacement assay based on Förster Resonance Energy Transfer (FRET) between terbium (Tb) ions and semiconductor quantum dots (QDs) as a proof-of-concept for sensitive and specific mix-and-measure quantification of a synthetic DNA analogue of PCA3. The assay utilized QDs synthesized through an aqueous one-pot method. The time-resolved (TR) FRET assays achieved a detection limit of 0.65 nmol L-1 by using a SPARK benchtop fluorescence plate reader and 0.32 nmol L-1 by using a KRYPTOR Compact PLUS clinical plate reader. Despite slightly decreased performance, the TR-FRET nanoassay demonstrated reliable quantification of nanomolar PCA3 concentrations also in samples containing up to 50% of serum. These findings underscore the potential of Tb-to-QD FRET assays for rapid clinical prostate cancer diagnostics, offering a promising tool for the early detection of PCA3 in a noninvasive manner.