A dual signal amplification photothermal biosensor based on Sn-CDs/NPC and DNA walker for prostate cancer cell...

A target-driven DNA walker photothermal sensor based on Sn-doped carbon dots loaded onto N-doped nanoporous carbon (Sn-CDs/NPC) was constructed for highly sensitive detection of prostate cancer cells LNCaP. Fe₃O₄@Apt/S3 served as a capture unit to specifically recognize and capture Prostate-Specific Membrane Antigen (PSMA)-overexpressing LNCaP cells, releasing the trigger strand S3. Fe₃O₄@S1/S2@Sn-CDs/NPC was designed as a signal unit, where S3 hybridized with S1 and initiated the Exo III-assisted DNA walker cyclic amplification strategy, continuously releasing the photothermal probe Sn-CDs/NPC. Following magnetic separation, the photothermal signals generated by the released Sn-CDs/NPC under 808 nm NIR laser irradiation were positively correlated with the concentration of LNCaP cells. Under optimized conditions, the cell quantification biosensor exhibited a linear range with a detection limit as low as 9 cells/mL, along with excellent selectivity, reproducibility, and storage stability. In spiked real blood and urine samples, the recoveries ranged from 95.2% to 98.6% and 95.5% to 104.8%, respectively. This technology integrates advantages of simple operation, high sensitivity, and low cost, providing a new technical pathway for early liquid biopsy of prostate cancer and holding promise for advancing the clinical translation of precision cancer diagnosis.