Urease-coated polydopamine nanomotors as self-propelled biosensors for non-invasive diagnosis: detection of prostate cancer-associated miR-141 in urine

Abstract

Prostate cancer (PCa) is a common health concern among men, and its early and non-invasive diagnosis is of critical importance. In this study, functionalized polydopamine/poly-L-lysine@urease (PDA/PLL@UR) nanomotors were chemically synthesized and employed for the detection of the prostate cancer-specific urinary biomarker miR-141. The catalytic decomposition of urea by urease enables autonomous propulsion of the nanomotors, enhancing the target recognition efficiency. FAM-labeled ssDNA probes were immobilized on the nanomotor surface specifically hybridized with miR-141, resulting in a significant decrease in fluorescence intensity. To further evaluate the diagnostic performance of the new mobile biosensing system, changes in the speed of nanomotors were monitored under an optical microscope. At the same time, the velocity measurements of the nanomotors were performed in PBS (pH 8) under 808 nm NIR irradiation, and the obtained results were compared with the self-propulsion velocities observed in the urea-containing medium. The nanomotors displayed self-propelled motion in urea solution, reaching an average velocity of 3.665 µm s⁻¹ at 150 nM urea concentration. Calibration curves constructed from fluorescence intensity and speed data exhibited strong linear correlations with high coefficients (R² = 0.98 and R² = 0.99), and the corresponding limits of detection (LoD) were calculated as 7.5 pM and 170 pM, respectively. The specificity of the system was assessed using miR-200b and miR-21 as controls, confirming that the nanomotors selectively responded only to miR-141. Overall, the developed PDA/PLL@UR nanomotors offer a novel nanomotor-based biosensing platform for the rapid, sensitive, and non-invasive detection of PCa biomarkers in urine samples. This approach holds considerable promise for future clinical diagnostic applications.