Upconversion luminescence–infrared absorption nanoprobes for the detection of prostate-specific antigen

Aiming to the ongoing challenge of accurate and sensitive detection for cancer biomarkers, antibody-functionalized NaYF4:Yb3+, Er3+@SiO2 nanorods were developed as upconversion luminescence (UCL)–infrared absorption (IRA) nanoprobes. Benefiting from the shielding effect of the SiO2 shell, an enhanced UCL was achieved. Additionally, an IRA detection signal was introduced by the Si-O-Si bonds of SiO2. Its mutual verification with UCL signal was favorable for ensuring the accuracy of the assay. A UCL-IRA sandwich detection method was established for the detection of the prostate-specific antigen. The UCL intensity at 542 nm and IRA at 1095 cm−1 were chosen for quantitative assay. The method has high sensitivity (0.05 pg mL−1) and selectivity. The range of detection (200 fg mL−1–200 ng mL−1) was singnificantly broadened compared with that of single-readout UCL or IRA detection. The assay performance of human serum samples demonstrated the practicability of the method in clinical cancer diagnosis.