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. [Figure not available: see fulltext.]