Enhanced long-lasting luminescence nanorods for ultrasensitive detection of SARS-CoV-2 N protein

Persistent luminescence nanomaterials can remain luminescence when the light source is turned off, which exhibits promise in biosensor and bioimaging fields since they have the ability to completely eradicate tissue autofluorescence. Although significant progress has been made in the persistent luminescence biosensing, there is still a dearth of long-afterglow detection platform with low limit of detection (LOD) and high sensitivity. Herein, Zn₂GeO₄:Mn, Cr persistently luminescent nanorods (PLNRs) with superior persistent luminescence and long afterglow time were developed. The addition of Cr³⁺ manifestly improves persistent luminescence intensity and afterglow duration through creating a deep defect trap. Then the biosensors were constructed by combining the Zn₂GeO₄:Mn,Cr PLNRs-antibody and Fe₃O₄ magnetic nanoparticles (MNPs)-antibody for nucleocapsid protein detection based on electrostatic attraction. The LOD value for nucleocapsid protein realizes as low as 39.82 ag/mL, which is much lower than the previously reported persistent luminescent-based biosensors. Accordingly, the low detection sensitivity is attributed to fluorescence resonance energy transfer. In addition, high specificity is also achieved. Therefore, the as-prepared Zn₂GeO₄:Mn,Cr persistently luminescent materials can act as the promising candidate in biosensors applications. This strategy provides effective guidance for the development of biosensing platforms with high sensitivity and specificity.