Detection of phospholipase A in serum based on LRET mechanism between upconversion nanoparticles and SYBR green I.

Phospholipase A (PLA) may be a vital biomarker for the prediction and diagnosis of some diseases. Consequently, it is of great significance to quantitatively detect PLA in biologic samples. Herein, on the basis of the principle of luminescence resonance energy transfer (LRET) between upconversion nanoparticles (UCNPs) and SYBR Green I (SG), we proposed a technology for the highly sensitive detection of PLA amount. Therein, as an energy receptor, SG will be quantitatively loaded into liposomes firstly. Then, due to the hydrolysis of liposomes under the catalysis of PLA, SG will be released and inserted into the double-stranded DNA (dsDNA) on the surface of UCNPs, which triggers the LRET because of the shortening of effective spatial distance between UCNPs and SG. Under exciting of NIR light, UCNPs emit luminescence at 476 nm, which makes SG emit fluorescence at 522 nm through LRET. Under optimal conditions, the emission intensity ratio (I/I) increased linearly with the PLA amount in the range of 20 U/L to 400 U/L, and the limit of detection (LOD) reached 15 U/L. Here, after comparing with the clinical standard method, it is found that the biosensor is expected to provide a convenient and sensitive assay for the detection of PLA in actual serum samples. Furthermore, such biosensor can also be used to test the inhibitor of PLA.