Sensitive and high resolution subcutaneous fluorescence in vivoimaging using upconversion nanoparticles and microarrays

A sensitive and high resolution small animal in vivoimaging system using upconversion nanoparticles (UNPs) and microarrays was developed. The fluorescence tomography using UNPs could achieve higher precision than that using ordinary fluorophores, which was theoretically explained by the finite element method (FEM). Given the autofluorescence-insensitive property of UNPs, a high subcutaneous detection sensitivity of 0.93 10 super(-4) wt% could be achieved with a UNP volume of similar to 10 mu L in tissue phantoms. Furthermore, UNP fluorophore microarrays (25, 50 and 100 mu m arrays) embedded under mouse skin were prepared for subcutaneous in vivodetection. An optical clearing method was applied to enhance the skin transparency and improve the spatial resolution. The results demonstrated that the optimized system could achieve a spatial resolution of 50 mu m for in vivodetection of subcutaneous UNP microarrays. Taken together, we conclude that the proposed system and UNP microarrays could achieve sensitive, high resolution subcutaneous in vivodetection, and have great potential for high throughput detection of tumors and other diseases.