Harnessing Energy Enrichment Strategy for Designing Innovative Sandwich-Structured Upconversion Nanoprobes

), the upconversion luminescence (UCL) intensity of the as-prepared SWUCNPs was greatly improved, with the UCL at 540 nm increased by 56 times and the UCL at 655 nm increased by 117 times. In proof-of-concept applications, this innovative structure has been utilized for high-sensitivity detection of ascorbic acid. The strategy reported here opens a novel pathway toward the preparation of highly sensitive upconversion nanoprobes.