An upconversion nanocomposite for fluorescence resonance energy transfer based cholesterol-sensing in human serum

Upconversion nanophosphors (UCNPs) are extremely useful for analytical applications, since they display a high signal-to-noise ratio, and their photobleaching can be ignored. Herein, a novel upconversion nanocomposite composed of beta-cyclodextrin (beta-CD) derivative modified UCNPs and rhodamine B (RB) was prepared for the detection of cholesterol (Cho). The upconversion luminescence (UCL) emission can serve as a Cho-sensing signal by an effective fluorescence resonance energy transfer (FRET) process, using UCNPs as the donor and RB as the quencher. The sensor for Cho detection in human serum shows excellent sensitivity and selectivity, which has the potential for clinical applications in the analysis of other biological and environmental samples.