Quantum dots (QDs), as novel fluorescent nanomaterials, have been widely used in fluorescent sensing and visual detection with high sensitivity and specificity analysis of target, owing to their excellent optical and electrical properties. The review addresses the surface functionalization of QDs that able to the use of sensing, and discusses different sensing mechanism including fluorescence resonance energy transfer (FRET), electron transfer (CT), direct fluorescent sensing, bioluminescence resonance energy transfer (BRET), chemiluminescence resonance energy transfer (CRET) and electrochemiluminescence (ECL), being applied in the different sensing systems. The challenges and existing problems of QDs fluorescent sensing application are summarized. Meanwhile fluorescent sensing of QDs will develop in the field of the good biocompatibility, real time visualization of sensing in cells or in vivo, multiplexed detection in complex systems and the function of sensing with logic-gate operations in the future.

Contents
1 Introduction
2 Photo-properties of quantum dots
3 Surface chemistry and conjugates of quantum dots
4 Mechanisms and design strategies of quantum dots fluorescence sensing
4.1 Fluorescence resonance energy transfer
4.2 Electron transfer
4.3 Direct fluorescent sensing
4.4 Bioluminescence resonance energy transfer
4.5 Chemiluminescence resonance energy transfer
4.6 Electrochemiluminescence
5 Conclusion