Quantum dots (QDs), as a novel outstanding fluorescent nano-materials, have been widely used in biological analysis and biomedical diagnosis, and have achieved a series of important research progress in the past ten years. In this paper, we review current approaches to the synthesis and functionalization of QDs, and their applications in pathogen detection, bio-chip, bio-molecular interactions, biosensor, cell imaging, gene silence, targeted drug delivery, photodynamic therapy and botanical research. Meanwhile, the prospects and research directions of QDs are given based on the analysis of this research field.

Contents
1 Introduction
2 Quantum Dots
2.1 The Properties of Quantum Dots
2.2 Synthesis of Quantum Dots
2.3 Functional of Modification
3 The Bio-analysis and Medical Diagnostic Applications of Quantum Dots
3.1 Pathogen Detection 3.2 Bio-chip
3.3 Biosensor
3.4 Research of Bio-molecular Interaction and Molecular Conformation
3.5 The Application of Optical Beads
3.6 Cell Imaging
3.7 Gene Silence
3.8 Targeted Drug Delivery
3.9 Photodynamic Therapy
3.10 In Vivo Imaging
3.11 Botanical Research
4 Biological Toxicity
5 Conclusions and Outlook