The Surface Modification Of Quantum Dots And Fingerprint Detection Applications

Fingerprint, is the nipple pattern of human hand skin surface, and it refers to the marks by fingers touching some objects in the judicial work. Because of its unique and lifelong unchanged characteristics, it is a main basis to judge individual identification. So it plays an extremely important role in judicial investigation and case analysis, and it can help testing and punishing crimes suspects when fingerprints were developed well. According to developing principle, current fingerprint developing methods include physical method, chemical method and optical method. However, these methods have some limitations in the application, and the objects are various, so it needs to seek methods to develop fingerprints on different surfaces. And it is also an important task for fingerprinting researchers to study fingerprint developing methods and improve the detection effect.Quantum Dots (QDs) is an important nanometer material. It has a series of excellent physical and chemical properties and fluorescence properties and was widely applied in biology, medicine, etc. Recently, it was gradually applied in fingerprint detection and achieved good effect. Firstly, we synthesized QDs modified by different reagents, then these QDs were applied to detected fingerprints on non-porous surfaces based on their advantages, and we also made some surface modifications to the QDs.Three chapters are included in this thesis. The first chapter is review, mainly introduced the main methods of fingerprint detection and the characteristics of these methods, especially the application of nanometer materials in fingerprint detection was discussed. The second chapter and the third chapter are research reports, and the main contents are as follows:1. CdTe@CdS QDs modified by thioglycolic acid and glutathione was prepared in aqueous solution. The synthesized CdTe@CdS QDs was characterized by transmission electron microscopy, fluorescent spectrometry and uv-vis absorption spectrometry respectively. And we also studied the spectrogram variation of CdTe@CdS QDs in different refluxing time. Finally, we used QDs solution to detect latent fingerprints on non-porous surfaces.2. L-cysteine modified CdTe QDs was prepared in aqueous solution. Then it was centrifugated and dried, and the dried power was used to detect latent fingerprints. Based on the reaction principle of Schiff base, we made a surface modification to CdTe QDs, and as a result, L-cysteine was connected with L-arginine through p-phthalaldehyde. We also examined variation of the fluorescence properties after QDs was modified.