Magnetic Fluorescent Bifunctional Nanoparticles And Skin Fingerprint Detection Applications

Fingerprint is special skin ridge lines form of human (including primates) and typical of genetic traits, it refers to mastoid patterns of the human hand skin surface. Fingerprint as the first of the material vidence has been recognized by the world and widely used in investigation cases. Therefore, the main problem of usi ng fingerprint is finds it on a wide variety of objects at the scene of the crime. Fingerprints left on most subject can be discovered by forensic workers through exploration, research and practice more than a century. However, the existing methods have some limitations for some special object of the fingerprint left. As some violence case often need extracting fingerprint from the victim body. Because of the human skin surface has sweat gland and sebaceous gland. The fingerprint residues were easily contaminat by secretions on skin substance, coupled with the greater scaling of the skin itself. Therefore, the discovered of fingerprint on human skin surface is a major challenge for forensic workers. Magnetic fluorescent bifunetional nanomaterials were prepared using superior performance of magnetic and fluorescence nanomaterials. It was used to detect fingerprint on skin surface.Three chapters are included in this thesis. One chapter is review, mainly introduced the advantage and disadvantage of the existing methods for detecting fingerprint on the skin surface. The basic concepts, character and application of magnetic, fluorescence and magnetic bifunetional nanomaterials were introduced. The second chapter and the third chapter are research reports, and the main contents are as follows:1. Fe3O4magnetic nanoparticles were prepared by coprecipitation. In order to prevent the fluorescence intensity of Fe3O4/SiO2@Gd2O3:Eu, Bi nanoparticle is too low. We made a surface modification to Fe3O4/SiO2nanomaterials. The synthesized of Fe3O4and Fe3O4/SiO2nanomaterials were characterized by SEM and IR respectively.2. Rare earth nitrate for raw materials prepared Gd2O3:Eu, Bi nanoparticle by total precipitation method. Fe3O4/SiO2nanoparticle as a magnetic nuclear prepared Fe3O4/SiO2@Gd2O3:Eu, Bi nanoparticle of shell structure by total precipitation method. The particle has excellent magnetic properties and fluorescence property at the same time with. Application of Fe3O4/SiO2@Gd2O3:Eu, Bi powder for detecting latent fingerprint on skin surface. After detecting, the fingerprint profile is clearly visible and renders some fingerprint ridges.