Spectral Analysis Of Sulfide Quantum Dots And Applications In Biomedicine

Quantum Dots, as known as semiconductor nanocrystal, composed by II-VI or III-V main group element, and the size of it is between 1-10nm. Beause the size of quantum dots is same as Bohr radius and it has a large surface area. The atoms at surface are vastly different that in the particle. Therefore, the surface effects and quantum size effect of nanoparticles have very strong influence on the optical properties and results in the new features different from the body material.In recent years, the unique nature of semiconductor quantum dots has attracted increasing attention in physical, chemistry, materials, biology.The main advantages of quantum dots in biological fluorescent tag areas are using the same light source to obtained multi-channel simultaneously tests. The characteristics of the quantum dots in biology, medicine has broad application prospects. In this paper, the main research will be in the spectral properties of sulfide quantum dots and the biomedical applications. The major results are as follows:1. Apply water co-precipitation at low temperatures, we prepared Mn-doped ZnS quantum dots successfully. XRD, HRTEM and UV absorption spectra measurement showed that diameter of quantum dots is about 5nm. An orange-red emission peaked at 585 nm for ZnS: Mn quantum dots by PL analysis. The results revealed that the the emission originated from the 4T1-6A1transition of Mn2+. The effect of preparation concentration on luminescent properties is also discussed. The peak position of ZnS: Mn was adjusted about 7nm red-shift by core-shell structure.2. We prepared ZnS: Cu quantum dots with 5nm diameter by water co-precipitation. When excited under 301nm, a blue emission peaked at 470nm was obtained. We tried to improved emission intensity through charge compensation and surface modification method. We also adjusted the emission wavelength to 500nm by change the doping concentration.3. PbS quantum dots were synthesized and there is an emission at the 1179 nm near infrared region. The spherical shape 9.5nm in diameter PbS quantum dots was found by transmission electron microscope. The luminescent mechanism and quantum size effect of PbS was also discussed.4.This paper also makes a preliminary explore on quantum dots used in biological cells and drug detection. Apply ZnS: Mn quantum dots on biological imaging, one can see quantum dots have been successful linked with phagocyte and the luminescence of quantum dots not be affected. The completed thioglycolic acid modified ZnS: Mn quantum dots were used in silybin soybean detection. The results showed that absorbance of a derivative differential derived of silybin hybrid has linear relationship with phospholipid concentrations. From equations obtained, we could conclude that coating concentration of phospholipid should not exceed 5%.