Research On The Coupling Of Fluorescent Quantum Dots And Biomolecules

Quantum dots(QDs), also known as semiconductor nanoparticles ,which are a kind of nanomaterials and the diameter are less than 100nm. This nanomateridals have the character of quantum, and the structure and nature have changed from the macroscopy to the microcosmic. Quantum dots is between bulk materials and small molecules, and with with many of the unique characters.In recent years, quantum dots have been widely used in biological and medical fields because of their advantages, and made a great progress. To be compared with the traditional organic dyes, quantum dots are stable and with broad excitation spectra and narrow emission spectra, and can give the light with different colors. Quantum dots can be conjugated to the biological molecular through the surface modifacation, because quantum dots and biological molecular are at the same size range.Fluorescent quantum dots are widely used in targeting and biological tracer due to their florescent light. Currently ,many quantum dots with good characters are made in organic phase, and must be transferred to aqueous phase in order to conjugate to biological moleculars.Synthesis of quantum dots in organic phase is very difficult and toxiferous. Many people are research on synthesis quantum dots in aqueous phase.We synthesis CdTe quantum dots in aqueous phase With MPA as a stabilizer, in order to gain the carboxy group which can conjugate to the molecular on the surface. We gain quantum dot with different sizes and colors, and the XRD shows that it is zinc blende. The fluorescence spectra shows that our quantum dots are very stable, and the fluorescence intensity decrease 8.36% after 30 days at room temperature.BSA is a protein which is widely used in many fields, so we made our quantum dots conjugate to BSA with covalent bond. The spectroscopy and SDS-PAGE show that the BSA is conjugate to quantum dots successfully. The QDs-BSA can be separated from CdTe quantum dots by sephadex G-100. This provides the basis for biological targeting.We investigated the conjugation of CdTe and enzyme. We conjugated CdTe to Alcalase and lipase successfully, and it can be certified by SDS-PAGE and Sephadex G-100. The QDs-Enzyme can be separated from CdTe quantum dots by sephadex G-100. This provides a new method for ELISA tracing.Annexin V is a protein which is on the surface of sensory nerve specifically, and do not reside on the surface of motor nerve. In order to improve the effectiveness of surgical nerve repair operation, we introduce CdTe quantum dots. We conjugated CdTe to Anti-annexin V, so the position will show fluorescence when CdTe-IgG conjugate to Annexin V on the surface of sensory nerve .To sum up, we conjugated CdTe to BSA,Alcalase ane lipase with the mehtod of covalent conjugation and provided the basis of certain experimental for the applications of quantum dot in the field of biology. After that, we conjugate CdTe to Anti-annexin V, laid the foundation for the identification of sensory nerve and motor nerve in the clinical surgery.