The Preparation And Applications Of Fluorescent Sensors Based On Water-soluble Quantum Dots

Quantum dots(QDs) have attracted great attention in the past decades due to their unique properties. QDs with the ideal properities, such as narrow, symmetrical and size-tunable emission spectrum, broad excitation spectrum, high photostability,and well biocompatibility, have been employed widely in chemical, biosensing,medicine and electronics field. The study of high selective and sensitive fluorescent biosensor was an important research direction in QDs application. In this article, we have developed a novel ultrasensitive carboxymethyl chitosan-quantum dot-based fluorescence nanosensor for lysozyme detection, a novel aqueous synthesis methods of Zn Te/Zn Se and Mn2+-doped Zn Te/Zn Se Type-II core/shell quantum dots, and the highly sensitive and selective detection of phosphate based Mn2+-doped Zn Te/Zn Se QDs.In chapter 1, we introduced the luminescent property, the synthesis methods, the development of doped-QDs and core/shell QDs.In chapter 2, we developed an ultrasensitive “turn on–off” fluorescence nanosensor with the carboxymethyl chitosan(CMCS) modified QDs for lysozyme detection. The N-acetyl-glucosamine section along the CMCS chains was hydrolyzed by lysozyme resulting the PL quenching. The new analytical method has been employed to detect the concentration of lysozyme in human serum samples successfully.In chapter 3, a novel approaches for the synthesis of Type-II core/shell quantum dots(Zn Te/Zn Se QDs) and Mn2+-doped Type-II core/shell quantum dots(Mn:Zn Te/Zn Se QDs) were studied. Extensive efforts were also made to optimize the synthesis conditions to improve luminescence performance.In chapter 4, we described a highly sensitive detection of phosphate based Mn-doped Zn Te/Zn Se QDs. Mg2+ was found to enhance QDs PL by the passivated surface nonradiative relaxation centers of QDs. The PL intensity were quenched due to the aggregation species of QDs via electrostatic attraction between Pi and Mg2+ on the surface of QDs. Therefore, the amount of Pi can be detected.