Synthesis Of Quantum Dots And Its Application In Biological Detection

Compared to traditional fluorescent nanomaterials, fluorescent nanomaterials have highstrength, excellent light stability, excellent biocompatibility and bio-accurate targeting, so thatin chemical sensors, bio-analysis, testing and other fields has been widely used, andunprecedented attention and attention by researcher. Currently, the most studied, the fastestgrowing nanomaterials is semiconductor quantum dots and carbon materials fluorescentquantum dot. The QDs have significant advantages of higher brightness and stability againstphotobleaching, large absorption cross sections over a broad range of excitation wavelengths,relatively high quantum yield, and a stable surface for further chemical modification. But,almost all semiconductor quantum dots contain Cd, Pb, Hg and other heavy metal ion, so it iscurrent trends to development of novel fluorescent nanomaterials does not contain heavymetals.This dissertation consists of three chapters.Chapter one: Overview of the concept of nanomaterials, the focus is on semiconductorquantum dots, the concept, the nature, characteristics and application of graphene quantumdots.Chapter two: QDs can be excited at a single excitation wavelength, and the twocontrasting colored fluorescence signals can be monitored at the same time without spectraloverlap, we can simultaneous detection of Con A and PNA can be realized by excitingdifferent-colored QDs. Moreover, this approach allows rapid and precise quantitativedetermination of lectins by evaluating changes in fluorescent intensity and semiquantitativedetermination of lectin by digital visualization upon UV lamp illumination as well. Thehigh-affinity, multivalent interaction of lectins with carbohydrate groups on the surface ofQDs results in agglutination and thus the fluorescence decrease of the QD supernatants due tothe formation of numerous noncovalent cross-links between the QDs. Since QDs can beexcited at a single excitation wavelength, two contrasting colored fluorescence signals can bemonitored at the same time without spectra overlap, leading to the simultaneous detection ofCon A and PNA.Chapter third: This section we first synthesized graphene oxide use the improvedHummers, and then synthesis graphene quantum dots (GQDs). Using the horseradishperoxidase activity of graphene quantum dots, we designed simple, fast and accurate methodfor detecting hydrogen peroxide and glucose, this method is simple in principle. Becausegraphene quantum dots have high dispersion, low toxicity, biocompatibility, easy to binding biomolecular, it can be applied in different areas, such as biotechnology, medical diagnosticsand environmental monitoring.