Quantum dots

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Transcript of Quantum dots

Quantum Dots Future Technology

Profundizacin en Qumica Analtica

Quantum Dots as pH Probes for Study of the Enzyme Kinetics

Ala Salem Alnaimat


- What is Quantum Dots (QDs)?- Properties of QDs- Applications of QDs

ObjectiveAdvantages & Disadvantages MethodologyResultsconclusions


What is Quantum Dots (QDs)? QDs are luminescent semiconductor nanocrystals of an approximately 2100 nm ( 10-50 atoms) in diameter.

Properties of QDs: 1- high brightness due to the extinction coefcient2- broad absorption characteristics and a narrow band width in emission spectra.3- Longer uorescence lifetime ranging from 10 - 40 ns compared to the organic dyes.

The Quantum Dot3

Applications of QDs: Computing : increase the performance and storage of computersBiology: Cell labelling, cancer therapy, and lymphocyte immunologyLight emitting devices (LOD): displays industry

Photovoltaic devices: increase the efficiency and reduce the cost of today's typical silicon Photovoltaic cells.Security Tags: can be detected using the night-vision goggles

4Advantages & Disadvantages of QDsAdvantages: water soluble substances. Compared with the traditional analytical methods based organic dyes using QDs as pH probes was found to be a convenient, rapid and specic method for the kinetics studies.

Disadvantages: QDs may be toxic according to its composition which includes some heavy metals, and also the degradation of QDs is still unknown specially inside the living organism.

5ObjectiveQDs were used as pH probe for a reaction kinetic study of the hydrolysis of glycidyl butyrate catalyzed by porcine pancreatic lipase (PPL)


Glycidyl butyrate solutionZnS QDs solutionPhosphate buffer saline ((PBS)

(PPL) Enzyme solution

Incubation at 25C for 1 min.7Results

The uorescence intensity of ZnS QDs linearly decreases with time increasing, which indicates that QDs can be successfully used as pH probes for enzyme reaction kinetic study.Time ( a-j): 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 min8

The effect of The emission spectra of ZnS QDs to different additives. (a) Ultra pure water; (b) methanol; (c) PPL; (d) glycidyl butyrate; (e) glycidol.on the uorescence intensity of QDs is investigatedNo signicant inuence of all these materials on the uorescence intensity of QDs is observed.9conclusionsThe proposed method was found to improve stability, sensitivity and a monitoring range for determination proton concentration as compared to the methods based on the organic dyes.References:Dudu Wua, Zhi Chenb ZnS quantum dots as pH probes for study of enzyme reaction kinetics Enzyme and Microbial Technology 51 (2012) 47 52.

Tan Jun, Wang Bochu, Zhu Liancai Quantum Dots: A novel tool to discovery Pakistan Journal of Biological Science. 9 (5) 917- 922, 2006

1010Muchas Gracias .11