Biocompatible chitosan-coated ZnS quantum dots [CS-ZnS QDs] and chitosan-coated ZnS:Mn2+ quantum dots [CS-ZnS:Mn2+ QDs] were successfully fabricated via a convenient one-step γ-radiation route. The as-obtained QDs were around 5 nm in diameter with excellent water-solubility. These QDs emitting strong visible blue or orange light under UV excitation were successfully used as labels for PANC-1 ce...

...................................................................................................................... iii CHAPTER 1: BACKGROUND OF QUANTUM DOTS...................................................1 1.1 What Are Quantum Dots ................................................................................1 1.2 Fluorescence and Fluorescence Sensing......................................

We report a synthesis of highly luminescent (CdSe)ZnS composite quantum dots with CdSe cores ranging in diameter from 23 to 55 Å. The narrow photoluminescence (fwhm e 40 nm) from these composite dots spans most of the visible spectrum from blue through red with quantum yields of 30-50% at room temperature. We characterize these materials using a range of optical and structural techniques. Optic...

Luminescent colloidal semiconductor nanocrystals (quantum dots) are robust inorganic fluoro phores that have the potential to circumvent some of the functional limitations encountered by organic dyes in sensing and biotechnological applications. Quantum dots exhibit size-dependent tunable, narrow fluorescence emission spectra that span the visible spectrum and have broad absorption spectra. Thi...

Carbon-based "quantum" dots or carbon dots are surface-functionalized small carbon nanoparticles. For bright fluorescence emissions, the carbon nanoparticles may be surface-doped with an inorganic salt and then the same organic functionalization. In this study, carbon dots without and with the ZnS doping were prepared, followed by gel-column fractionation to harvest dots of 40% and 60% in fluor...

Recently, a new simple method for the purification of CdSe-CdS-ZnS quantum dots by using membrane filtration, the filtration process, successfully separated the oleic acid from quantum dots through membranes purification after synthesis; purification of quantum dots is a very significant part of post synthetical treatment that determines the properties of the material. We explore the possibilit...

Alloyed CdSeS nanocrystals allow tuning between the CdSe and CdS band edges while remaining relatively small. The CdSeS cores also lead to a reduced electron confinement energy and a slower biexciton decay rate compared to CdSe cores of similar sizes. A ZnS shell synthesis procedure allows stable CdSeS/ZnS colloidal quantum dots (QDs) suitable for single dot imaging. These are compared to CdSe/...

A new room-temperature phosphorescence (RTP) mercury ions sensor has been developed based on cetyltrimethylammonium bromide-capped Mn-doped ZnS quantum dots (CTAB/Mn-ZnS QDs) and label-free thymine (T)-rich aptamer. The formed T-Hg(2+)-T dsDNA can linearly quench the RTP of Mn-ZnS QDs through electron transfer and aggregation effect, and give a detection limit of 1.5 nM.

We propose and demonstrate the fabrication of flexible, freestanding films of InP/ZnS quantum dots (QDs) using fatty acid ligands across very large areas (greater than 50 cm × 50 cm), which have been developed for remote phosphor applications in solid-state lighting. Embedded in a poly(methyl methacrylate) matrix, although the formation of stand−alone films using other QDs commonly capped with ...

Recently, quantum dots have been used as molecular probes substituting for conventional organic fluorophores. Quantum dots are stable against photobleaching and have more controllable emission bands, broader absorption spectra, and higher quantum yields. In this study, an array of ZnS-coated CdSe quantum dots on a slide glass has been prepared by photolithographic method. The array pattern was ...