Preparation and Characterization of Fluorescent CdS Quantum Dots used for the Direct Detection of GST Fusion Proteins

Abstract

Advances in the life sciences are now closely linked to the availability of new experimental tools that allow for the manipulation of biomolecules and the study of biological processes at the molecular level. In this context, we have optimized a synthesis process to obtain glutathione‐capped fluorescent CdS nanoparticles to specifically detect Glutathione S‐Transferase (GST) ‐tagged proteins. Using our method, based on five different heating steps, brightly fluorescent and biocompatible CdS quantum dots of different sizes can be obtained. QD optical behaviour has been evaluated studying both absorbance and fluorescence. For all the samples, the excitonic absorption onset clearly shows a blue shift at 512nm in comparison with that of bulk CdS, due to the quantum confinement effect. At increased average sizes of the nanocrystal, the emission fluorescent band shows a red shift, from 440nm to 540nm. Among different QD solutions, we demonstrate an expansion of the emission range up to ~100 nm, thus improving their features as biomarkers. Moreover we show that optimized glutathionecapped quantum dots can directly bind GST blotted onto polyvinylidene difluoride (PVDF) membranes, and thus are suitable for the direct detection of GST fusion proteins

An advanced conjugation strategy for the preparation of quantum dot-antibody immunoprobes

“…9 Their typical core-shell structure and material composition reect their impressive opto-chemical properties for instance size-tunable emission, excellent signal brightness, and nearly no-photobleaching 8 whereas charged ligands on the surface provide water solubility and biocompatibility. 10 The ability to link QDs with various bioactive molecules without losing the aforementioned characteristics provides wide-eld applications. Quantum dot-based immunochromatographic assays 11,12 or QD-FRET biosensing devices 13 are only two examples of numerous methods using QDs as a signal generating probe.…”

The Energy Levels Splitting Calculated for Electrons in a Double Cd_1-XZn_xs Quantum Dot

“…On the subject of Cd 1-x Zn x S quantum dots (QDs), their technological potentialities have been demonstrated. In this context, we can cite red-light-emitting diodes (LEDs) fabricated using CdSe/Cd 1-x Zn x S quantum dots (QDs) [11], blue liquid laser with an ultralow threshold achieved by engineering unconventional ternary CdZnS/ZnS alloyed-core/shell QDs [12], fluorescent CdS QDs used for the direct detection of fusion proteins [13] and most promising materials in solar cell fabrication [14]. Our actual challenge is to use Cd 1−x Zn x S QDs grown on nominal and vicinal Si surfaces [15][16][17] in order to obtain reliable structures for novel nanotechnological applications such as nanomemories, nanolasers and nanodevices.…”

Light Emitting “Polymer-Nanoparticles” Coatings on Macroporous Silicon Substrates

“…Nanostructures based on semiconductor materials have promising applications including the optoelectronic devices such as light-emitting diodes [3] and next generation of quantum dot solar cells [4]. Moreover, nanoscale semiconductors functionalized with biomolecules are promising as molecular fluorescent probes in biological applications [5]. Deposition of light-emitting nanocrystals on structured silicon substrates will favor development of new waveguide amplifiers and lasers for silicon micro-and nanophotonics.…”