Photoluminescence transformation of core/shell CdSe/ZnS quantum dots at the conjugation to biomolecules

2012 ◽  
Vol 1376 ◽  
Author(s):  
T. V. Torchynska ◽  
I. Ch. Ballardo Rodríguez ◽  
Ye. Shcherbyna
Keyword(s):  
Quantum Dots ◽  
High Energy ◽  
Core Shell ◽  
Polymer Interfaces ◽  
Cdse Core ◽  
Exciton Emission ◽  
Pl Spectra ◽  
Pl Spectrum ◽  
The Comparative Study ◽  
Color Emission

AbstractThe paper presents the results of PL spectrum analysis of CdSe/ZnS QDs covered by PEG polymer with and without bioconjugation to bio-molecules .– the Osteopontin antibodies. Commercial CdSe/ZnS QDs used in the study are characterized by the color emission with the maximum at 640 nm (1.96 eV) at 300K. It is shown that PL spectra of nonconjugated QDs can be presented as a superposition of PL bands related to exciton emission in the CdSe core (1.96 eV) and some high energy PL bands (in the spectral range 2.37 .– 3.00 eV). The comparative study of PL spectrum at high (300K) and low (10K) temperatures has testified that high energy PL bands deal with electronhole emission via interface states at the CdSe/ZnS/polymer interfaces.It is revealed that the QD bioconjugation to the anti Osteopontin antibody is accompanied by the change dramatically in PL spectra. Main features of PL spectrum transformstions deal with decreasing the PL intensity of interface related PL bands and the rise of intensity of CdSe core related PL bands. The explanation of mentioned effects has been proposed on the base of re-charging of interface related states at the bioconjugation process.

Micro-Photoluminescence Study of Bio-conjugated CdSe/ZnS Nanocrystals

2013 ◽  
Vol 1617 ◽  
pp. 157-162
Author(s):  
L. Borkovska ◽  
N. Korsunska ◽  
T. Stara ◽  
O. Kolomys ◽  
V. Strelchuk ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Thermal Annealing ◽  
Interleukin 10 ◽  
Half Width ◽  
Core Shell ◽  
Cdse Core ◽  
Photoluminescence Study ◽  
Pl Spectra ◽  
Band Position ◽  
Zns Nanocrystals

ABSTRACTThe effect of bio-conjugation of CdSe/ZnS core-shell quantum dots (QDs) with Interleukin 10 (IL-10) antibodies on the aging of photoluminescence (PL) spectra of the QDs was investigated. The aging occurred upon storage of QDs for about 2 years or thermal annealing at 190 oC for up to 12 hours at atmospheric ambience and consisted in “blue” shifting the PL band position, increasing a PL band half-width and decreasing the PL intensity. The bio-conjugation is found to promote PL aging. The aging upon storage is attributed to the oxidation that decreases the QD core dimension, while the aging upon thermal annealing can be due to both oxidation and alloying of CdSe core and ZnS shell.

Emission variation in CdSe/ZnS quantum dots conjugated to Papilloma virus antibodies

2013 ◽  
Vol 1617 ◽  
pp. 139-144
Author(s):  
Juan A. Jaramillo Gómez ◽  
Tetyana V. Torchynska ◽  
Jose L. Casas Espinola ◽  
Janna Douda
Keyword(s):  
Quantum Dots ◽  
High Energy ◽  
Optical Measurements ◽  
Gaussian Shape ◽  
Excitation Light ◽  
Original Solution ◽  
Papilloma Virus ◽  
Exciton Emission ◽  
Pl Spectra ◽  
The Core

ABSTRACTThe paper presents a comparative study of the photoluminescence (PL) and Raman scattering spectra of core-shell CdSe/ZnS quantum dots (QDs) in nonconjugated states and after the conjugation to the anti-human papilloma virus (HPV), HPV 16-E7, antibodies. All optical measurements are performed on the dried droplets of the original solution of nonconjugated and bioconjugated QDs located on the Si substrate. CdSe/ZnS QDs with emission at 655 nm have been used. PL spectra of nonconjugated QDs are characterized by one Gaussian shape PL band related to the exciton emission in the CdSe core. PL spectra of bioconjugated QDs have changed essentially: the core PL band shifts into the high energy spectral range (“blue” sift) and becomes asymmetric. A set of physical reasons has been proposed for the “blue” shift explanation of the core PL band in bioconjugated QDs. The variation of PL spectra versus excitation light intensities has been studied to analyses the exciton emission via excited states in QDs. Finally the PL spectrum transformation for the core emission in bioconjugated QDs has been attributed to the electronic quantum confined effects stimulated by the electric charges of bioconjugated antibodies.

Resistive Switching in CdTe/CdSe Core–Shell Quantum Dots Embedded Chitosan-Based Memory Devices

2021 ◽  
Author(s):  
Zolile Wiseman Dlamini ◽  
Sreedevi Vallabhapurapu ◽  
Olamide Abiodun Daramola ◽  
Potlaki Foster Tseki ◽  
Rui Werner Macedo Krause ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Resistive Switching ◽  
Core Shell ◽  
Cdse Core ◽  
Active Layers ◽  
Ag Electrodes ◽  
Exponential Decrease ◽  
Conductive Bridge ◽  
Bipolar Memory ◽  
State Resistance

In this paper, we report on the resistive switching (RS) and conduction mechanisms in devices consisting of CdTe/CdSe core–shell quantum dots embedded chitosan composites active layer. Two devices with active layers sandwiched between (1) Al and Ag, and (2) ITO and Ag electrodes were studied. Both devices exhibited bipolar memory behavior with [Formula: see text] V and [Formula: see text][Formula: see text]V, for the Al-based device, while [Formula: see text] V and [Formula: see text][Formula: see text]V were observed for the ITO-based device, enabling both devices to be operated at low powers. However, the switching mechanisms of both devices were different, i.e., RS in Al device was attributed to conductive bridge mechanism, while space-charge-limited driven conduction filament attributed the switching mechanism of the ITO device. Additionally, the Al-based device showed long retention ([Formula: see text][Formula: see text]s) and a reasonable large ([Formula: see text]) ON/OFF ratio. Additionally, for this device, we also observed sweeping cycle-induced reversal of voltage polarity of the [Formula: see text] and [Formula: see text]. In contrast, we observed that increasing sweeping cycles resulted in an exponential decrease of the OFF-state resistance of the ITO-based device.

Photoluminescence properties of CdTe∕CdSe core-shell type-II quantum dots

2006 ◽  
Vol 99 (12) ◽  
pp. 123521 ◽  
Author(s):  
C. H. Wang ◽  
T. T. Chen ◽  
K. W. Tan ◽  
Y. F. Chen ◽  
C. T. Cheng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Type Ii ◽  
Photoluminescence Properties ◽  
Cdse Core ◽  
Shell Type

Effect of Cores on Photoluminescence of Hybrid SiO2-Coated CdTe Quantum Dots

2020 ◽  
Vol 20 (9) ◽  
pp. 5478-5485
Author(s):  
Cong Xie ◽  
Yubin Zhao ◽  
Yuxiang Song ◽  
Yingjie Liu ◽  
Yaya Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Stability ◽  
Sol Gel ◽  
Quantum Yields ◽  
Core Shell ◽  
Aqueous Synthesis ◽  
Pl Spectra ◽  
Cdte Qds ◽  
Sol Gel Process ◽  
20 Nm

Compared with conventional semiconductor quantum dots, hybrid SiO2 coated CdTe QDs exhibited high stability, long fluorescent lifetime, high photoluminescence quantum yields, and well biocompatibility. In this paper, CdTe QDs with tunable PL from green to red emitting were prepared by an aqueous synthesis. A sol–gel process resulted in CdTe QDs coated with a hybrid SiO2 shell contained CdS-like clusters to obtain red-shifted PL spectra, increased PL efficiency and high stability. The clusters were formed by the reaction of Cd2+ and S2− ions generated via the decomposition of thioglycolic acid. The clusters around CdTe cores created a core–shell structure which is very similar with traditional semiconductor core–shell QDs. After being coated with a hybrid SiO2 shell, the PL of green-emitting naked CdTe QDs was red-shifted largely (~30 nm) while the PL of yellowemitting CdTe QDs revealed a small red-shifted (~20 nm). Furthermore, The PL of red-emitting naked CdTe QDs was red-shifted much small (less than 10 nm). This phenomenon is ascribed to the change of band gap of CdTe cores with sizes. The red-shift of PL spectra is attributed to the CdS-like clusters around the core rather than the thickness of the hybrid SiO2 shell.

scholarly journals Thermally induced atomic reconstruction of PbSe/CdSe core/shell quantum dots into PbSe/CdSe bi-hemisphere hetero-nanocrystals

2011 ◽  
Vol 21 (31) ◽  
pp. 11556 ◽  
Author(s):  
Dominika Grodzińska ◽  
Francesca Pietra ◽  
Marijn A. van Huis ◽  
Daniel Vanmaekelbergh ◽  
Celso de Mello Donegá
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Cdse Core ◽  
Thermally Induced

In Situ Synthesis of CdTe/CdSe Core−Shell Quantum Dots

2007 ◽  
Vol 19 (11) ◽  
pp. 2715-2717 ◽  
Author(s):  
Heonjin Seo ◽  
Sang-Wook Kim
Keyword(s):  
Quantum Dots ◽  
In Situ Synthesis ◽  
Core Shell ◽  
Cdse Core
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