SYNTHESIS, PHASE TRANSFER AND SURFACE MODIFICATION OF HYDROPHOBIC QUANTUM DOTS FOR BIOAPPLICATIONS

2013 ◽  
Vol 06 (03) ◽  
pp. 1330003 ◽  
Author(s):  
RUILI ZHANG ◽  
XIAO ZHANG ◽  
XIAOYU LI ◽  
PING YANG
Keyword(s):  
Quantum Dots ◽  
Surface Modification ◽  
Phase Transfer ◽  
Sol Gel ◽  
Water Phase ◽  
Core Shell ◽  
Anisotropic Growth ◽  
Preparation Conditions ◽  
Sol Gel Process ◽  
Preparation Phase

We review the preparation, phase transfer, surface modification and possible bioapplications of hydrophobic CdSe based quantum dots (QDs). CdSe cores with rod and spherical morphologies were prepared through adjusting preparation conditions. The photoluminescence (PL) of the QDs depended strongly on preparation conditions. The QDs were coated with semiconductor shells to improve their PL properties. Anisotropic growth occurred during shell coating. Core/shell QDs revealed tunable PL and high PL efficiencies up to 90%. The phase transfer of QDs from oil phase to water phase was carried out via polymer or a sol–gel process. The silanization of the QDs plays an important role for the sol–gel process. Because of a SiO2 coating, the surface modification of the QDs for bioapplications became easy. After transferring into water phase, the QDs still retained high PL efficiency. Because of their high PL, these biofunctional materials could provide a platform for various applications.

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 Carbon Quantum Dots Encapsulated Molecularly Imprinted Fluorescence Quenching Particles for Sensitive Detection of Zearalenone in Corn Sample

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 438 ◽  
Author(s):  
Manyu Shao ◽  
Ming Yao ◽  
Sarah De Saeger ◽  
Liping Yan ◽  
Suquan Song
Keyword(s):  
Quantum Dots ◽  
Fluorescence Quenching ◽  
Sol Gel ◽  
Carbon Quantum Dots ◽  
Detection Range ◽  
Molecularly Imprinted ◽  
Relative Standard ◽  
Sol Gel Process ◽  
One Step ◽  
Optimized Conditions

An eco-friendly and efficient one-step approach for the synthesis of carbon quantum dots (CDs) that encapsulated molecularly imprinted fluorescence quenching particles (MIFQP) and their application for the determination of zearalenone (ZEA) in a cereal sample are described in this study. CDs with high luminescence were first synthesized, and then encapsulated in the silica-based matrix through a non-hydrolytic sol-gel process. The resulting ZEA-imprinted particles exhibited not only an excellent specific molecular recognition of ZEA, but also good photostability and obvious template binding-induced fluorescence quenching. Under the optimized conditions, the fluorescence intensity of MIFQP was inversely proportional to the concentration of ZEA. By validation, the detection range of these fluorescence quenching materials for ZEA was between 0.02 and 1.0 mg L−1, and the detection limit was 0.02 mg L−1 (S/N = 3). Finally, the MIFQP sensor was successfully applied for ZEA determination in corn with recoveries from 78% to 105% and the relative standard deviation (RSD %) was lower than 20%, which suggests its potential in actual applications.

Synthesis of Hollow Titania Photocatalytic Particles Using Yeast as Templates

2013 ◽  
Vol 699 ◽  
pp. 126-132 ◽  
Author(s):  
Toshiyuki Nomura ◽  
Syota Tanii ◽  
Hayato Tokumoto ◽  
Yasuhiro Konishi
Keyword(s):  
Pore Diameter ◽  
Sol Gel ◽  
Solid Particles ◽  
Core Shell ◽  
Average Pore ◽  
Inorganic Particles ◽  
Sol Gel Process ◽  
Yeast Powder ◽  
Titania Precursor ◽  
Hydrolysis Of

Hollow inorganic particles have attracted considerable interest for a variety of applications. In this work, yeast powder was used as a bio-template to fabricate yeast/titania core-shell spheres. A titania precursor was deposited via the hydrolysis of tetraisopropyl titanate. Triethanolamine was employed to control the reaction rate of the sol-gel process. The hollow titania particles with a diameter of approximately 4 m and a thickness of approximately 54 nm were successfully obtained after calcination of the core-shell spheres at 700 °C. The crystal structure of the particles was anatase. The specific surface area and the average pore diameter were 21.4 m2/g and 1.6 nm, respectively. The photocatalytic activity of the hollow particles was higher compared with that of solid particles.

Photoluminescence of ZnO quantum dots produced by a sol–gel process

2008 ◽  
Vol 30 (8) ◽  
pp. 1233-1239 ◽  
Author(s):  
Debasis Bera ◽  
Lei Qian ◽  
Subir Sabui ◽  
Swadeshmukul Santra ◽  
Paul H. Holloway
Keyword(s):  
Quantum Dots ◽  
Sol Gel ◽  
Sol Gel Process ◽  
Zno Quantum Dots

SiO2 Beads with Quantum Dots: Synthesis and Bioapplication

2011 ◽  
Vol 306-307 ◽  
pp. 16-19
Author(s):  
Ping Yang ◽  
Norio Murase ◽  
Ai Yu Zhang ◽  
Yong Qiang Cao ◽  
Yuan Na Zhu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Self Assembly ◽  
Ligand Exchange ◽  
Colloidal Solution ◽  
Phase Transfer ◽  
Shell Growth ◽  
Sol Gel ◽  
High Brightness ◽  
Potential Use ◽  
Poor Solvent

Aqueous CdTe and organic CdSe/ZnS quantum dots (QDs) were encapsulated into SiO2beads using various controlled sol-gel processes. Ligand exchange is a key to adjust the QD number in each bead and get a high photoluminescence (PL). Namely, partial ligand exchange from thioglycolic acid to 3-mercaptopropyotrimethoxysilane (MPS) on the CdTe QDs enables retention of the initial PL efficiency of the QDs in water, while the simultaneous addition of a poor solvent (ethanol) resulted in regulated assembly of the QDs through condensation of hydrolyzed MPS. SiO2beads thus prepared had, for example, a diameter of 17 nm and contained 3 QDs each. The PL efficiency of these beads was 30%, while the initial PL efficiency was 38% in a colloidal solution. In addition, a method including surface silanization, phase transfer and self-assembly, and SiO2shell growth has been developed to incorporate multiple hydrophobic CdSe/ZnS QDs into SiO2beads where they are well suited for bio-application due to their high brightness, less-cytotoxic, and non-blinking nature. To investigate the potential use for labeling in bio-applications, SiO2beads with multiple QDs were conjugated with IgG using streptavidin-maleimide as linkers. This preparation method is an important step towards fabricating intensely emitting biocompatible SiO2beads impregnated with semiconductor QDs.

Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

2016 ◽  
Vol 16 (4) ◽  
pp. 3914-3920 ◽  
Author(s):  
G. Z Li ◽  
F. H Liu ◽  
Z. S Chu ◽  
D. M Wu ◽  
L. B Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
Spherical Shape ◽  
Core Shell ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

The Preparation of Fluorescent Nano Dye-Silica Particles by Sol-Gel Process

2007 ◽  
Vol 124-126 ◽  
pp. 651-654 ◽  
Author(s):  
Young Joo Na ◽  
Sang Joon Park ◽  
Ji Hyeon Kim ◽  
Jong Sung Kim
Keyword(s):  
Shell Structure ◽  
Sol Gel ◽  
Silica Nanoparticle ◽  
Fluorescent Dye ◽  
Core Shell ◽  
Fluorescent Intensity ◽  
Sol Gel Process ◽  
Fluorescent Spectrum ◽  
Core Shell Structure ◽  
Trimethoxy Silane

The core-shell structure of dye-silica nanoparticle has been prepared. The dye-silica nanoparticle can be used as a substitute of fluorescent dye for bio analysis. The hybrid organicinorganic nanoparticle was prepared by sol-gel process using organic modified silane as the coupling agent for flourescent dye and silica. The size of the particle was about 50 nm, which was measured by DLS and confirmed by SEM photograph. The fluorescent dye (fluorescein-5-maleimide) was reacted with (3-mercaptopropyl) trimethoxy silane to produce dye-silane compound, followed by the sol-gel reaction with tetraethoxysilane(TEOS) and water to produce core-shell structure. The fluorescent spectrum showed that the fluorescent intensity of dye-silica nanoparticle was higher than that of fluorescent dye.

scholarly journals Cotton fabric surface modification for improved UV radiation protection using sol–gel process

2007 ◽  
Vol 104 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Noureddine Abidi ◽  
Eric Hequet ◽  
Sowmitri Tarimala ◽  
Lenore L. Dai
Keyword(s):  
Surface Modification ◽  
Radiation Protection ◽  
Uv Radiation ◽  
Cotton Fabric ◽  
Sol Gel ◽  
Sol Gel Process ◽  
Fabric Surface

Synthesis and Characterization of Ag Nanoparticle, Ag-TiO2 Nanoparticle and Ag-TiO2-Chitosan Complex and Their Application to Antibiosis and Deodorization

2004 ◽  
Vol 820 ◽  
Author(s):  
Young Hwan Kim ◽  
Young Soo Kang
Keyword(s):  
Thermal Decomposition ◽  
Sol Gel ◽  
Oxide Shell ◽  
Synthesis And Characterization ◽  
Core Shell ◽  
Ag Nanoparticle ◽  
Sol Gel Process ◽  
Core Shell Structure ◽  
Silver Core

AbstractAg nanoparticles have been prepared by thermal decomposition of Ag-oleate complex using electric furnace at 300 °C for about 4 hrs. TEM images of the particles showed 2-dimensional assembly of particles with diameter of 8.0 ± 1.3 nm, demonstrating the uniformity of these nanoparticles. Ag-TiO2 nanoparticles were synthesized by sol-gel process and they had core-shell structure. Results showed the formation of the silver core and titanium oxide shell. In this study, we investigated the structure of Ag nanoparticle and Ag-TiO2 nanoparticle and Ag-TiO2-chitosan complex and their functions of antibiosis and deodorization.

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