scholarly journals Luminomagnetic Silica-Coated Heterodimers of Core/Shell FePt/Fe3O4 and CdSe Quantum Dots as Potential Biomedical Sensor

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Caio Guilherme Secco de Souza ◽  
João Batista Souza ◽  
Watson Beck ◽  
Laudemir Carlos Varanda
Keyword(s):  
Quantum Dots ◽  
Saturation Magnetization ◽  
Biomedical Applications ◽  
Colloidal Stability ◽  
Silica Coating ◽  
Magnetic Core ◽  
Superparamagnetic Nanoparticles ◽  
Cdse Quantum Dots ◽  
Water Dispersible ◽  
Growth Method

We report the synthesis of a new multifunctional nanomaterial based on silica-coated FePt/Fe3O4-CdSe heteronanostructures, combining luminescent and magnetic properties in a promising bifunctional sensor for biomedical applications. Spherical Fe3O4-coated FePt (FePt/Fe3O4) superparamagnetic nanoparticles (10.8 ± 1.5 nm) with high saturation magnetization and controlled size and shape were obtained using thermal decomposition coupled with seed-mediated growth method. Luminescent property was added to the nanomaterial by using the FePt/Fe3O4 magnetic core as seed and growing the CdSe quantum dots (2.7 ± 0.6 nm) onto its surface in a heterodimer-like structure using the hot-injection approach. The FePt/Fe3O4-CdSe luminomagnetic heteronanostructures were coated with silica shell using the reverse-micelle microemulsion route to avoid solvent-quenching effects. After silica coating, the water-dispersible heteronanostructures showed a diameter of 25.3 ± 2 nm, high colloidal stability, magnetic saturation of around 11 emu g−1, and photoluminescence in the blue-green region, as expected for potential bifunctional platform in biomedical applications. The saturation magnetization of heteronanostructures can be increased to 28 emu g−1 by annealing at 550°C due to the presence of the FePt phase.

A small heterobifunctional ligand provides stable and water dispersible core–shell CdSe/ZnS quantum dots (QDs)

Nanoscale ◽  
2018 ◽  
Vol 10 (42) ◽  
pp. 19720-19732 ◽  
Author(s):  
Gianluca Salerno ◽  
Simona Scarano ◽  
Marianna Mamusa ◽  
Marco Consumi ◽  
Stefano Giuntini ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Colloidal Stability ◽  
Core Shell ◽  
Water Dispersible

A small heterobifunctional ligand provides easy to handle and hydrophilic QDs with enhanced colloidal stability.

White/blue-emitting, water-dispersible CdSe quantum dots prepared by counter ion-induced polymer collapse

2015 ◽  
Vol 47 ◽  
pp. 420-427 ◽  
Author(s):  
Jing Wang ◽  
Jane Betty Goh ◽  
M. Cynthia Goh ◽  
Neeraj Kumar Giri ◽  
Matthew F. Paige
Keyword(s):  
Quantum Dots ◽  
Cdse Quantum Dots ◽  
Water Dispersible ◽  
Polymer Collapse ◽  
Counter Ion

Magneto-Structural and Antimicrobial Properties of Sodium Doped Lanthanum Manganite Magnetic Nanoparticles for Biomedical Applications: Influence of Silica Coating

2018 ◽  
Vol 37 ◽  
pp. 117-127 ◽  
Author(s):  
Cyril O. Ehi-Eromosele ◽  
J.A.O. Olugbuyiro ◽  
A. Edobor-Osoh ◽  
A.A. Adebisi ◽  
O.A. Bamgboye ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Magnetic Nanoparticles ◽  
Structural Properties ◽  
Biomedical Applications ◽  
Colloidal Stability ◽  
Antimicrobial Properties ◽  
Silica Coating ◽  
Coated Sample ◽  
Lanthanum Manganites ◽  
Doped Lanthanum Manganites

Coating of magnetic nanoparticles (MNPs) is usually a requirement prior to their utilization in biomedical applications. However, coating can influence the magneto-structural properties of MNPs thereby imparting their applications. The present work highlights the combustion synthesis of Na-doped lanthanum manganites (LNMO) and the influence of silica coatings on the magneto-structural properties, colloidal stability and antimicrobial properties of LNMO MNPs with their biomedical applications in mind. The crystalline perovskite structure was the same both for the bare and silica coated LNMO samples while there was a slight increase in crystallite size after coating. The FTIR spectral analysis, reduction in agglomeration of the particles and the elemental composition of the coated nanoparticles confirmed the presence of silica. The magnetization values of 34 emu/g and 29 emu/g recorded for bare and coated LNMO samples, respectively show that LNMO MNPs retained its ferromagnetic behaviour after silica coating. The pH dependent zeta potentials of the coated sample is-22.20 mV at pH 7.4 (physiological pH) and-18 mV at pH 5.0 (cell endosomal pH). Generally, silica coating reduced the antibacterial activity of the sample except forBacillussppwhere the antibacterial activity was the same with the bare sample. These results showed that while silica coating had marginal effect on the crystalline structure, size and magnetization of LNMO MNPs, it reduced the antibacterial activity of LNMO MNPs and enhanced greatly the colloidal stability of LNMO nanoparticles. Keywords: Na-doped lanthanum manganites, Silica coating, magnetic nanoparticles, biomedical applications, antimicrobial properties, colloidal stability

scholarly journals Preparation of CdSe Quantum Dots using kinetic growth method

2014 ◽  
Vol 7 (9) ◽  
pp. 41-44
Author(s):  
Mekandan M ◽  
◽  
Senthil Kumar P ◽  
Sarala Ruby ◽  
Ponraj vikaram
Keyword(s):  
Quantum Dots ◽  
Cdse Quantum Dots ◽  
Kinetic Growth ◽  
Growth Method

Colloidal stable quantum dots modified by dual functional group polymers for inkjet printing

2017 ◽  
Vol 5 (19) ◽  
pp. 4629-4635 ◽  
Author(s):  
Ting Han ◽  
Ye Yuan ◽  
Xiao Liang ◽  
Yang Zhang ◽  
Chuanxi Xiong ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Inkjet Printing ◽  
Colloidal Stability ◽  
Functional Group ◽  
Water Dispersible ◽  
Dual Functional ◽  
Stable Quantum

A new ligand was reported to effectively prepare water-dispersible QDs with remarkable colloidal stability for inkjet printing.

scholarly journals Encapsulation of Dual Emitting Giant Quantum Dots in Silica Nanoparticles for Optical Ratiometric Temperature Nanosensors

2020 ◽  
Vol 10 (8) ◽  
pp. 2767 ◽  
Author(s):  
Elisabetta Fanizza ◽  
Haiguang Zhao ◽  
Simona De Zio ◽  
Nicoletta Depalo ◽  
Federico Rosei ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Silica Nanoparticles ◽  
Near Infrared ◽  
Strong Dependence ◽  
Sio2 Nanoparticles ◽  
Silica Coating ◽  
Systematic Investigation ◽  
Dual Emission ◽  
Water Dispersible ◽  
Infrared Spectral

Accurate temperature measurements with a high spatial resolution for application in the biomedical fields demand novel nanosized thermometers with new advanced properties. Here, a water dispersible ratiometric temperature sensor is fabricated by encapsulating in silica nanoparticles, organic capped PbS@CdS@CdS “giant” quantum dots (GQDs), characterized by dual emission in the visible and near infrared spectral range, already assessed as efficient fluorescent nanothermometers. The chemical stability, easy surface functionalization, limited toxicity and transparency of the silica coating represent advantageous features for the realization of a nanoscale heterostructure suitable for temperature sensing. However, the strong dependence of the optical properties on the morphology of the final core–shell nanoparticle requires an accurate control of the encapsulation process. We carried out a systematic investigation of the synthetic conditions to achieve, by the microemulsion method, uniform and single core silica coated GQD (GQD@SiO2) nanoparticles and subsequently recorded temperature-dependent fluorescent spectra in the 281-313 K temperature range, suited for biological systems. The ratiometric response—the ratio between the two integrated PbS and CdS emission bands—is found to monotonically decrease with the temperature, showing a sensitivity comparable to bare GQDs, and thus confirming the effectiveness of the functionalization strategy and the potential of GQD@SiO2 in future biomedical applications.

scholarly journals Laser-induced fluorescence measurements on CdSe quantum dots

2010 ◽  
Vol 4 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Zoltan Győri ◽  
Dávid Tátrai ◽  
Ferenc Sarlós ◽  
Gábor Szabó ◽  
Ákos Kukovecz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Laser System ◽  
Laser Induced Fluorescence ◽  
Growth Time ◽  
Single Shot ◽  
Cdse Quantum Dots ◽  
Time Resolved ◽  
Fluorescence Measurements ◽  
Decay Times ◽  
Growth Method

In this paper, we report on photoluminescence decay measurements on CdSe quantum dots (QDs) as a function of size in the diameter range of 2.1 to 3.5 nm. The nanoparticles were synthesized by the kinetic growth method from CdO and elemental Se precursors. We studied the effects of growth time on the diameter, emission spectrum and the fluorescence lifetime of the synthesized QDs. The decay time measurements were performed using single shot time-resolved laser-induced fluorescence techniques using a Nd:YAG laser system. Two different decay times were measured on each CdSe sample, a fast one and a relatively slow one. The slow decay was found to be size dependent whereas the fast one was independent of the QD diameter. .

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