Article

Veinot, Jonathan GC; Galloro, Josie; Pugliese, Linda; Bell, Valerie; Pestrin, Robert; Pietro, William J.

doi:10.1139/v98-115

Cited by 14 publications

(18 citation statements)

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“…81 Also, the surface states of smaller particles can be easily stabilized due to a large percentage of atoms on or near the surface as well as a higher curvature and show less PL emission due to the more efficient transfer of electrons to suitable species adsorbed on the surfaces. On the other hand, it has been demonstrated by Fogg et al 82 and Veinot et al 83 that the coordination of electrondonating compounds, such as an amine and phosphine oxide, significantly improves the PL performance of CdS NPs. Therefore, the anionic surfactants are expected to produce CdS NPs with a better PL emission when compared to cationic surfactants.…”

Section: Pl Emissionmentioning

confidence: 98%

The critical role of surfactants towards CdS nanoparticles: synthesis, stability, optical and PL emission properties

2013

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a Cadmium sulfide (CdS) nanoparticles (NPs), prepared by a convenient chemical precipitation method, have been characterized using techniques such as TEM, XRD, zeta potential, absorption and photoluminescence (PL) emission spectroscopy to establish the structure directing role of different cationic and anionic surfactants and their impact on the nanoparticles stabilization. In the synthesis of the CdS NPs, cadmium acetate and sodium sulfide, employed as starting reagents, were dissolved in aqueous solutions of different surfactants to study the effect of their structures on the nucleation, growth, optical and PL emission properties of the NPs. By varying the surfactant species, the CdS NPs have significantly different optical and PL emission properties despite being produced under similar reaction conditions. Depending on the surfactant structure, the growing CdS NPs were stabilized by the surfactants to different extents.For example, in the surfactant with the longest chain length (e.g. cetyltrimethylammonium bromide; CTAB), the CdS NPs were most stable, whereas using a surfactant with a smaller chain length i.e. DTAB, the NPs were unstable for even 1 h. On the other hand, anionic surfactants of even smaller chain lengths were able to stabilize the CdS NPs for quite long times. The generalized study of growth of spherical CdS NPs involves monitoring the kinetics during the progress of the reaction. Additionally, an interesting prominent effect of surfactant structure on the PL emission properties of the NPs has been established under identical reaction conditions.

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Section: Pl Emissionmentioning

confidence: 98%

The critical role of surfactants towards CdS nanoparticles: synthesis, stability, optical and PL emission properties

2013

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“…Since the use of ligand-conjugated QDs as fluorescent biolabeling reagents was reported in 1998 by the groups of Alivisatos [51] and Nie [52], many approaches to QD applications have been realized in the bioanalytical field such as DNA sequencing, tissue immune-diagnostics and single molecular imaging [53][54][55][56][57][58][59][60][61][62][63][64][65][66]. The advantages of QDs as biolabeling agents are (i) tunability of the emission wavelength by changing the particle size, (ii) a sharp and symmetrical emission peak, (iii) the high intensity and long lifetime of the fluorescence and (iv) a wide range of excitation wavelengths.…”

Section: Preparation Of Cds Quantum Dots By Co-precipitation In the Pmentioning

confidence: 99%

“…Several approaches to fluorescence activation based on the confinement of charge carriers within the QD cores have been reported [59][60][61][62]. For example, the coordination of electron-donating compounds such as amines and phosphine oxide significantly increases the fluorescence intensity [63,64]. In the case of QD stabilization by the PAMA homopolymer, the amino groups in the side chain of PAMA were used not only for coordination on the CdS surface but also for solubilization in the aqueous phase.…”

Section: Preparation Of Cds Quantum Dots By Co-precipitation In the Pmentioning

confidence: 99%

Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

Nagasaki

2010

Science and Technology of Advanced Materials

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A poly(ethylene glycol)-b-poly [2-(N,N-dimethylamino)ethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol) (PEG) chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs) were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained had controlled sizes and narrow size distributions. They also showed high dispersion stability owing to the presence of PEG tethering chains on the surface. The same strategy should also be applicable to the fabrication of semiconductor quantum dots and inorganic porous nanoparticles. The preparation of nanoparticles in situ, i.e. in the presence of acetal-PEG-b-PAMA, gave the most densely packed polymer layer on the nanoparticle surface; this was not observed when coating preformed nanoparticles. PEG/polyamine block copolymer was more functional on the metal surface than PEG/polyamine graft copolymer, as confirmed by angle-dependent x-ray photoelectron spectroscopy. We successfully solubilized the C 60 fullerene into aqueous media using acetal-PEG-b-PAMA. A C 60 /acetal-PEG-b-PAMA complex with a size below 5 nm was obtained by dialysis. The preparation and characterization of these materials are described in this review.

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“…Pietro and co-workers reported that certain organic-capped CdSe nanocrystals lost fluorescence upon photoexcitation due to a loss of electrons from the nanocrystals through the organic ligands [4]. Guyot-Sionnest and co-workers have recently described the quenching of band-edge luminescence in organically capped CdSe nanocrystals via the injection of electrons into the nanocrystals using sodium biphenyl [5].…”

Section: Resultsmentioning

confidence: 99%

Quenching Phenomena in Water-Soluble CdSe/ZnS Quantum Dots

et al. 2001

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Semiconductor nanocrystals are expected to play an important role in the development of novel electronic and optoelectronic devices, and have already shown promise in the area of biological reporters for medical screening and sensor applications. We have been involved in developing luminescent CdSe/ZnS core-shell nanocrystals (or quantum dots, QDs) for use in self-assembled structures and as fluorescent reporters in immunoassay-based biodetectors. As part of our efforts to bind semiconductor CdSe/ZnS quantum dots to antibody proteins for our immunoassay work, we functionalized the nanocrystal surfaces with a variety of organic acid salts to impart water solubility to the nanocrystals.During the course of working with these derivatized, water-soluble quantum dots, we observed significant differences in their chemical reactivities and physical characteristics compared to those of underivatized CdSe/ZnS nanocrystals. One of the most striking differences observed is the reactivity of the derivatized and underivatized nanocrystals with stainless steel surfaces. The fluorescence of aqueous mixtures of our water-soluble nanocrystals is immediately quenched upon exposure of the mixtures to stainless steel (SS) surfaces or to chromium oxide, whereas underivatized quantum dots exhibit little or no reactivity at all. As has been reported by several other laboratories, the water-soluble nanocrystals also exhibit significantly lower quantum yields compared to the underivatized nanocrystals. We discuss the unusual reactivity exhibited by these nanocrystals, and suggest possible explanations for their interesting chemical behavior. We also describe methods to prevent the quenching of water-soluble derivatized quantum dots by stainless steel and metal oxides.

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Article

Cited by 14 publications

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The critical role of surfactants towards CdS nanoparticles: synthesis, stability, optical and PL emission properties

The critical role of surfactants towards CdS nanoparticles: synthesis, stability, optical and PL emission properties

Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

Quenching Phenomena in Water-Soluble CdSe/ZnS Quantum Dots

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