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Nanomaterials
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Current Trends in Colloidal Nanocrystals
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Current Trends in Colloidal Nanocrystals

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (30 November 2015) | Viewed by 48508

Special Issue Editor

Prof. Dr. Marek Osinski

E-Mail Website
Guest Editor
Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, NM 87106-4343, USA
Interests: synthesis and characterization of colloidal nanocrystals; biomedical applications of colloidal nanoparticles; quantum dot imaging and sensing; nanoscintillators for nuclear radiation detection; nanophosphors; solar hydrogen; optoelectronic devices and materials; optoelectronic integrated circuits; memristors; spintronics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Interest in colloidal nanocrystals is fostered by their widespread potential applications in diverse areas, such as electronics, optoelectronics, photovoltaics, nanocomposites, chemical catalysis, environmental science, microscopy, magnetic resonance imaging, biology, medicine, and pharmacology, among others. This diversity of application makes colloidal nanocrystals one of the hottest research topics in the last decade. Novel applications are enabled by the unique properties of nanocrystals, such as the ability to tune their electronic structure and their optical, magnetic, and chemical properties by varying the physical size of the crystal. These unique properties are due to two main reasons: the quantum effects at the nanoscale, and a dramatic increase of the surface to volume ratio.

This Special Issue of Nanomaterials is aimed at covering recent progress in colloidal nanocrystals. Previously unpublished papers are solicited that focus on novel insights and fundamental studies concerning the formation of colloidal nanocrystals, novel methods of controlling nanocrystal morphology, size, phase, composition, and doping, and novel characterization techniques. Special emphasis will be given to new contributions covering the synthesis and characterization of highly monodisperse colloidal nanocrystals fabricated in large volumes.

Prof. Dr. Marek Osiński
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • inorganic nanocrystals
  • colloidal quantum dots
  • synthesis of colloidal nanocrystals
  • characterization of colloidal nanocrystals

Published Papers (7 papers)

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Research

2190 KiB  
Article
Rapid Nanoparticle Synthesis by Magnetic and Microwave Heating
by Viktor Chikan and Emily J. McLaurin
Nanomaterials 2016, 6(5), 85; https://doi.org/10.3390/nano6050085 - 05 May 2016
Cited by 66 | Viewed by 8833
Abstract
Traditional hot-injection (HI) syntheses of colloidal nanoparticles (NPs) allows good separation of the nucleation and growth stages of the reaction, a key limitation in obtaining monodisperse NPs, but with limited scalability. Here, two methods are presented for obtaining NPs via rapid heating: magnetic [...] Read more.
Traditional hot-injection (HI) syntheses of colloidal nanoparticles (NPs) allows good separation of the nucleation and growth stages of the reaction, a key limitation in obtaining monodisperse NPs, but with limited scalability. Here, two methods are presented for obtaining NPs via rapid heating: magnetic and microwave-assisted. Both of these techniques provide improved engineering control over the separation of nucleation and growth stages of nanomaterial synthesis when the reaction is initiated from room temperature. The advantages of these techniques with preliminary data are presented in this prospective article. It is shown here that microwave assisted heating could possibly provide some selectivity in activating the nanomaterial precursor materials, while magnetic heating can produce very tiny particles in a very short time (even on the millisecond timescale), which is important for scalability. The fast magnetic heating also allows for synthesizing larger particles with improved size distribution, therefore impacting, not only the quantity, but the quality of the nanomaterials. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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3888 KiB  
Article
Application of L-Aspartic Acid-Capped ZnS:Mn Colloidal Nanocrystals as a Photosensor for the Detection of Copper (II) Ions in Aqueous Solution
by Jungho Heo and Cheong-Soo Hwang
Nanomaterials 2016, 6(5), 82; https://doi.org/10.3390/nano6050082 - 27 Apr 2016
Cited by 10 | Viewed by 5524
Abstract
Water-dispersible ZnS:Mn nanocrystals (NCs) were synthesized by capping the surface with polar L-aspartic acid (Asp) molecules. The obtained ZnS:Mn-Asp NC product was optically and physically characterized using the corresponding spectroscopic methods. The ultra violet-visible (UV-VIS) absorption spectrum and photoluminescence (PL) emission spectrum of [...] Read more.
Water-dispersible ZnS:Mn nanocrystals (NCs) were synthesized by capping the surface with polar L-aspartic acid (Asp) molecules. The obtained ZnS:Mn-Asp NC product was optically and physically characterized using the corresponding spectroscopic methods. The ultra violet-visible (UV-VIS) absorption spectrum and photoluminescence (PL) emission spectrum of the NCs showed broad peaks at 320 and 590 nm, respectively. The average particle size measured from the obtained high resolution-transmission electron microscopy (HR-TEM) image was 5.25 nm, which was also in accordance with the Debye-Scherrer calculations using the X-ray diffraction (XRD) data. Moreover, the surface charge and degree of aggregation of the ZnS:Mn-Asp NCs were determined by electrophoretic and hydrodynamic light scattering methods, respectively. These results indicated the formation of agglomerates in water with an average size of 19.8 nm, and a negative surface charge (−4.58 mV) in water at ambient temperature. The negatively-charged NCs were applied as a photosensor for the detection of specific cations in aqueous solution. Accordingly, the ZnS:Mn-Asp NCs showed an exclusive luminescence quenching upon addition of copper (II) cations. The kinetic mechanism study on the luminescence quenching of the NCs by the addition of the Cu2+ ions proposed an energy transfer through the ionic binding between the two oppositely-charged ZnS:Mn-Asp NCs and Cu2+ ions. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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3611 KiB  
Article
Colloidal Gold-Mediated Delivery of Bleomycin for Improved Outcome in Chemotherapy
by Celina Yang, Jamie Uertz and Devika B. Chithrani
Nanomaterials 2016, 6(3), 48; https://doi.org/10.3390/nano6030048 - 10 Mar 2016
Cited by 24 | Viewed by 6068
Abstract
Nanoparticles (NPs) can be used to overcome the side effects of poor distribution of anticancer drugs. Among other NPs, colloidal gold nanoparticles (GNPs) offer the possibility of transporting major quantities of drugs due to their large surface-to-volume ratio. This is while confining these [...] Read more.
Nanoparticles (NPs) can be used to overcome the side effects of poor distribution of anticancer drugs. Among other NPs, colloidal gold nanoparticles (GNPs) offer the possibility of transporting major quantities of drugs due to their large surface-to-volume ratio. This is while confining these anticancer drugs as closely as possible to their biological targets through passive and active targeting, thus ensuring limited harmful systemic distribution. In this study, we chose to use bleomycin (BLM) as the anticancer drug due to its limited therapeutic efficiency (harmful side effects). BLM was conjugated onto GNPs through a thiol bond. The effectiveness of the chemotherapeutic drug, BLM, is observed by visualizing DNA double strand breaks and by calculating the survival fraction. The action of the drug (where the drug takes effect) is known to be in the nucleus, and our experiments have shown that some of the GNPs carrying BLM were present in the nucleus. The use of GNPs to deliver BLM increased the delivery and therapeutic efficacy of the drug. Having a better control over delivery of anticancer drugs using GNPs will establish a more successful NP-based platform for a combined therapeutic approach. This is due to the fact that GNPs can also be used as radiation dose enhancers in cancer research. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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3180 KiB  
Article
Energy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications
by Paul C. Stanish and Pavle V. Radovanovic
Nanomaterials 2016, 6(2), 32; https://doi.org/10.3390/nano6020032 - 15 Feb 2016
Cited by 8 | Viewed by 6142
Abstract
Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely [...] Read more.
Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely on a multicomponent approach, which produces sub-optimal quality white light. Here, we report the design and preparation of a colloidal white-light emitting nanocrystal conjugate. This conjugate is obtained by linking colloidal Ga2O3 and II–VI nanocrystals in the solution phase with a short bifunctional organic molecule (thioglycolic acid). The two types of nanocrystals are electronically coupled by Förster resonance energy transfer owing to the short separation between Ga2O3 (energy donor) and core/shell CdSe/CdS (energy acceptor) nanocrystals, and the spectral overlap between the photoluminescence of the donor and the absorption of the acceptor. Using steady state and time-resolved photoluminescence spectroscopies, we quantified the contribution of the energy transfer to the photoluminescence spectral power distribution and the corresponding chromaticity of this nanocrystal conjugate. Quantitative understanding of this new system allows for tuning of the emission color and the design of quasi-single white light emitting inorganic phosphors without the use of rare-earth elements. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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1487 KiB  
Article
Composites of Quasi-Colloidal Layered Double Hydroxide Nanoparticles and Agarose Hydrogels for Chromate Removal
by Gyeong-Hyeon Gwak, Min-Kyu Kim and Jae-Min Oh
Nanomaterials 2016, 6(2), 25; https://doi.org/10.3390/nano6020025 - 26 Jan 2016
Cited by 8 | Viewed by 5081
Abstract
Composite hydrogels were prepared that consisted of quasi-colloidal layered double hydroxide (LDH) nanoparticles and agarose via the electrophoretic method, starting from three different agarose concentrations of 0.5, 1, and 2 wt/v%. The composite hydrogel was identified to have a uniform distribution of LDH [...] Read more.
Composite hydrogels were prepared that consisted of quasi-colloidal layered double hydroxide (LDH) nanoparticles and agarose via the electrophoretic method, starting from three different agarose concentrations of 0.5, 1, and 2 wt/v%. The composite hydrogel was identified to have a uniform distribution of LDH nanoparticles in agarose matrix. Microscopic studies revealed that the composite hydrogel had a homogeneous quasi-colloidal state of LDHs, while the simple mixture of LDH powder and agarose hydrogels did not. It was determined that agarose concentration of the starting hydrogel did not significantly influence the amount of LDH that developed in the composite. The chromate scavenging efficiency of the composite hydrogel and corresponding agarose or mixture hydrogel was evaluated with respect to time, and chromate concentration. In general, the composite hydrogels exhibited much higher chromate removal efficacy compared with agarose or mixture hydrogels. Through estimating chromate adsorption by LDH moiety in the composite or mixture hydrogel, it was suggested that the agarose component facilitated the stability and dispersibility of the quasi-colloidal state of LDH nanoparticles in the composite resulting in high adsorption efficacy. From Freundlich isotherm adsorption fitting, composites were determined to possess beneficial cooperative adsorption behavior with a high adsorption coefficient. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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Graphical abstract

1724 KiB  
Article
White Light-Emitting Diodes Based on AgInS2/ZnS Quantum Dots with Improved Bandwidth in Visible Light Communication
by Cheng Ruan, Yu Zhang, Min Lu, Changyin Ji, Chun Sun, Xiongbin Chen, Hongda Chen, Vicki L. Colvin and William W. Yu
Nanomaterials 2016, 6(1), 13; https://doi.org/10.3390/nano6010013 - 08 Jan 2016
Cited by 54 | Viewed by 10293
Abstract
Quantum dot white light-emitting diodes (QD-WLEDs) were fabricated from green- and red-emitting AgInS2/ZnS core/shell QDs coated on GaN LEDs. Their electroluminescence (EL) spectra were measured at different currents, ranging from 50 mA to 400 mA, and showed good color stability. The [...] Read more.
Quantum dot white light-emitting diodes (QD-WLEDs) were fabricated from green- and red-emitting AgInS2/ZnS core/shell QDs coated on GaN LEDs. Their electroluminescence (EL) spectra were measured at different currents, ranging from 50 mA to 400 mA, and showed good color stability. The modulation bandwidth of previously prepared QD-WLEDs was confirmed to be much wider than that of YAG:Ce phosphor-based WLEDs. These results indicate that the AgInS2/ZnS core/shell QDs are good color-converting materials for WLEDs and they are capable in visible light communication (VLC). Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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1033 KiB  
Article
Surface Properties and Photocatalytic Activities of the Colloidal ZnS:Mn Nanocrystals Prepared at Various pH Conditions
by Jungho Heo and Cheong-Soo Hwang
Nanomaterials 2015, 5(4), 1955-1970; https://doi.org/10.3390/nano5041955 - 11 Nov 2015
Cited by 11 | Viewed by 5914
Abstract
Water-dispersible ZnS:Mn nanocrystals (NC) were synthesized by capping the surface with mercaptoacetic acid (MAA) molecules at three different pH conditions. The obtained ZnS:Mn-MAA NC products were physically and optically characterized by corresponding spectroscopic methods. The UV-Visible absorption spectra and PL emission spectra showed [...] Read more.
Water-dispersible ZnS:Mn nanocrystals (NC) were synthesized by capping the surface with mercaptoacetic acid (MAA) molecules at three different pH conditions. The obtained ZnS:Mn-MAA NC products were physically and optically characterized by corresponding spectroscopic methods. The UV-Visible absorption spectra and PL emission spectra showed broad peaks at 310 and 590 nm, respectively. The average particle sizes measured from the HR-TEM images were 5 nm, which were also supported by the Debye-Scherrer calculations using the X-ray diffraction (XRD) data. Moreover, the surface charges and the degrees of aggregation of the ZnS:Mn-MAA NCs were determined by electrophoretic and hydrodynamic light scattering methods, indicating formation of agglomerates in water with various sizes (50–440 nm) and different surface charge values accordingly the preparation conditions of the NCs (−7.59 to −24.98 mV). Finally, the relative photocatalytic activities of the ZnS:Mn-MAA NCs were evaluated by measuring the degradation rate of methylene blue (MB) molecule in a pseudo first-order reaction condition under the UV-visible light irradiation. As a result, the ZnS:Mn-MAA NC prepared at the pH 7 showed the best photo-degradation efficiency of the MB molecule with the first-order rate constant (kobs) of 2.0 × 10−3·min−1. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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