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17 pages, 3685 KiB

Open AccessArticle

In Vivo-In Vitro Comparative Toxicology of Cadmium Sulphide Quantum Dots in the Model Organism Saccharomyces cerevisiae

by Luca Pagano, Marina Caldara, Marco Villani, Andrea Zappettini, Nelson Marmiroli and Marta Marmiroli

Nanomaterials 2019, 9(4), 512; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9040512 - 02 Apr 2019

Cited by 10 | Viewed by 2745

Abstract

The aim of this work was to use the yeast Saccharomyces cerevisiae as a tool for toxicogenomic studies of Engineered Nanomaterials (ENMs) risk assessment, in particular focusing on cadmium based quantum dots (CdS QDs). This model has been exploited for its peculiar features: [...] Read more.

The aim of this work was to use the yeast Saccharomyces cerevisiae as a tool for toxicogenomic studies of Engineered Nanomaterials (ENMs) risk assessment, in particular focusing on cadmium based quantum dots (CdS QDs). This model has been exploited for its peculiar features: a short replication time, growth on both fermentable and oxidizable carbon sources, and for the contextual availability of genome wide information in the form of genetic maps, DNA microarray, and collections of barcoded mutants. The comparison of the whole genome analysis with the microarray experiments (99.9% coverage) and with the phenotypic analysis of 4688 barcoded haploid mutants (80.2% coverage), shed light on the genes involved in the response to CdS QDs, both in vivo and in vitro. The results have clarified the mechanisms involved in the exposure to CdS QDs, and whether these ENMs and Cd²⁺ exploited different pathways of response, in particular related to oxidative stress and to the maintenance of mitochondrial integrity and function. Saccharomyces cerevisiae remains a versatile and robust alternative for organismal toxicological studies, with a high level of heuristic insights into the toxicology of more complex eukaryotes, including mammals. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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14 pages, 2381 KiB

Open AccessArticle

Enhancing Third- and Fifth-Order Nonlinearity via Tunneling in Multiple Quantum Dots

by Si-Cong Tian, Huan-Yu Lu, Hang Zhang, Li-Jie Wang, Shi-Li Shu, Xin Zhang, Guan-Yu Hou, Zi-Ye Wang, Cun-Zhu Tong and Li-Jun Wang

Nanomaterials 2019, 9(3), 423; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9030423 - 12 Mar 2019

Cited by 11 | Viewed by 2580

Abstract

The nonlinearity of semiconductor quantum dots under the condition of low light levels has many important applications. In this study, linear absorption, self-Kerr nonlinearity, fifth-order nonlinearity and cross-Kerr nonlinearity of multiple quantum dots, which are coupled by multiple tunneling, are investigated by using [...] Read more.

The nonlinearity of semiconductor quantum dots under the condition of low light levels has many important applications. In this study, linear absorption, self-Kerr nonlinearity, fifth-order nonlinearity and cross-Kerr nonlinearity of multiple quantum dots, which are coupled by multiple tunneling, are investigated by using the probability amplitude method. It is found that the linear and nonlinear properties of multiple quantum dots can be modified by the tunneling intensity and energy splitting of the system. Most importantly, it is possible to realize enhanced self-Kerr nonlinearity, fifth-order nonlinearity and cross-Kerr nonlinearity with low linear absorption by choosing suitable parameters for the multiple quantum dots. These results have many potential applications in nonlinear optics and quantum information devices using semiconductor quantum dots. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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14 pages, 2659 KiB

Open AccessArticle

Full Counting Statistics of Electrons through Interaction of the Single Quantum Dot System with the Optical Field

by Weici Liu, Faqiang Wang, Zhilie Tang and Ruisheng Liang

Nanomaterials 2019, 9(3), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9030394 - 08 Mar 2019

Cited by 2 | Viewed by 2466

Abstract

In this paper, using the particle-number-resolved master equation, the properties of full counting statistics (FCS) are investigated for a single quantum dot (QD) system interacting with optical fields in the thermal state, Fock state, coherent state, and coherent state with random phase. In [...] Read more.

In this paper, using the particle-number-resolved master equation, the properties of full counting statistics (FCS) are investigated for a single quantum dot (QD) system interacting with optical fields in the thermal state, Fock state, coherent state, and coherent state with random phase. In these diverse quantum states of optical fields, average tunneling currents have different step shoulder heights at a lower bias voltage with the same light intensity, and a staircase-shaped current can be induced unexpectedly in vacuum state optical field. The characteristics of the Fano factor and skewness in the coherent state differ from those in all of the other cases. For avalanche-like transport at a lower bias voltage, the mechanism is a dynamical channel blockade in a moderate electron–photon interaction regime. There is a pronounced negative differential conductance that results from tuning the phase of the coherent state optical field in a symmetric QD system. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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11 pages, 4732 KiB

Open AccessArticle

Photoelectrocatalytic Hydrogen Generation Enabled by CdS Passivated ZnCuInSe Quantum Dot-Sensitized TiO₂ Decorated with Ag Nanoparticles

by Weili Li, Hongchao Geng, Lu Yao, Kesheng Cao, Pengtao Sheng and Qingyun Cai

Nanomaterials 2019, 9(3), 393; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9030393 - 08 Mar 2019

Cited by 10 | Viewed by 3174

Abstract

Here we present the photoelectrocatalytic hydrogen generation properties of CdS passivated ZnCuInSe (ZCISe) quantum dots (QDs) supported by TiO₂ nanowires decorated with Ag nanoparticles. In this configuration, Ag nanoparticles were sandwiched between the photo-electrons collector (TiO₂) and photo-sensitizers (ZCISe), and [...] Read more.

Here we present the photoelectrocatalytic hydrogen generation properties of CdS passivated ZnCuInSe (ZCISe) quantum dots (QDs) supported by TiO₂ nanowires decorated with Ag nanoparticles. In this configuration, Ag nanoparticles were sandwiched between the photo-electrons collector (TiO₂) and photo-sensitizers (ZCISe), and acted as an electron relay speeding up the charge carrier transport. ZCISe and CdS enabled the optical absorption of the photoelectrode ranging from ultraviolet to near infrared region, which significantly enhanced the solar-to-chemical energy conversion efficiency. A photocurrent of 10.5 mA/cm² and a hydrogen production rate of about 52.9 μmol/h were achieved under simulated sunlight (1.5 AG). Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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10 pages, 2074 KiB

Open AccessCommunication

DNA-Based Assembly of Quantum Dots into Dimers and Helices

by Tao Zhang and Tim Liedl

Nanomaterials 2019, 9(3), 339; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9030339 - 02 Mar 2019

Cited by 14 | Viewed by 4537

Abstract

Owing to their unique optical properties, colloidal quantum dots (QDs) have attracted much attention as versatile fluorescent markers with broad biological and physical applications. On the other hand, DNA-based assembly has proven to be a powerful bottom-up approach to create designer nanoscale objects [...] Read more.

Owing to their unique optical properties, colloidal quantum dots (QDs) have attracted much attention as versatile fluorescent markers with broad biological and physical applications. On the other hand, DNA-based assembly has proven to be a powerful bottom-up approach to create designer nanoscale objects and to use these objects for the site-directed arrangement of guest components. To achieve good colloidal stability and accurate positioning of QDs on DNA templates, robust QD surface functionalization is crucial. Here, we present a simple and reliable conjugation method for the direct attachment of DNA molecules to QDs. Phosphorothiolated regions of chimera oligonucleotides are attached and incorporated into a ZnS layer freshly growing in situ on QDs that were rendered water soluble with hydrophilic ligands in a prior step. The reaction can be completed in a 2 mL plastic tube without any special equipment. The utility of these DNA-labeled QDs is demonstrated via prototypical assemblies such as QDs dimers with various spacings and chiral helical architectures. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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9 pages, 2337 KiB

Open AccessArticle

A Novel Fluorescence and SPE Adsorption Nanomaterials of Molecularly Imprinted Polymers Based on Quantum Dot-Grafted Covalent Organic Frameworks for the High Selectivity and Sensitivity Detection of Ferulic Acid

by Yu Wang, Yuzhen Wang and Huilin Liu

Nanomaterials 2019, 9(2), 305; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9020305 - 23 Feb 2019

Cited by 24 | Viewed by 4430

Abstract

A fluorescence and solid phase extraction (SPE) adsorption nanomaterials of molecularly imprinted polymers (MIPs) based on quantum dot-grafted covalent organic frameworks (QD-grafted COFs) was prepared by one-pot surface-imprinting synthesis method. Amino groups of silane reagent were at the surface of QDs to coordinate [...] Read more.

A fluorescence and solid phase extraction (SPE) adsorption nanomaterials of molecularly imprinted polymers (MIPs) based on quantum dot-grafted covalent organic frameworks (QD-grafted COFs) was prepared by one-pot surface-imprinting synthesis method. Amino groups of silane reagent were at the surface of QDs to coordinate COFs efficiently by Schiff-base reactions, providing thermal and chemical stability to MIPs. It also reacted with the phenolic hydroxyl groups of ferulic acid (FA) through non-covalent interactions. The nanomaterials were used as fluorescence sensing and SPE adsorption toward determination of ferulic acid. The MIPs based on QD-grafted COFs had good fluorescence response ability, and quenching linearly at concentrations of ferulic acid from 0.03 to 60 mg kg⁻¹, with a detection limit of 5 µg kg⁻¹. At the same time, it exhibited a good SPE adsorption ability, and the FA extraction was from 1.63 to 3.11 mg kg⁻¹ in grain by-products by SPE coupled with high performance liquid chromatography/mass spectrometry (HPLC/MS). The fluorescence and SPE-HPLC/MS were used for the efficient detection of ferulic acid in real samples with recovery values of 88–114% and 90–97%, respectively. Furthermore, the nanomaterials of MIPs based on QD-grafted COFs were used for FA detection with high sensitivity and selectivity, and it also increased the recycling of waste resources. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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10 pages, 2189 KiB

Open AccessArticle

Quantum Dot Doping-Induced Photoluminescence for Facile, Label-Free, and Sensitive Pyrophosphatase Activity Assay and Inhibitor Screening

by Yishen Tian, Lijie Hao, Chao Wang, Xiaoyan Yang and Shufeng Liu

Nanomaterials 2019, 9(1), 111; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9010111 - 18 Jan 2019

Cited by 6 | Viewed by 3422

Abstract

Development of simple, convenient, and sensitive assay methods for pyrophosphatase (PPase) activity is of importance, for disease diagnosis and drug discovery. Herein, a simple, rapid, label-free, and sensitive fluorescence sensor for PPase activity assay is developed, using Cu²⁺ doping-induced quantum dot (QD) [...] Read more.

Development of simple, convenient, and sensitive assay methods for pyrophosphatase (PPase) activity is of importance, for disease diagnosis and drug discovery. Herein, a simple, rapid, label-free, and sensitive fluorescence sensor for PPase activity assay is developed, using Cu²⁺ doping-induced quantum dot (QD) photoluminescence as a signal reporter. The Cu²⁺ doping of ZnSe QD can induce a dopant-dependent emission response, which will be inhibited after the premixing of Cu²⁺ with pyrophosphate (PPi), to form a Cu²⁺-PPi complex. Then, the hydrolysis of PPi into phosphate (Pi), specifically catalyzed by PPase, liberates the free Cu²⁺ to regain the QD doping for the fluorescence response, which is highly dependent on the PPase activity. The PPase can be sensitively and selectively assayed, with a detection limit of 0.1 mU/mL. The developed sensing strategy can be also employed for the PPase inhibitor screening. Thus, the current QD doping-based sensing strategy offers an efficient and promising avenue for Cu²⁺, PPi, or PPase-related target analysis, and might hold great potential for the further applications in the clinical disease diagnosis. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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14 pages, 991 KiB

Open AccessArticle

Realization of the Kohn’s Theorem in Ge/Si Quantum Dots with Hole Gas: Theory and Experiment

by Hayk A. Sarkisyan, David B. Hayrapetyan, Lyudvig S. Petrosyan, Eduard M. Kazaryan, Anton N. Sofronov, Roman M. Balagula, Dmitry A. Firsov, Leonid E. Vorobjev and Alexander A. Tonkikh

Nanomaterials 2019, 9(1), 56; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9010056 - 03 Jan 2019

Cited by 14 | Viewed by 3144

Abstract

This article discusses specific quantum transitions in a few-particle hole gas, localized in a strongly oblate lens-shaped quantum dot. Based on the adiabatic method, the possibility of realizing the generalized Kohn theorem in such a system is shown. The criteria for the implementation [...] Read more.

This article discusses specific quantum transitions in a few-particle hole gas, localized in a strongly oblate lens-shaped quantum dot. Based on the adiabatic method, the possibility of realizing the generalized Kohn theorem in such a system is shown. The criteria for the implementation of this theorem in a lens-shaped quantum dot, fulfilled in the experiment, is presented. An analytical expression is obtained for the frequencies of resonant absorption of far-infrared radiation by a gas of heavy holes, which depends on the geometric parameters of the quantum dot. The results of experiments on far-infrared absorption in the arrays of p-doped Ge/Si quantum dots grown by molecular beam epitaxy (MBE) with gradually increasing average number of holes in dot are presented. Experimental results show that the Coulomb interaction between the holes does not affect the resonant frequency of the transitions. A good agreement between the theoretical and experimental results is shown. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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10 pages, 3521 KiB

Open AccessArticle

The Recognition of Sweat Latent Fingerprints with Green-Emitting Carbon Dots

by Dan Zhao, Wenting Ma and Xincai Xiao

Nanomaterials 2018, 8(8), 612; https://0-doi-org.brum.beds.ac.uk/10.3390/nano8080612 - 12 Aug 2018

Cited by 29 | Viewed by 5919

Abstract

The recognition of fingerprints has played an extremely important role in criminal investigations, due to its uniqueness. This paper reports on the recognition of sweat latent fingerprints using green-emitting, environment-friendly carbon dots prepared with DL-malic acid and ethylenediamine, and the exploration of impacting [...] Read more.

The recognition of fingerprints has played an extremely important role in criminal investigations, due to its uniqueness. This paper reports on the recognition of sweat latent fingerprints using green-emitting, environment-friendly carbon dots prepared with DL-malic acid and ethylenediamine, and the exploration of impacting factors in the development process of fingerprints. The experiments showed that better fingerprint images could be obtained when the latent fingerprints are developed in green-emitting carbon dots with pH 9 for 30 min, at room temperature. The reported method was also effective for latent fingerprints on a variety of substrates, as well as for those water-immersed ones, where the developed fingerprint remained stable after long-term preservation. Furthermore, the fluorescent three-dimensional fingerprint image could provide direct and simple evidence on pressing habits. The objective of this paper was to present this method. The method may help to narrow the range of suspects during criminal investigations and in forensic science. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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Review

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36 pages, 6854 KiB

Open AccessReview

Optical Properties, Synthesis, and Potential Applications of Cu-Based Ternary or Quaternary Anisotropic Quantum Dots, Polytypic Nanocrystals, and Core/Shell Heterostructures

by Xue Bai, Finn Purcell-Milton and Yuri K. Gun’ko

Nanomaterials 2019, 9(1), 85; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9010085 - 10 Jan 2019

Cited by 72 | Viewed by 12549

Abstract

This review summaries the optical properties, recent progress in synthesis, and a range of applications of luminescent Cu-based ternary or quaternary quantum dots (QDs). We first present the unique optical properties of the Cu-based multicomponent QDs, regarding their emission mechanism, high photoluminescent quantum [...] Read more.

This review summaries the optical properties, recent progress in synthesis, and a range of applications of luminescent Cu-based ternary or quaternary quantum dots (QDs). We first present the unique optical properties of the Cu-based multicomponent QDs, regarding their emission mechanism, high photoluminescent quantum yields (PLQYs), size-dependent bandgap, composition-dependent bandgap, broad emission range, large Stokes’ shift, and long photoluminescent (PL) lifetimes. Huge progress has taken place in this area over the past years, via detailed experimenting and modelling, giving a much more complete understanding of these nanomaterials and enabling the means to control and therefore take full advantage of their important properties. We then fully explore the techniques to prepare the various types of Cu-based ternary or quaternary QDs (including anisotropic nanocrystals (NCs), polytypic NCs, and spherical, nanorod and tetrapod core/shell heterostructures) are introduced in subsequent sections. To date, various strategies have been employed to understand and control the QDs distinct and new morphologies, with the recent development of Cu-based nanorod and tetrapod structure synthesis highlighted. Next, we summarize a series of applications of these luminescent Cu-based anisotropic and core/shell heterostructures, covering luminescent solar concentrators (LSCs), bioimaging and light emitting diodes (LEDs). Finally, we provide perspectives on the overall current status, challenges, and future directions in this field. The confluence of advances in the synthesis, properties, and applications of these Cu-based QDs presents an important opportunity to a wide-range of fields and this piece gives the reader the knowledge to grasp these exciting developments. Full article

(This article belongs to the Special Issue Applications of Quantum Dots)

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