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Quantum dot

Jing-Hui Zhang, Tai Sun, Aping Niu, Yu-Mei Tang, Shun Deng, Wei Luo, Qun Xu, Dapeng Wei, De-Sheng Pei
Graphene quantum dots (GQDs) has been widely used in enormous fields, however, the inherent molecular mechanism of GQDs for potential risks in biological system is still elusive to date. In this study, the outstanding reduced graphene quantum dots (rGOQDs) with the QY as high as 24.62% were successfully synthesized by the improved Hummers method and DMF hydrothermal treatment approach. The rGOQDs were N-doped photoluminescent nanomaterials with functional groups on the surface. The fluorescent bio-imaging was performed by exposing zebrafish in different concentrations of the as-prepared rGOQDs, and the distribution of rGOQDs was successfully observed...
April 15, 2017: Biomaterials
Haiyan Wang, Qihai Zhang, Huanshun Yin, Minghui Wang, Wenjing Jiang, Shiyun Ai
N(6)-methyladenosine (m(6)A) is an enigmatic and abundant internal modification in eukaryotic messenger RNA (mRNA), which could affect various aspects of RNA metabolism and mRNA translation. Herein, a novel photoelectrochemical (PEC) immunosensor was constructed for m(6)A detection based on the inhibition of Cu(2+) to the photoactivity of g-C3N4/CdS quantum dots (g-C3N4/CdS) heterojunction, where g-C3N4/CdS heterojunction was used as photoactive material, anti-m(6)A antibody as recognition unit for m(6)A-containing RNA, Phos-tag-biotin as link unit and avidin functionalized CuO as PEC signal indicator...
April 12, 2017: Biosensors & Bioelectronics
Li Li, Dehui Yin, Kun Xu, Yushen Liu, Dandan Song, Juan Wang, Chao Zhao, Xiuling Song, Juan Li
Brucellosis is a serious zoonosis with a rapid increase in incidence across epidemic regions. Currently, there are numerous methods for diagnosing brucellosis. However, these studies often have a few defects, such as low sensitivity, poor specificity, time consuming, laborious, and even potential biological risk. To overcome these shortcomings, we have developed a rapid, sensitive and accurate diagnosis procedure for brucellosis based on the immune magnetic beads (IMB) probe and quantum dots (QDs) - staphylococcal protein A (SPA) probe...
April 6, 2017: Journal of Pharmaceutical and Biomedical Analysis
Yuan Guo, Xiaoqing Zeng, Haiyan Yuan, Yunmei Huang, Yanmei Zhao, Huan Wu, Jidong Yang
In this study, a novel method for chiral recognition of phenylglycinol (PG) enantiomers was proposed. Firstly, water-soluble N-acetyl-l-cysteine (NALC)-capped CdTe quantum dots (QDs) were synthesized and experiment showed that the fluorescence intensity of the reaction system slightly enhancement when added PG enantiomers to NALC-capped CdTe quantum dots (QDs), but the R-PG and S-PG could not be distinguished. Secondly, when there was Ag(+) presence in the reaction system, the experiment result was extremely interesting, the PG enantiomers cloud make NALC-capped CdTe QDs produce different fluorescence signal, in which the fluorescence of S-PG+Ag(+)+NALC-CdTe system was significantly enhanced, and the fluorescence of R-PG+Ag(+)+NALC-CdTe system was markedly decreased...
April 18, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Kunmeng Li, Chunhui Xia, Baiqi Wang, Hetao Chen, Tong Wang, Qian He, Hailong Cao, Yu Wang
Liver cancer (LC) is a serious disease that threatens human lives. LC has a high recurrence rate and poor prognosis. LC stem cells (LCSCs) play critical roles in these processes. However, the mechanism remains unclear. Reactive oxygen species (ROS) can be used to determine cell apoptosis and proliferation. However, studies of the effects of exogenous nanomaterials on LCSC ROS changes are rarely reported. In this work, quantum dots (QDs) were prepared using a hydrothermal method, and QDs were further modified with polyethylene glycol (PEG) and bovine serum albumin (BSA) using a chemical approach...
April 12, 2017: Colloids and Surfaces. B, Biointerfaces
Qianglu Lin, Hyeong Jin Yun, Wenyong Liu, Hyung-Jun Song, Nikolay S Makarov, Oleksandr Isaienko, Tom Nakotte, Gen Chen, Hongmei Luo, Victor I Klimov, Jeffrey M Pietryga
The use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic devices typically requires post-synthetic chemical surface treatments to enhance electronic coupling between QDs and allow for efficient charge transport in QD films. Despite their importance to solar cells, and infrared (IR) light-emitting diodes and photodetectors, advances in these chemical treatments for lead chalcogenide (PbE, E = S, Se, Te) QDs have lagged behind those of, for instance, II-VI semiconductor QDs. Here, we introduce a method for fast and effective ligand exchange for PbE QDs in solution, resulting in QDs completely passivated by a wide range of small anionic ligands...
April 21, 2017: Journal of the American Chemical Society
G Krishnamurthy Grandhi, Ranjani Viswanatha
The success of heterostructure quantum dots in optoelectronic and photovoltaic applications is based on our understanding of photo-generated charge carrier localization. However, often the actual location of charge carriers in heterostructure semiconductors is quite different from their predicted positions leading to sub-optimal results. In this work, photoluminescence of Cu doped heterostructures have been used to study the charge localization of alloys, inverse type I, type II and quasi type II core/shell structures and graded alloys...
April 21, 2017: Journal of Physical Chemistry Letters
Meng-Lin Tsai, Dung-Sheng Tsai, Libin Tang, Lih-Juann Chen, Shu Ping Lau, Jr-Hau He
Despite great improvements in traditional inorganic photodetectors and photovoltaics, more progress is needed in the detection/collection of light at low-level conditions. Traditional photodetectors tend to suffer from high noise when operated at room temperature; therefore these devices require additional cooling systems to detect weak or dim light. Conventional solar cells also face the challenge of poor light-harvesting capabilities in hazy or cloudy weather. The real world features such varying levels of light, which makes it important to develop strategies that allow optical devices to function when conditions are less than optimal...
April 21, 2017: ACS Nano
Yan Li, Sen Li, Yingmin Wang, Jun Wang, Hui Liu, Xinqian Liu, Lifeng Wang, Xiaoguang Liu, Wendong Xue, Ning Ma
In this work, phosphorus-doped graphene quantum dots (P-GQDs) with a high phosphorus doping content (>7 at%) are synthesized via an electrochemical approach. Sodium phytate (C6H6Na12O24P6), a green food antioxidant additive, is used as the electrolyte for providing both a phosphorus source and an electrolysis environment. The obtained P-GQDs exhibit excellent scavenging activity of free radicals, such as hydroxyl radicals (˙OH) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Combined with Raman, FT-IR, and XPS spectral analyses, the reason for high phosphorus content and the mechanism of free radical scavenging of P-GQDs are investigated in our work...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
Seyed Mohsen Izadyar, Mohammad Razaghi, Abdollah Hassanzadeh
In this paper, a theoretical model for a quantum dot semiconductor optical amplifier (QDSOA) is proposed. The dynamics of carriers in ground, excited, and continuum states and wetting layer are considered in this model. The effects of the second excited state (ES2) inclusion are investigated for the first time, to the best of our knowledge, in the proposed QDSOA model. Moreover, the inhomogeneous broadening effect due to size distribution of dots, and the homogeneous broadening effect of a single dot in the gain spectrum by grouping of dots based on their optical resonant frequency, are included in the model...
April 20, 2017: Applied Optics
Samadhan P Pawar, Laxman S Walekar, Dattatray B Gunjal, Dattatray K Dalavi, Anil H Gore, Prashant V Anbhule, Shivajirao R Patil, Govind B Kolekar
We here for the first time demonstrate an analytical approach for the highly selective and sensitive detection of amoxicillin (Amox) in aqueous medium based on the fluorescence quenching of quantum dots (QDs). The change in fluorescence intensity of mercaptopropionic acid-capped cadmium sulphide (MPA-CdS) QDs is attributed to the increasing concentration of Amox. The results show that the fluorescence quenching of QDs by Amox takes place through both static and dynamic types of quenching mechanism. The fluorescence quenching of QDs with increase in concentration of Amox shows the linear range between 5 μg ml(-1) and 30 μg ml(-1) and the limit of detection (LOD) is 5...
April 21, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
Xu-Bing Li, Yu-Ji Gao, Hao-Lin Wu, Yang Wang, Qing Guo, Mao-Yong Huang, Bin Chen, Chen-Ho Tung, Li-Zhu Wu
Due to their enhanced light harvesting, favored interfacial charge transfer and excellent proton reduction activity, hybrid photocatalysts of metallic 1T-MoS2 nanosheets and inorganic-ligand stabilized CdSe/ZnS QDs obtained via a self-assembly approach can produce H2 gas with a rate of ∼155 ± 3.5 μmol h(-1) mg(-1) under visible-light irradiation (λ = 410 nm), the most exceptional performance of solar H2 evolution using MoS2 as a cocatalyst known to date.
April 21, 2017: Chemical Communications: Chem Comm
Ruslan Álvarez-Diduk, Jahir Orozco, Arben Merkoçi
Simple, inexpensive and rapid sensing systems are very demanded for a myriad of uses. Intrinsic properties of emerging paper-based analytical devices have demonstrated considerable potential to fulfill such demand. This work reports an easy-to-use, low cost, and disposable paper-based sensing device for rapid chemical screening with a smartphone readout. The device comprises luminescent graphene quantum dots (GQDs) sensing probes embedded into a nitrocellulose matrix where the resonance energy transfer phenomenon seems to be the sensing mechanism...
April 20, 2017: Scientific Reports
Yuqing Dong, Guorui Jin, Changchun Ji, Rongyan He, Min Lin, Xin Zhao, Ang Li, Tian Jian Lu, Feng Xu
Tracking the distribution and degradation of hydrogels in vivo is important for various applications including tissue engineering and drug delivery. Among various imaging modalities, fluorescence imaging has attracted intensive attention due to their high sensitivity, low cost and easy operation. Particularly, upconversion nanoparticles (UCNPs) that emit visible lights upon near-infrared (NIR) light excitation as tracking probes are promising in deciphering the fate of hydrogels after transplantation. Herein, we reported a facile and non-invasive in vivo hydrogel tracking method using UCNPs, where the degradation of hydrogels was determined using the decrease in fluorescence intensity from the UCNPs encapsulated in the hydrogels...
April 17, 2017: Acta Biomaterialia
Phitchan Sricharoen, Nunticha Limchoowong, Yonrapach Areerob, Prawit Nuengmatcha, Suchila Techawongstien, Saksit Chanthai
Fe3O4/hydroxyapatite/graphene quantum dots (Fe3O4/HAP/GQDs) nanocomposite was synthesized and used as a novel magnetic adsorbent. This nanocomposite was characterized using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetization property. The Fe3O4/HAP/GQDs was applied to pre-concentrate copper residues in Thai food ingredients (so-called "Tom Yum Kung") prior to determination by inductively coupled plasma-atomic emission spectrometry...
July 2017: Ultrasonics Sonochemistry
Hanyang Gao, Chen Xue, Guoxin Hu, Kunxu Zhu
In this research, three kinds of graphene quantum dots (GQDs)-pristine graphene quantum dots (PGQDs), expanded graphene quantum dots (EGQDs) and graphene oxide quantum dots (GOQDs)-were produced from natural graphite, expanded graphite, and oxide graphite respectively in an ultrasound-assisted supercritical CO2 (scCO2)/H2O system. The effects of aqueous solution content ratio, system pressure, and ultrasonic power on the yields of different kinds of GQDs were investigated. According to these experiment results, the combination of the intense knocking force generated from high-pressure acoustic cavitation in a scCO2/H2O system and the superior penetration ability of scCO2 was considered to be the key to the successful exfoliation of such tiny pieces from bulk graphite...
July 2017: Ultrasonics Sonochemistry
Salvador Hernández-Martínez, Minerva Sánchez-Zavaleta, Kevin Brito, Antonia Herrera-Ortiz, Sheila Ons, Fernando G Noriega
Allatotropins (AT) are neuropeptides with pleotropic functions on a variety of insect tissues. They affect processes such as juvenile hormone biosynthesis, cardiac rhythm, oviduct and hindgut contractions, nutrient absorption and circadian cycle. The present work provides experimental evidence that AT elicits immune responses in two important mosquito disease vectors, Anopheles albimanus and Aedes aegypti. Hemocytes and an immune-competent mosquito cell line responded to AT by showing strong morphological changes and increasing bacterial phagocytic activity...
2017: PloS One
Dirk König, Daniel Hiller, Sebastian Gutsch, Margit Zacharias, Sean Smith
All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusion, statistics of small numbers, quantum- or dielectric confinement...
April 20, 2017: Scientific Reports
Chunchuan Gu
The development of advanced methods for accurately monitoring cell apoptosis has extensive significance in the diagnostic and pharmaceutical fields. In this study, we developed a rapid, sensitive and selective approach for the detection of cell apoptosis by combining the site-specific recognition and cleavage of the DEVD-peptide with quantum dots (QDs)-based fluorescence resonance energy transfer (FRET). Firstly, biotin-peptide was conjugated on the surface of AuNPs to form AuNPs-pep through the formation of an Au-S bond...
April 19, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
Bin Bin Chen, Rong Sheng Li, Meng Li Liu, Hong Zhi Zhang, Cheng Zhi Huang
The easy fabrication of single-layered graphene quantum dots (s-GQDs) still faces challenge. Herein, we report an efficient route to fabricate s-GQDs within 5 min at room temperature by introducing a simple self-exothermic reaction. The as-prepared s-GQDs can specifically bind with aluminium ions to produce an aggregation-induced emission enhancement effect.
April 19, 2017: Chemical Communications: Chem Comm
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