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carbon dot

Khwaja Salahuddin Siddiqi, Azamal Husen, Sayed Sartaj Sohrab, Mensur Osman Yassin
Nanomaterials (NMs) are receiving remarkable attention due to their unique properties and structure. They vary from atoms and molecules along with those of bulk materials. They can be engineered to act as drug delivery vehicles to cross blood-brain barriers (BBBs) and utilized with better efficacy and safety to deliver specific molecules into targeted cells as compared to conventional system for neurological disorders. Depending on their properties, various metal chelators, gold nanoparticles (NPs), micelles, quantum dots, polymeric NPs, liposomes, solid lipid NPs, microparticles, carbon nanotubes, and fullerenes have been utilized for various purposes including the improvement of drug delivery system, treatment response assessment, diagnosis at early stage, and management of neurological disorder by using neuro-engineering...
August 10, 2018: Nanoscale Research Letters
Yang Liu, Junjun Liu, Jiayi Zhang, Xiucun Li, Fangsiyu Lin, Nan Zhou, Bai Yang, Laijin Lu
Surgical resection is recognized as a mainstay in the therapy of malignant brain tumors. In clinical practice, however, surgeons face great challenges in identifying the tumor boundaries due to the infiltrating and heterogeneous nature of neoplastic tissues. Contrast-enhanced magnetic resonance imaging (MRI) is extensively used for defining the brain tumor in clinic. Disappointingly, the commercially available (MR) contrast agents show the transient circulation lifetime and poor blood-brain barrier (BBB) permeability, which seriously hamper their abilities in tumor visualization...
July 31, 2018: ACS Omega
Yuan-Yuan Ding, Xiao-Juan Gong, Yang Liu, Wen-Jing Lu, Yi-Fang Gao, Ming Xian, Shao-Min Shuang, Chuan Dong
Long wavelength (i.e., orange- to red-light) fluorescence emission and functionality are critically longing for the development and applications of carbon dots (CDs) toward biosensor and bioimaging analysis. Herein, the N-doped carbon dots (N-CDs) with bright orange fluorescence emission at 592 nm were facilely synthesized via p-phenylenediamine as a carbon precursor by microwave method. The as-prepared N-CDs exhibit favorable biocompatibility, excellent water solubility, highly optical stabilities and display sensitive pH response behavior...
November 1, 2018: Talanta
Katerina K Karali, Lamprini Sygellou, Constantine D Stalikas
Tris-(hydroxymethyl)-aminomethane and urea were used as low-cost precursor compounds to synthesize highly fluorescent N-doped carbon nanodots (CNDs), in an environmentally-friendly, inexpensive process. The as-prepared CNDs exhibit blue fluorescence, excellent photostability under various conditions, water dispersibility and stability over several parameters, such as a wide range of pH. The N-doped CNDs were applied as a multi-probe fluorescence quenching system to the sensitive detection of nitrite (NO2 - ), nitrate (NO3 - ) and ferric (Fe3+ ) ions in food matrices...
November 1, 2018: Talanta
Shunwei Chen, Naeem Ullah, Rui-Qin Zhang
Recent experiments have suggested that exciton self-trapping plays an important role in governing the optical properties of graphene quantum dots (GQDs) and carbon dots (CDs), while the molecular structures related to this phenomenon remain unclear. This theoretical study reports exciton self-trapping induced by edge-bonded ether (C-O-C) groups in graphene nanosheets. Density functional theory (DFT) and time-dependent DFT calculations show that the initially delocalized electron and hole are trapped in the vicinity of the edge ether groups on graphene nanosheets upon excited-state (S1) relaxation, accompanied by structural planarization of the seven-membered cyclic ether rings in the same region...
August 7, 2018: Journal of Physical Chemistry Letters
Sergii Kalytchuk, Yu Wang, Katerina Polakova, Radek Zbořil
Carbon dots (CDs) rank among the most promising luminescent nanomaterials for anti-counterfeiting application owing to their high fluorescence quantum yield and nontoxicity. Herein we report a novel, high-level security performance anti-counterfeiting strategy achieved by fluorescence lifetime-encoded carbon dot fluorescent inks. CD inks have identical steady-state emission properties, but they have distinctive and well-separated fluorescence lifetimes allowing authentication of security tags using exclusively fluorescence lifetime imaging (FLI)...
August 7, 2018: ACS Applied Materials & Interfaces
Shaohua Liu, Jiale Cui, Jingbin Huang, Boshi Tian, Fan Jia, Zhenling Wang
Nitrogen-doped carbon dots (N-CDs) with well-distribution size and strong blue emission were successfully synthesized via a simple mild hydrothermal strategy using citric acid and ethylenediamine as co-precursors. The highly fluorescent N-CDs exhibit high fluorescence quantum yield (QY, 58.6%), excitation-independent emission behavior, and good photostability. The experimental results showed that the N-CDs can be served as a fluorescent sensing platform for detection of Cr(VI) ions due to the effective fluorescence quenching effect of Cr(VI) ions...
July 31, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Yuyan Jiang, Kanyi Pu
Biophotonics as an interdisciplinary frontier plays an increasingly important role in modern biomedical science. Optical agents are generally involved in biophotonics to interpret biomolecular events into readable optical signals for imaging and diagnosis or to convert photons into other forms of energy (such as heat, mechanical force, or chemical radicals) for therapeutic intervention and biological stimulation. Development of new optical agents including metallic nanoparticles, quantum dots, up-conversion nanoparticles, carbon dots, and silica nanoparticles has contributed to the advancement of this field...
August 3, 2018: Accounts of Chemical Research
Jabran Saleem, Liming Wang, Chunying Chen
Cancer remains one of the major health problems all over the world and conventional therapeutic approaches have failed to attain an effective cure. Tumor microenvironments (TME) present a unique challenge in tumor therapy due to their complex structures and multiple components, which also serve as the soil for tumor growth, development, invasion, and migration. The complex TME includes immune cells, fibrous collagen structures, and tortuous blood vessels, in which conventional therapeutic approaches are rendered useless...
August 2, 2018: Advanced Healthcare Materials
Feng Li, Dayong Yang, Huaping Xu
Carbon dots (CDs) are new materials with capability in bioimaging, optical device, catalysis, and many other fields. Their advantages, such as ease of large-scale preparation, low cost of precursor, highly tunable photoluminescence, satisfactory biocompatibility, and photostability against photobleaching, make them competitive alternatives to conventional semiconductor-based quantum dots and organic dyes. In order to overwhelm other luminescent materials in applications, their functionalities are still needed to improve in spite of the above mentioned advantages...
August 2, 2018: Chemistry: a European Journal
Mengxiao Li, Yu Feng, Qingyong Tian, Weijing Yao, Li Liu, Xuan Li, Huanjun Wang, Wei Wu
Advanced fluorescent materials have demonstrated great value in the anti-counterfeiting field for information storage and hiding. In this work, a novel strategy for producing UV light-switchable fluorescent patterns to hide and store information is proposed based on carbon dots (CDs) and Y2O3:Eu composites with exceptional optical properties. CDs can present blue emission under both 254 nm and 365 nm UV light excitation, but Y2O3:Eu can only arouse a red color under 254 nm light excitation. Under conventional 365 nm excitation, a single blue color and partial information are shown, however, the whole information in patterns can be displayed under specific 254 nm excitation...
July 30, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Y Tian, L Li, X Guo, A Wójtowicz, L Estevez, M J Krysmann, A Kelarakis
This study focuses on the structural rearrangements and the photoluminescent behavior of pyrolytically derived carbon dots when subjected to a series of cyclic voltammetry sweeps. Although the electrical signals involved are not pronounced, multiple electrochemical cycling results in a progressive suppression of the photoluminescence, so that after 42 sweeps the intensity is reduced by one order of magnitude. At the same time, the fluorescence component stemming from the organic fluorophores is blue-shifted, while the contribution of the carbogenic cores is red-shifted...
July 30, 2018: Chemical Communications: Chem Comm
Rüstem Keçili, Chaudhery Mustansar Hussain
Molecularly imprinted polymers (MIPs) are a type of tailor-made materials that have ability to selectively recognize the target compound/s. MIPs have gained significant research interest in solid-phase extraction, catalysis, and sensor applications due to their unique properties such as low cost, robustness, and high selectivity. In addition, MIPs can be prepared as composite nanomaterials using nanoparticles, multiwalled carbon nanotubes (MWCNTs), nanorods, quantum dots (QDs), graphene, and clays. This review paper aims to demonstrate and highlight the recent progress of the applications of imprinted nanocomposite materials in analytical chemistry...
2018: International Journal of Analytical Chemistry
Venkatramana D Krishna, Kai Wu, Diqing Su, Maxim C J Cheeran, Jian-Ping Wang, Andres Perez
In recent years a number of new nanotechnology based platforms have been developed for detection of wide variety of targets including infectious agents, protein biomarkers, nucleic acids, drugs, and cancer cells. Nanomaterials such as magnetic nanoparticles, quantum dots, carbon nanotubes, nanowires, and nanosensors like giant magnetoresistance (GMR) sensors are used to quantitatively detect biomolecules with, experimentally, relatively good accuracy. There has been a growing interest in the use of magnetic fields in biosensing applications...
October 2018: Food Microbiology
Panpan Zhu, Zhen Cheng, Lingling Du, Qian Chen, Ke Jun Tan
A new Cu-doped dual-emission carbon dots was synthesized rapidly and simply via one-pot solvothermal method and its special photoluminescence mechanism was studied. Dual-emission carbon dots have two fluorescence emission peaks under one-wavelength excitation and can be used as dual-signal sensor which is usually designed with two or more substances. The prepared carbon dots show excellent water solubility, photostability, salt tolerance and special optical properties. The raw material ratio, solvent, pH, time and synthesis temperature were optimized...
July 29, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jieping Luo, Xin Shen, Bingzhi Li, Xiaoyun Li, Xuemin Zhou
A fluorometric ATP assay is described that makes use of carbon dots and graphene oxide along with toehold-mediated strand displacement reaction. In the absence of target, the fluorescence of carbon dots (with excitation/emission maxima at 360/447 nm) is strong and in the "on" state, because the signal probe hybridizes with the aptamer strand and cannot combine with graphene oxide. In the presence of ATP, it will bind to the aptamer and induce a strand displacement reaction. Consequently, the signal probe is released, the sensing strategy will change into the "off" state with the addition of graphene oxide...
July 28, 2018: Mikrochimica Acta
Shan Huang, Erli Yang, Jiandong Yao, Yi Liu, Qi Xiao
An ultrasensitive fluorometric assay is described for the determination of the activity of the enzyme α-glucosidase in waters and living cells. Carbon dots doped with nitrogen and boron (N,B-CDs) were prepared that have excitation/emission peaks at 400/510 nm and a fluorescence quantum yield of 47%. 4-Nitrophenylglucoside is added and then hydrolyzed by α-glucosidase to form yellow 4-nitrophenol which screens off fluorescence due to an inner filter effect. The method was applied to the determination of α-glucosidase activity and has a 3 mU mL-1 detection limit...
July 28, 2018: Mikrochimica Acta
Xiaoyang Yue, Xuli Miao, Zhenyuan Ji, Xiaoping Shen, Hu Zhou, Lirong Kong, Guoxing Zhu, Xiaoyun Li, Sayyar Ali Shah
In this work, an all solid direct Z-scheme photocatalyst of monoclinic dibismuth tetraoxide microrods/nitrogen-doped carbon dots (m-Bi2 O4 /NCDs) has been constructed through a simple one-step hydrothermal method. The m-Bi2 O4 /NCDs photocatalyst exhibits excellent photocatalytic activity for the degradation of methylene orange (MO) and phenol under visible light irradiation. The pollutants of MO (10 mg L-1 ) and phenol (45 mg L-1 ) could be efficiently degraded by m-Bi2 O4 /NCDs within 30 and 120 min, respectively, which is much better than that of the single m-Bi2 O4 , indicating that the introduction of NCDs into m-Bi2 O4 can effectively improve the photocatalytic activity...
July 21, 2018: Journal of Colloid and Interface Science
Yan Zhan, Ting Geng, Yingliang Liu, Chaofan Hu, Xuejie Zhang, Bingfu Lei, Jianle Zhuang, Xu Wu, Di Huang, Guanjun Xiao, Bo Zou
Carbon dots (CDs) have gained intensive interests owing to their unique structure and excellent optoelectronic performances. However, to acquire CDs with broadband emission spectrum still remains an issue. In this work, nitrogen doped CDs (N-CDs) with near-ultraviolet (NUV), visible and near-infrared (NIR) emission were synthesized via one-pot solvothermal strategy, and the excitation-independent NUV and NIR emission and excitation-dependent visible emission were observed in the photoluminescence (PL) spectra of N-CDs...
July 26, 2018: ACS Applied Materials & Interfaces
Dingying Shan, Jer-Tsong Hsieh, Xiaochun Bai, Jian Yang
Fluorescence imaging has emerged as a promising technique for monitoring and assessing various biologically relevant species in cells and organisms, driving the demand for effective fluorescent agents with good biocompatibility and high fluorescence performance. However, traditional fluorescent agents, such as quantum dots (QDs) and organic dyes, either suffer from toxicity concerns or poor fluorescence performance (e.g., low photobleaching-resistance). In this regard, citrate-based fluorescent biomaterials, which are synthesized from the natural and biocompatible precursor of citric acid (CA), have become competitive alternatives for fluorescence imaging owing to their biocompatibility, cost effectiveness, straightforward synthetic routes, flexible designability, as well as strong fluorescence with adjustable excitation/emission wavelengths...
July 26, 2018: Advanced Healthcare Materials
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