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https://www.readbyqxmd.com/read/29667403/rapid-detection-of-mercury-ions-based-on-nitrogen-doped-graphene-quantum-dots-accelerating-formation-of-manganese-porphyrin
#1
Dong Peng, Li Zhang, Ru-Ping Liang, Jian-Ding Qiu
Mercuric ion (HgII) is a stable form of mercury pollution with high toxicity and bioaccumulation ability, and the sensitive and visible determination is of great importance. Herein, a simple method to magically improve the complexation reaction rate between porphyrin and manganous ions (MnII) have been proposed by using the synergistic effect of trace nitrogen doped graphene quantum dots (NGQDs) and Hg(II). A mechanism is proposed in accordance with a substitution reaction in which the deformed porphyrin nucleus by relatively larger Hg(II) ions is favourable for attacking of small divalent metal ions carried by NGQDs from the back...
April 18, 2018: ACS Sensors
https://www.readbyqxmd.com/read/29666792/steady-state-linear-and-non-linear-optical-spectroscopy-of-organic-chromophores-and-bio-macromolecules
#2
REVIEW
Marco Marazzi, Hugo Gattuso, Antonio Monari, Xavier Assfeld
Bio-macromolecules as DNA, lipid membranes and (poly)peptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes-often drugs or pollutants-that can (photo)sensitize the bio-macromolecule leading to eventual chemical modifications, thus damages...
2018: Frontiers in Chemistry
https://www.readbyqxmd.com/read/29665212/a-white-light-emitting-quantum-dot-complex-for-single-particle-level-interaction-with-dopamine-leading-to-changes-in-color-and-blinking-profile
#3
Sabyasachi Pramanik, Satyapriya Bhandari, Uday Narayan Pan, Shilaj Roy, Arun Chattopadhyay
The interaction of the neurotransmitter dopamine is reported with a single particle white light-emitting (WLE) quantum dot complex (QDC). The QDC is composed of yellow emitting ZnO quantum dots (Qdots) and blue emitting Zn(MSA)2 complex (MSA = N-methylsalicylaldimine) synthesized on their surfaces. Sensing is achieved by the combined changes in the visual luminescence color from white to blue, chromaticity color coordinates from (0.31, 0.33) to (0.24, 0.23) and the ratio of the exponents (αon /αoff ) of on/off probability distribution (from 0...
April 17, 2018: Small
https://www.readbyqxmd.com/read/29664607/polyserotonin-nanoparticles-as-multifunctional-materials-for-biomedical-applications
#4
Nako Nakatsuka, Mohammad Mahdi Hasani-Sadrabadi, Kevin M Cheung, Thomas D Young, Ghasem Bahlakeh, Alireza Moshaverinia, Paul S Weiss, Anne M Andrews
Serotonin-based nanoparticles represent a class of previously unexplored multifunctional nanoplatforms with potential biomedical applications. Serotonin, under basic conditions, self-assembles into monodisperse nanoparticles via autoxidation of serotonin monomers. To demonstrate potential applications of polyserotonin nanoparticles for cancer therapeutics, we show that these particles are biocompatible, exhibit photothermal effects when exposed to near-infrared radiation, and load the chemotherapeutic drug doxorubicin releasing it contextually and responsively in specific microenvironments...
April 17, 2018: ACS Nano
https://www.readbyqxmd.com/read/29660581/metal-enhanced-fluorescence-mef-for-biosensors-general-approaches-and-a-review-of-recent-developments
#5
REVIEW
Yoon Jeong, Yun-Min Kook, Kangwon Lee, Won-Gun Koh
Fluorescence-based biosensor platforms have been intensively investigated not only to increase the sensitivity but also to improve the performance of biosensors. By exploiting metal from the macroscopic down to the nanoscopic surface, various architectures have been devised to manipulate fluorescence signals (enhancement, quenching) within near-optical fields. The interaction of a metallic surface with proximal fluorophores (in the range of 5-90 nm) has beneficial effects on optical properties such as an increased quantum yield, improved photostability and a reduced lifetime of fluorophores...
April 7, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29659243/carbonization-of-human-fingernails-towards-the-sustainable-production-of-multifunctional-nitrogen-and-sulfur-co-doped-carbon-nanodots-with-highly-luminescent-probing-and-cell-proliferative-migration-properties
#6
Theodoros G Chatzimitakos, Athanasia Kasouni, Anastassios N Troganis, Constantine D Stalikas
A simple, yet effective method is employed to prepare multifunctional fluorescent carbon nanodots (CNDs) from human fingernails. The results demonstrate that the CNDs have excellent optical properties and a quantum yield of 81%, which is attributed to the intrinsic composition of precursor material itself. The CNDs are used to develop an ultra-sensitive fluorescent probe for the detection of hexavalent chromium (limit of detection: 0.3 nM) via a combined inner- filter and static mechanism. Moreover, the toxicity of the CNDs over four epithelial cell lines is assessed...
April 16, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29658165/electrochemical-monitoring-of-malondialdehyde-biomarker-in-biological-samples-via-electropolymerized-amino-acid-chitosan-nanocomposite
#7
Mohammad Hasanzadeh, Fozieh Mokhtari, Vahid Jouyban-Gharamaleki, Ahad Mokhtarzadeh, Nasrin Shadjou
This study reports on the electropolymerization of a low toxic and biocompatible nanopolymer with entitle poly arginine-graphene quantum dots-chitosan (PARG-GQDs-CS) as a novel strategy for surface modification of glassy carbon surface and preparation of a new interface for measurement of malondialdehyde (MDA) in exhaled breath condensate. Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of GQDs-CS nanostructures on a PARG prepolymerized on the surface of glassy carbon electrode using cyclic voltammetry techniques in the regime of -1...
April 15, 2018: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/29652405/quantum-annealing-versus-classical-machine-learning-applied-to-a-simplified-computational-biology-problem
#8
Richard Y Li, Rosa Di Felice, Remo Rohs, Daniel A Lidar
Transcription factors regulate gene expression, but how these proteins recognize and specifically bind to their DNA targets is still debated. Machine learning models are effective means to reveal interaction mechanisms. Here we studied the ability of a quantum machine learning approach to predict binding specificity. Using simplified datasets of a small number of DNA sequences derived from actual binding affinity experiments, we trained a commercially available quantum annealer to classify and rank transcription factor binding...
2018: NPJ quantum information
https://www.readbyqxmd.com/read/29649877/%C3%AE-n-methylamino-l-alanine-bmaa-not-involved-in-alzheimer-s-disease
#9
Arvi Rauk
β-N-Methylamino-L-alanine (BMAA) is a neurotoxic agent implicated in ALS, Parkinson's and Alzheimer's diseases. It is produced by blue-green algae and could find its way via fish and seafood into the human food supply. Isolation from biological samples yields the compound in monomeric and protein-bound form. It has been suggested that the protein-bound fraction may result from genetic misincorporation into proteins in place of serine. Concomitant misfolding of the mutated proteins may be responsible for the neurological diseases...
April 12, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29644847/preparation-of-microkernel-based-mesoporous-sio2-cdte-sio2-sio2-fluorescent-nanoparticles-for-imaging-screening-and-enrichment-of-heat-shock-protein-90-inhibitors-from-tripterygium-wilfordii
#10
Yue Hu, Zhao Yi Miao, Xiaojing Zhang, Xiaotong Yang, Yingying Tang, Sheng Yu, ChenXiao Shan, Hongmei Wen, Dong Zhu
The currently utilized ligand fishing for bioactive molecular screening from complex matrixes cannot perform imaging screening. Here, we developed a new solid-phase ligand fishing coupled with in situ imaging protocol for the specific enrichment and identification of heat shock protein 90 (Hsp 90) inhibitors from Tripterygium wilfordii, utilizing a multiple-layer and microkernel-based mesoporous nanostructure composed of a protective silica coating CdTe quantum dots (QDs) core and a mesoporous silica shell, i...
April 12, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29629108/photolabile-coumarins-with-improved-efficiency-through-azetidinyl-substitution
#11
Giovanni Bassolino, Christoph Nançoz, Zacharias Thiel, Estelle Bois, Eric Vauthey, Pablo Rivera-Fuentes
Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7-diethylamino and julolidine-fused analogues. The efficiency of the photorelease reactions of the azetidinyl-substituted compounds was 2- to 5-fold higher than the corresponding diethylamino coumarins...
January 14, 2018: Chemical Science
https://www.readbyqxmd.com/read/29620851/antimicrobial-amino-functionalized-nitrogen-doped-graphene-quantum-dots-for-eliminating-multidrug-resistant-species-in-dual-modality-photodynamic-therapy-and-bioimaging-under-two-photon-excitation
#12
Wen-Shuo Kuo, Yu-Ting Shao, Chih-Hui Yang, Keng-Shiang Huang, Miao-Hsi Hsieh, Pei-Chi Chen, Chia-Yuan Chang, Chia-Hung Huang, Chih-Li Lilian Hsu, Ting-Mao Chou, Jiu-Yao Wang, Ping-Ching Wu
Developing a nanomaterial for use in highly efficient dual-modality two-photon photodynamic therapy (PDT) involving reactive oxygen species (ROS) generation and for use as a two-photon imaging contrast probe is currently desirable. Here, graphene quantum dots (GQDs) doped with nitrogen and functionalized with an amino group (amino-N-GQDs) serving as a photosensitizer in PDT had superior ability to generate ROS than did unmodified GQDs. Multidrug-resistant (MDR) species were completely eliminated at an ultralow energy (239...
April 5, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29609367/development-of-a-tio-2-sio-2-waveguide-mode-chip-for-an-ultraviolet-near-field-fluorescence-sensor
#13
Chiaki Kuroda, Midori Nakai, Makoto Fujimaki, Yoshimichi Ohki
Aimed at detecting fluorescent-labeled biological substances sensitively, a sensor that utilizes near-field light has attracted much attention. According to our calculations, a planar structure composed of two dielectric layers can enhance the electric field of UV near-field light effectively by inducing waveguide-mode (WM) resonance. The fluorescence intensity obtainable by a WM chip with an optimized structure is 5.5 times that obtainable by an optimized surface plasmon resonance chip. We confirmed the above by making a WM chip consisting of TiO2 and SiO2 layers on a silica glass substrate and by measuring the fluorescence intensity of a solution of quantum dots dropped on the chip...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29604520/nanomaterials-and-phase-sensitive-based-signal-enhancment-in-surface-plasmon-resonance
#14
REVIEW
Saeideh Mohammadzadeh-Asl, Ahmad Keshtkar, Jafar Ezzati Nazhad Dolatabadi, Miguel de la Guardia
Measurement of small molecules in extremely dilute concentrations of analyte play an important role in different issues ranging from food industry to biological, pharmaceutical and therapeutical applications. Surface plasmon resonance (SPR) sensors can be a suitable choice for detection of small molecules based on interactions with biomolecules. However, sensitivity of the system for detection of these molecules is very low. Improving sensitivity has been a challenge for years. Therefore, different methods have been used to enhance SPR signals...
March 23, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29600450/quantum-cascade-lasers-based-detection-of-nitric-oxide
#15
Gracia Montilla-Bascón, Julien Mandon, Frans J M Harren, Luis A J Mur, Simona M Cristescu, Elena Prats
Despite the established importance of nitric oxide (NO) in many physiological and molecular processes in plants, most methods for quantifying NO are open to criticism This reflects the differing methods either lacking specificity or sensitivity, or even from an undue dependence of results on experimental conditions (i.e., chemical concentrations, pH, etc.). In this chapter we describe a protocol to measure gaseous NO produced by a biological sample using quantum cascade laser (QCL)-based spectroscopy. This technique is based on absorption of the laser light by the NO molecules which have been passed from a biological sample into an optical s cell that is equipped with two mirrors placed at both ends...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29596353/benveniste-s-experiments-explained-by-a-non-conventional-experimenter-effect
#16
Francis Beauvais
Background: Benveniste's biology experiments suggested the existence of molecular-like effects without molecules ("memory of water"). In this article, it is proposed that these disputed experiments could have been the consequence of a previously unnoticed and non-conventional experimenter effect. Methods: A probabilistic modelling is built in order to describe an elementary laboratory experiment. A biological system is modelled with two possible states ("resting" and "activated") and exposed to two experimental conditions labelled "control" and "test", but both are biologically inactive...
March 29, 2018: Medicines (Basel, Switzerland)
https://www.readbyqxmd.com/read/29595149/tunable-single-and-double-emission-semiconductor-nanocrystal-quantum-dots-a-multianalyte-sensor
#17
Ratneshwar Kumar Ratnesh, Mohan Singh Mehata
We have prepared stable colloidal CdTe and CdTe/ZnS core-shell quantum dots (QDs) using hot injection chemical route. The developed CdTe QDs emit tunable single and dual photoluminescence (PL) bands, originating from the direct band edge and the surface state of QDs, as evident by the steady-state and time-resolved spectroscopy. The developed CdTe and CdTe/ZnS QDs act as optical sensors for the detection of metal ions (e.g., Fe2+ and Pb2+) in the feed water. The PL quenching in the presence of analytes has been examined by both the steady-state and time-resolved PL spectroscopy...
March 29, 2018: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/29594574/aptamer-based-fluorescent-platform-for-ultrasensitive-adenosine-detection-utilizing-fe-3-o-4-magnetic-nanoparticles-and-silver-nanoparticles
#18
Yueyue Song, Guanhong Xu, Fangdi Wei, Yao Cen, Muhammad Sohail, Menglan Shi, Xiaoman Xu, Yunsu Ma, Yujie Ma, Qin Hu
The authors describe an aptamer-based fluorescent assay for adenosine (Ade). It is based on the interaction between silver nanoparticles (AgNPs) and CdTe quantum dots (QDs). The beacon comprises a pair of aptamers, one conjugated to Fe3 O4 magnetic nanoparticles, the other to AgNPs. In the presence of Ade, structural folding and sandwich association of the two attachments takes place. After magnetic separation, the associated sandwich structures are exposed to the QDs. The AgNPs in sandwich structures act as the signaling label of Ade by quenching the fluorescence of QDs (at excitation/emission wavelengths of 370/565 nm) via inner filter effect, electron transfer and trapping processes...
January 27, 2018: Mikrochimica Acta
https://www.readbyqxmd.com/read/29594523/red-emitting-and-highly-stable-carbon-dots-with-dual-response-to-ph-values-and-ferric-ions
#19
Yuanqing Sun, Xiaojie Wang, Chan Wang, Dingyi Tong, Qian Wu, Kaili Jiang, Yingnan Jiang, Chuanxi Wang, Minghui Yang
The authors describe strongly red-emitting carbon dots (CDs) which were obtained via microwave synthesis using phenylenediamine as the carbon source. The structural and optical properties of the resultant CDs are studied in some detail. The CDs possess (a) longwave emission (peaking at 620 nm under 470 nm excitation), (b) a quantum yield of ~15%, (c) a size of typically 3.8 nm; and (d) good photostability. The CDs have a pH-dependet response that covers the pH 5 to 10 range, and their fluorescence is quenched by ferric ions...
January 4, 2018: Mikrochimica Acta
https://www.readbyqxmd.com/read/29594097/designing-superoxide-generating-quantum-dots-for-selective-light-activated-nanotherapy
#20
Samuel M Goodman, Max Levy, Fei-Fei Li, Yuchen Ding, Colleen M Courtney, Partha P Chowdhury, Annette Erbse, Anushree Chatterjee, Prashant Nagpal
The rapid emergence of superbugs, or multi-drug resistant (MDR) organisms, has prompted a search for novel antibiotics, beyond traditional small-molecule therapies. Nanotherapeutics are being investigated as alternatives, and recently superoxide-generating quantum dots (QDs) have been shown as important candidates for selective light-activated therapy, while also potentiating existing antibiotics against MDR superbugs. Their therapeutic action is selective, can be tailored by simply changing their quantum-confined conduction-valence band (CB-VB) positions and alignment with different redox half-reactions-and hence their ability to generate specific radical species in biological media...
2018: Frontiers in Chemistry
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