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https://www.readbyqxmd.com/read/29216759/pharmaceutical-potential-of-quantum-dots
#1
Swati Jha, Prateek Mathur, Suman Ramteke, Narendra Kumar Jain
Quantum dots (QDs) or fluorescent nanocrystals are designed nanoparticles that are promising for several biological and bio-medical applications as well as drug delivery and simultaneous cellular imaging. QD's have exhibited promising potential primarily in receptor based targeting as a result of their distinctive physicochemical properties. Functionalized QDs (f-QDs) have been developed as effective, safe, nano-sized smart systems to deliver a wide range of bio-actives. Surface modified fluorescent carbon QDs with surface modification have attracted attention as targeting ligand to accomplish cellular targeting with enhanced specificity...
December 7, 2017: Artificial Cells, Nanomedicine, and Biotechnology
https://www.readbyqxmd.com/read/29216421/multidimensional-quantum-mechanical-modeling-of-electron-transfer-and-electronic-coherence-in-plant-cryptochromes-the-role-of-initial-bath-conditions
#2
David Mendive-Tapia, Etienne Mangaud, Thiago Firmino, Aurélien de la Lande, Michele Desouter-Lecomte, Hans-Dieter Meyer, Fabien Gatti
A multi-dimensional quantum mechanical protocol is used to describe the photo-induced electron transfer and electronic coherence in plant cryptochromes without any semi-empirical, e.g. experimentally obtained, parameters. Starting from a two-level spin-boson Hamiltonian we look at the effect that the initial photo-induced nuclear bath distribution has on an intermediate step of this biological electron transfer cascade for two idealized cases. The first assumes a slow equilibration of the nuclear bath with respect to the previous electron transfer step that leads to an ultrafast decay with little temperature dependence; whilst the second assumes a prior fast bath equilibration on the donor potential energy surface leading to a much slower decay, which contrarily displays a high temperature dependence and a better agreement with previous theoretical and experimental results...
December 7, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29205243/fluorescence-quenching-of-the-n-methylquinolinium-cation-by-pairs-of-water-or-alcohol-molecules
#3
Flor Rodríguez-Prieto, Carlos Costa Corbelle, Berta Fernández, Jorge A Pedro, M Carmen Ríos Rodríguez, Manuel Mosquera
N-Methylquinolinium cation (MQ+) in its first-excited singlet state is a strong oxidant commonly used as a photosensitizer, whose fluorescence is therefore quenched by electron donors. Interestingly, the fluorescence of MQ+ is also quenched by hydroxy compounds such as water and alcohols, more difficult to oxidize. We investigated the quenching mechanism of MQ+ fluorescence by small amounts of water and alcohols in acetonitrile solution. The fluorescence intensities and lifetimes exhibited a nonlinear dependence on the quencher concentration...
December 5, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29203839/generation-of-photonic-entanglement-in-green-fluorescent-proteins
#4
Siyuan Shi, Prem Kumar, Kim Fook Lee
Recent development of spectroscopic techniques based on quantum states of light can precipitate many breakthroughs in observing and controlling light-matter interactions in biological materials on a fundamental quantum level. For this reason, the generation of entangled light in biologically produced fluorescent proteins would be promising because of their biocompatibility. Here we demonstrate the generation of polarization-entangled two-photon state through spontaneous four-wave mixing in enhanced green fluorescent proteins...
December 5, 2017: Nature Communications
https://www.readbyqxmd.com/read/29200197/control-of-piezoelectricity-in-amino-acids-by-supramolecular-packing
#5
Sarah Guerin, Aimee Stapleton, Drahomir Chovan, Rabah Mouras, Matthew Gleeson, Cian McKeown, Mohamed Radzi Noor, Christophe Silien, Fernando M F Rhen, Andrei L Kholkin, Ning Liu, Tewfik Soulimane, Syed A M Tofail, Damien Thompson
Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V-1, limiting technological applications...
December 4, 2017: Nature Materials
https://www.readbyqxmd.com/read/29199588/recent-advances-in-nanoparticle-based-targeted-drug-delivery-systems-against-cancer-and-role-of-tumor-microenvironment
#6
Usman Ali Ashfaq, Muhammad Riaz, Erum Yasmeen, Muhammad Zubair Yousaf
Cancer is one of the major causes of death worldwide. The silent activation of cellular factors responsible for deviation from normal regulatory pathways leads to the development of cancer. Nano-biotechnology is a novel drug-delivery system with high potential of efficacy and accuracy to target lethal cancers. Various biocompatible nanoparticle (NP)-based drug-delivery systems such as liposomes, dendrimers, micelles, silica, quantum dots, and magnetic, gold, and carbon nanotubes have already been reported for successful targeted cancer treatment...
2017: Critical Reviews in Therapeutic Drug Carrier Systems
https://www.readbyqxmd.com/read/29188850/fabrication-of-carbon-quantum-dots-with-nano-defined-position-and-pattern-in-one-step-via-sugar-electron-beam-writing
#7
Yuyan Weng, Zhiyun Li, Lun Peng, Weidong Zhang, Gaojian Chen
Quantum dots (QDs) are promising materials in nanophotonics, biological imaging, and even quantum computing. Precise positioning and patterning of QDs is a prerequisite for realizing their actual applications. Contrary to the traditional two discrete steps of fabricating and positioning QDs, herein, a novel sugar-electron-beam writing (SEW) method is reported for producing QDs via electron-beam lithography (EBL) that uses a carefully chosen synthetic resist, poly(2-(methacrylamido)glucopyranose) (PMAG). Carbon QDs (CQDs) could be fabricated in situ through electron beam exposure, and the nanoscale position and luminescence intensity of the produced CQDs could be precisely controlled without the assistance of any other fluorescent matter...
November 30, 2017: Nanoscale
https://www.readbyqxmd.com/read/29185694/the-molecular-mechanism-of-substrate-recognition-and-catalysis-of-the-membrane-acyltransferase-pata-from-mycobacteria
#8
Montse Tersa, Lluís Raich, David Albesa-Jové, Beatriz Trastoy, Jacques Prandi, Martine Gilleron, Carme Rovira, Marcelo E Guerin
Glycolipids play a central role in a variety of important biological processes in all living organisms. PatA is a membrane acyltransferase involved in the biosynthesis of phosphatidyl-myo-inositol mannosides (PIMs), key structural elements and virulence factors of Mycobacterium tuberculosis. PatA catalyzes the transfer of a palmitoyl moiety from palmitoyl-CoA to the 6-position of the mannose ring linked to the 2-position of inositol in PIM1/PIM2. We report here the crystal structure of PatA in the presence of 6-O-palmitoyl-α-D-mannopyranoside, unraveling the acceptor binding mechanism...
November 29, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/29185339/ultra-bright-fluorescent-silica-nanoparticle-embedded-with-conjugated-oligomers-and-their-application-for-latent-fingerprint-detection
#9
Shijie Zhang, Ronghua Liu, Qianling Cui, Yu Yang, Qian Cao, Wenqiang Xu, Lidong Li
Fluorescent micro- and nano-sized particles have a broad range of applications in biology, medicine, and engineering. For these uses the materials should have high emission efficiency and good photostability. However, many organic fluorophores suffer from aggregation-induced quenching effects and photobleaching. Here, we used a simple method based on covalently blending a fluorescent conjugated oligomer with silica nanoparticles to achieve emission quantum yields as high as 97%. The resulting system also showed excellent stability under continuous light illumination, a range of pH values and temperatures, and in common solvents...
November 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29178547/-safe-by-design-ligand-coated-zno-nanocrystals-engineered-by-an-organometallic-approach-unique-physicochemical-properties-and-low-negative-toxicological-effect-toward-lung-cells
#10
Janusz Lewinski, Małgorzata Wolska-Pietkiewicz, Katarzyna Tokarska, Agnieszka Grala, Anna Wojewódzka, Elżbieta Chwojnowska, Justyna Grzonka, Piotr Cywiński, Krzysztof Kruczała, Zbigniew Sojka, Michał Chudy
The unique physicochemical properties and biocompatibility of zinc oxide nanocrystals (ZnO NCs) are strongly dependent on the nanocrystal-ligand interface which is largely determined by synthetic procedures. Advancing a novel organometallic self-supporting approach we prepared and fully characterized stable ZnO NCs coated with densely packed 2-(2-methoxyethoxy)acetate ligand shell (i.e. ligand acting as a miniPEG prototype) with the average core size and hydrodynamic diameter of 4-5 nm and ca. 12 nm, respectively, as a model system for biological studies...
November 27, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29178081/stimuli-responsive-nanocarriers-for-intracellular-delivery
#11
REVIEW
Lemmuel L Tayo
The emergence of different nanoparticles (NPs) has made a significant revolution in the field of medicine. Different NPs in the form of metallic NPs, dendrimers, polymeric NPs, carbon quantum dots and liposomes have been functionalized and used as platforms for intracellular delivery of biomolecules, drugs, imaging agents and nucleic acids. These NPs are designed to improve the pharmacokinetic properties of the drug, improve their bioavailability and successfully surpass physiological or pathological obstacles in the biological system so that therapeutic efficacy is achieved...
November 25, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/29171858/advances-in-single-quantum-dot-based-nanosensors
#12
Juan Hu, Zi-Yue Wang, Chen-Chen Li, Chun-Yang Zhang
Single-molecule detection provides a simple and ultrasensitive platform to quantify target molecules by simply counting the individual fluorescence signals. Quantum dots (QDs) are novel semiconductor nanocrystals with distinct characteristics of high brightness, large Stokes shift and broad absorption spectra, high molar extinction coefficients, high quantum yield, good photostability and long fluorescence lifetime. The combination of single-molecule detection with QDs enables the development of single QD-based nanosensors with extremely high sensitivity...
November 24, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29170771/a-fluorescent-combinatorial-logic-gate-with-na-h-enabled-or-and-h-driven-low-medium-high-ternary-logic-functions
#13
Jasmine M A Spiteri, Carl J Mallia, Glenn J Scerri, David C Magri
A novel fluorescent molecular logic gate with a 'fluorophore-spacer1-receptor1-spacer2-receptor2' format is demonstrated in 1 : 1 (v/v) methanol/water. The molecule consists of an anthracene fluorophore, and tertiary alkyl amine and N-(2-methoxyphenyl)aza-15-crown-5 ether receptors. In the presence of threshold concentrations of H(+) and Na(+), the molecule switches 'on' as an AND logic gate with a fluorescence quantum yield of 0.21 with proton and sodium binding constants of log βH+ = 9.0 and log βNa+ = 3...
November 24, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29168793/synthesis-analysis-cholinesterase-inhibiting-activity-and-molecular-modelling-studies-of-3-dialkylamino-2-hydroxypropyl-4-alkoxy-carbonyl-amino-benzoates-and-their-quaternary-ammonium-salts
#14
Tereza Padrtova, Pavlina Marvanova, Klara Odehnalova, Renata Kubinova, Oscar Parravicini, Adriana Garro, Ricardo D Enriz, Otakar Humpa, Michal Oravec, Petr Mokry
Tertiary amines 3-(dialkylamino)-2-hydroxypropyl 4-[(alkoxycarbonyl)amino]benzoates and their quaternary ammonium salts were synthesized. The final step of synthesis of quaternary ammonium salts was carried out by microwave-assisted synthesis. Software-calculated data provided the background needed to compare fifteen new resulting compounds by their physicochemical properties. The acid dissociation constant (pKa) and lipophilicity index (log P) of tertiary amines were determined; while quaternary ammonium salts were characterized by software-calculated lipophilicity index and surface tension...
November 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29165495/electronic-structure-and-dynamics-of-torsion-locked-photoactive-yellow-protein-chromophores
#15
Alice Henley, Matus E Diveky, Anand M Patel, Michael A Parkes, James C Anderson, Helen H Fielding
The photocycle of photoactive yellow protein (PYP) begins with small-scale torsional motions of the chromophore leading to large-scale movements of the protein scaffold triggering a biological response. The role of single-bond torsional molecular motions of the chromophore in the initial steps of the PYP photocycle are not fully understood. Here, we employ anion photoelectron spectroscopy measurements and quantum chemistry calculations to investigate the electronic relaxation dynamics following photoexcitation of four model chromophores, para-coumaric acid, its methyl ester, and two analogues with aliphatic bridges hindering torsional motions around the single bonds adjacent to the alkene group...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29165486/optical-control-of-mitochondrial-reductive-reactions-in-living-cells-using-an-electron-donor-acceptor-linked-molecule
#16
Yuta Takano, Reina Munechika, Vasudevanpillai Biju, Hideyoshi Harashima, Hiroshi Imahori, Yuma Yamada
It has been known for decades that intracellular redox reactions control various vital functions in living systems, which include the synthesis of biomolecules, the modulation of protein functions, and cell signaling. Although there have been several reports on the control of such functions using DNA and RNA, the non-invasive optical control of biological functions is an important ongoing challenge. In this study, a hybrid of an electron donor-acceptor linked molecule based on a ferrocene(Fc)-porphyrin(ZnP)-fullerene(C60) analogue and an elaborately designed nano-carrier, referred to herein as a MITO-Porter, resulted in a successful photoinduced intermolecular electron transfer reaction via the long-lived intramolecular charge separation, leading to site-specific reductive reactions in the mitochondria of living HeLa cells...
November 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/29165453/structural-and-electronic-properties-of-barbituric-acid-and-melamine-containing-ribonucleosides-as-plausible-components-of-prebiotic-rna-implications-for-prebiotic-self-assembly
#17
Sarabjeet Kaur, Purshotam Sharma, Stacey D Wetmore
The RNA world hypothesis assumes that RNA was the first informational polymer that originated from prebiotic chemical soup. However, since the reaction of d-ribose with canonical nucleobases (A, C, G and U) fails to yield ribonucleosides (rNs) in substantial amounts, the spontaneous origin of rNs and the subsequent synthesis of RNA remains an unsolved mystery. To this end, it has been suggested that RNA may have evolved from primitive genetic material (preRNA) composed of simpler prebiotic heterocycles that spontaneously form glycosidic bonds with ribose...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29164985/bio-soliton-model-that-predicts-non-thermal-electromagnetic-frequency-bands-that-either-stabilize-or-destabilize-living-cells
#18
J H Geesink, D K F Meijer
Solitons, as self-reinforcing solitary waves, interact with complex biological phenomena such as cellular self-organization. A soliton model is able to describe a spectrum of electromagnetism modalities that can be applied to understand the physical principles of biological effects in living cells, as caused by endogenous and exogenous electromagnetic fields and is compatible with quantum coherence. A bio-soliton model is proposed, that enables to predict which eigen-frequencies of non-thermal electromagnetic waves are life-sustaining and which are, in contrast, detrimental for living cells...
2017: Electromagnetic Biology and Medicine
https://www.readbyqxmd.com/read/29164858/circular-dichroism-of-cdse-nanocrystals-bound-by-chiral-carboxylic-acids
#19
Mayank Puri, Vivian E Ferry
Chiral semiconductor nanocrystals, or quantum dots (QDs), are promising materials for applications in biological sensing, photonics, and spin-polarized devices. Many of these applications rely on large dissymmetry, or g-factors, the difference in absorbance between left- and right-handed circularly polarized light compared to the unpolarized absorbance. The majority of chiral QDs, specifically CdSe, reported to date have used thiolated amino acid ligands to introduce chirality onto the nanoparticles, but these systems have ultimately reported small g-factors of ∼2 × 10(-4)...
November 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/29164479/spectro-analytical-computational-and-in-vitro-biological-studies-of-novel-substituted-quinolone-hydrazone-and-it-s-metal-complexes
#20
Narsimha Nagula, Sudeepa Kunche, Mohmed Jaheer, Ravi Mudavath, Sreekanth Sivan, Sarala Devi Ch
Some novel transition metal [Cu (II), Ni (II) and Co (II)] complexes of nalidixic acid hydrazone have been prepared and characterized by employing spectro-analytical techniques viz: elemental analysis, (1)H-NMR, Mass, UV-Vis, IR, TGA-DTA, SEM-EDX, ESR and Spectrophotometry studies. The HyperChem 7.5 software was used for geometry optimization of title compound in its molecular and ionic forms. Quantum mechanical parameters, contour maps of highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) and corresponding binding energy values were computed using semi empirical single point PM3 method...
November 21, 2017: Journal of Fluorescence
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