scholarly journals DNA-Biofunctionalization of CTAC-Capped Gold Nanocubes

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1119 ◽  
Author(s):  
Nicole Slesiona ◽  
Sophie Thamm ◽  
H. Lisa K. S. Stolle ◽  
Viktor Weißenborn ◽  
Philipp Müller ◽  
...  
Keyword(s):  
Ligand Exchange ◽  
Cetyltrimethylammonium Bromide ◽  
Clinical Diagnostics ◽  
Enhanced Fluorescence ◽  
Nanoparticle Surface ◽  
Modified Dna ◽  
Close Proximity ◽  
Biological Recognition ◽  
High Concentrations ◽  
Field Enhancements

Clinical diagnostics and disease control are fields that strongly depend on technologies for rapid, sensitive, and selective detection of biological or chemical analytes. Nanoparticles have become an integral part in various biomedical detection devices and nanotherapeutics. An increasing focus is laid on gold nanoparticles as they express less cytotoxicity, high stability, and hold unique optical properties with the ability of signal transduction of biological recognition events with enhanced analytical performance. Strong electromagnetic field enhancements can be found in close proximity to the nanoparticle that can be exploited to enhance signals for e.g., metal-enhanced fluorescence or Raman spectroscopy. Even stronger field enhancements can be achieved with sharp-edged nanoparticles, which are synthesized with the help of facet blocking agents, such as cetyltrimethylammonium bromide/chloride (CTAB/CTAC). However, chemical modification of the nanoparticle surface is necessary to reduce the particle’s cytotoxicity, stabilize it against aggregation, and to bioconjugate it with biomolecules to increase its biocompatibility and/or specificity for analytical applications. Here, a reliable two-step protocol following a ligand exchange with bis (p-sulfonatophenyl) phenyl phosphine (BSPP) as the intermediate capping-agent is demonstrated, which results in the reliable biofunctionalization of CTAC-capped gold nanocubes with thiol-modified DNA. The functionalized nanocubes have been characterized regarding their electric potential, plasmonic properties, and stability against high concentrations of NaCl and MgCl2.

scholarly journals Effective replacement of cetyltrimethylammonium bromide (CTAB) by mercaptoalkanoic acids on gold nanorod (AuNR) surfaces in aqueous solutions

Nanoscale ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 658-668 ◽  
Author(s):  
Rafael del Caño ◽  
Jose M. Gisbert-González ◽  
Jose González-Rodríguez ◽  
Guadalupe Sánchez-Obrero ◽  
Rafael Madueño ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Gold Nanorods ◽  
Ligand Exchange ◽  
Cetyltrimethylammonium Bromide ◽  
Gold Nanorod ◽  
Experimental Conditions ◽  
Seed Mediated ◽  
The Stability

The highly packed cetyltrimethylammonium bromide bilayer on the surface of gold nanorods synthesized by the seed-mediated procedure hampers the complete ligand exchange under experimental conditions that preserves the stability of the dispersions.

PEGylated AIEgen Molecular Probe for Hypoxia-Mediated Tumor Imaging and Photodynamic Therapy

2021 ◽  
Author(s):  
Jun Li ◽  
Wei Liu ◽  
Zhuhao Li ◽  
Yingcai Hu ◽  
Jinfeng Yang ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Tumor Imaging ◽  
Fluorescence Emission ◽  
Molecular Probe ◽  
Enhanced Fluorescence ◽  
High Concentrations

Unlike the aggregation caused quenching (ACQ) and reduced singlet oxygen (1O2) production of traditional photosensitizers at high concentrations, AIEgen photosensitizers show enhanced fluorescence emission and photosensitization ability in the aggregated...

scholarly journals Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label

2014 ◽  
Vol 10 ◽  
pp. 2166-2174 ◽  
Author(s):  
Nattawut Yotapan ◽  
Chayan Charoenpakdee ◽  
Pawinee Wathanathavorn ◽  
Boonsong Ditmangklo ◽  
Hans-Achim Wagenknecht ◽  
...  
Keyword(s):  
Optical Properties ◽  
Nucleic Acid ◽  
Peptide Nucleic Acid ◽  
Nile Red ◽  
Fluorescent Label ◽  
Dna Duplexes ◽  
Enhanced Fluorescence ◽  
Structure And Dynamics ◽  
Close Proximity ◽  
Base Insertion

DNA or its analogues with an environment-sensitive fluorescent label are potentially useful as a probe for studying the structure and dynamics of nucleic acids. In this work, pyrrolidinyl peptide nucleic acid (acpcPNA) was labeled at its backbone with Nile red, a solvatochromic benzophenoxazine dye, by means of click chemistry. The optical properties of the Nile red-labeled acpcPNA were investigated by UV–vis and fluorescence spectroscopy in the absence and in the presence of DNA. In contrast to the usual quenching observed in Nile red-labeled DNA, the hybridization with DNA resulted in blue shifting and an enhanced fluorescence regardless of the neighboring bases. More pronounced blue shifts and fluorescence enhancements were observed when the DNA target carried a base insertion in close proximity to the Nile red label. The results indicate that the Nile red label is located in a more hydrophobic environment in acpcPNA–DNA duplexes than in the single-stranded acpcPNA. The different fluorescence properties of the acpcPNA hybrids of complementary DNA and DNA carrying a base insertion are suggestive of different interactions between the Nile red label and the duplexes.

A Mechanism for Both Capacitative Ca2+ Entry and Excitation-Contraction Coupled Ca2+ Release by the Sarcoplasmic Reticulum of Skeletal Muscle Cells

2002 ◽  
Vol 227 (6) ◽  
pp. 425-431 ◽  
Author(s):  
Mohammad Naimul Islam ◽  
Bisni Narayanan ◽  
Raymond S. Ochs
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Muscle Cells ◽  
Cell Types ◽  
Release Channel ◽  
Close Proximity ◽  
High Concentrations ◽  
Combined Channel ◽  
Uncompetitive Inhibitor

We have previously established that L6 skeletal muscle cell cultures display capacitative calcium entry (CCE), a phenomenon established with other cells in which Ca2+ uptake from outside cells increases when the endoplasmic reticulum (sarcoplasmic reticulum in muscle, or SR) store is decreased. Evidence for CCE rested on the use of thapsigargin (Tg), an inhibitor of the SR CaATPase and consequently transport of Ca2+ from cytosol to SR, and measurements of cytosolic Ca2+. When Ca2+ is added to Ca2+-free cells in the presence of Tg, the measured cytosolic Ca2+ rises. This has been universally interpreted to mean that as SR Ca2+ is depleted, exogenous Ca2+ crosses the plasma membrane, but accumulates in the cytosol due to CaATPase inhibition. Our goal in the present study was to examine CCE in more detail by measuring Ca2+ in both the SR lumen and the cytosol using established fluorescent dye techniques for both. Surprisingly, direct measurement of SR Ca2+ in the presence of Tg showed an increase in luminal Ca2+ concentration in response to added exogenous Ca2+. While we were able to reproduce the conventional demonstration of CCE—an increase of Ca2+ in the cytosol in the presence of thapsigargin—we found that this process was inhibited by the prior addition of ryanodine (Ry), which inhibits the SR Ca2+ release channel, the ryanodine receptor (RyR). This was also unexpected if Ca2+ enters the cytosol first. When Ca2+ was added prior to Ry, the later was unable to exert any inhibition. This implies a competitive interaction between Ca2+ and Ry at the RyR. In addition, we found a further paradox: we had previously found Ry to be an uncompetitive inhibitor of Ca2+ transport through the RyR during excitation-contraction coupling. We also found here that high concentrations of Ca2+ inhibited its own uptake, a known feature of the RyR. We confirmed that Ca2+ enters the cells through the dihydropyridine receptor (DHPR, also known as the L-channel) by demonstrating inhibition by diltiazem. A previous suggestion to the contrary had used Mn2+ in place of direct Ca2+ measurements; we showed that Mn2+ was not inhibited by diltiazem and was not capacitative, and thus not an appropriate probe of Ca2+ flow in muscle cells. Our findings are entirely explained by a new model whereby Ca2+ enters the SR from the extracellular space directly through a combined channel formed from the DHPR and the RyR. These are known to be in close proximity in skeletal muscle. Ca2+ subsequently appears in the cytosol by egress through a separate, unoccupied RyR, explaining Ry inhibition. We suggest that upon excitation, the DHPR, in response to the electrical field of the plasma membrane, shifts to an erstwhile-unoccupied receptor, and Ca2+ is released from the now open RyR to trigger contraction. We discuss how this model also resolves existing paradoxes in the literature, and its implications for other cell types.

scholarly journals Evaluation of aerial technogenic pollution near industrial enterprises in the tundra zone (by the example of Vorkuta city)

2019 ◽  
pp. 94-105
Author(s):  
M. I. Vasilevich ◽  
R. S. Vasilevich ◽  
D. N. Gabov ◽  
B. M. Kondratenok
Keyword(s):  
Power Plant ◽  
Snow Cover ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
Quantitative Chemical Analysis ◽  
Space Images ◽  
Industrial Enterprises ◽  
Coal Particles ◽  
Close Proximity ◽  
High Concentrations

The quantitative chemical analysis of snow cover has been carried out for the Vorkuta agglomeration territory. The on-site ingress of pollutants in close proximity to industrial enterprises in Vorkuta is calculated. The schematic maps of substance distribution in snow in the studied area are built using space images. The control levels of aerotechnogenic pollution are established for the city, industrial zones and adjacent territories for the purpose of subsequent ecological monitoring. The pH value of snowmelt water reaches 6.5-7.2 due to a high content of alkaline components (calcium and magnesium carbonates) in snow. The snow cover of the Vorkuta agglomeration is highly enriched with heavy metals. The maximum permissible concentrations are exceeded for manganese, nickel, aluminum, vanadium, molybdenum and mercury. High concentrations of mercury in snow are supposedly related to coal combustion at the thermal power plant. After that mercury may be occluded on a surface of coal particles and ashes. It is shown that it is possible to establish the zones of the greatest aerogenic impact according to the content of mercury and vanadium in the snow. Factor analysis was used to identify the mechanisms of pollutants and factors forming the chemical composition of the snow cover. The share of elements in the suspended solids is more than 60% of their total content in snowmelt water. High concentrations of suspended particles (up to 720 mg/dm3) were observed in the snow of Vorkuta. The most severe pollution of the snow cover is registered in close proximity to thermal power plant №2. According to the calculations of the total pollution index, the highest excess of substance increment over the background level was noted in the sanitary protection zone around the thermal power plant №2.

scholarly journals Application of cellular and artificial membranes in nanomedicine

2020 ◽  
Vol 15 (4) ◽  
pp. 290-299
Author(s):  
Mikhail Galkin ◽  
Keyword(s):  
Targeted Drug Delivery ◽  
Lipid Membranes ◽  
Plasma Membranes ◽  
Vaccine Development ◽  
Therapeutic Potential ◽  
Cell Types ◽  
Clinical Diagnostics ◽  
Advantages And Disadvantages ◽  
Nanoparticle Surface ◽  
Diagnostics And Therapy

The use of nanoparticles in treatment and diagnostics of a number of disorders is becoming more and more popular. Further investigations are needed for improving the specificity of nanoparticle action, precisely targeted drug delivery, decreasing opsonization of nanoparticles by macrophages. Numerous ways of nanoparticle surface modification have been successfully tested for increasing their therapeutic potential and reducing possible side effects. Nanoparticle encapsulation using plasma membranes of red blood cells as well as other cell types has been recently introduced. This field of translational medicine substantially expands opportunities for nanoparticle application in clinical diagnostics and therapy of cancer, cardiovascular diseases, in vaccine development etc. This review focuses on ways, advantages and disadvantages of using cellular membranes in nanomedicine. Application of artificial lipid membranes in nanoparticles encapsulation is proposed.

Maintenance of quantal size and immediately releasable granules in rat chromaffin cells by glucocorticoid

2005 ◽  
Vol 289 (5) ◽  
pp. C1122-C1133 ◽  
Author(s):  
Jianhua Xu ◽  
Kim San Tang ◽  
Van B. Lu ◽  
Chandana P. Weerasinghe ◽  
Amy Tse ◽  
...  
Keyword(s):  
Chromaffin Cells ◽  
Flash Photolysis ◽  
Defined Medium ◽  
Quantal Size ◽  
Close Proximity ◽  
Different Populations ◽  
High Concentrations ◽  
Paracrine Actions ◽  
Cells Cultured

Glucocorticoid is reported to regulate catecholamine synthesis and storage. However, it is not clear whether the actual amount of catecholamine released from individual granules (quantal size, Q) in mature chromaffin cells is affected by glucocorticoid. Using carbon fiber amperometry, we found that dexamethasone did not affect mean cellular Q or the proportional release from different populations of granules in rat chromaffin cells cultured for 1 day in a serum-free defined medium. After two extra days of culture in the defined medium, there was a rundown in mean cellular Q, and it was associated with a shift in the proportional release from the different granule populations. This phenomenon could not be rescued by serum supplementation but could be prevented by dexamethasone via an action that was independent of changes in voltage-gated Ca2+ channel (VGCC) density. Using simultaneous measurements of membrane capacitance and cytosolic Ca2+ concentration, we found that for cells cultured in defined medium dexamethasone enhanced the exocytotic response triggered by a brief depolarization (50 ms) without affecting the VGCC density or the fast exocytotic response triggered via flash photolysis of caged Ca2+. Thus glucocorticoid may regulate the number of immediately releasable granules that are in close proximity to a subset of VGCC. Because chromaffin cells in vivo are exposed to high concentrations of glucocorticoid, our findings suggest that the paracrine actions of glucocorticoid maintain the mean catecholamine content in chromaffin cell granules as well as the colocalization of releasable granules with VGCCs.

Carbon nanodots as ligand exchange probes in Au@C-dot nanobeacons for fluorescent turn-on detection of biothiols

Nanoscale ◽  
2015 ◽  
Vol 7 (5) ◽  
pp. 1802-1808 ◽  
Author(s):  
Sonam Mandani ◽  
Bhagwati Sharma ◽  
Deepa Dey ◽  
Tridib K. Sarma
Keyword(s):  
Ligand Exchange ◽  
Au Nanoparticle ◽  
Carbon Nanodots ◽  
Turn On ◽  
Nanoparticle Surface

Au@C-dot nanocomposite functions as a fluorescent turn-on sensor for the selective assay of biothiols based on ligand exchange occurring on the Au nanoparticle surface and replacement of C-dots.

scholarly journals Facile phase transfer of gold nanorods and nanospheres stabilized with block copolymers

2018 ◽  
Vol 9 ◽  
pp. 616-627 ◽  
Author(s):  
Yaroslav I Derikov ◽  
Georgiy A Shandryuk ◽  
Raisa V Talroze ◽  
Alexander A Ezhov ◽  
Yaroslav V Kudryavtsev
Keyword(s):  
Ligand Exchange ◽  
Au Nanoparticles ◽  
Phase Transfer ◽  
Hybrid Composites ◽  
Transmission Electron Microscopy Data ◽  
Optical Absorbance ◽  
Nanoparticle Surface ◽  
Transmission Electron ◽  
Fast Route ◽  
Microscopy Data

A fast route to transfer Au nanoparticles from aqueous to organic media is proposed based on the use of a high molecular mass diblock copolymer of styrene and 2-vinylpyridine for ligand exchange at the nanoparticle surface. The method enables the preparation of stable sols of Au nanorods with sizes of up to tens of nanometers or Au nanospheres in various organic solvents. By comparing the optical absorbance spectra of Au hydro- and organosols with the data of numerical simulations of the surface plasmon resonance, we find that nanoparticles do not aggregate and confirm the transmission electron microscopy data regarding their shape and size. The proposed approach can be effective in preparing hybrid composites without the use of strong thiol and amine surfactants.

scholarly journals High concentrations of a novel peptide, neuropeptide Y, in the innervation of mouse and rat heart.

1984 ◽  
Vol 32 (5) ◽  
pp. 467-472 ◽  
Author(s):  
J Gu ◽  
J M Polak ◽  
J M Allen ◽  
W M Huang ◽  
M N Sheppard ◽  
...  
Keyword(s):  
Neuropeptide Y ◽  
Rat Heart ◽  
High Performance ◽  
Cardiac Tissue ◽  
Close Association ◽  
Mouse Heart ◽  
Close Proximity ◽  
Identical Position ◽  
High Concentrations ◽  
Noradrenergic Fibers

A newly discovered bioactive peptide, neuropeptide Y (NPY), has been found in the innervation of the mouse and rat heart by immunocytochemistry, NPY-immuno-reactive nerves were very dense around the nodal tissues. They also surrounded the coronary arteries and arterioles and were found in close association with the cardiac muscle. The distribution of NPY-containing nerves paralleled that of noradrenergic fibers, demonstrated by the use of antibodies to the catecholamine-converting enzymes tyrosine hydroxylase and dopamine beta-hydroxylase. Furthermore, NPY was seen to be present in a proportion of intrinsic neurons mostly found in the atria and in close proximity to the nodal tissue. The concentrations of extractable NPY-immunoreactive material (about 150 pmol/g in whole mouse heart) by far surpasses those of the other peptides so far reported in the cardiac tissue. High performance liquid chromatography demonstrated the NPY immunoreactivity to elute in a single sharp peak, in an identical position to brain NPY.

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