An overview of gastrointestinal mucus rheology under different pH conditions and introduction to pH-dependent rheological interactions with PLGA and chitosan nanoparticles

2020 ◽  
Author(s):  
Gustavo Ruiz-Pulido ◽  
Dora I. Medina
Keyword(s):  
Chitosan Nanoparticles ◽  
Mucus Rheology ◽  
Ph Conditions ◽  
Ph Dependent

scholarly journals Systematic exploration of the pH dependence of a peptide hydrogel

2019 ◽  
Vol 97 (6) ◽  
pp. 430-434 ◽  
Author(s):  
Natashya Falcone ◽  
Tsuimy Shao ◽  
Xiaoyi Sun ◽  
Heinz-Bernhard Kraatz
Keyword(s):  
Mechanical Strength ◽  
Narrow Range ◽  
Ph Dependence ◽  
Stimuli Responsive ◽  
Systematic Exploration ◽  
Ph Conditions ◽  
Ph Dependent ◽  
Functional Biomaterials ◽  
Peptide Hydrogel

Stimuli-responsive peptide gels are a growing class of functional biomaterials that are involved in many applications in research. Here, we present a novel di-peptide hydrogel from the compound Boc–Phe–Trp–OH in various buffer and pH conditions. We examine the effects of different stimuli, including temperature and pH, on the mechanical strength of the gels through frequency rheology studies. We found that this hydrogelator is highly pH dependent, only forming a gel in a narrow range of pH 6–7. This hydrogelator hold promise for the development of new stimuli-responsive biomaterials for specific applications that require this type of specific stimuli.

Phloretin loaded chitosan nanoparticles augments the pH-dependent mitochondrial-mediated intrinsic apoptosis in human oral cancer cells

2019 ◽  
Vol 130 ◽  
pp. 997-1008 ◽  
Author(s):  
Arokia Vijaya Anand Mariadoss ◽  
Ramachandran Vinayagam ◽  
Vijayalakshmi Senthilkumar ◽  
Manickam Paulpandi ◽  
Kadarkarai Murugan ◽  
...  
Keyword(s):  
Oral Cancer ◽  
Cancer Cells ◽  
Chitosan Nanoparticles ◽  
Intrinsic Apoptosis ◽  
Ph Dependent ◽  
Oral Cancer Cells

scholarly journals A New pH-Dependent Macrocyclic Rhodamine B-Based Fluorescent Probe for Copper Detection in White Wine

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4514 ◽  
Author(s):  
Nour Doumani ◽  
Elias Bou-Maroun ◽  
Jacqueline Maalouly ◽  
Maya Tueni ◽  
Adrien Dubois ◽  
...  
Keyword(s):  
Rhodamine B ◽  
White Wine ◽  
Green Solvent ◽  
Acidic Media ◽  
One Pot ◽  
Acidic Conditions ◽  
Ph Conditions ◽  
Ph Dependent ◽  
Copper Detection ◽  
Color Emission

For efficiently measuring copper (II) ions in the acidic media of white wine, a new chemosensor based on rhodamine B coupled to a tetraazamacrocyclic ring (13aneN4CH2NH2) was designed and synthesized by a one-pot reaction using ethanol as a green solvent. The obtained chemosensor was characterized via NMR, UV and fluorescent spectra. It was marked with no color emission under neutral pH conditions, with a pink color emission under acidic conditions, and a magenta color emission under acidic conditions where copper (II) ions were present. The sensitivity towards copper (II) ions was tested and verified over Ca2+, Ag+, Zn2+, Mg2+, Co2+, Ni2+, Fe2+, Pb2+, Cd2+, Fe3+, and Mn2+, with a detection limit of 4.38 × 10−8 M in the fluorescence spectrum.

scholarly journals Activation of Fusion by the SER Virus F Protein: a Low-pH-Dependent Paramyxovirus Entry Process

2003 ◽  
Vol 77 (11) ◽  
pp. 6520-6527 ◽  
Author(s):  
Shaguna Seth ◽  
Annelet Vincent ◽  
R. W. Compans
Keyword(s):  
Elevated Temperatures ◽  
Protein A ◽  
Syncytium Formation ◽  
Simian Virus ◽  
Low Ph ◽  
F Protein ◽  
Simian Virus 5 ◽  
Cytoplasmic Content ◽  
Ph Conditions ◽  
Ph Dependent

ABSTRACT SER virus, a paramyxovirus closely related to simian virus 5, induces no syncytium formation. The SER virus F protein has a long cytoplasmic tail (CT), and truncation or mutations of the CT result in enhanced syncytium formation (S. Seth, A. Vincent, and R. W. Compans, J. Virol. 77:167-178, 2003; S. Tong, M. Li, A. Vincent, R. W. Compans, E. Fritsch, R. Beier, C. Klenk, M. Ohuchi, and H.-D. Klenk, Virology 301:322-333, 2002). We hypothesized that the presence of the long CT serves to stabilize the metastable conformation of the F protein. We observed that the hemifusion, cytoplasmic content mixing, and syncytium formation ability of the wild-type SER virus F coexpressed with the SER virus hemagglutinin-neuraminidase (HN) protein was enhanced, both qualitatively and quantitatively, at elevated temperatures. We also observed enhanced hemifusion, content mixing, and syncytium formation in SER virus F- and HN-expressing cells at reduced pH conditions ranging between 4.8 and 6.2. We have obtained evidence that in contrast to other paramyxoviruses, entry of SER virus into cells occurs by a low-pH-dependent process, indicating that the conversion to the fusion-active state for SER virus F is triggered by exposure to reduced pH.

scholarly journals Supramolecular polyelectrolyte complex (SPEC): pH dependent phase transition and exploitation of its carrier properties

Soft Matter ◽  
2016 ◽  
Vol 12 (7) ◽  
pp. 1989-1997 ◽  
Author(s):  
Subharanjan Biswas ◽  
Ethayaraja Mani ◽  
Arobendo Mondal ◽  
Ashwani Tiwari ◽  
Soumyajit Roy
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Polyacrylic Acid ◽  
Polyelectrolyte Complex ◽  
Ph Conditions ◽  
Ph Dependent

A supramolecular polyelectrolyte complex (SPEC) consisting of polyacrylic acid and guanidine is reported which can carry functional moieties like drugs and dyes and release them in certain pH conditions owing to pH dependent phase transitions of the complex.

Electrochemical and Spectroelectrochemical Characterization of Water-soluble, β-Pyrrolebrominated Cobalt Porphyrins

1998 ◽  
Vol 02 (05) ◽  
pp. 429-437 ◽  
Author(s):  
FRANCIS D'SOUZA ◽  
YI-YING HSIEH ◽  
G. R. DEVIPRASAD
Keyword(s):  
Water Soluble ◽  
Redox Couple ◽  
Redox Potentials ◽  
Complete Elimination ◽  
Porphyrin Derivatives ◽  
Cobalt Porphyrins ◽  
Bulk Electrolysis ◽  
Ph Conditions ◽  
Ph Dependent

The electrochemical and spectroelectrochemical characterization of two water-soluble porphyrins, namely the tetrachloro salt of cobalt(II) tetrakis-(N-methyl pyridyl)-β-octabromoporphyrin, [( Br 8 TMPyP ) Co II] Cl 4, and the tetrasodium salt of cobalt(II) tetrakis-(4-sulfonatophenyl)-β-octabromoporphyrin, Na 4[( Br 8 TPPS ) Co II], under different pH conditions is reported. The investigated porphyrins are highly non-planar and electron-deficient owing to the presence of eight bromides at the β-pyrrole positions and the four meso-aryl substituents. The redox potentials corresponding to the first oxidation and first reduction are shifted positively compared with the redox potentials of the respective unbrominated porphyrin derivatives. Spectroelectrochemical studies reveal the formation of a cobalt(III) complex during the first oxidation of both cobalt porphyrins. The first reduction of Br 8 TPPS ) Co II]4− results in a cobalt(I) complex, while involvement of the peripheral N-methyl pyridyl groups in the case of Br 8 TMPyP ) Co II]4+ is suggested. The peak potentials of the first oxidation corresponding to a Co II/ Co III redox couple of both investigated compounds are found to be pH-dependent. Debromination of the β-pyrrole bromo substituents of Br 8 TMPyP ) Co II]4+ at more negative potentials is observed. The UV-vis spectrum obtained after bulk electrolysis of Br 8 TMPyP ) Co II]4+ at −1.0 V vs Ag / AgCl followed by reoxidation at 0.2 V indicates complete elimination of the bromo substituents of the porphyrin periphery.

scholarly journals The Application of Reversible Intramolecular Sulfonamide Ligation to Modulate Reactivity in Organometallic Ruthenium(II) Diamine Complexes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 244
Author(s):  
Samuel A. Kemp ◽  
Timothy J. Prior ◽  
Huguette Savoie ◽  
Ross W. Boyle ◽  
Benjamin S. Murray
Keyword(s):  
Healthy Tissue ◽  
Central Metal Atom ◽  
Dependent Manner ◽  
Central Metal ◽  
Coordination Environment ◽  
Typical Cell ◽  
Arene Ligand ◽  
Ph Conditions ◽  
Ph Dependent

Metallation of biomacromolecular species forms the basis for the anticancer activity of many metallodrugs. A major limitation of these compounds is that their reactivity is indiscriminate and can, in principle, occur in healthy tissue as well as cancerous tissue, potentially leading to side effects in vivo. Here we present pH-dependent intramolecular coordination of an arene-tethered sulfonamide functionality in organometallic ruthenium(II) ethylenediamine complexes as a route to controlling the coordination environment about the central metal atom. Through variation of the sulfonamide R group and the length of the tether linking it to the arene ligand the acidity of the sulfonamide NH group, and hence the pH-region over which regulation of metal coordination occurs, can be modulated. Intramolecular sulfonamide ligation controlled the reactivity of complex 4 within the physiologically relevant pH-region, rendering it more reactive towards 5ʹ-GMP in mildly acidic pH-conditions typical of tumour tissue compared to the mildly alkaline pH-conditions typical of healthy tissue. However, the activation of 4 by ring-opening of the chelate was found to be a slow process relative to the timescale of typical cell culture assays and members of this series of complexes were found not to be cytotoxic towards the HT-29 cell line. These complexes provide the basis for the development of analogues of increased potency where intramolecular sulfonamide ligation regulates reactivity and therefore cytotoxicity in a pH-dependent, and potentially, tissue-dependent manner.

Impacts of pH-dependent metal speciation on the decomposition of triclosan by sulfate radicals

2012 ◽  
Vol 12 (6) ◽  
pp. 837-843 ◽  
Author(s):  
Prince Nfodzo ◽  
Qinhong Hu ◽  
Hyeok Choi
Keyword(s):  
Endocrine Disruption ◽  
Metal Speciation ◽  
Decomposition Kinetics ◽  
Sulfate Radicals ◽  
Ph Conditions ◽  
Ph Dependent ◽  
Kinetics Of ◽  
Potential Threshold ◽  
Significant Attention

The presence of triclosan (TCS) in water resources has drawn significant attention due to its endocrine disruption potential. Sulfate radicals (SRs), generated particularly by the metal-mediated activation of peroxymonosulfate (PMS), have been proposed to effectively decompose TCS and many other pharmaceuticals and personal care products. In spite of its significance for understanding the efficiency of SR generation and catalytic/non-catalytic nature of the oxidation reaction, metal speciation has not been adequately highlighted in previous studies. This study investigated the detailed changes in metal speciation in cobalt/PMS and iron/PMS systems and correlated it with TCS decomposition under different pH conditions. A rapid oxidation of Co2+ to Co3+ and Fe2+ to Fe3+ generally corresponded with pseudo-steady state decomposition kinetics of TCS after its initial fast decomposition. The presence of potential threshold concentrations of metals to effectively activate PMS was found. A strong catalytic activity was observed for Co/PMS system at pH 3, where most of Co was present in the form of dissolved Co2+. The pH impacts were different for Co/PMS and Fe/PMS. TCS oxidation was fast at pH 5 for Co and pH 3 for Fe. However, long-term mineralization of TCS seemed less dependent on pH.

pH-dependent structural changes in haemoglobin component V from the midge larvaPropsilocerus akamusi(Orthocladiinae, Diptera)

2010 ◽  
Vol 66 (3) ◽  
pp. 258-267 ◽  
Author(s):  
Takao Kuwada ◽  
Tomokazu Hasegawa ◽  
Takashi Takagi ◽  
Isamu Sato ◽  
Fumio Shishikura
Keyword(s):  
Functional Properties ◽  
Structural Changes ◽  
Ph Dependence ◽  
Oxygen Affinity ◽  
Side Chain ◽  
Ligand Molecule ◽  
Distal Side ◽  
Ph Conditions ◽  
Ph Dependent ◽  
Dependent Behaviour

Haemoglobin component V (Hb V) from the midge larvaPropsilocerus akamusiexhibits oxygen affinity despite the replacement of HisE7 and a pH-dependence of its functional properties. In order to understand the contribution of the distal residue to the ligand-binding properties and the pH-dependent structural changes in this insect Hb, the crystal structure of Hb V was determined under five different pH conditions. Structural comparisons of these Hb structures indicated that at neutral pH ArgE10 contributes to the stabilization of the haem-bound ligand molecule as a functional substitute for the nonpolar E7 residue. However, ArgE10 does not contribute to stabilization at acidic and alkaline pH because of the swinging movement of the Arg side chain under these conditions. This pH-dependent behaviour of Arg results in significant differences in the hydrogen-bond network on the distal side of the haem in the Hb V structures at different pH values. Furthermore, the change in pH results in a partial movement of the F helix, considering that coupled movements of ArgE10 and the F helix determine the haem location at each pH. These results suggested that Hb V retains its functional properties by adapting to the structural changes caused by amino-acid replacements.

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