scholarly journals Solvent Effects in Highly Efficient Light-Induced Molecular Aggregation

2019 ◽  
Vol 9 (24) ◽  
pp. 5381 ◽  
Author(s):  
Masayuki Shirakawa ◽  
Takayoshi Kobayashi ◽  
Eiji Tokunaga
Keyword(s):  
Aqueous Solution ◽  
Ethanol Solution ◽  
Gradient Force ◽  
Molecular Aggregation ◽  
Irradiation Intensity ◽  
Dipole Interactions ◽  
Absorbance Change ◽  
Irradiation Volume ◽  
Induced Aggregation ◽  
Close Distance

It has been reported that when irradiated with laser light non-resonant with the main absorption peaks, porphyrin molecules (4-[10,15,20-tris(4-sulfophenyl)-21,24-dihydroporphyrin-5-yl]benzenesulfonic acid, TPPS) in an aqueous solution become 10,000 to 100,000 times more efficient in light-induced molecular aggregation than expected from the ratio of gradient force potential to the thermal energy of molecules at room temperature. To determine the mechanism of this phenomenon, experiments on the light-induced aggregation of TPPS in alcohol solutions (methanol, ethanol, and butanol) were performed. In these alcohol solutions, the absorbance change was orders of magnitude smaller than in the aqueous solution. Furthermore, it was found that the absorbance change in the aqueous solution tended to be saturated with the increase of the irradiation intensity, but in the ethanol solution, the absorbance change increased linearly. These results can be qualitatively explained by the model in which intermolecular light-induced interactions between molecules within a close distance among randomly distributed molecules in the laser irradiation volume are highly relevant to the signal intensity. However, conventional dipole–dipole interactions, such as the Keesom interaction, are not quantitatively consistent with the results.

scholarly journals Efficient Molecular Aggregation of Rhodamine 6G and Pseudoisocyanine by Light-Induced Force

2020 ◽  
Vol 10 (10) ◽  
pp. 3563
Author(s):  
Masayuki Shirakawa ◽  
Takayoshi Kobayashi ◽  
Eiji Tokunaga
Keyword(s):  
Thermal Equilibrium ◽  
Room Temperature ◽  
Rhodamine 6G ◽  
Gradient Force ◽  
Molecular Aggregation ◽  
Benzenesulfonic Acid ◽  
Absorbance Changes ◽  
Lock In ◽  
Induced Aggregation ◽  
Force Potential

A highly efficient light-induced aggregation of porphyrin molecules in solution was recently reported for 4-[10,15,20-tris(4-sulfophenyl)-21,24-dihydroporphyrin-5-yl]benzenesulfonic acid (TPPS). Here, we demonstrate that rhodamine 6G (R6G) and pseudoisocyanine (PIC) also show efficient light-induced aggregation in unsaturated aqueous solution, being detected with a multichannel lock-in amplifier as the absorbance decrease/increase in the monomers/aggregates, induced by a laser at 633 nm, which is non-resonant off their main monomer absorption wavelengths. The light-induced aggregation states are H-aggregates that are hardly formed in the thermal equilibrium. The similar absorbance changes are absent in the monomer molecules fixed in polyvinyl alcohol (PVA) films. The aggregation efficiency defined as ( Δ A / A ) / ( U t r a p / k B T ) , where A is the absorbance of the monomers, Δ A is the absorbance increase in the aggregates, U t r a p is the optical gradient force potential, and k B T is the thermal energy at room temperature, is approximately 100 for R6G and 500 for PIC, which are much smaller than that of TPPS.

scholarly journals Thermoresponsive Polymers as Macromolecular Coordination Ligands: Complexation-Dependence of Thermally Induced Aggregation in Aqueous Solution

2021 ◽  
Author(s):  
Maximilian Felix Toni Meier ◽  
Franck Thetiot ◽  
Narsimhulu Pittala ◽  
Ingo Lieberwirth ◽  
Cleiton Kunzler ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermoresponsive Polymers ◽  
Thermally Induced ◽  
Coordination Sites ◽  
Induced Aggregation

We have designed novel macromolecular coordination ligands (MCLs) by conjugation of thermoresponsive polymers based on poly(N-isopropylacrylamide) (M ̅_n around 3 to 25 kg∙mol-1) with 1,2,4-triazole coordination sites. These triazole units...

A Small-Angle X-Ray Scattering Study on Pre-Irradiated Malate Synthase. The Influence of Formate, Superoxide Dismutase, and Catalase on the X-Ray Induced Aggregation of the Enzyme

1985 ◽  
Vol 40 (5-6) ◽  
pp. 364-372 ◽  
Author(s):  
P. Zipper ◽  
R. Wilfing ◽  
M. Kriechbaum ◽  
H. Durchschlag
Keyword(s):  
Aqueous Solution ◽  
Superoxide Dismutase ◽  
Small Angle ◽  
Malate Synthase ◽  
X Ray ◽  
X Ray Scattering ◽  
X Irradiation ◽  
The Mean ◽  
Induced Aggregation ◽  
Ray Scattering

Abstract The sulfhydryl enzyme malate synthase from baker’s yeast was X-irradiated with 6 kGy in air-saturated aqueous solution (enzyme concentration: ≃ 10 mg/ml; volume: 120 μl), in the absence or presence of the specific scavengers formate, superoxide dismutase, and catalase. After X-irradiation, a small aliquot of the irradiated solutions was tested for enzymic activity while the main portion was investigated by means of small-angle X-ray scattering. Additionally, an unir­radiated sample without additives was investigated as a reference. Experiments yielded the fol­lowing results: 1. X-irradiation in the absence of the mentioned scavengers caused considerable aggregation, fragmentation, and inactivation of the enzyme. The dose Dt37 for total (= repairable + non­-repayable) inactivation resulted as 4.4 kGy. The mean radius of gyration was found to be about 13 nm. The mean degree of aggregation was obtained as 5.7, without correction for fragmenta­tion. An estimation based on the thickness factor revealed that about 19% of material might be strongly fragmented. When this amount of fragments was accordingly taken into account, a value of 7.1 was obtained as an upper limit for the mean degree of aggregation. The observed retention of the thickness factor and the finding of two different cross-section factors are in full accord with the two-dimensional aggregation model established previously (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99 - 121 (1980)). 2. The presence of catalytic amounts of superoxide dismutase and/or catalase, in the absence of formate, during X-irradiation reduced both aggregation and inactivation significantly. 3. The presence of formate (10 or 100 mᴍ) during X-irradiation led to a strong decrease of aggregation and inactivation. This effect was more pronounced with the higher formate concen­tration or when superoxide dismutase and/or catalase were simultaneously present during X-irradiation. The presence of formate also reduced the amount of fragments significantly. 4. The results clearly show that the aggregation and inactivation of malate synthase upon X-irradiation in aqueous solution are mainly caused by OH·; to a minor extent O·̄2 and H2O2 are additionally involved in the damaging processes.

Target induced aggregation of modified Au@Ag nanoparticles for surface enhanced Raman scattering and its ultrasensitive detection of arsenic(iii) in aqueous solution

RSC Advances ◽  
2015 ◽  
Vol 5 (95) ◽  
pp. 77755-77759 ◽  
Author(s):  
Bo Yang ◽  
Xiaochun Chen ◽  
Renyong Liu ◽  
Bianhua Liu ◽  
Changlong Jiang
Keyword(s):  
Aqueous Solution ◽  
Spectroscopic Technique ◽  
Ultrasensitive Detection ◽  
Selective Detection ◽  
Raman Spectroscopic ◽  
Highly Sensitive ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Induced Aggregation

A highly sensitive and selective detection of As(iii) was reported by target induced aggregation of nanoparticles enhanced Raman spectroscopic technique.

scholarly journals Adsorption of Acid Dyes from Aqueous Solution on a Chitosan-cotton Composite Material Prepared by a New Pad-dry Process

2011 ◽  
Vol 6 (3) ◽  
pp. 155892501100600 ◽  
Author(s):  
Mahjoub Jabli ◽  
Mohamed Hassen V. Baouab ◽  
Mohamed Sadok Roudesli ◽  
Aghleb Bartegi
Keyword(s):  
Aqueous Solution ◽  
Indigo Carmine ◽  
Langmuir Equation ◽  
Acid Dyes ◽  
Chain Molecules ◽  
Dry Process ◽  
Dipole Interactions ◽  
Cure Time ◽  
Recovery Angle ◽  
Acid Blue

In this paper, we developed a method that may be considered as an easy and economical way to prepare chitosan-cotton composite (CH-cotton) materials using an electrolytes-free pad-dry process in which the cure step was performed in an oven microwave to provide a cotton fabric with greatly enhanced affinity for acid dyes. Evidence of successful interaction between cotton and CH through formation of hydrogen bonding and/or ion dipole interactions was analysed by FTIR spectroscopy. Influence of cure time onto the weight per surface unit of samples has been studied and five CH-cotton composite materials with different %CH content (I-V) were prepared. Crosslinking of cellulosic chain molecules of cotton fiber through CH segments was confirmed by Wrinkle Recovery Angle (WRA) and Tensile properties measurements. CH-cotton samples were then tested as adsorbent of four acid dyes from no-electrolytes aqueous solution [Indigo Carmine (AB74), Acid Red 183 (AR183), Acid Blue 161 (AB161) and Acid Yellow 17 (AY17)]. Results were monitored using, reflectance spectro-colorimeter and spectrophotometer analyses. Data obtained with treated cotton showed better dye exhaustion than obtained with untreated one. The modelling of the adsorption isotherms was performed by Langmuir equation and the thermodynamic parameters were evaluated. Globally, the lack of affinity of cotton for acid dyes is widely overcome by the use of low %CH content ranging from 0.079 to 0.515

scholarly journals Design and Characterization of Ethosomes for Transdermal Delivery of Caffeic Acid

Pharmaceutics ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 740
Author(s):  
Supandeep Singh Hallan ◽  
Maddalena Sguizzato ◽  
Paolo Mariani ◽  
Rita Cortesi ◽  
Nicolas Huang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Caffeic Acid ◽  
High Performance ◽  
Drug Stability ◽  
Ethanol Solution ◽  
Correlation Spectroscopy ◽  
Poloxamer 407 ◽  
Transdermal Administration ◽  
Antioxidant Power ◽  
Acid Diffusion

The present investigation describes a formulative study aimed at designing ethosomes for caffeic acid transdermal administration. Since caffeic acid is characterized by antioxidant potential but also high instability, its encapsulation appears to be an interesting strategy. Ethosomes were produced by adding water into a phosphatidylcholine ethanol solution under magnetic stirring. Size distribution and morphology of ethosome were investigated by photon correlation spectroscopy, small-angle X-ray spectroscopy, and cryogenic transmission electron microscopy, while the entrapment capacity of caffeic acid was evaluated by high-performance liquid chromatography. Caffeic acid stability in ethosome was compared to the stability of the molecule in water, determined by mass spectrometry. Ethosome dispersion was thickened by poloxamer 407, obtaining an ethosomal gel that was characterized for rheological behavior and deformability. Caffeic acid diffusion kinetics were determined by Franz cells, while its penetration through skin, as well as its antioxidant activity, were evaluated using a porcine skin membrane–covered biosensor based on oxygen electrode. Ethosome mean diameter was ≈200 nm and almost stable within three months. The entrapment of caffeic acid in ethosome dramatically prolonged drug stability with respect to the aqueous solution, being 77% w/w in ethosome after six months, while in water, an almost complete degradation occurred within one month. The addition of poloxamer slightly modified vesicle structure and size, while it decreased the vesicle deformability. Caffeic acid diffusion coefficients from ethosome and ethosome gel were, respectively, 137- and 33-fold lower with respect to the aqueous solution. At last, the caffeic acid permeation and antioxidant power of ethosome were more intense with respect to the simple solution.

scholarly journals Silicone Oil- and Agitation-Induced Aggregation of a Monoclonal Antibody in Aqueous Solution

2009 ◽  
Vol 98 (9) ◽  
pp. 3167-3181 ◽  
Author(s):  
Renuka Thirumangalathu ◽  
Sampathkumar Krishnan ◽  
Margaret Speed Ricci ◽  
David N. Brems ◽  
Theodore W. Randolph ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Monoclonal Antibody ◽  
Silicone Oil ◽  
Induced Aggregation

Oil-Induced Aggregation of Block Copolymer in Aqueous Solution

2007 ◽  
Vol 111 (38) ◽  
pp. 11140-11148 ◽  
Author(s):  
Jun-he Ma ◽  
Yun Wang ◽  
Chen Guo ◽  
Hui-zhou Liu ◽  
Ya-lin Tang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Block Copolymer ◽  
Induced Aggregation

The aniline catalysed decarboxylation of oxaloacetic acid

1965 ◽  
Vol 18 (3) ◽  
pp. 337 ◽  
Author(s):  
RW Hay
Keyword(s):  
Aqueous Solution ◽  
Transition State ◽  
Ethanol Solution ◽  
Keto Group ◽  
Fast Process ◽  
Schiff’S Base ◽  
Oxaloacetic Acid ◽  
Single Proton ◽  
Rate Determining Step ◽  
Rate Profile

Aniline catalysis of the decarboxylation of oxaloacetic acid, HO2CCOCH2CO2H + CH3COCO2H + CO2, has been studied in water and ethanol as solvent at 25�. In aqueous solution a maximum occurs in the pH-rate profile at pH 3.9, indicating the participation of a single proton in the transition state. Experiments with the half ester HO2CCOCH2CO2Et, which does not decarboxylate in the presence of amines, suggest that in aqueous solution the intermediate in the reaction is a carbinolamine formed between the amine and the keto group of the acid, and not a Schiff's base as has been previously suggested. In ethanol solution the intermediate is a Schiff's base, and formation of the Schiff's base is the rate-determining step, the actual decarboxylation being a fast process.

scholarly journals Temperature Induced Aggregation and Clouding in Humic Acid Solutions

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Leah Shaffer ◽  
Ray von Wandruszka
Keyword(s):  
Aqueous Solution ◽  
Light Scattering ◽  
Humic Acid ◽  
Dynamic Light Scattering ◽  
Acid Solutions ◽  
Inverse Temperature ◽  
Mechanical Agitation ◽  
Coulombic Repulsion ◽  
Polarity Sensitive ◽  
Induced Aggregation

Humic acids in aqueous solution demonstrate inverse temperature-solubility relationships when solution conditions are manipulated to reduce coulombic repulsion among the humic polyanions. These effects were followed by dynamic light scattering (DLS) measurements of the resulting aggregates, as well as the addition of a polarity sensitive fluorescent probe (pyrene). The humic solutions could be primed for temperature induced clouding by carefully lowering the pH to a point where hydration effects became dominant. The exact value of the cloud point (CP) was a function of both pH and humate concentration. The CPs mostly lay in the range 50–90°C, but DLS showed that temperature induced aggregation proceeded from approximately 30°C onward. Similar effects could be achieved by adding multivalent cations at concentrations below those which cause spontaneous precipitation. The declouding of clouded humate solutions could be affected by lowering the temperature combined with mechanical agitation to disentangle the humic polymers.

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