Probing Hydrophobic Interactions between Polymer Surfaces and Air Bubbles or Oil Droplets: Effects of Molecular Weight and Surfactants

Langmuir ◽  
2021 ◽  
Author(s):  
Diling Yang ◽  
Lei Xie ◽  
Xiaohui Mao ◽  
Lu Gong ◽  
Xuwen Peng ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hydrophobic Interactions ◽  
Polymer Surfaces ◽  
Air Bubbles ◽  
Oil Droplets

scholarly journals Valonea Tannin: Tyrosinase Inhibition Activity, Structural Elucidation and Insights into the Inhibition Mechanism

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2747
Author(s):  
Jiaman Liu ◽  
Yuqing Liu ◽  
Xiaofeng He ◽  
Bo Teng ◽  
Jacqui M. McRae
Keyword(s):  
Molecular Weight ◽  
Structure Function ◽  
Hydrophobic Interactions ◽  
Average Molecular Weight ◽  
Commercial Application ◽  
Inhibition Mechanism ◽  
Resonance Spectroscopy ◽  
Inhibition Activity ◽  
Tyrosinase Inhibition ◽  
Function Activity

Valonea tannin is a natural product readily extracted from acorn shells that has been suggested to have potential skin whitening properties. This study investigated the tyrosinase inhibition activity of extracted valonea tannin and the associated structure–function activity. Nuclear magnetic resonance spectroscopy and molecular weight analysis with gel permeation chromatography revealed that valonea tannin could be characterized as a hydrolysable tannin with galloyl, hexahydroxydiphenoyl and open formed-glucose moieties and an average molecular weight of 3042 ± 15 Da. Tyrosinase inhibition assays demonstrated that valonea tannin was 334 times more effective than gallic acid and 3.4 times more effective than tannic acid, which may relate to the larger molecular size. Kinetic studies of the inhibition reactions indicated that valonea tannin provided tyrosinase inhibition through mixed competitive–uncompetitive way. Stern–Volmer fitted fluorescence quenching analysis, isothermal titration calorimetry analysis and in silico molecule docking showed valonea tannin non-selectively bound to the surface of tyrosinase via hydrogen bonds and hydrophobic interactions. Inductively coupled plasma-optical emission spectroscopy and free radical scavenging assays indicated the valonea tannin had copper ion chelating and antioxidant ability, which may also contribute to inhibition activity. These results demonstrated the structure–function activity of valonea tannin as a highly effective natural tyrosinase inhibitor that may have commercial application in dermatological medicines or cosmetic products.

MICROFLOTATION OF FINE OIL DROPLETS BY SMALL AIR BUBBLES: EXPERIMENT AND THEORY

2001 ◽  
Vol 36 (1) ◽  
pp. 1-15 ◽  
Author(s):  
José A. Ramirez ◽  
Robert H. Davis
Keyword(s):  
Air Bubbles ◽  
Oil Droplets

scholarly journals Induction and Coverage Times for Crude Oil Droplets Spreading on Air Bubbles

2013 ◽  
Vol 47 (24) ◽  
pp. 14154-14160 ◽  
Author(s):  
Mona Eftekhardadkhah ◽  
Gisle Øye
Keyword(s):  
Crude Oil ◽  
Air Bubbles ◽  
Oil Droplets

scholarly journals Communication: On the Stability and Necessary Electrophoretic Mobility of Bare Oil Nanodroplets in Water

2020 ◽  
Author(s):  
Saranya Pullanchery ◽  
Sergey Kulik ◽  
halil okur ◽  
Hilton. B. de Aguiar ◽  
Sylvie Roke
Keyword(s):  
Electrophoretic Mobility ◽  
Dlvo Theory ◽  
Air Bubbles ◽  
Oil Droplets ◽  
Cleaning Procedure ◽  
Charged Droplets ◽  
Oil In Water ◽  
The Creation ◽  
The Stability ◽  
The 19Th Century

Hydrophobic oil droplets, particles and air bubbles can be dispersed in water as kinetically stabilized dispersions. It has been established since the 19th century that such objects harbor a negative electrostatic potential roughly twice larger than the thermal energy. The source of this charge continues to be one of the core observations in relation to hydrophobicity and its molecular explanation is still debated. What is clear though, is that the stabilizing interaction in these systems is understood in terms of electrostatic repulsion via DLVO theory. Recent work [Carpenter et al., PNAS 116 (2019) 9214] has added another element into the discussion, reporting the creation of bare near-zero charged droplets of oil in water that are stable for several days. Key to the creation of the droplets is a rigorous glassware cleaning procedure. Here, we investigate these conclusions and show that the cleaning procedure of glassware has no influence on the electrophoretic mobility of the droplets, that oil droplets with near-zero charge are unstable, and provide an alternative possible explanation for the observations involving glass surface chemistry.

The Coagulation of Latices by Polar-Nonpolar Liquids

1938 ◽  
Vol 11 (1) ◽  
pp. 87-91
Author(s):  
F. K. Daniel ◽  
H. Freundlich ◽  
K. Söllner
Keyword(s):  
Molecular Weight ◽  
Liquid Phase ◽  
Isoamyl Alcohol ◽  
Isobutyric Acid ◽  
Butyl Alcohol ◽  
Organic Liquids ◽  
Air Bubbles ◽  
Small Molecular Weight ◽  
Gutta Percha ◽  
Nonpolar Liquids

Abstract (1) Diluted latices—Abiarana gutta-percha latex was specially investigated—may be coagulated by shaking them with organic liquids, not miscible with water in all proportions, provided that the liquids form a second liquid phase and that their molecules have a polar-nonpolar structure (butyl alcohol, isobutyric acid, cyclohexanol, etc.). Nonpolar liquids (petroleum ether, chloroform, etc.) do not coagulate diluted latices on shaking under these conditions. (2) This coagulating action can be explained by assuming that the latex particles are strongly accumulated at the interfaces of polar-nonpolar liquids and water; this is not the case with nonpolar liquids. (3) Small concentrations of some polar-nonpolar substances of small molecular weight, soluble in water, can also coagulate Abiarana gutta-percha latex if they form unstable foams; this was observed with propanol and isopropanol. If the foam formed under these conditions is stable, as with small concentrations of dissolved butanol and isobutanol, no coagulation takes place. This behavior can be explained as in (2), the air bubbles behaving like the second liquid phase. (4) Jelutong latex is known to contain an excess of resins, compared with the amount of rubber. A method of coagulating this latex quickly and separating the resins from the rubber consists in shaking the latex for some seconds with certain polar-nonpolar liquids, forming a second liquid phase, such as isobutyl or isoamyl alcohol. A lump of rubber is accumulated at the interface of the two liquids; the resins are contained in the organic phase.

scholarly journals Multiple air-bubble enhanced oil rupture on nanostructured cellulose fabric for easy-oil cleaning fouled in a dry state

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Min-Sung Kim ◽  
Tae-Jun Ko ◽  
Seong Jin Kim ◽  
Young-A. Lee ◽  
Kyu Hwan Oh ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Solid Fraction ◽  
High Aspect Ratio ◽  
Air Bubbles ◽  
Oil Droplets ◽  
Water Contact ◽  
Air Bubble ◽  
Cellulose Fabric ◽  
Oily Water ◽  
Oil Fouling

Abstract Nanostructured cellulose fabric with an air-bubble-enhanced anti-oil fouling property is introduced for quick oil-cleaning by water even with the surface fouled by oil before water contact under a dry state. It is very challenging to recover the super-hydrophilicity because once the surface is oil-fouled, it is hard to be re-wetted by water. Anti-oil-fouling under a dry state was realized through two main features of the nanostructured, porous fabric: a low solid fraction with high-aspect-ratio nanostructures significantly increasing the retracting forces, and trapped multiscale air bubbles increasing the buoyancy and backpressure for an oil-layer rupture. The nanostructures were formed on cellulose-based rayon microfibers through selective etching with oxygen plasma, forming a nanoscale open-pore structure. Viscous crude oil fouled on a fabric under a dry state was cleaned by immersion into water owing to a higher water affinity of the rayon material and low solid fraction of the high-aspect-ratio nanostructures. Air bubbles trapped in dry porous fibers and nanostructures promote oil detachment from the fouled sites. The macroscale bubbles add buoyancy on top of the oil droplets, enhancing the oil receding at the oil-water-solid interface, whereas the relatively smaller microscale bubbles induce a backpressure underneath the oil droplets. The oil-proofing fabric was used for protecting underwater conductive sensors, allowing a robot fish to swim freely in oily water.

scholarly journals Effect of Hydrophobic Interactions on Lower Critical Solution Temperature for Poly(N-isopropylacrylamide-co-dopamine Methacrylamide) Copolymers

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 991 ◽  
Author(s):  
Alberto García-Peñas ◽  
Chandra Sekhar Biswas ◽  
Weijun Liang ◽  
Yu Wang ◽  
Pianpian Yang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Lower Critical Solution Temperature ◽  
Hydrophobic Interactions ◽  
Structural Information ◽  
Drug Carriers ◽  
Solution Temperature ◽  
Polymerization Degree ◽  
Tissue Engineering Scaffolds ◽  
Critical Solution Temperature ◽  
Precise Control

For the preparation of thermoresponsive copolymers, for e.g., tissue engineering scaffolds or drug carriers, a precise control of the synthesis parameters to set the lower critical solution temperature (LCST) is required. However, the correlations between molecular parameters and LCST are partially unknown and, furthermore, LCST is defined as an exact temperature, which oversimplifies the real situation. Here, random N-isopropylacrylamide (NIPAM)/dopamine methacrylamide (DMA) copolymers were prepared under a systematical variation of molecular weight and comonomer amount and their LCST in water studied by calorimetry, turbidimetry, and rheology. Structural information was deduced from observed transitions clarifying the contributions of molecular weight, comonomer content, end-group effect or polymerization degree on LCST, which were then statistically modeled. This proved that the LCST can be predicted through molecular structure and conditions of the solutions. While the hydrophobic DMA lowers the LCST especially the onset, polymerization degree has an important but smaller influence over all the whole LCST range.

Elastin-derived peptide binding to a hydrophobic domain on neutrophil elastase

1994 ◽  
Vol 72 (9-10) ◽  
pp. 419-427 ◽  
Author(s):  
Suresh C. Tyagi ◽  
Sanford R. Simon
Keyword(s):  
Molecular Weight ◽  
Neutrophil Elastase ◽  
Protein Fraction ◽  
Competitive Inhibition ◽  
Hydrophobic Interactions ◽  
Human Aorta ◽  
Low Molecular Weight ◽  
Human Neutrophil Elastase ◽  
Amidolytic Activity ◽  
Hydrophobic Domain

To understand the contributions of binding of elastin to domains removed from the active site of neutrophil elastase, we isolated an elastin-derived peptide (EDP) fraction, which we have previously shown was tightly linked to neutrophil elastase after prolonged digestion of elastin but which can be released from the enzyme with hydroxylamine. Elastin from human aorta was incubated with human neutrophil elastase under conditions favoring proteolysis. Low molecular weight species, including free EDP, were separated from the protein fraction by a small centrifuged gel filtration column. The high molecular weight protein fraction was subjected directly to 0.5 M hydroxylamine. The reaction mixture was then fractionated on a phosphocellulose column using an ionic gradient. A fraction was collected that exhibited fluorescence with a peak at ~410 nm when excited at 320 nm, indicating the presence of desmosine and (or) isodesmosine. A second peak with amidolytic activity towards methoxysuccinyl-Ala-Ala-Pro-Val-p-nitroaniline (MeOSucAAPVpNa), but no fluorescence at 410 nm was also detected at the same elution volume where free elastase appeared. After removal of low molecular weight digestion products but prior to treatment with hydroxylamine, the putative elastase–EDP complex possessed no amidolytic activity towards MeOSucAAPVpNa. When the liberated EDP was added to elastase in an amidolytic assay, the EDP behaved as only a partial noncompetitive inhibitor [Formula: see text], but bound with high affinity to neutrophil elastase [Formula: see text], as detected by its ability to quench elastase endogenous fluorescence. The complete emission spectrum of the mixture of elastase and EDP obtained at excitation wavelengths specific for tryptophan and desmosine/isodesmosine suggests that the EDP was in a hydrophobic environment which was close to at least one of the three tryptophan residues in the enzyme. Based on fluorescence energy transfer, we have estimated a distance between the elastase and EDP of ~10 ± 3 Å (1 Å = 0.1 nm) during elastinolysis. This pattern of binding to a hydrophobic site on neutrophil elastase without competitive inhibition of amidolytic activity was consistent with the importance of hydrophobic interactions between neutrophil elastase and elastin within a region of the enzyme removed from the active site.Key words: proteinase, elastase, elastin, extracellular matrix, elastin-derived peptide.

CHARACTERIZATION OF THE INITIAL WEATHERING OF PETROLEUM HYDROCARBONS BY FTIR SPECTROSCOPY AND SUPERCRITICAL FLUID CHROMATOGRAPHY

1989 ◽  
Vol 1989 (1) ◽  
pp. 427-431 ◽  
Author(s):  
Lamya Mansur ◽  
Alan Williams ◽  
Keith D. Bartle ◽  
Mark W. Raynor
Keyword(s):  
Molecular Weight ◽  
Crude Oil ◽  
Ftir Spectroscopy ◽  
Supercritical Fluid ◽  
Supercritical Fluid Chromatography ◽  
Hydrocarbon Composition ◽  
Oil Droplets ◽  
Weathering Processes ◽  
Chemical Measurements ◽  
Single Droplets

ABSTRACT Chemical changes resulting from the weathering processes of oils have been investigated on a bench scale weathering apparatus. A multicomponent oil simulating crude oil was developed for this purpose. Hydrocarbon concentrations resulting from evaporation and dissolution were measured using Fourier transform infrared (FTIR) spectroscopy and interpreted by a computer program (CIRCOM), which uses the method of principal components regression for multicomponent quantitative analysis. This method could be fast and accurate for quantitative assessments of changes in chemical and physical properties of an oil. However, this study outlines only the chemical measurements of saturated and aromatic hydrocarbon composition. Experiments were also undertaken to study weathering processes on oil droplets. In this technique single droplets of crude oil were suspended in water, the trends of dissolution were studied, and the behavior of the remaining heavy fraction assessed by FTIR spectroscopy and capillary column supercritical fluid chromatography (SFC). SFC was used to identify compounds, especially high molecular weight alkanes, and their changes in concentration with time in suspension in water. The results show that the main changes in the composition of oil droplets in stagnant waters are loss of low molecular weight material and differential loss of high boiling n-alkanes compared to their isoprenoid counterparts. FTIR spectroscopy and SFC proved powerful techniques for detecting minimal weathering processes, including oxidation, dissolution, and microbial degradation.

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