Influence Of Surface Hydrophobicity Research Articles

Enhanced thrombolytic effect induced by acoustic cavitation generated from nitrogen-doped annealed nanodiamond particles

In biomedical research, ultrasonic cavitation, especially inertial cavitation (IC) has attracted extensive attentions due to its ability to induce mechanical, chemical and thermal effects. Like ultrasound contrast agent (UCA) microbubbles or droplets, acoustic cavitation can be effectively triggered beyond a certain pressure threshold through the interaction between ultrasound and nucleation particles, leading to an enhanced thrombolytic effect. As a newly developed nanocarbon material, nitrogen-doped annealed nanodiamond (N-AND) has shown promising catalytic performance. To further explore its effects on ultrasonic cavitation, N-AND was synthesized at the temperature of 1000 °C. After systematic material characterization, the potential of N-AND to induce enhanced IC activity was assessed for the first time by using passive cavitation detection (PCD). Based on experiments performed at varied material suspension concentration and cycle number, N-AND demonstrated a strong capability to generate significant cavitation characteristics, indicating the formation of stable bubbles from the surface of the materials. Furthermore, N-AND was applied in the in vitro thrombolysis experiments to verify its contribution to ultrasound thrombolysis. The influence of surface hydrophobicity on the cavitation potentials of ND and N-AND was innovatively discussed in combination with the theory of mote-induced nucleation. It is found that the cavitation stability of N-AND was better than that of the commercial UCA microbubbles. This study would provide better understanding of the potential of novel carbonous nanomaterials as cavitation nuclei and is expected to provide guidance for their future biomedical and industrial applications.

Amphiphilic nanogels: influence of surface hydrophobicity on protein corona, biocompatibility and cellular uptake.

Background and purposeNanogels (NGs) are promising drug delivery tools but are typically limited to hydrophilic drugs. Many potential new drugs are hydrophobic. Our study systematically investigates amphiphilic NGs with varying hydrophobicity, but similar colloidal features to ensure comparability. The amphiphilic NGs used in this experiment consist of a hydrophilic polymer network with randomly distributed hydrophobic groups. For the synthesis we used a new synthetic platform approach. Their amphiphilic character allows the encapsulation of hydrophobic drugs. Importantly, the hydrophilic/hydrophobic balance determines drug loading and biological interactions. In particular, protein adsorption to NG surfaces is dependent on hydrophobicity and critically determines circulation time. Our study investigates how network hydrophobicity influences protein binding, biocompatibility and cellular uptake.MethodsBiocompatibility of the NGs was examined by WST-1 assay in monocytic-like THP-1 cells. Serum protein corona formation was investigated using dynamic light scattering and two-dimensional gel electrophoresis. Proteins were identified by liquid chromatography-tandem mass spectrometry. In addition, cellular uptake was analyzed via flow cytometry.ResultsAll NGs were highly biocompatible. The protein binding patterns for the two most hydrophobic NGs were very similar to each other but clearly different from the hydrophilic ones. Overall, protein binding was increased with increasing hydrophobicity, resulting in increased cellular uptake.ConclusionOur study supports the establishment of structure–property relationships and contributes to the accurate balance between maximum loading capacity with low protein binding, optimal biological half-life and good biocompatibility. This is an important step to derive design principles of amphiphilic NGs to be applied as drug delivery vehicles.

The influence of surface hydrophobicity in fluidization of ultrafine Al2O3 particles

A new approach is hereby presented to study the influence of surface properties on ultrafine alumina (Al2O3) particles towards a fluidized performance by changing the ultrafine particles (Al2O3) surface hydrophobic degree. A number of variables that affects fluidization performance of ultrafine particles (Al2O3), including hydrophobicity has been studied. The minimum full fluidization velocities (Umff), average bed pressure drop (ΔPa), standard deviation in pressure drop (σp) and so on, has been found to depend on the hydrophobic degree, which is a function of the ultrafine particles (Al2O3) surface properties. After treatment of the ultrafine particles (Al2O3) with a surfactant, the liquid-solid contact angle on the ultrafine particles (Al2O3) raises, thus changing the interaction between the ultrafine particles (Al2O3) and also between the ultrafine particles (Al2O3) with the micro-fluidized bed wall surface. Furthermore, some changes in important parameters such as particle size (simple agglomerate size), bulk density, flow function plots, maximum wall friction angle, BET parameters and so on were also evaluated. The fluidization of ultrafine particles is attractive, if the interaction forces between the ultrafine particles (Al2O3) and also between the ultrafine particles (Al2O3) with the micro-fluidized bed wall surface can be artificially controlled. Moreover, it is possible to achieve a better fluidization performance on the ultrafine particles (Al2O3). However, more investigation is required to improve the fluidization performance of the ultrafine particles.

Influence of Surface Hydrophobicity on the Esterification of Fatty Acids over Solid Catalysts

The relative roles of surface acidity and hydrophobicity in the methylation of fatty acids (C 8 - C 18 ) to the corresponding methyl esters were investigated over three solid acid catalysts: Fe-Zn double-metal cyanide (DMC), sulfated zirconia (SZ), and Al-MCM-41. The esterification reaction was faster and the apparent activation energy was lower over SZ and Al-MCM-41 than on DMC because of their higher acid strength, specific surface area, and pore diameter. Over SZ and Al-MCM-41, the apparent activation energy for esterification increased with the chain length of the fatty acid. A reverse trend, however, was observed over DMC. The relative adsorption of methanol and fatty acids (compared to water) was higher on DMC than on SZ and Al-MCM-41. Hence, in addition to the acidic and textural properties, surface hydrophobicity and relative surface coverage by reactants/products also play an important role in reactions of long-chain fatty acids with alcohols on solid catalysts.

The Influence of Surface Hydrophobicity on Polyacrylamide Adsorption

The adsorption of a modified polyacrylamide on gold surfaces coated with varying proportions of -CH3- and -OH-terminated alkanethiols (producing substrates of varying hydrophobicity: thetac=75, 98, and 119 degrees), was investigated using quartz crystal microbalance with dissipation (QCM-D), tapping-mode atomic force microscopy (TM-AFM), and captive bubble contact angle measurements. The QCM-D data for the polymer adsorbing on the different substrates indicates that the polymer adsorbs faster and to a greater extent on surfaces with higher hydrophobicity. Dissipation data from the QCM-D suggests that the adsorbed polymer undergoes a conformational change when adsorbing onto the substrates of higher hydrophobicity, forming a less rigid extended layer as the adsorption progresses toward the maximum adsorbed amount. AFM imaging of the adsorbed layer illustrates that the polymer layer is incomplete on all three substrates, and that the underlying substrate hydrophobicity has a role in determining the morphology (distribution, coverage, and thickness) of the adsorbed layer. Contact angle measurements of the polymer-coated substrates show variation in the ability of the polymer to reduce the hydrophobicity of the substrates. The role of coverage and distribution of adsorbed polymer on the surface hydrophobicity reduction is discussed.

Polymer and protein surface coatings on silicone: effect on Staphylococcus epidermidis adhesion and colonization

Background Surface modifications of silicone have been attempted to reduce the incidence of shunt infections. However, the influence of surface hydrophobicity, roughness, and functional groups on bacterial adhesion has not been fully elucidated, and reports of protein effects are conflicting. Therefore, we have tested silicone coated with different biopolymers, silanes, and proteins to determine how these modifications influence Staphylococcus epidermidis adhesion and colonization.

Infrared study of the influence of surface hydrophobicity of the support of Rh/SiO2 catalysts

The characteristics of the superficial structure of a hydrophobic silica subjected to treatment at various temperatures and heating times, and of the Rh catalysts supported on the silica, are studied by FTIR. The catalysts obtained have different dispersions that depend on the superficial methoxyl fraction of the support, and are independent of the superficial OH groups. This procedure for changing the metal dispersion is different from the pretreatment of the catalyst reported previously.

Influence of Surface Hydrophobicity on the Layer Properties of Adsorbed Nonionic Surfactants

The structure of adsorbed octa(oxyethlyene) n-dodecyl ether (C12E8) layers at a series of gold−alkanethiolate surfaces was investigated by atomic force microscopy. The hydrophobicity of the surfaces was systematically varied by changing the relative amounts of chemisorbed thiohexadecane (CH3(CH2)15SH) and thiohexadecanol (CH2OH(CH2)15SH) surface groups. This allowed complete control over the hydrophobicity of the surface. Adsorption was studied on five different thiol-modified gold surfaces prepared from solutions containing 0%, 25%, 50%, 75%, and 100% hexadecane thiol, respectively (henceforth referred to as 0% CH3, 25% CH3, 50% CH3, 75% CH3, and 100% CH3). The following general evolution of the adsorbed layer morphology with increasing surface hydrophobicity was observed: diffuse micellar coverage; dense micellar coverage; bilayer; and finally a monolayer structure at the most hydrophobic surface. The adsorbed layer structure observed at the different surfaces was interpreted in terms of the effective interaction between different parts of the surfactant and the solid surface. On the basis of our adsorption data, we also infer that hydrophobic interactions are the main driving force for adsorption of ethylene oxide segments at partially hydroxylated surfaces (such as silica) and that hydrogen bonding reduces the free energy penalty of displacing water.

The Influence of Surface Hydrophobicity on the Adsorbed Conformation of a β-Sheet-Forming Synthetic Peptide

Far-UV CD spectra were recorded from a synthetic β-sheet-forming peptide (LKWK(LK) 8), adsorbed onto several aqueous-quartz interfaces contained in a specially constructed cell. These hydrophilic quartz interfaces could be made hydrophobic by chemical modification with C18 alkyl chains. The hydrophobic quartz provides a model system for oil-in-water emulsions and cell membranes. The peptide had multiconformational properties. β-sheet structure was induced into the molecule with increasing NaCl concentrations, whereas 2,2,2-trifluoroethanol induced α-helix. Radiolabeling of the peptide for surface concentration measurements was also found to introduce considerable β-sheet structure. The characterization of the adsorbed spectra was partly achieved using far-UV CD spectra of β-peptide adsorbed onto hydrophilic colloidal silica particles, which eliminated orientation effects.