Changes In Surface Hydrophobicity Research Articles

Ultrasound-assisted extraction of protein from Bombay locusts and its impact on functional and antioxidative properties

Impact of ultrasound-assisted process (UAP) on yield, functional properties, antioxidant properties and molecular characteristics of protein extracted from Bombay locusts (BL) (Patanga succinta L.) was studied. Different conditions of UAP were implemented for different amplitudes (40–60%) and times (10–30 min) during aqueous extraction. Notably, UAP could enhance yield and protein recovery, compared with those from typical process (TP) (continuously stirred at 100 rpm at room temperature for 1 h). UAP conditions used governed the change of surface hydrophobicity and free α-amino content of BL. UAP could improve solubility of BL, especially at pH levels higher than 2. UAP had no significant (p > 0.05) detrimental effects on foaming capacity and stability of BL. Nevertheless, UAP, particularly at 50–60% amplitudes, affected the emulsion activity and stability of BL. UAP provided BL with high radical scavenging activities and good electron donating ability, especially that from 60% amplitude for 20 min (UAP-60/20). UAP-60/20 showed the impact on change of isoelectric point and molecular characteristic monitored by Fourier transform infrared (FTIR) of BL, compared to those from TP. In addition, BL was also an excellent source of both essential and nonessential amino acids. Therefore, UAP potentially enhanced BL extraction efficiency, resulting the BL with good functional and antioxidative properties.

Structural and Functional Characteristics of Microplastic Associated Biofilms in Response to Temporal Dynamics and Polymer Types

The colonization of bacterial communities and biofilm formation on microplastics (MPs) have aroused great concern recently. However, the influence of time and polymer types on the structural and functional characteristics of biofilms remains unclear. In this study, three types of MPs (polyethylene, polypropylene, and polystyrene) were exposed for different time periods (10, 20 and 30days) in seawater using a microcosm experiment. Microscopic spectroscopy and high-throughput gene sequencing techniques were used to reveal the temporal changes of structural and functional characteristics of MPs associated biofilms. The results indicate that the biofilm formation is affected by both the incubation time and the polymer type. In addition, bacterial diversity and community structure in the biofilms show selectivity towards seawater, and tend to shift over time and among different polymer types. Moreover, biofilms are shown to harbor plastic degrading bacteria, leading to the changes of functional groups and surface hydrophobicity, and thereby enhancing the biodegradation of MPs.

Modification of functional, rheological and structural characteristics of myofibrillar proteins by high-intensity ultrasonic and papain treatment

The effects of sonication duration (15 and 30 min) and papain enzyme treatments on the conformational, physicochemical and functional traits of myofibrillar proteins (MPs) were addressed in this study. As the ultrasound duration was increased, the water holding capacity (WHC), solubility, foaming and emulsifying properties were improved as a result of the changes in the particles size distribution and zeta potential. Our results indicated that the turbulence force caused increments in the surface hydrophobicity and significant changes in the secondary structure. Also, the rheological properties were influenced by both cavitation force and papain treatment. According to the observations, the samples treated with sonication (for 15 and 30 min) and enzyme were more elastic with higher viscosity, as compared to the control. Compared with the control, enzymolyzed samples indicated better functionality. Moreover, papain treatment led to the increase of the hydrophobicity groups on the surface of proteins and the decrease of the amount of α-helix and β-sheet structures. It was noteworthy that the most changes in the structure and techno-functionality of myofibrillar proteins were observed for the sample affected by the simultaneous application of papain treatment and 15 min sonication. The highest values in the surface hydrophobicity, specific surface area, net charge, storage modulus, solubility and WHC belonged to this sample. However, enzyme-modified samples exposed to the longer sonication time (30 min) demonstrated reductions in solubility, WHC and surface hydrophobicity, as well as increases in the particle size distribution and protein turbidity.

Inhibitory effects of Lactobacillus brevis KU15153 against Streptococcus mutans KCTC 5316 causing dental caries

This study determined the inhibitory effect of Lactobacillus brevis KU15153 against cariogenic Streptococcus mutans KCTC 5316. Antimicrobial activity, auto-aggregation, cell surface hydrophobicity, exopolysaccharides (EPS) production, biofilm formation, and morphological changes were assessed in the presence of L. brevis KU15153. L. brevis KU15153 exhibited the highest antimicrobial activity against S. mutans KCTC 5316 (28.67 ± 4.16 mm). Auto-aggregation (38.32%), cell surface hydrophobicity (27.08%), and EPS production rate (58.52%) of S. mutans KCTC 5316 slightly decreased upon treatment with L. brevis KU15153. Additionally, crystal violet stanning and scanning electron microscopy confirmed the L. brevis KU15153-mediated inhibition of biofilm formation by S. mutans KCTC 5316 in comparison to that observed in the negative control (untreated S. mutans KCTC 5316). These results indicate that the L. brevis KU15153 could be used as a potential probiotic for maintaining oral health.

Improvement in mechanical, physical and biological properties of eucalyptus and pine woods by raw pine resin in situ polymerization

A raw pine resin, which is a cheap, renewable and easily obtainable forest resource, was used to impregnate two different fast-growing solid woods (Eucalyptus grandis Hill Maiden and Pinus elliottii Engelm) and in situ polymerized to improve their hygroscopic, chemical, morphological, mechanical, and thermogravimetric properties. Biodegradation resistance against subterranean termites and white-rot fungus was also addressed. The treatment yielded changes in colorimetric properties, dimensional stability and surface hydrophobicity. Compared to its respective untreated wood, the treated pine one presented increases within 40–50 % in ASE, whereas the treated eucalyptus wood showed negative values around -15 % in this same comparison. Increases in MOE (70 %) and MOR (50 %) were obtained for the pine wood, whereas the same properties were unaffected for the eucalyptus wood. Thermal and biological properties of both woods were also positively affected. These results were associated with the solidified raw pine resin inside the wood structure, which was confirmed by infrared spectroscopy and SEM images, especially for the pine due to its large and long tracheids, as well as its lignin content and overall composition.

Soybean germination limits the role of cell wall integrity in controlling protein physicochemical changes during cooking and improves protein digestibility

Previous studies showed that in vitro digestibility of proteins in cooked beans is modulated by heat treatment and that the effect may be different whether proteins are heated in intact cotyledon or in a bean flour. In this study, germinated and non-germinated soybean cotyledons and flour were boiled at 100 °C for varying times (30, 90, or 180 min). After grinding, the level of trypsin inhibitors, protein aggregation, surface hydrophobicity, the secondary structure, and in vitro digestibility were studied. The presence of an intact cell wall during cooking increased protein denaturation temperature by about 10% and reduced the denaturation of trypsin inhibitors, and induced distinct changes in protein surface hydrophobicity and secondary structure. These physicochemical properties translated into an increment in protein degree of hydrolysis (DH, 72%) of protein cooked for 30 min as flour compared to proteins cooked in intact soybean tissues (64%). Increase in cooking times (90 and 180 min) resulted in limited improvement in the protein digestibility and changes in protein physicochemical properties for both boiled cotyledons and flour. Soybean germination resulted in distinct changes in protein physicochemical properties and higher protein DH% of raw soybean (61%) compared to non-germinated raw soybean (36%). An increase in protein digestibility of germinated soybean was also observed after boiling for both cotyledon and flour. However, significant differences in DH% were not observed between proteins boiled in intact cotyledon and in a flour. This work provides extra knowledge of the role of cellular integrity on protein properties in plant foods and suggests that germination or grinding before cooking may increase protein digestibility.

Influence of thermal processing on the physicochemical properties of bovine lactoferrin

Aqueous solutions of lactoferrin (LF) were subjected to thermal processing (72, 80, 85, 95 °C for 15 s) using a rheometer. Despite the low protein concentration and low ionic strength of the LF solutions, analyses post-processing revealed the presence of heat-induced, covalently-linked, protein aggregates. Aggregation was accompanied by increased surface hydrophobicity and zeta-potential and changes to the secondary structure of the protein, including reduction in the proportion of alpha helix domains coupled with increased intermolecular beta sheet structures. The native red colour of the protein was lost upon thermal processing, not attributable to the release of LF-bound iron. Micro-differential scanning calorimetry showed LF to be irreversibly denatured on heating with endotherms observed at 58.7 °C (apo-LF) and 89.6 °C (holo-LF). Thermal processing at 72–95 °C resulted in irreversible changes to the structural and physicochemical properties of bovine LF, whereby the lowest heating intensity had the least impact on LF structure.

Effects of fermentation with Bacillus natto on the allergenicity of peanut

In the present study, we evaluated the immunoreactivity reduction of raw peanut pulp (RPP) by using a combination protocol of autoclave and fermentation with Bacillus natto. Assessing through an indirect ELISA, we found that the method reduced more than 77.3% of the IgE reactivity in peanut protein preparations. Further analyses with SDS-PAGE and Coomassie staining revealed that sequential autoclave and fermentation for different time caused gradually degradation of high molecular weight peanut proteins. Results from Circular dichroism and Ultraviolet absorption spectroscopies indicated that the autoclave and fermentation induced extensive proteolysis, unfolding and conformational changes, and reduction of α-helices, which all affected epitopes formation significantly. The effects of the method on peanut protein structure were further proved by the changes of surface hydrophobicity, assessed by ANS fluoresence probe, and by the alteration of free sulfhydryl groups, measured by SH-interacting DTNB. Interestingly, during the process of fermentation for 48 h, the immunoreactivity reduction of RPP was positively correlated with the content of free sulfhydryl group and negatively correlated with UV absorption intensity at 210 nm. Therefore, autoclaving assisted fermentation with Bacillus natto was an effective procedure to diminish the allergens in raw peanuts.

Effect of glyoxal and 1-methylisatin on stress-induced fibrillation of Hen Egg White Lysozyme: Insight into the anti-amyloidogenic property of the compounds with possible therapeutic implications

Systemic amyloidosis is a hereditary disorder that mostly arises as a result of specific point mutations to the wild type gene of lysozyme, forming mutant lysozyme variants leading to aggregation of the protein. The small monomeric protein Hen Egg White Lysozyme (HEWL) is a structural homolog of Human Lysozyme and is widely used as a model protein to investigate protein aggregation. In the present study, we have investigated the effect of 1-methylisatin, an indole derivative and glyoxal, a reactive dicarbonyl compound, on stress-induced aggregation of HEWL. Interaction of the compounds with HEWL induced changes in structure and surface hydrophobicity of the protein as evident from CD spectroscopy, tryptophan fluorescence and ANS binding studies. Additional experiments (Thioflavin T fluorescence, AFM imaging and DLS studies) demonstrate that stress induces amyloid-like fibrillation of HEWL, however, prior modification of the protein with glyoxal or 1-methylisatin significantly reduces its susceptibility to aggregation. High resolution mass spectrometric analysis indicated that 1-methylisatin primarily complexes with the protein in the form of a dimer. On the other hand, glyoxal-mediated modification of the protein induces formation of glycated adducts (carboxymethyllysine, hydroimidazolone). The results highlight possible clinical implications of the compounds in treatment of systemic amyloidosis and protein conformational disorder.

Ultrasonic treatment on physicochemical properties of water-soluble protein from Moringa oleifera seed

Effect of ultrasonic power on the structure and functional properties of water-soluble protein extracted from defatted Moringa oleifera seed were explored. The results showed that ultrasonic treatment could reduce β-sheet and β-turn content of water-soluble protein from Moringa oleifera seed (MOWP) and increase the content of random coil and α-helix. Changes in intrinsic fluorescence spectra, surface hydrophobicity (H0) and thermal behaviors indicated that ultrasonic had significant effect on the tertiary structure of MOWP. The results of SEM and SDS-PAGE showed that the MOWP was aggregated but not significantly degraded by ultrasound. The solubility, foaming properties and emulsifying properties of MOWP increased firstly and then decreased with the increase of ultrasonic power. Ultrasonic treatment altered the functional properties of MOWP, which might be attributed to the exposure of hydrophilic group and the change of and secondary and tertiary structure.

Effects of surfactants on the remediation of petroleum contaminated soil and surface hydrophobicity of petroleum hydrocarbon degrading flora

It has been proven that surfactants used in the remediation of petroleum hydrocarbon contaminated soil have great application potential. In this study, the effects of five surfactants (SDBS, Tween80, Tween60, rhamnolipid and TRS-1) on leaching of petroleum hydrocarbons from soil were investigated through orthogonal experiments, and petroleum hydrocarbon components were analyzed by GC/MS. The effects of surfactants on the degradation of petroleum hydrocarbon were analyzed by the changes of microbial growth curve and surface hydrophobicity. The results showed that surfactant type, temperature and surfactant concentration had significant effects on the removal rate of petroleum hydrocarbon. Tween80, rhamnolipid and TRS-1 have good bio-friendliness and a high removal rate of petroleum hydrocarbons (up to 65%), suitable for the restoration of the soil used in the experiment And Surfactants exhibited a higher removal rate for small molecules and petroleum hydrocarbons with odd carbon atoms. Surfactants have a certain modification effect on the surface of relatively hydrophilic bacteria under the initial conditions, making their surface properties develop in the direction of enhanced hydrophobicity, and the hydrophobicity has increased from less than 20% to about 40%.

Comparison of surface and foaming properties of soy lipophilic protein with those of glycinin and β-conglycinin

Soy lipophilic protein (LP) is considered to form a major fraction of soy protein isolate, in addition to β-conglycinin (7 S) and glycinin (11 S). LP consists of phospholipid-protein complex and phospholipid-free protein molecules. Surface and foaming properties of LP were compared to those of 7 S and 11 S. These soy protein samples were prepared under mild conditions in order to avoid thermal denaturation, which enabled us to study the effects of heat treatment on surface and foaming properties of the proteins. Without heat treatment, the surface and foaming properties of LP were superior to those of other soy protein fractions, suggesting the phospholipid-protein complex in LP can produce fine bubbles with high drainage stability. Despite low surface and foaming properties of non-heated 7 S and 11 S, heat treatment improved the surface and foaming properties of 7 S and 11 S dramatically, which could be relevant to heat-induced changes in particle size, zeta-potential and surface hydrophobicity of 7 S and 11 S molecules. On the other hand, the foaming ability of LP was declined, but the foam stability was increased to maintain the foam volume up to the final stage of observation, by heating. In the foam stabilized by heated LP, medium sized bubbles as well as fine bubbles were produced. The improved foam stability may be attributed to the combination effect of the delayed drainage from the lamellar phase of fine bubbles and the increased resistance to the bursting of medium sized bubble.

Surface hydrophobicity change on adiabatic two-phase flow pattern transitions in horizontal tubes

The effect of surface hydrophobicity on the air-water two-phase flow pattern transition was experimentally investigated. Experiments and the two-phase flow visualization were carried out in a hydrophobic polymer tube (4.76 mm ID). The tube material is fluorinated ethylene propylene (FEP) with a hydrophobic surface, and the static contact angle of a water droplet on a smooth surface is 97.28°. The channel surface was roughened to increase the hydrophobicity. The increased surface roughness results in a microstructured surface texture that forms a fine air trapped layer below the liquid droplet on the polymer surface. The channel surface was rotary ground by sandpaper number grit 400, 320, 100, and 80 to develop microstructure textured surface. The measured static contact angle of the roughened surface was 110.7°, 113.26°, 121.03°, and, 126.28° in order of increasing surface roughness. The two-phase flow of the channels with different contact angles was visualized by a high-speed camera and the flow pattern maps were constructed. Even under the same phase superficial velocity conditions, differences in the degree of hydrophobicity lead to transitions to entirely different patterns. The two-phase flow pattern map with the change in hydrophobicity is partitioned by the change in the modified Weber number as a factor indicative of the degree of surface hydrophobicity. The modified Weber number is defined as the ratio of flow inertia to adhesion force, and the new pattern map of the two-phase flow is redefined to take into account the wall hydrophobicity change.

Effects of dual-frequency ultrasound with different energy irradiation modes on the structural and emulsifying properties of soy protein isolate

The effects of dual-frequency ultrasound pretreatments with different energy irradiation modes, including energy-gathered ultrasound (EGU), energy-divergent ultrasound (EDU) and slit ultrasound (SU) on the solubility and emulsifying properties of soy protein isolate (SPI) were investigated. The surface hydrophobicity, intrinsic fluorescence spectra, and circular dichroism spectra of SPI were determined. Results revealed that all ultrasonic pretreatments increased the solubility of SPI significantly (P ≤ 0.05). Ultrasonic pretreatments with EDU and SU could not improve the emulsifying activity (P > 0.05). The emulsion stability index of SPI treated by EGU was higher than those of EDU and SU with the same ultrasonic time and power density. Changes in surface hydrophobicity and intrinsic fluorescence showed the unfolding of protein and exposure of hydrophobic groups as a result of action of ultrasound. The CD spectra of SPI pretreated by optimal EGU, EDU and SU showed that dual-frequency ultrasound induced the decrease of β-sheet contents and increase of α-helix and random coil contents significantly (P ≤ 0.05). In conclusion, the influence of EGU on the structural and emulsifying properties of SPI was more significant than those of EDU and SU.

Terpolymer resin containing bioinspired borneol and controlled release of camphor: Synthesis and antifouling coating application

Marine biofouling can cause a biocorrosion, resulting in degradation and failure of materials and structures. In order to prevent sea creatures from attaching to the surface, in this work, a new environmentally friendly antifouling coating by incorporating antibacterial polymers and natural antifouling agents has been designed and synthesized. Surface chemical composition and changes in surface hydrophobicity were studied by FTIR spectroscopy and contact angle measurements, respectively. Measurements of mass loss of antifouling resin were also carried out and the release rate of camphor from antifouling coating was tested by using UPLC. It had been found that the changes in the content of triisopropylsilylacrylate (TIPSA) (from 4% to 12%) and isobornyl methacrylate (IBOMA) (from 50% to 16.7%) did not significantly affect the release of camphor. The content of IBOMA decreased from 50% to 16.7%, the antifouling performance of the resin system appeared slightly reduced. In addition, rosin could help regulate the release rate of the resin system to desorb camphor slowly in water in a controlled manner. Furthermore, the antifouling capability of as-prepared samples was evaluated via algae suppression experiments and marine field tests. This study highlighted the environmentally friendly antifouling coating as a potential candidate and efficient strategy to prohibit biofouling in seawater.

Germicidal Ultraviolet Light Does Not Damage or Impede Performance of N95 Masks Upon Multiple Uses.

The COVID-19 pandemic is increasing the need for personal protective equipment (PPE) worldwide, including the demand for facial masks used by healthcare workers. Disinfecting and reusing these masks may offer benefits in the short term to meet urgent demand. Germicidal ultraviolet light provides a nonchemical, easily deployable technology capable of achieving inactivation of H1N1 virus on masks. Working with N95-rated masks and nonrated surgical masks, we demonstrated that neither 254 nor 265 nm UV-C irradiation at 1 and 10 J/cm2 had adverse effects on the masks’ ability to remove aerosolized virus-sized particles. Additional testing showed no change in polymer structure, morphology, or surface hydrophobicity for multiple layers in the masks and no change in pressure drop or tensile strength of the mask materials. Results were similar when applying 254 nm low-pressure UV lamps and 265 nm light-emitting diodes. On the basis of the input from healthcare workers and our findings, a treatment system and operational manual were prepared to enable treatment and reuse of N95 facial masks. Knowledge gained during this study can inform techno-economic analyses for treating and reusing masks or lifecycle assessments of options to reduce the enormous waste production of single-use PPE used in the healthcare system, especially during pandemics.

Influence of the Nitrogen exposure time to the plasma treatment on the wettability of polystyrene surfaces

The wettability of material can change from hydrophobic to hydrophilic when treated using plasma nitrogen. The present work investigated the influence of the plasma treatment duration on the modification of polystyrene’s surface coating on a glass surface. The polystyrene layer was produced by means of spin coating method with the rotational speed of 3000 RPM for 1 minute. The plasma was established by a 2 MHz RF generator at the power of 40 watts, pressure of 0.3 Torr, flow rate 40 mL/min. The samples were treated at various exposure time which were 2 min, 5 min, 10 min, and 15 min. The wettability of the polystyrene was measured using a contact angle measurement before and after the nitrogen plasma treatment. Polar functional groups related to the wettability were observed by a Fourier Transform Infrared (FTIR). The longer the treatment duration, the smaller the contact angle was observed. A very low contact angle of 6.42° was achieved at a power of 40 watt at 0.3 torr for the exposure time of 15 min. This means that the surface of the polystyrene changed to super hydrophilic or super wetting. The FTIR results show the spectra of NH2 and C-H functional group at the wavenumber of 3485 cm1 and 2962 cm1, respectively. These functional groups indicate the existence of the polar groups, which contribute to the change of surface hydrophobicity into hydrophilicity.

Light-Activatable Transfection System Using Hybrid Vectors Composed of Thermosensitive Dendron Lipids and Gold Nanorods.

Background: Gene delivery to target cells is crucially important to establish gene therapy and regenerative medicine. Although various virus-based and synthetic molecule-based gene vectors have been developed to date, selective transfection in a site or a cell level is still challenging. For this study, both light-responsive and temperature-responsive synthetic gene vectors were designed for spatiotemporal control of a transfection system. Methods: 11-Mercaptoundecanoic acid-coated gold nanorods were mixed with polyamidoamine dendron-bearing lipids of two types having amino-terminus or ethoxydiethylene glycol-terminus to obtain hybrid vectors. Hybrid vectors were mixed further with pDNA. Then we investigated their physicochemical properties and transfection efficacy with or without near infrared laser irradiation. Results: Hybrid vectors formed complexes with pDNA and exhibited enhanced photothermal property under near infrared laser irradiation compared with parent gold nanorods. Transfection efficacy of complexes was promoted considerably by brief laser irradiation soon after complex application to the cells. Analysis of intracellular distribution revealed that laser irradiation promoted the adsorption of complexes to the cells and cytosolic release of pDNA, which is derived from the change in surface hydrophobicity of complexes through dehydration of temperature-responsive groups. Conclusions: Hybrid vector is promising as a light-activatable transfection system.

Effect of ultrasound on physicochemical and foaming properties of a protein concentrate from giant squid (Dosidicus gigas) mantle

Giant squid (Dosidicus gigas) proteins have appropriate functional properties, albeit of smaller magnitude in comparison to other marine species. Therefore, this research characterizes the ultrasound-induced (20 kHz; 20 and 40% amplitude; 0, 1, 3 and 5 min) changes to the physicochemical and foaming properties of mantle proteins. The changes in pH, electrophoretic profile, viscosity, surface hydrophobicity, particle size and zeta potential, as well as foaming capacity and stability were evaluated. A slight decrease (p ≥ 0.05) in the pH occurred as the ultrasound time increased. While no changes in SDS-PAGE (reducing and non-reducing) were detected, native PAGE revealed new bands. Ultrasound increased the viscosity and surface hydrophobicity, and decreased the particle size and net surface charge. Moreover, foaming capacity was improved and foaming stability was maintained at 100% for 1 h. Therefore, the application of ultrasound represents an alternative to improve the foaming properties.

Sulfidation of Ag and ZnO Nanomaterials Significantly Affects Protein Corona Composition: Implications for Human Exposure to Environmentally Aged Nanomaterials.

The physicochemical properties of engineered nanomaterials can change drastically during aging in the environment. Understanding how these changes influence protein corona formation on nanomaterials is critical for accurately predicting the human exposure risks of aged nanomaterials. Here, we show that sulfidation, a prevalently occurring environmental aging process, of Ag and ZnO nanomaterials significantly affected the protein compositions of the hard corona formed in human saliva, sweat, and bronchoalveolar lavage fluid, corresponding to three most common exposure pathways, that is, ingestion, dermal contact, and inhalation. In particular, a diverse variety of proteins selectively associated with either sulfidized or pristine nanomaterials. Random forest classification of the proteomic data revealed that this selective protein adsorption process was mainly dictated by electrostatic interaction, hydrophobic interaction, and steric hindrance between proteins and nanomaterials, which were susceptible to the changes in surface charge, hydrophobicity, and aggregation status of nanomaterials induced by sulfidation. Furthermore, even for the proteins that do not exhibit distinct adsorption selectivity between sulfidized and pristine nanomaterials, sulfidation altered the extents of impact of nanomaterials on the conformation and likely functions of the adsorbed proteins. These findings unearth a previously neglected mechanism via which environmental sulfidation process mediates the biological effects of soft-metal-containing nanomaterials.