Different Degrees Of Hydrophilicity Research Articles

Recent Advances on Starch-Based Adsorbents for Heavy Metal and Emerging Pollutant Remediation

Starch is one of the most abundant polysaccharides in nature and has a high potential for application in several fields, including effluent treatment as an adsorbent. Starch has a unique structure, with zones of different crystallinity and a glycosidic structure containing hydroxyl groups. This configuration allows a wide range of interactions with pollutants of different degrees of hydrophilicity, which includes from hydrogen bonding to hydrophobic interactions. This review article aims to survey the use of starch in the synthesis of diverse adsorbents, in forms from nanoparticles to blends, and evaluates their performance in terms of amount of pollutant adsorbed and removal efficiency. A critical analysis of the materials developed, and the results obtained is also presented. Finally, the review provides an outlook on how this polysaccharide can be used more effectively and efficiently in remediation efforts in the near future.

Scaling Laws in Polysaccharide Rheology: Comparative Analysis of Water and Ionic Liquid Systems.

This study investigates the rheological behavior of two plant-based polysaccharides, with different degrees of hydrophilicity, agar (highly hydrophilic) and guar gum (hydrophilic), in water and 1-ethyl-3-methylimidazolium acetate (EMImAc). The rheological response of these polymers is highly dependent on the solvent's ability to disrupt intermolecular associations. In water, agar forms hydrogels, while guar gum behaves as a viscoelastic liquid with slow modes. The plateau modulus (GN0) scales with polymer concentration (c) as GN0 ∼ c3, consistent with other natural polymers. In EMImAc, both polysaccharides form viscoelastic liquids, exhibiting GN0 ∼ c2.3, as expected for semiflexible polymer solutions. However, the terminal relaxation time, τD, and the specific viscosity, ηsp, scale as τD ∼ c5.3 and ηsp ∼ c7.6, indicative of intermolecular chain-chain associations. Despite the solvent or polysaccharide, the fractional viscosity overshoot and the shear strain at the maximum stress show a terminal Weissenberg number dependence similar to other synthetic polymers.

Enhanced Antifouling Capability of In Situ-Grown Hydrophilic-Hydrophobic Nanodomains on Membrane Surface in the Ultralow Pressurized Ultrafiltration Process.

Although hydrophilic modification of the membrane surface is widely adopted, polymeric membranes still suffer from irreversible fouling caused by hydrophilic components in surface water. Here, an ultrathin hydrogel layer (40 nm) with hydrophilic-hydrophobic textures was in situ grown onto the polysulfone ultrafiltration membrane surface using an organic-radical-initiated interfacial polymerization technique. The interfacial polymerization of hydrophilic and hydrophobic monomers ensured the molecular-scale distribution of hydrophilic and hydrophobic nanodomains on the membrane surface. These nanodomains, with their molecular lengths, facilitated dynamic repulsion interactions between the uniformly textured surface and foulant components with different degrees of hydrophilicity. Chemical force characterization confirmed that the adhesion force between the hydrophilic-hydrophobic textured membrane surface and foulants (dodecane, bovine serum albumin, and humic acid) was greatly reduced. Dynamic filtration experiments showed that a hydrophilic-hydrophobic textured membrane always possessed the largest water flux and the best antifouling performance. Furthermore, the foulant coverage ratio on the membrane surface was first evaluated by measuring changes in surface streaming potentials, which demonstrated a 69% reduction in the amount of foulant adhering to the hydrophilic-hydrophobic textured membrane surface. Therefore, the construction of hydrophilic-hydrophobic nanodomains on the membrane surface provides a promising strategy for alleviating membrane fouling caused by both hydrophobic and hydrophilic components during ultralow pressurized ultrafiltration processes.

Gamma-irradiated janus electrospun nanofiber membranes for desalination and nuclear wastewater treatment

This study presents the fabrication of double-layer electrospun nanofibrous membranes (DL-ENMs) using polyvinylidene fluoride (PVDF) and polyether sulfone (PES) based polymers with different degrees of hydrophilicity (PES, sulfonated PES, and PES with hydroxyl terminals). A comparative analysis was carried out with single-layer electrospun nanofiber membranes (SL-ENM) with a total thickness of about 375 μm. Using feed solutions, including sodium chloride, sodium nitrate, and simulated nuclear wastewater (SNWW), the performance of DL-ENMs was evaluated for desalination and radionuclide decontamination by direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD) techniques. The results showed that DL-ENMs, especially those incorporating a sulfonated PES-based hydrophilic layer, exhibited superior permeate fluxes, reaching values of 72.72 kg/m2.h and 73.27 kg/m2.h in the DCMD using aqueous feed solutions of NaCl and NaNO3, respectively, and 70.80 kg/m2.h and 41.96 kg/m2.h using aqueous feed solutions of SNWW in DCMD and AGMD, respectively. Both SL-ENMs and DL-ENMs exhibited high rejection efficiencies and decontamination factors for the feed solutions (>99.9%). In addition, the prepared ENMs were exposed to gamma radiation to evaluate their applicability in real-life applications. The result of irradiation revealed the negative impact of gamma radiation on the fluorine content of PVDF which could be a critical point in using PVDF as a hydrophobic material for decontaminating nuclear wastewater by membrane distillation.

Aromatized liposomes for sustained drug delivery

Insufficient drug loading and leakage of payload remain major challenges in designing liposome-based drug delivery systems. These phenomena can limit duration of effect and cause toxicity. Targeting the rate-limiting step in drug release from liposomes, we modify (aromatized) them to have aromatic groups within their lipid bilayers. Aromatized liposomes are designed with synthetic phospholipids with aromatic groups covalently conjugated onto acyl chains. The optimized aromatized liposome increases drug loading and significantly decreases the burst release of a broad range of payloads (small molecules and macromolecules, different degrees of hydrophilicity) and extends their duration of release. Aromatized liposomes encapsulating the anesthetic tetrodotoxin (TTX) achieve markedly prolonged effect and decreased toxicity in an application where liposomes are used clinically: local anesthesia, even though TTX is a hydrophilic small molecule which is typically difficult to encapsulate. Aromatization of lipid bilayers can improve the performance of liposomal drug delivery systems.

Ring-Fused meso-Tetraarylchlorins as Auspicious PDT Sensitizers: Synthesis, Structural Characterization, Photophysics, and Biological Evaluation.

Novel 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused meso-tetraarylchlorins, with different degrees of hydrophilicity (with methyl ester, hydroxymethyl, and carboxylic acid moieties), have been synthesized and their photophysical characterization as well as in vitro photocytotoxicity assessment against human melanoma and esophageal and bladder carcinomas was carried out. An integrated analysis of the photosensitizers’ performance, considering the singlet oxygen generation data, cell internalization, and intracellular localization, allowed to establish relevant structure-photoactivity relationships and the rationalization of the observed photocytotoxicity. In the diacid and monoalcohol series, chlorins derived from meso-tetraphenylporphyrin proved to be the most efficient photodynamic therapy agents, showing IC50 values of 68 and 344 nM against A375 cells, respectively. These compounds were less active against OE19 and HT1376 cells, the diacid chlorin with IC50 values still in the nano-molar range, whereas the monohydroxymethyl-chlorin showed significantly higher IC50 values. The lead di(hydroxymethyl)-substituted meso-tetraphenylchlorin confirmed its remarkable photoactivity with IC50 values below 75 nM against the studied cancer cell lines. Subcellular accumulation of this chlorin in the mitochondria, endoplasmic reticulum, and plasma membrane was demonstrated.

Synthesis and application of smart gel material modified silica microspheres for pH-responsive hydrophilicity in liquid chromatography.

Inspired by porous smart gel materials, we designed pH-responsive polymer-modified silica microspheres as liquid chromatography stationary phase materials by a one-step strategy. The free radicals generated by the oxidation of dopamine are used to initiate the cross-linking polymerization of functional monomers. At the same time, the good adhesion of dopamine enables the polymer to be modified on silica. The hydrophilicity of this new stationary phase can change in response to the pH of the mobile phase and the stationary phase has weaker hydrophilicity under acidic (pH = 3.78) mobile phase conditions and stronger hydrophilicity under neutral mobile phase conditions. The hydrophilicity difference of the stationary phase leads to the selectivity difference in separation. To evaluate the chromatographic performance of this new stationary phase, 10 oligosaccharides and 9 nucleosides/bases were separated on this stationary phase. This paper will provide good guidance for us to achieve more pH-responsive hydrophilic/hydrophobic stationary phases in the future.

Independent co-delivery of model actives with different degrees of hydrophilicity from oil-in-water and water-in-oil emulsions stabilised by solid lipid particles via a Pickering mechanism: a-proof-of-principle study

HypothesisThe development of vehicles for the co-encapsulation of actives with diverse characteristics and their subsequent controllable co-delivery is gaining increasing research interest. Predominantly centred around pharmaceutical applications, the majority of such co-delivery approaches have been focusing on solid formulations and less so on liquid-based systems. Simple emulsions can be designed to offer a liquid-based microstructural platform for the compartmentalised multi-delivery of actives. ExperimentsIn this work, solid lipid nanoparticle stabilised Pickering emulsions were used for the co-encapsulation/co-delivery of two model actives with different degrees of hydrophilicity. Lipid particles containing a model hydrophobic active were prepared in the presence of either Tween 20 or whey protein isolate, and were then used to stabilise water-in-oil or oil-in-water emulsions, containing a secondary model active within their dispersed phase. FindingsSolid lipid nanoparticles prepared with either type of emulsifier were able to provide stable emulsions. Release kinetic data fitting revealed that different co-delivery profiles can be achieved by controlling the surface properties of the lipid nanoparticles. The current proof-of-principle study presents preliminary data that confirm the potential of this approach to be utilised as a flexible liquid-based platform for the segregated co-encapsulation and independent co-release of different combinations of actives, either hydrophobic/hydrophilic or hydrophobic/hydrophobic, with diverse release profiles.

Platinum(II) ring-fused chlorins as efficient theranostic agents: Dyes for tumor-imaging and photodynamic therapy of cancer

The discovery of Pt-chlorin-type theranostic agents is described. Luminescent Pt(II) 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused chlorins, with different degrees of hydrophilicity, have been synthesized and their in vitro photocytotoxicity against human melanoma, oesophageal and bladder carcinomas was studied. A di(hydroxymethyl)-substituted chlorin was identified as a privileged molecule to explore imaging-guided photodynamic therapy. In addition to the high activity as PDT agent and absence of cytotoxicity per se, this molecule showed the ideal photophysical and photochemical properties. In vivo studies using a A375 melanoma mouse model, proved the extraordinary properties of this chlorin as a luminescent probe and the ability to impair tumor growth, making image guided treatment and follow up a possibility.

Initial mass uptake dynamics and diffusivity of cyclohexane vapor in nano-scale bitumen films coated on substrates with different degrees of hydrophilicity

Absorption of cyclohexane vapor into thin bitumen films with 0.5 wt% and 2 wt% bitumen coated on samples containing large spherical particles made up of borosilicate glass and fine particles with different chemical compositions (borosilicate glass versus kaolin clay) was studied using a gravimetric technique. Samples containing glass fines and clay fines are denoted as SA and SB, respectively. Fines refer to the particles with sizes less than 45 µm and their concentration varied from 5 to 20 wt% in SA and SB. The results clearly showed that the chemical composition of the fines significantly affected the cyclohexane initial mass uptake rate and that this rate exhibited a negative bitumen content dependence with the dependence of SA much stronger than that of SB. This is because glass (SA samples) is much more hydrophilic than clay (SB samples). As a result, SA rendered a stronger concentration gradient of the polar bitumen molecules in the film thickness direction than SB, thereby stronger negative bitumen content dependence. Diffusion coefficients were estimated using the cyclohexane initial uptake rates and the surface area average film thicknesses of the samples and were found that the diffusion coefficient increased with increasing bitumen content (i.e., film thickness) in both SA and SB cases. Varying fines content did not have any effect on the cyclohexane initial mass uptake rate. It was found that increase in the fines content decreased the bitumen film thickness, thereby decreasing the diffusion coefficient that is offset by the increase in the amount of cyclohexane dissolved at the interface.

Maximizing the grafting of zwitterions onto the surface of ultrafiltration membranes to improve antifouling properties

Superhydrophilic zwitterions have been extensively exploited for surface modification to improve antifouling properties. However, it remains challenging to form layers of <20 nm with high zwitterion content on the surfaces with different degrees of hydrophilicity. We demonstrate that amine-functionalized sulfobetaine (SBAm) can be co-deposited with dopamine on ultrafiltration (UF) membranes, leading to a thickness of 10 nm to 50 nm and an SBAm content of up to 31 mass% in the coating layers. The covalently grafted SBAm is stable underwater and improves the antifouling properties, as evidenced by the lower trans-membrane pressure required to retain targeted water fluxes than that required for the pristine membranes. The SBAm is also more effective than conventionally used sulfobetaine methacrylate (SBMA) for the zwitterion grafting on the surface to improve antifouling properties.

Traction force measurements on male Strepsiptera (Insecta) revealed higher forces on smooth compared with hairy substrates.

The aim of this study was to find out how strongly the parasitic insect Stylopsovinae, which has tarsi equipped with tenent hairs and lacking claws, attaches to different substrates. We investigated adhesion of male S. ovinae to the abdomen of its hymenopteran host (Andrena vaga), the hairier abdomen of a Bombus sp. and two artificial smooth reference surfaces with different degrees of hydrophilicity. In our experiments, the male S. ovinae developed significantly higher forces on smooth surfaces. However, the forces were significantly lower on all the hymenopteran surfaces used in the experiment. The absence of anisotropy in the force grip in cranial/caudal direction relative to the host might indirectly indicate that S. ovinae generate forces by adhesion rather than mechanical interlocking with the host hairs. The tolerance of the attachment system of S. ovinae to the substrate chemistry might be explained by the primary contribution of van der Waals interactions and not capillary forces to adhesion in S. ovinae.

Screening effect of monolayer van der Waals crystals on surface deicing: a molecular simulation study.

Our extensive molecular dynamics simulations reveal a significant screening effect of monolayer graphene and hexagonal boron nitride (h-BN) on surface deicing of substrates with different degrees of hydrophilicity, including superhydrophilic (SHP) and superhydrophobic (SHB) substrates. Compared with bare surfaces, graphene and h-BN reduce the interfacial shear strength and the normal detaching strength of ice on an SHP substrate but increase the shear and detaching strengths on hydrophobic and SHB substrates. However, the shear and detaching strengths of ice become approximately unified on all of the surfaces, when interface ice layers melt into liquid water, demonstrating the screening capability from graphene and h-BN that weakens the influence of substrates on ice adhesion. Graphene and h-BN coatings suppress ice premelting on the SHP surface and change the dielectric constant of interface ice or water. This work could deepen our understanding of the role of van der Waals crystals in deicing coating.

NIPAM-based Microgel Microenvironment Regulates the Therapeutic Function of Cardiac Stromal Cells.

To tune the chemical, physical, and mechanical microenvironment for cardiac stromal cells to treat acute myocardial infarction (MI), we prepared a series of thermally responsive microgels with different surface charges (positive, negative, and neutral) and different degrees of hydrophilicity, as well as functional groups (carboxyl, hydroxyl, amino, and methyl). These microgels were used as injectable hydrogels to create an optimized microenvironment for cardiac stromal cells (CSCs). Our results indicated that a hydrophilic and negatively charged microenvironment created from poly( N-isopropylacrylamide- co-itaconic acid) was favorable for maintaining high viability of CSCs, promoting CSC proliferation and facilitating the formation of CSC spheroids. A large number of growth factors, such as vascular endothelial growth factor (VEGF), insulin-like growth factor I (IGF-1), and stromal-derived factor-1 (SDF-1) were released from the spheroids, promoting neonatal rat cardiomyocyte activation and survival. After injecting the poly( N-isopropylacrylamide- co-itaconic acid) microgel into mice, we examined their acute inflammation and T-cell immune reactions. The microgel itself did not elicit obvious immune response. We then injected the same microgel-encapsulated with CSCs into MI mice. The result revealed the treatment-promoted MI heart repair through angiogenesis and inhibition of apoptosis with an improved cell retention rate. This study will open a door for tailoring poly( N-isopropylacrylamide)-based microgel as a delivery vehicle for CSC therapy.

PO-422 Disagregation in biological medium of promising theranostic agents for cancer

IntroductionWe recently developed a new type of photochemically stable platinum (II) chlorins, which are remarkable photosensitizers that can be used in photodynamic therapy (PDT), due to its therapeutic capacity. Simultaneously, due to its highly luminescence proprieties, in the biological relevant 650–850 nm red and near infrared spectral region, they may be used for biological imaging. In addition, photophysical studies indicate that they may be used as ratiometric oxygen sensors.Material and methodsCompounds with different degrees of hydrophilicity were synthesised and characterised. Photocytotoxicity studies were carried out against two human tumour cell lines, the OE19 line of oesophageal carcinoma and the A375 line of melanocytic melanoma. The formulation of the sensitizers consisted in a 1 mg/mL solution in DMSO and the desired concentrations being achieved by successive dilutions. The sensitizers were administered in several concentrations (from 50 nM to 10 µM) and, 24 hour after incubation, cells were washed with PBS and new drug-free medium was added. Plates were irradiated (<580 nm) with a fluence rate of 7.5 mW/cm2, to reach 10 J. Controls were performed on every test. Evaluation by MTT assay was performed 24 hour after the photodynamic treatment. The IC50 values were calculated.Results and discussionsPreliminary cytotoxicity studies indicate that, in both cell lines, platinum (II) chlorins with more hydrophilic features require lower doses of photosensitizer to induce a significant photocytotoxic effect on tumour cells. Our best results were IC50 value of 165.9 nM (confidence interval at 95%: [77.9; 356.6]) for A375 line and 498.6 nM (confidence interval at 95%: [283.5; 876.5]) for OE19 line. However, and given that the confidence intervals were too large, it was hypothesised that this type of compounds would be aggregating in the biological medium. This hypothesis was corroborated by additional photophysical studies. As such, disaggregation was performed with the use of a non-ionic surfactant since surface active agents (surfactants) has been widely used for enhancing solubilisation of poorly soluble drugs.ConclusionAlthough photocytotoxicity studies reveal that the platinum (II) chlorins tested would be very promising for PDT, further cytotoxicity studies will be carried out using a novel formulation.This work was funded by Fundação para a Ciência e a Tecnologia (FCT): POCI-01–0145-FEDER-PTDC/QEQ-MED/0262/2014;COMPETE 2020 POCI-01–0145-FEDER-007630 and POCI-01–0145-FEDER-007440.

Controlled release of fragrance with cross-linked polymers: synthesis and hydrolytic property of cross-linked amphiphilic copolymers bearing octanal-derived acetal moieties

A cross-linked amphiphilic polymethacrylate, composed of hydrophobic octanal-derived acetal and hydrophilic poly(ethylene glycol) moieties, was synthesized with different degrees of hydrophilicity. The polymer hydrophilicity was estimated based on measurements of contact angles with water. Release of octanal was achieved in a biphasic system composed of hexane and an aqueous suspension of the polymers. The acetal moieties of the polymers were gradually hydrolyzed in an acidic solution, releasing octanal continuously for 600 h. The amount of released octanal increased with an increase in the hydrophilicity of the polymer under acidic conditions.

PVDF/PMMA membranes for lemon juice clarification: fouling analysis

Microfiltration/ultrafiltration membranes with different degrees of hydrophilicity and structural characteristics from poly(vinylidene fluoride) (PVDF), polymethylmetacrylate (PMMA), and polyvinylpirrolidone (PVP) in dimethylformamide (DMF) solvent were prepared to be used in the lemon juice clarification. The effect of transmembrane pressure (Δp = 0.4–1 bar) and tangential feed velocity (v = 0.2–1 m/s) on permeate flux and juice quality at T = 20°C was examined. The membrane containing 15% of PVDF, 5% PMMA, and 5% PVP (mean pore radii rpm = 0.25μm and porosity ε = 0.25) achieved the best performance at Δp = 1 bar and v = 1 m/s, with a final permeate flux at quasi-steady state of 32.5 (L/hm2). The clarified lemon juice presented physical, chemical, and nutritional characteristics comparable to the fresh lemon juice, and 100% of total solid rejection. Membrane fouling was evaluated by applying different fouling models. Results indicated that a good fitting correlation between the experimental data and both complete blocking and cake models was achieved.

Hydrothermal Growth Mechanism of Controllable Hydrophilic Titanate Nanostructures on Medical NiTi Shape Memory Alloy

Different titanate nanostructures were deposited on the surface of NiTi by a hydrothermal process using 5-20 M NaOH at 90-150 °C for 6-72 h. SEM and XRD analyses revealed that different structures such as nanoflakes, nanorods, nanograins, nanofibers, microwhiskers, etc., were formed. As the processing time was increased, the nanoflakes evolve into nanofibers or microwhiskers. Compared with pristine NiTi, the new surfaces displayed different degrees of hydrophilicity. A formation mechanism adopting the growth unit model of anion coordination-polyhedra is proposed. The general formation of titanate nanostructures can be visualized as a sequence of nucleation, formation, and combination of the growth units. The excellent controllability of this process with precise accuracy offers incredible potential in the surface modification of NiTi biomedical materials for medical applications.

Experimental adhesives with different hydrophilicity: microshear test in after 1, 7, and 90 days' storage.

To assess the microshear bond strength of 3 experimental adhesives with different degrees of hydrophilicity after 1, 7 and 90 days of storage. The bonding effectiveness of three experimental two-step etch-and-rinse adhesives (bis- GMA, bis-EMA/bis-GMA, polybutadiene [C6H12]) and one commercial adhesive (Single Bond) to sound hydrated dentin was determined using the microshear test with delimitation of the adhesive area after 1, 7, and 90 days of storage in water at 37°C. Two-way ANOVA was performed at the 0.05 probability level. The fractures were classified as adhesive, cohesive in dentin, cohesive in resin, and mixed. The experimental adhesives showed values in the range of 11.31 to 12.96 MPa, with polybutadiene (PBH) showing the lowest bond strengths, bis-GMA the highest, and bis-EMA/bis-GMA intermediary values. Single Bond yielded bond strengths of approximately 24 MPa. Water storage decreased the bond strength in all adhesives. Adhesive fractures were predominant in experimental adhesives, while mixed fractures were the most frequent type in the Single Bond group. The experimental dentin adhesives of this study were able to form resin tags, but they could not penetrate into the collagen fibers and form hybrid layers. The resulting low bond strength decreased with increasing length of storage.

Humidity sensors based on Aurivillius type Bi2MO6 (M = W, Mo) oxide films

Humidity sensors based on Aurivillius type Bi2MO6 (M=W or Mo) materials have been fabricated using the “Doctor Blade” method. The structure and morphology of the fabricated films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sensing properties were investigated with respect to both impedance and capacitance characteristics. The humidity sensing tests displayed ultrahigh sensitivities with impedance changes of 4–5 orders of magnitude with the increase of the relative humidity (RH) from 11 to 95%. The Bi2MO6 materials furthermore revealed a rapid response and recovery time with good reproducibility. The sensing properties of the Bi2WO6 sample are superior to those of the Bi2MoO6 materials due to their larger surface-to-volume ratio and different degrees of hydrophilicity. In addition, the sensing mechanism of the Bi2MO6 based sensors is discussed. These results open up promising applications of Aurivillius type oxides in electronic devices for highly sensitive environmental monitoring and humidity control.