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LL-III is an anticancer peptide and has the ability to translocate across tumor cell membranes, which indicates that its action mechanism could be non-membranolytic. However, the exact mechanism through which the peptide gains access into the cell cytoplasm is still unknown. Here, we use a plethora of physico-chemical techniques to characterize the interaction of LL-III with liposomes mimicking the lipid matrix of the tumor cell membrane and its effect on the microstructure and thermotropic properties of the membrane. Furthermore, the effect of the presence of Ca

Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, “pin-point”, functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demonstrated by several techniques. Turbidimetric analysis showed that PDA coating affected the aqueous stability of HNTs@PDA compared to both HNTs@ZnO and HNTs. Notably, hyperthermia studies revealed that the nanomaterial induced a local thermic rise, up to 50 °C, under near-infrared (NIR) irradiation. Furthermore, secondary functionalization of HNTs@PDA by selective grafting of biotin onto the PDA coating followed by avidin binding was also accomplished.

The waste-to-wealth strategy is encouraging the design of a plethora of new value-added materials, by exploiting the chemical and biological richness of biowastes. Humic Acids (HA) are mostly intriguing because of their amphiphilic supramolecular associations which are responsible for several assets, such as adsorption ability towards small molecules, metal ion chelation, redox behavior, and antibacterial activity. The molecular combination of HA with semiconductor nanoparticles represents a valuable strategy to obtain nanostructured hybrid materials and interfaces with advanced features. Concurrently, it permits to overcome intrinsic limits of such organic fraction, including poor stability, fast conformational dynamics, or rapid reactivity in aqueous media. Herein, hybrid HA/ZnO nanoparticles are synthetized through a bottom-up strategy, exerting an improved pro-oxidant behavior by generating Reactive Oxygen Species, even without light irradiation, favoring an enhanced photocatalytic and antimicrobial activity against different bacterial pathogens. Several techniques, including SEM/TEM, DLS, ζ-potential, XRD, FTIR, TGA/DSC, EPR and DRUV, allows to define the structure-property-function relationships, thus highlighting the crucial role of a fine conjugation amongst the metal oxide precursor and bioderived fraction to drive the pro-oxidant activity. This study provides strategic guidelines to easily produce low-cost organo-inorganic nanomaterials with redox and biocide properties, aimed at coping environmental and health issues.

Various catalysts were used to catalyze the ethoxylation reaction of C12–14 primary alcohols with ethylene oxide. Alcohol ethoxylates with a ratio of ethylene oxide/substrate near 3 were synthesized. The catalysts influenced the reaction rate, molecular weight distribution of adducts, and formation of byproducts. The physicochemical properties of ethoxylates obtained using different catalytic systems were analyzed, and their functional properties, i.e., wetting and permeation, were investigated. The results showed that the products obtained using the catalysts MCT-09 and NAE-03 had a narrower oligomer distribution and excellent wetting properties compared with those obtained using conventional ethoxylation catalysts.

The use of technologies based on soft polymer particles represents an effective way to deliver target molecules with a specific function. To design a well-performing delivery system, it is fundamental to rationalize both the aggregation and the structural properties of such particles. In this study, we present the kinetic and structural characterization over time of poly(vinyl alcohol) (PVA) microgels obtained through a salting-out process in the presence of NaCl. We have analyzed how both the polymer and salt concentrations affect the aggregation process. The aggregation rate as well as the morphology and physico-chemical parameters, such as mass and chain density of the microgels, have been determined through static and dynamic light scattering and discussed in the framework of the diffusion-limited and reaction-limited colloid aggregation. Insights into the polymer chain arrangements and their dynamics have been gained by means of small-angle neutron scattering and neutron spin-echo measurements. As a result, it was found that NaCl induces a liquid phase separation in solution with the formation of spherical PVA microaggregates, which grow under a reaction-limited aggregation mechanism. The particles increase their size and compactness over time. Within the aggregate, the polymer chains are locally organized to form randomly oriented lamellae with a thickness of about 60 Å. The internal dynamics is a complex mixture of diffusion, Zimm dynamics, and possibly effects from crowding with the transition to a Rouse-like behavior. The microparticle preparation based on the salting-out process constitutes a novelty, if compared to the methods already existing and based on the use of chemical cross-linkers, and is a cheap and easy protocol that allows tuning both particle size and density by varying the salt concentration.

Metal oxide-organic hybrid semiconductors exhibit specific properties depending not only on their composition but also on the synthesis procedure, and particularly on the functionalization method, determining the interaction between the two components. Surface adsorption is the most common way to prepare organic-modified metal oxides. Here a simple sol-gel route is described as an alternative, finely controlled strategy to synthesize titanium oxide-based materials containing organic molecules coordinated to the metal. The effect of the molecular structure of the ligands on the surface properties of the hybrids is studied using three enediols able to form charge transfer complexes: catechol, dopamine, and ascorbic acid. For each system, the process conditions driving the transition from the sol to chemical, physical, or particulate gels are explored. The structural, optical, and photoelectrochemical characterization of the amorphous hybrid materials shows analogies and differences related to the organic component. In particular, electron paramagnetic resonance (EPR) spectroscopy at room temperature reveals the presence of organic radical species with different evolution and stability, and photocurrent measurements prove the effective photosensitization of TiO

Metal oxide-organic hybrid semiconductors exhibit specific properties depending not only on their composition but also on the synthesis procedure, and particularly on the functionalization method, determining the interaction between the two components. Surface adsorption is the most common way to prepare organic-modified metal oxides. Here a simple sol–gel route is described as an alternative, finely controlled strategy to synthesize titanium oxide-based materials containing organic molecules coordinated to the metal. The effect of the molecular structure of the ligands on the surface properties of the hybrids is studied using three enediols able to form charge transfer complexes: catechol, dopamine, and ascorbic acid. For each system, the process conditions driving the transition from the sol to chemical, physical, or particulate gels are explored. The structural, optical, and photoelectrochemical characterization of the amorphous hybrid materials shows analogies and differences related to the organic component. In particular, electron paramagnetic resonance (EPR) spectroscopy at room temperature reveals the presence of organic radical species with different evolution and stability, and photocurrent measurements prove the effective photosensitization of TiO2 in the visible range induced by interfacial ligand-to-metal charge transfer.

Methylobacterium extorquens is a facultative methylotrophic Gram-negative bacterium, often associated with plants, that exhibits a unique ability to grow in the presence of high methanol concentrations, which serves as a single carbon energy source. We found that M. extorquens strain PA1 secretes a mixture of different exopolysaccharides (EPSs) when grown in reference medium or in presence of methanol, that induces the secretion of a peculiar and heterogenous mixture of EPSs, with different structure, composition, repeating units, bulk and a variable degree of methylation. These factors influenced 3D structure and supramolecular assets, diffusion properties and hydrodynamic radius, and likely contribute to increase methanol tolerance and cell stability. No direct methanol involvement in the EPSs solvation shell was detected, indicating that the polymer exposure to methanol is water mediated. The presence of methanol induces no changes in size and shape of the polymer chains, highlighting how water-methanol mixtures are a good solvent for refEPS and metEPS.

Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, ''pin-point", functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demonstrated by several techniques. Turbidimetric analysis showed that PDA coating affected the aqueous stability of HNTs@PDA compared to both HNTs@ZnO and HNTs. Notably, hyperthermia studies revealed that the nanomaterial induced a local thermic rise, up to 50 C, under near-infrared (NIR) irradiation.

Three different deep eutectic solvent (DES)-based extraction procedures were rationally designed and optimized for the recovery of antioxidants from chestnut wood fiber (CWF), a clean and largely available solid waste of the tannin industry. First, a mild protocol was developed using a choline chloride (ChCl)/tartaric acid DES at 50 °C, for 90 min. Ellagic acid (EA) was identified as the only low molecular weight phenolic component of the extract. In other experiments, harsher conditions were explored involving treatment of CWF with ChCl-based DESs at 120 °C for 8 h, which afforded a solid sample characterized by high phenolic content (up to 1.0 mg of gallic acid equivalents/mg of sample) and antioxidant properties (EC50

This work studies the interaction of organic nanoparticles (ON) with various dyes in aqueous solution, to elucidate the role of ON on transport and fate of dyes in the environment, and on dyes removal from wastewater. Studied dyes are Acid Red 66 (AR66), Methylene Blue (MB), Reactive Black 5 (RB5), and Reactive Violet 5 (RV5). ON are extracted from organic matter of anthropogenic origin through resuspension of its colloidal fraction, and successive filtration and dialysis of the obtained suspension. Mechanisms of interaction are investigated initially through three-dimensional excitation emission matrix (3DEEM) analysis. Obtained data indicate that dynamic interactions occur strongly between dye molecules and ON aggregates. 3DEEM spectra of mixed samples containing ON together with one of the tested dyes, present a shape similar to the one of ON alone, but each of them is characterized by specific differences in terms of peaks quenching and shift. The analysis of these singularities suggests that dye molecules are bound to the functional groups of ON through H-bonds, according to the following steps: i) dyes reach the surface of ON aggregates; ii) the molecules pass through the hydrophilic surface of ON aggregates, and reach their hydrophobic core; iii) the dyes are sequestrated into the hydrophobic core of ON aggregates. Nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies analysis confirm the formation of supramolecular aggregates with stable micellar hydrophobic structure, mainly consisting of aliphatic fractions of ON, which explain the disappearance of aromatic groups signals from dyes.

The functional properties of metal oxide semiconductors depend on intrinsic and extrinsic defects. The population of intrinsic defects is strongly affected by the synthesis method and subsequent treatments of the material, while extrinsic defects can originate from suitable doping. Stoichiometric ZrO2 is a nonreducible oxide with a large band gap. Therefore, controlling and modulating its defect profile to induce energy states in the band gap is the sole possibility to make it a photocatalyst responsive to visible light. We report a method, based on low temperature sol−gel synthesis coupled with treatments performed in mild conditions, to obtain undoped visible light-responsive ZrO2−x. The electronic structure of these materials is interpreted in relation to their oxygen vacancy defect population. On the basis of a wide set of experimental measurements (X-ray photoelectron, steady-state and time-resolved photoluminescence, electron paramagnetic resonance, and UV−visible diffuse reflectance spectroscopy) and supported by density functional theory calculations, we demonstrate, for the first time, the predominance of positively charged F-center oxygen vacancies that do not give rise to Zr3+ species.

Reported herein is the purification of the pigment of black sturgeon caviar and its unambiguous identification as a typical eumelanin by means of chemical degradation coupled with electron paramagnetic resonance (EPR) evidence. HPLC and LC-MS analysis of oxidative degradation mixtures revealed the formation of pyrrole-2,3,5-tricarboxylic acid (PTCA), a specific marker of eumelanin pigments, in yields compatible with a 6.5% w/w pigment content. EPR spectral features and parameters were in close agreement with those reported for a typical natural eumelanin such as Sepia melanin from squid ink. The identification for the first time of eumelanin in a fish roe is expected to provide a novel molecular basis for the valorization of black caviar and production wastes thereof in food chemistry and diet.

Identification of strategies to prolong emulsion kinetic stability is a fundamental challenge for many scientists and technologists. We investigated the relationship between the emulsion stability and the surfactant supramolecular organization at the oil&ndash, water interface. The pseudo-phase diagrams of emulsions formed by water and, alternatively, a linear or a branched oil, stabilized by mixtures of two sugar-based surfactants, Span80 and Tween80, are presented. The surfactant ordering and dynamics were analyzed by electron paramagnetic resonance (EPR) spectroscopy. In Oil-in-Water (O/W) emulsions, which are stable for more than four days, disordered surfactant tails formed a compact and viscous layer. In Water-in-Oil (W/O) emulsions, whose stability is much lower, surfactants formed an ordered layer of extended tails pointing toward the continuous apolar medium. If linear oil was used, a narrow range of surfactant mixture composition existed, in which emulsions did not demix in the whole range of water/oil ratio, thus making it possible to study the phase inversion from O/W to W/O structures. While conductometry showed an abrupt inversion occurring at a well-defined water/oil ratio, the surfactant layer microstructure changed gradually between the two limiting situations. Overall, our results demonstrate the interconnection between the emulsion stability and the surfactant layer microstructuring, thus indicating directions for their rational design.

Lipopolysaccharides (LPS) are complex amphiphilic macromolecules forming the external leaflet of the outer membrane of Gram-negative bacteria. The LPS glycolipid portion, named Lipid A, is characterized by a disaccharide backbone carrying multiple acyl chains. Some Lipid A bear very-long-chain-fatty-acids (VLCFA), biosynthesized to span the entire lipid membrane profile. The synbiontic Bradyrhizobium BTAi1 strain carries an unique Lipid A specie, named HoLA, in which VLCFA terminus is covalently-bonded to hopanoid, a triterpenoid displaying structural similarity with eukaryotic sterols. Here, we investigate the role of HoLA in regulating self-assembly, microstructure and thermotropicity of lipid membranes composed by 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-1′-rac-glycerol. DLS and SANS indicated the formation of multilamellar aggregates whose size increases when the hopanoid is present in the bilayer. EPR and DSC showed that HoLA induced a more rigid and ordered organization among the lipids in the bilayer, evocative of a mechanical strengthening. Notably, the presence of calcium ions promote an increase of the bilayer thickness and vesicles size, leading to low curvature aggregates. These results highlight the key role of the hopanoid covalently-linked to VLCFA in defining the physico-chemical properties of bacterial envelope, thus offering a robust scientific basis for the interpretation of the biological activity of the considered strain.

The bacterial cytoplasmic membrane is the innermost bacterial membrane and is mainly composed of three different phospholipid species, i.e., phosphoethanolamine (PE), phosphoglycerol (PG), and cardiolipin (CL). In particular, PG and CL are responsible for the negative charge of the membrane and are often the targets of cationic antimicrobial agents. The growing resistance of bacteria toward the available antibiotics requires the development of new and more efficient antibacterial drugs. In this context, studying the physicochemical properties of the bacterial cytoplasmic membrane is pivotal for understanding drug-membrane interactions at the molecular level as well as for designing drug-testing platforms. Here, we discuss the preparation and characterization of PE/PG/CL vesicle suspensions, which contain all of the main lipid components of the bacterial cytoplasmic membrane. The vesicle suspensions were characterized by means of small-angle neutron scattering, dynamic light scattering, and electron paramagnetic spectroscopy. By combining solution scattering and spectroscopy techniques, we propose a detailed description of the impact of different CL concentrations on the structure and dynamics of the PE/PG bilayer. CL induces the formation of thicker bilayers, which exhibit higher curvature and are overall more fluid. The experimental results contribute to shed light on the structure and dynamics of relevant model systems of the bacterial cytoplasmic membrane.

The formulation of highly concentrated products with low viscosity is a key issue of the surfactants industry, for both economic and ecological reasons. The rational design of surfactant tails bearing a limited number of short side chains has been proposed as a suitable strategy to meet this demand, with negligible effects on biodegradability. In this work, we investigate a mixed surfactant system, in which the branched surfactant N,N-dimethyl-2-propylheptan-1-amine oxide (C10DAO-branched) is combined with a linear alkyl ethoxysulfate one (AES). For comparison, we also study the mixtures in which the branched amine oxide is replaced by its linear isomer (C10DAO-linear). The phase behavior of this surfactant mixture in water is investigated across the entire composition range by polarized optical microscopy and small angle X-ray scattering. Moreover, the shear viscosities and viscoelastic moduli of representative samples are determined by rheological measurements. C10DAO-branched/AES aqueous mixtures form isotropic micellar solution and lamellar structures. Low viscosity was found for all these mixtures, including the most concentrated ones. In contrast, in C10DAO-linear/AES mixtures an extended hexagonal phase is detected, which presents a high viscosity. These results demonstrate tail branching and mixed aggregation to synergistically contribute to the design of high-concentration low-viscosity surfactant mixtures.

Hybrid Melanin-TiO

Humic acids (HAs) provide an important bio-source for redox-active materials. Their functional chemical groups are responsible for several properties, such as metal ion chelating activity, adsorption ability towards small molecules and antibacterial activity, through reactive oxygen species (ROS) generation. However, the poor selectivity and instability of HAs in solution hinder their application. A promising strategy for overcoming these disadvantages is conjugation with an inorganic phase, which leads to more stable hybrid nanomaterials with tuneable functionalities. In this study, we demonstrate that hybrid humic acid/titanium dioxide nanostructured materials that are prepared via a versatile in situ hydrothermal strategy display promising antibacterial activity against various pathogens and behave as selective sequestering agents of amoxicillin and tetracycline antibiotics from wastewater. A physicochemical investigation in which a combination of techniques were utilized, which included TEM, BET, 13C-CPMAS-NMR, EPR, DLS and SANS, shed light on the structure-property-function relationships of the nanohybrids. The proposed approach traces a technological path for the exploitation of organic biowaste in the design at the molecular scale of multifunctional nanomaterials, which is useful for addressing environmental and health problems that are related to water contamination by antibiotics and pathogens.

Gp36 is the virus envelope glycoproteins catalyzing the fusion of the feline immunodeficiency virus with the host cells. The peptide C8 is a tryptophan-rich peptide corresponding to the fragment 770W-I777 of gp36 exerting antiviral activity by binding the membrane cell and inhibiting the virus entry. Several factors, including the membrane surface charge, regulate the binding of C8 to the lipid membrane. Based on the evidence that imperceptible variation of membrane charge may induce a dramatic effect in several critical biological events, in the present work we investigate the effect induced by systematic variation of charge in phospholipid bilayers on the aptitude of C8 to interact with lipid membranes, the tendency of C8 to assume specific conformational states and the re-organization of the lipid bilayer upon the interaction with C8. Accordingly, employing a bottom-up multiscale protocol, including CD, NMR, ESR spectroscopy, atomistic molecular dynamics simulations, and confocal microscopy, we studied C8 in six membrane models composed of different ratios of zwitterionic/negatively charged phospholipids. Our data show that charge content modulates C8-membrane binding with significant effects on the peptide conformations. C8 in micelle solution or in SUV formed by DPC or DOPC zwitterionic phospholipids assumes regular β-turn structures that are progressively destabilized as the concentration of negatively charged SDS or DOPG phospholipids exceed 40%. Interaction of C8 with zwitterionic membrane surface is mediated by Trp1 and Trp4 that are deepened in the membrane, forming H-bonds and cation-π interactions with the DOPC polar heads. Additional stabilizing salt bridge interactions involve Glu2 and Asp3. MD and ESR data show that the C8-membrane affinity increases as the concentration of zwitterionic phospholipid increases. In the lipid membrane characterized by an excess of zwitterionic phospholipids, C8 is adsorbed at the membrane interface, inducing a stiffening of the outer region of the DOPC bilayer. However, the bound of C8 significantly perturbs the whole organization of lipid bilayer resulting in membrane remodeling. These events, measurable as a variation of the bilayer thickness, are the onset mechanism of the membrane fusion and vesicle tubulation observed in confocal microscopy by imaging zwitterionic MLVs in the presence of C8 peptide.

Aiming for novel tools for anticancer therapies, a ruthenium complex, covalently linked to a cholesterol-containing nucleolipid and stabilized by co-aggregation with a biocompatible lipid, is here presented. The amphiphilic ruthenium complex, named ToThyCholRu, is intrinsically negatively charged and has been inserted into liposomes formed by the cationic 1,2-dioleyl-3-trimethylammoniumpropane chloride (DOTAP) to hinder the degradation kinetics typically observed for known ruthenium-based antineoplastic agents. The here described nanovectors contain up to 30% in moles of the ruthenium complex and are stable for several weeks. This drug delivery system has been characterized using dynamic light scattering (DLS), small angle neutron scattering (SANS), neutron reflectivity (NR) and electron paramagnetic resonance (EPR) techniques. Fluorescence microscopy, following the incorporation of rhodamine-B within the ruthenium-loaded liposomes, showed fast cellular uptake in human carcinoma cells, with a strong fluorescence accumulation within the cells. The in vitro bioactivity profile revealed an important antiproliferative activity and, most remarkably, the highest ability in ruthenium vectorization measured so far. Cellular morphological changes and DNA fragmentation provided evidence of an apoptosis-inducing activity, in line with several in vitro studies supporting apoptotic events as the main cause for the anticancer properties of ruthenium derivatives. Overall, these data highlighted the crucial role played by the cellular uptake properties in determining the anticancer efficacy of ruthenium-based drugs, showing DOTAP as a very efficient nanocarrier for their stabilization in aqueous media and transport in cells. In vitro bioscreens have shown the high antiproliferative activity of ToThyCholRu–DOTAP liposomes against specific human adenocarcinoma cell types. Furthermore, these formulations have proved to be over 20-fold more effective against MCF-7 and WiDr adenocarcinoma cells with respect to the nude ruthenium complex AziRu we have previously described.

Hydrogen production by photocatalytic water splitting is one of the most promising sustainable routes to store solar energy in the form of chemical bonds. To obtain significant H

In recent years, interest in the class of water-soluble polymers—hydrophobically modified alkali soluble emulsion (HASE)—has increased on a surprising scale. With respect to other associative polymers, they have several advantages in terms of cost and ease of handling and utilization. In addition, unlike the solvent-based formulations, these water-soluble systems do not contain volatile solvents and hence do not contribute to environmental problems. In solutions, HASE polymers form a transient network through molecular associations between the hydrophobic groups. Due to these hydrophobic interactions, they have been increasingly used as rheology modifiers for various applications, such as paints, cosmetics, and personal care and paper coating products. These associative polymers have an architectural richness that allows the fine tuning of several physicochemical properties, and their optimal use requires controlling polymer concentration, molecular weight, size of the hydrophobic groups, and characteristics of the polymeric backbone. We give an overview of several studies on HASE polymers reported in the literature, focusing on the molecular structure, the synthetic methodologies, and—more specifically—on the factors that affect the rheology of their aqueous mixtures. As a general rule for the optimal HASE design and formulative exploitation, we highlight that the hydrophobic hanging groups are responsible for the rheological changes in the liquid phase, while the steric hindrance of the polymeric backbone and of the hydrophobic groups causes the stiffness.

Hydrogen production by photocatalytic water splitting is one of the most promising sustainable routes to store solar energy in the form of chemical bonds. To obtain significant H2 evolution rates (HERs) a variety of defective TiO2 catalysts were synthesized by means of procedures generally requiring highly energy-consuming treatments, e.g. hydrogenation. Even if a complete understanding of the relationship between defects, electronic structure and catalytic active sites is far from being achieved, the band gap narrowing and Ti3+-self-doping have been considered essential to date. In most reports a metal co-catalyst (commonly Pt) and a sacrificial electron donor (such as methanol) are used to improve HERs. Here we report the synthesis of TiO2/C bulk heterostructures, obtained from a hybrid TiO2-based gel by simple heat treatments at 400 °C under different atmospheres. The electronic structure and properties of the grey or black gel-derived powders are deeply inspected by a combination of classical and less conventional techniques, in order to identify the origin of their photoresponsivity. The defective sites of these heterostructures, namely oxygen vacancies, graphitic carbon and unpaired electrons localized on the C matrix, result in a remarkable visible light activity in spite of the lack of band gap narrowing or Ti3+-self doping. The materials provide HER values ranging from about 0.15 to 0.40 mmol h−1 gcat−1, under both UV- and visible-light irradiation, employing glycerol as sacrificial agent and without any co-catalyst.

pH-sensitive surfactants find applications in many fields, including responsive drug delivery and smart material design. The rational design of the surfactant molecular structure leads to species presenting strong variations of the micellization parameter (e.g., critical micelle concentration, cmc, and aggregate dimension) in a controlled pH range. In the present work, the micellization of the branched amine oxide surfactant N,N-dimethyl-2-propylheptan-1-amine oxide (C10DAO-branched) is studied as a function of pH in dilute aqueous mixtures. Its behavior is compared with that of the linear isomer N,N-dimethyldecan-1-amine oxide (C10DAO-linear). The samples are investigated by potentiometric titrations, fluorescence spectroscopy, and Dynamic Light Scattering (DLS). With increasing pH, micellized C10DAO-branched presents a higher tendency to remain in the protonated/cationic form with respect to the linear isomer. As a consequence, the minimum cmc value, observed when the protonated and the deprotonated/zwitterionic forms of the surfactant coexist in the micelles, is shifted to higher pH values. The volume of these C10DAO-branched “mixed micelles” is more than one order of magnitude higher than that of completely protonated or deprotonated aggregates. This is a singularity of the branched surfactant, not observed for the linear isomer. Overall, the results highlight that the branched molecular architecture of the surfactant tail, favoring the formation of low-curvature aggregates, enhances H-bonding between the protonated and deprotonated headgroups, which synergistically stabilizes the flatter surface of bulkier aggregates. Taking into account the good biodegradability of surfactants with a limited number of short side chains, purposely designed branched surfactants appear as a suitable option to accurately tune supramolecular aggregation in pH-responsive formulations.

Disclosed herein is the first experimental evidence for a direct correlation between the broadband visible light absorption (“blackness”) and the coexistence of reduced and oxidized substructures in a set of model polymers from isomeric dihydroxynaphthalenes structurally related to fungal melanin (mycomelanin) from 1,8-dihydroxynaphthalene. Excellent linear plots (r2 = 0.97 and 0.94) were determined between the integrals of featureless absorbance curves over the 400–800 nm range, the electron spin density values in the EPR spectra and the width of selected oligomer peak clusters in the MALDI-MS spectra. Blackness, which is shown to be strongly interrelated with electron spin density, is thus proposed herein as a robust index of redox inhomogeneity and electron complexity reflecting the shift of oligomer populations toward highest oxidation states.

Polyunsaturated omega-3 fatty acid docosahexaenoic acid (DHA) is found in very high concentrations in a few peculiar tissues, suggesting that it must have a specialized role. DHA was proposed to affect the function of the cell membrane and related proteins through an indirect mechanism of action, based on the DHA-phospholipid effects on the lipid bilayer structure. In this respect, most studies have focused on its influence on lipid-rafts, somehow neglecting the analysis of effects on liquid disordered phases that constitute most of the cell membranes, by reporting in these cases only a general fluidifying effect. In this study, by combining neutron reflectivity, cryo-transmission electron microscopy, small angle neutron scattering, dynamic light scattering and electron paramagnetic resonance spectroscopy, we characterize liquid disordered bilayers formed by the naturally abundant 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and different contents of a di-DHA glycero-phosphocholine, 22:6-22:6PC, from both a molecular/microscopic and supramolecular/mesoscopic viewpoint. We show that, below a threshold concentration of about 40% molar percent, incorporation of 22:6-22:6PC in the membrane increases the lipid dynamics slightly but sufficiently to promote the membrane deformation and increase of multilamellarity. Notably, beyond this threshold, 22:6-22:6PC disfavours the formation of lamellar phases, leading to a phase separation consisting mostly of small spherical particles that coexist with a minority portion of a lipid blob with water-filled cavities. Concurrently, from a molecular viewpoint, the polyunsaturated acyl chains tend to fold and expose the termini to the aqueous medium. We propose that this peculiar tendency is a key feature of the DHA-phospholipids making them able to modulate the local morphology of biomembranes. This journal is

Phenolic polymers produced by enzymatic oxidation under biomimetic and eco-friendly reaction conditions are usually endowed with potent antioxidant properties. These properties, coupled with the higher biocompatibility, stability and processability compared to low-molecular weight phenolic compounds, open important perspectives for various applications. Herein, we report the marked boosting effect of acid treatment on the antioxidant properties of a series of polymers obtained by peroxidase-catalyzed oxidation of natural phenolic compounds. Both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated a remarkable increase in the antioxidant properties for most phenolic polymers further to the acid treatment. In particular, up to a ca. 60% decrease in the EC50 value in the DPPH assay and a 5-fold increase in the Trolox equivalents were observed. Nitric oxide- and superoxide-scavenging assays also indicated highly specific boosting effects of the acid treatment. Spectroscopic evidence suggested, in most cases, that the occurrence of structural modifications induced by the acid treatment led to more extended &pi, electron-conjugated species endowed with more efficient electron transfer properties. These results open new perspectives toward the design of new bioinspired antioxidants for application in food, biomedicine and material sciences.