Pluronic 123 Liquid Lyotropic Crystals for Transdermal Delivery of Caffeic Acid-Insights from Structural Studies and Drug Release.

BACKGROUND: This study aims to evaluate the percutaneous permeation profiles of caffeic acid (CA) from the cubic and hexagonal liquid crystalline phases of Pluronic P123/water mixtures. METHOD: The resulting drug-loaded mesophases were subjected to characterisation through deuterium nuclear magnetic resonance spectroscopy and polarised optical microscopy observations. These analyses aimed to evaluate the structural changes that occurred in the mesophases loading with CA. Additionally, steady and dynamic rheology studies were conducted to further explore their mechanical properties and correlate them to the supramolecular structure. Finally, CA release experiments were carried out at two different temperatures to examine the behaviour of the structured systems in a physiological or hyperthermic state. RESULTS: As the concentration of the polymer increases, an increase in the viscosity of the gel is noted; however, the addition of caffeic acid increases microstructure fluidity. It is observed that the temperature effect conforms to expectations. The increase in temperature causes a decrease in viscosity and, consequently, an increase in the rate of permeation of caffeic acid. CONCLUSIONS: The CA permeation profile from the prepared formulations is mostly dependent on the structural organisation and temperature. Cubic mesophase LLC 30/CA showed greater skin permeation with good accumulation in the skin at both tested temperatures.

NMR Self-Diffusion and Transverse Relaxation Time in Bitumen: The Effect of Aging.

In this investigation the dynamics of two types of bitumens with different penetration grade were tested by using dynamic shear rheometry (DSR) and Nuclear Magnetic Resonance (NMR) at unaged conditions, and upon both short- and long-term artificial aging. The gel-sol transition temperature T g e l → s o l * ${{T}_{gel\to sol}^{^{\ast}}}$ was found to increase with increasing the time of aging treatment. Arrhenius parameters of the viscosity were found, unexpectedly, to be correlated with those of simple liquids, suggesting that the two kinds of systems, although chemically and physically quite different, share the same basic process at the molecular level. The molecular dynamics has been then investigated by NMR Pulsed Field Gradient Stimulated-Echo (PFGSE) and relaxometry (Carr-Purcell-Meiboom-Gill, CPMG, spin-echo pulse sequence) to capture the effect of aging upon dynamics variables such as self-diffusion coefficients D and transverse relaxation times T2 . The translational diffusion at T> T g e l → s o l * ${{T}_{gel\to sol}^{^{\ast}}}$ of the light molecular components of both types of bitumens was characterized by broad distributions of D which were found independent of the experimental time scale up to 0.2 s. Similarly, T2 data could be described as a continuous unimodal distributions of relaxation times determined both at T< T g e l → s o l * ${{T}_{gel\to sol}^{^{\ast}}}$ and T> T g e l → s o l * ${{T}_{gel\to sol}^{^{\ast}}}$ .

Pyrolysis and Gasification of a Real Refuse-Derived Fuel (RDF): The Potential Use of the Products under a Circular Economy Vision.

Refuse-Derived Fuels (RDFs) are segregated forms of wastes obtained by a combined mechanical-biological processing of municipal solid wastes (MSWs). The narrower characteristics, e.g., high calorific value (18-24 MJ/kg), low moisture content (3-6%) and high volatile (77-84%) and carbon (47-56%) contents, make RDFs more suitable than MSWs for thermochemical valorization purposes. As a matter of fact, EU regulations encourage the use of RDF as a source of energy in the frameworks of sustainability and the circular economy. Pyrolysis and gasification are promising thermochemical processes for RDF treatment, since, compared to incineration, they ensure an increase in energy recovery efficiency, a reduction of pollutant emissions and the production of value-added products as chemical platforms or fuels. Despite the growing interest towards RDFs as feedstock, the literature on the thermochemical treatment of RDFs under pyrolysis and gasification conditions still appears to be limited. In this work, results on pyrolysis and gasification tests on a real RDF are reported and coupled with a detailed characterization of the gaseous, condensable and solid products. Pyrolysis tests have been performed in a tubular reactor up to three different final temperatures (550, 650 and 750 °C) while an air gasification test at 850 °C has been performed in a fluidized bed reactor using sand as the bed material. The results of the two thermochemical processes are analyzed in terms of yield, characteristics and quality of the products to highlight how the two thermochemical conversion processes can be used to accomplish waste-to-materials and waste-to-energy targets. The RDF gasification process leads to the production of a syngas with a H2/CO ratio of 0.51 and a tar concentration of 3.15 g/m3.

The Structure of Bitumen: Conceptual Models and Experimental Evidences.

Bitumen, one of the by-products of petroleum industry processes, is the most common binder used in road pavements and in the construction industry in general. It is a complex organic mixture of a broad range of hydrocarbons classified into four chemical families, collectively known with the acronym SARA fractions, which include saturates, aromatics, resins and asphaltenes. Since the 1940s, researchers working on bitumen and the science behind its existence, nature and application have investigated the spatial organization and arrangement of several molecular species present in the binder. Therefore, several models have been proposed in the literature, and they are more or less corroborated by experimental studies, although most of them are model-dependent; for example, the structural investigations based on scattering techniques. One of the most popular models that has met with a wide consensus (both experimentally and of the modeling/computational type) is the one aiming at the colloidal description of bitumen's microstructure. Other types of models have appeared in the literature that propose alternative views to the colloidal scheme, equally valid and capable of providing results that comply with experimental and theoretical evidence. Spurred by the constant advancement of research in the field of bitumen science, this literature review is aimed at providing a thorough, continuous and adept state of knowledge on the modeling efforts herein elaborated, in order to more precisely describe the intricacy of the bituminous microstructure. In this body of work, experimental evidence, along with details of bitumen's microstructure (depicting the colloidal state of bitumen), is particularly emphasized. We will also try to shed light on the evolution of the experimental and theoretical results that have focused on the aspect of the association and aggregation properties of asphaltenes in various models and real systems.

Water-Based Aerosol for Book Deacidification: Experimental Apparatus and Theoretical Interpretation of Results.

One of the major problems in book conservation is the long-term deconstructive effect of acidity introduced into the paper by several additives, which, in the presence of humidity, generates a hydrogen cation with a strong catalytic role in cellulose depolymerization. Many types of treatment have been used in the past, but up to now, research for less-invasive, fast and cheap methods is still vividly ongoing. In this study, an approach to book deacidification is presented, where alkaline water solutions are administered to bound books in the form of micrometer-sized aerosol droplets, without using vacuum apparatus accessories. Alkaline clouds treatments were alternated with gentle air fluxes of drying steps. Few cycles are required to achieve uniform deacidification of books. The treatment could be conducted with proper apparatus on large volumes, resulting in rapid treatment time and low cost. The titration curve reporting the variation of book pH, with respect to the amount of absorbed alkaline aerosol, was built and interpreted in terms of a chemical model for the neutralization process. FTIR, PXRD and XRF spectroscopies were used to characterize the book chemistry. The effects of the treatment on the book were evaluated by measuring the degree of polymerization (DP) of the paper and the colorimetric coordinates of the paper and ink. Artificial aging tests revealed a general increase in the aging stability of the deacidified paper samples with respect to the untreated samples. Finally, the alkaline reserve data are discussed.

Chemical-physical and dynamical-mechanical characterization on Spartium junceum L. cellulosic fiber treated with softener agents: a preliminary investigation.

Long cellulose fiber (10-30 cm), extracted from Spartium junceum, was chemically treated with different softening agents with the aim to improve its textile applicability. A preliminary sensory evaluation of the treated fibers revealed an evident, though qualitative, improvement of the fiber softness. The effects of the softening agents on the fiber was evaluated quantitatively, by means of macroscopic measurements of the wettability, viscoelasticity, and thermal (thermal gravimetry) properties. Moreover, the effects of the softening treatments on the microscopic structure of the fiber and on its properties at a molecular level, were studied by optical and scanning electron microscope and X-ray diffraction (XRD), respectively. The macroscopic analysis showed that the softeners used increases the hydrophilicity and water wettability of the cellulose fiber with respect to the raw one. Moreover, the dynamical mechanical analysis on sample yarns showed that the softeners increase the interfiber frictional forces. A linear correlation between the interfiber friction and the increase of hydrophilicity and fiber wettability was shown. The treated fiber exhibits a more homogeneous thermal behaviour, due to more homogeneous structural features, since the thermal-induced cellulose fibrils depolimerization undergoes a marked temperature range contraction. These data can be well related with those obtained by microscopy analysis, showing that the fiber surface, after the treatment, appears thinner and less rough, as well as with the XRD analysis, which shows that softeners induce a significant decrease of the fiber crystallinity.

Wide Angle X-ray Scattering as a Technique of Choice to Probe Asphaltene Hierarchical Structures.

Bitumens are composite systems extensively used in road pavements. Due to their complex nature, a rational understanding of the relationships between composition, structure and performances of these materials is still far from being achieved, so research attempting to shed more light in this field is required. Here, we exploit Wide Angle X-ray Scattering (WAXS) as a technique of choice to shed light on the bitumen structure at different length scales. Diagnostic fingerprints, characterizing the WAXS profile, are correlated to specific Bragg distances which can be reasonably attributed to the molecular and supramolecular aggregation taking place at various levels of complexity leading to the formation of hierarchical structures. Due to the inherent instability of these materials some indications are given to obtain reliable structural data.

Novel pH sensitive ferrogels as new approach in cancer treatment: Effect of the magnetic field on swelling and drug delivery.

Ferrogels (or magnetic hydrogels) are cross-linked polymer networks containing magnetic nanoparticles: they are mechanically soft and highly elastic and at the same time they exhibit a strong magnetic response. Our work focuses on an combinatorial strategy to improve the efficacy of 5-Fluorouracil (5-FU) assisted chemotherapy, by developing novel multifunctional pH-sensitive ferrogels. We designed gels based on N,N'-dimethylacrylamide monomers polymerized in presence of methacrylic acid or 2-aminoethyl methacrylate hydrochloride, containing ferro-nanoparticles. The influence of polymeric matrix composition and exposition to magnetic field (MF) on swelling behavior and drugs release were investigated at pH 7.4 and 5. In particular, the magnetic field was obtained by using permanent magnetic bar (0.25 T) or electromagnet (0.5 and 1.2 T), with the aim to analyze quantitatively the magnetic effects. A strong influence of the magnetic field on ferrogels properties have been observed. Swelling analysis indicated a dependence on both pH and network composition, reaching a maximum at pH 7.4, for formulations containing methacrylic acid, while the application of MF appeared to decrease the swelling percentages. Release profiles of 5-FU showed effective modulation in release by application of MF: drug release is always higher in the presence of a magnetic field and generally increases with its intensity. The combining effect of pH sensitive properties and application of MF improved the performance of the systems. Results showed that our ferrogels may be technologically applicable as devices for delivery of 5-FU in a controllable manner.

The potential of the F127-water soft system towards selective solubilisation of iridium(III) octahedral complexes.

In order to obtain new functional soft systems for use as templating agents for the construction of functional mesostructured materials, the dynamic ordered soft systems formed by a hydrophilic ionic iridium(III) complex (IrPa) embedded into two different concentration F127-water mixtures have been investigated. To this aim, combined spectral and time-resolved photophysical techniques and rheological methods have been employed. The position of the chromophore inside the micellar, cubic and hexagonal phases of the F127 polymeric neutral surfactant in water was effectively determined. The hydrophilic character of the iridium(III) complex chosen allowed preferential functionalization of the F127 corona in the micellar and cubic phases.

Dynamical properties of self-assembled surfactant-based mixtures: triggering of one-dimensional anomalous diffusion in bis(2-ethylhexyl)phosphoric acid/n-octylamine systems.

The dynamic features of bis(2-ethylhexyl)phosphoric acid (HDEHP)/n-octylamine (NOA) mixtures have been investigated as a function of the NOA mole fraction and temperature by (1)H NMR spectroscopy and rheometry. All data consistently suggest a composition-induced glass-forming behavior. The microscopic factors responsible for this behavior have been highlighted and have been explained in terms of driving forces given by HDEHP-to-NOA proton transfer, the tendency of the resulting species to establish H bonds and to spatially segregate the alkyl chains. The study sheds light on the molecular mechanism responsible for the peculiar behavior of transport properties in such systems and furnishes basic knowledge to be used to design novel materials with planned physicochemical properties.

Rheological and rheo-SALS investigation of the multi-lamellar vesicle formation in the C12E3/D2O system.

Usually in nonionic surfactant aqueous systems of the C(n)E(m) type, a lamellar phase occurs over a wide temperature and concentration range. For some C(n)E(m) surfactants, multi-lamellar vesicle (MLV) formation has been observed when the lamellar phase is subjected to shear flow. This communication reports the shear flow behavior at different shear rate values of a C(n)E(m) (where "n" is 12 and "m" is 3) aqueous system at 34 °C. The typical transient viscosity behavior of the shear-induced MLV formation in C(12)E(3)/D(2)O at 50 wt% of surfactant has been observed. The MLV formation is confirmed by time-resolved rheo-small angle light scattering (SALS) experiments. The experimental data show an intermediate structure that has been attributed to a multi-lamellar cylinders (MLCs).

Multi-lamellar vesicle formation in a long-chain nonionic surfactant: C16E4/D2O system.

The temperature dependent rheological and structural behavior of a long-chain C(16)E(4) (tetraethylene glycol monohexadecyl ether) surfactant in D(2)O has been studied within the regime of low shear range. In the absence of shear flow, the system forms a lamellar liquid crystalline phase at relatively high temperatures. The present paper reports on the shear-induced multi-lamellar vesicle (MLV) formation in C(16)E(4)/D(2)O at 40 wt.% of surfactant in the temperature range of 40-55 °C. The transition from planar lamellar structure to multi-lamellar vesicles has been investigated by time-resolved experiments combining rheology and nuclear magnetic resonance (rheo-NMR), rheo small-angle neutron scattering (rheo-SANS) and rheometry. The typical transient viscosity behavior of MLV formation has been discovered at low shear rate value of 0.5s(-1).

Gels of Pluronic F127 and nonionic surfactants from rheological characterization to controlled drug permeation.

The role of nonionic vesicles on the rheological behavior of Pluronic F127 is investigated above the dilute regime and below the cloud point of the nonionic surfactant. F127 is a copolymer possessing sol-gel transition by heating attributed to a phase transition from micellar to cubic. The presence of surfactant vesicles is expected to enhance the compartmentalization of a variety of drugs, independently of their affinity to the solvent. Such entrapment would be suitable for controlled release of the drugs in different applications. We address here a mixed Pluronic-nonionic surfactant system with particular emphasis to the effects of the surfactant on the rheological properties of the Pluronics, and the correlation between these properties and drug release control. The results show that the rheological properties of the mixed system are mainly governed by the behavior of the polymer alone and that the mixed system can be useful to control the percutaneous permeation of a small drug, such as Diclofenac Sodium salt.

Effect of shear rates on the MLV formation and MLV stability region in the C12E5/D2O system: rheology and rheo-NMR and rheo-SANS experiments.

At high temperatures, pentaethylene glycol monododecyl ether (C12E5) in D2O forms a swollen lamellar phase. This letter reports the shear-induced multilamellar vesicle (MLV) formation in a sample that contains 40 wt % C12E5 dissolved in D2O at 55 °C. This transition has been investigated by time-resolved rheo-nuclear magnetic resonance, rheo small-angle neutron scattering, and rheometry. The typical transient viscosity behavior of MLV formation has been discovered at 1 s(-1). For the first time, it has been found that MLVs are not stable over time when subjected to high shear rates. Our results show that the MLV stability is confined in a narrow region in the range 1-10 s(-1) shear rates. This is not observed for other CnEm surfactants.

E, Z and positional-monoenoic phyto-fatty acids influencing membrane fluidity: DSC and NMR experiments.

The membrane fluidity of biological tissues is highly influenced by the π-bond position and isomeric configuration in the long chain of phyto-fatty acids (FAs). Z, E and positional isomeric monoenoic lipids, i.e. the phytomolecules oleic (OA), elaidic (EA), vaccenic acid (TV) and its Z-isomer (CV), have been evaluated for their effects on the fluidity of cellular membranes. To this purpose the Differential Scanning Calorimetry (DSC) and Deuterium Nuclear Magnetic Resonance ((2)H-NMR), are suitable techniques to understand the supramolecular lamellar structure during the order (gel)-disorder (fluid) transition. It was found that the presence of CV concentration, induces the biomimetic system to reach the first step to fluid phase earlier than the membrane containing OA. DSC showed that the endothermic peak onset of the membrane containing CV occurs at a lower temperature than that of a membrane containing an equal amount of OA. (2)H-NMR investigation confirmed the last statement. In fact the study of the main phase transition of the two different systems, revealed that model membrane containing a 3% (w/w) of CV goes in ripple phase, i.e. the first step to the fluid state, at a lower temperature as compared to the membrane of an identical system with OA.

Evidence of formation of ammonium perfluorononanoate/2H2O multilamellar vesicles: morphological analysis by rheology and rheo-2H NMR experiments.

Rheology and rheo-(2)H NMR measurements are presented for 30 wt % ammonium perfluorononanoate (APFN)/(2)H(2)O mixture in the temperature range 20-70 °C. A first-order lamellar-to-nematic transition occurs at 42 °C, and a first-order nematic-to-isotropic transition occurs at 49 °C. Different rheological behaviors of the lamellar phase were observed with increasing the temperature. The lamellar structure at low temperature (Lα(-)) has a clear gel-like viscoelasticity, while at high temperature the lamellar structure (Lα(+)) has a liquid-like response. In this study we have observed for the first time, along with the lamellar phase of a surfactant containing fluorinated fatty acid, the formation of multilamellar vesicles (MLVs) ("onions") induced by shear. With the aid of nonlinear rheology and rheo-NMR techniques, onion formation was found to occur in both temperature regimes of the lamellar phase, but at different strain units. It is suggested that the lamellar phase consists of smectic structures in both Lα(-) and Lα(+), but with different percentages of defect density.

NMR investigation of the dynamics of confined water in nafion-based electrolyte membranes at subfreezing temperatures.

The dynamical characteristics and the thermal analysis of water absorbed in filler-free Nafion and in silica or zirconia phosphate Nafion composites, between 20 and -50 degrees C, were investigated by NMR and DSC techniques. Self-diffusion coefficients and longitudinal NMR relaxation times (T(1)) put in evidence a fraction of water freezing at subzero temperatures. The complementary water fraction remains in the liquid state at least down to -50 degrees C. The freezing point (T(f)) depends on the initial water uptake of the electrolyte membrane and, for similar uptake values, water mobility is favorite in composites systems respect to the filler-free Nafion. By DSC thermograms the hydration water molecules number per sulfonic group in the filler-free Nafion was estimated, obtaining 8 molecules/SO(3)(-) group. In the Nafion/Zr(HPO(4))(2) composite, instead, the number of hydration water is about 20 molecules/ionic group, because of the acid nature of the zirconia particles. Below T(f), the presence of this nonfreezable water fraction allows proton transport, and therefore ensures ionic conductivity also at subzero temperatures.

Synthesis and properties of methacrylic-functionalized tween monomer networks.

Tween surfactants possess very interesting properties such as biodegradability, biocompatibility, and low toxicity. The synthesis of acrylate monomers by means of the chemical modification of polysorbate surfactants Tween 20, 40, and 60 with unsaturated groups is described. Monomers were obtained as a result of the reaction of methacrylic anhydride with different grades of Tween surfactants. Further polymerization was carried out in tetrahydrofuran, dimethylformamide, and a mixture of water-tetrahydrofuran. Physicochemistry properties of the polymer networks were investigated, and the obtained results reveal that they strongly depend on the type of solvent used during the polymerization, as well as on the concentration of the casting solution. In particular, our study demonstrated that, depending on the solvent boiling point, i.e., the facility to remove the solvent from the polymer matrix, it is possible to predict properties of the network morphology. Moreover, in vitro studies on controlled release were accomplished to demonstrate the possibility of utilizing these new materials as drug delivery systems. All resulting networks represent a novel class of cross-linked polymeric materials useful both in pharmaceutical and chemical applications.

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides.

Vesicles composed of sodium oleate (NaO) and monoolein (MO) are adequate candidates for drug nanoencapsulation and controlled release due to their stability and perceived biocompatibility. The object of the present study is to design hydrogels based on those anionic vesicles and polymers of both non-associative and associative type. The selected macromolecules were k-carrageenan (KC), carboxymethyl cellulose (CMC) and hydrophobically modified carboxymethyl cellulose (HMCMC). While the polymer-vesicle association was probed by rheology, the influence of the polymer on the vesicle stability was monitored by cryo-TEM and calorimetric measurements. The effects of the polymer on the rheological properties of surfactant aggregate solutions clearly depend on the polymer type: the storage moduli of the polymer-vesicle mixtures, compared to the vesicles alone, increases around 2 orders of magnitude if the polymer is non-associative and 4 orders of magnitude if the macromolecule is of associative type. As the vesicles are added, the non-associative polymer networks tend to be disrupted, while the networks formed by associative polymer get more robust. These observations can be explained by fundamental changes in electrostatic/hydrophobic interactions: vesicles entrapped in KC networks convert the polysaccharide in a highly charged entity and favor high electrostatic repulsions between the chains; this encourages network collapse. The opposite picture is experienced in HMCMC systems, i.e., such network is stabilized by the presence of vesicles. This is ascribed to the enhanced hydrophobic association, compensating the electrostatic repulsions between vesicles and polymer chains.