Three surfactants were selected from a series of EOx/POy/EOx triblock copolymers and ethoxylated octylphenol as nonionic templating agents for the synthesis of silica mesoporous materials at room temperature and by hydrothermal treatment. The surfactants were ethylene oxide-propylene oxide-ethylene oxide tri-block copolymers (Pluronic F68) and a polydisperse ethoxylated octylphenol (Triton X-100). The obtained materials were compared with SBA-15 mesoporous silica synthesized with Pluronic P123 surfactant and were used as support to obtain Ni and NiTi-silica catalysts (2.5% NiO, 5% TiO2). The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, IR and UV-Vis spectroscopy. Catalytic and photocatalytic activity of Ni and NiTi-silica samples were tested, with and without H2O2, for phenol and Brilliant Blue FCF dye oxidative degradation in the liquid phase. The obtained results showed a significant effect of surfactant on silica structure, morphology and texture, and catalytic and photocatalytic properties.

The study investigates mixtures of bovine serum albumin (BSA) and micellar carriers with incorporated pyrene (Py). Mono-disperse hexaethyleneglycol mono n -dodecyl ether (C 12 E 6 ) and respective, poly-disperse eicosaethyleneglycol mono n -tetradecyl ether (C 14 EO 20 ) are employed to get micellar carriers with different dimension and polarity. Pyrene is used both as a probe and model drug to get insight upon the albumin-carrier association and the medicine transport. At BSA addition upon the drug-carrier system, the emissive signal and lifetime of Py excimer decrease, while the monomer lifetime increases. The results prove the transport of the probe in small micellar clusters on the polypeptide chain. Comparison of the quenching of BSA fluorescence by surfactant or/and Py unveils a hybrid process when both quenchers are present. In accord, a non-radiative fluorescence resonance energy transfer (FRET) occurs between BSA tryptophan and Py with higher donor–acceptor distance, the longer the carrier’s alkyl and ethyleneoxide chains. Pyrene predominantly forms dynamic excimers in all studied systems, which shows that the probe’s environment is fluid. The pyrene association ratio provided by UV–Vis absorption spectra indicates the transfer of some Py monomers only from the C 12 E 6 micelles to nonpolar zones of protein. Differently, the long ethyleneoxide chains of C 14 EO 20 impede the pyrene relocation. The Py-loaded micelles stabilize the secondary structure of BSA. The work sheds light on the transport of drugs with micellar carriers from alkyl-ethoxylated nonionic surfactants.

Cultural heritage metallic artifacts are often subjected to environmental factors that promote degradation through corrosion processes. Anticorrosion protection is needed both for the long-term preservation of outdoor monuments and the short-term conservation of archaeological artifacts. In this work, functional nanocoatings based on ZnO nanoparticles (NPs) in a silica matrix are prepared as a replacement for a commercial Incralac lacquer. Facile sol–gel synthesis is employed for obtaining silica filmogenic materials, using tetraethoxysilane (TEOS) and 3-glycidyloxypropyl trimethoxysilane (GPTMS). Silica-based nanocomposite coatings, with and without ZnO NPs and benzotriazole (BTA) as anticorrosion agents, applied on copper coupons by brushing are characterized by using VIS and FTIR spectroscopy, SEM and AFM and compared to Incralac lacquer as reference materials. The optical and morphological properties of the proposed silica coatings are similar to the Incralac specimens. The protective effect against corrosion is investigated on the copper coupons as model metallic objects subjected to a corrosion test by using potentiodynamic polarization in a 3.5% NaCl solution at ambient temperature. The influence of the presence of BTA and ZnO NPs in both silica and Incralac coatings is studied, and the variations in the anticorrosive, morphological and optical properties with the concentration of ZnO NPs are evidenced. The presence of moderate concentrations of ZnO in both nanomaterials leads to changes in the color parameters slightly above the limit accepted in the field of cultural heritage (ΔE* 5.09 and 6.13), while a high ZnO concentration of 3% leads to higher values (ΔE* > 10). Regarding the anticorrosive effect, the silica-based coatings with ZnO and BTA present similar efficiencies to that of the Incralac reference material (corrosion rates in the range of 0.044–0.067 mm/year for silica coatings compared to 0.055 mm/year for Incralac).

Cleaning represents an important and challenging operation in the conservation of cultural heritage, and at present, a key issue consists in the development of more sustainable, "green" materials and methods to perform it. In the present work, a novel xylene-in-water microemulsion based on nonionic surfactants with low toxicity was obtained, designed as low-impact cleaning agent for metallic historic objects. Phase diagram of the mixtures containing polyoxyethylene-polyoxypropilene triblock copolymer Pluronic P84 and D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) as surfactants, water, ethanol and xylene was studied, and a microemulsion with low surfactant content was selected as suitable cleaning nanosystem. Essential oils (EOs) from thyme and cinnamon leaf were added to the selected microemulsion in order to include other beneficial properties such as anticorrosive and antifungal protection. The microemulsions with or without EOs were characterized by size, size distribution and zeta potential. The cleaning efficacy of the tested microemulsions was assessed based on their ability to remove two types of artificial dirt by using X-ray energy dispersion spectrometry (EDX), scanning electron microscopy (SEM), contact angle measurements and color analysis. Microemulsions exhibit high capacity to remove artificial dirt from model copper coupons in spite of very low content of the organic solvent. Both thyme and cinnamon oil loading microemulsions prove to significantly reduce the corrosion rate of treated metallic plates compared to those of bare copper. The antifungal activity of the novel type of microemulsion was evaluated against Aspergillus niger, reported as main treat in biocorrosion of historic copper artifacts. Application of microemulsion with small amounts of EOs on Cu plates inhibits the growth of fungi, providing a good fungicidal effect.

Biocompatible gel microemulsions containing natural origin excipients are promising nanocarrier systems for the safe and effective topical application of hydrophobic drugs, including antifungals. Recently, to improve fluconazole skin permeation, tolerability and therapeutic efficacy, we developed topical biocompatible microemulsions based on cinnamon, oregano or clove essential oil (CIN, ORG or CLV) as the oil phase and sucrose laurate (D1216) or sucrose palmitate (D1616) as surfactants, excipients also possessing intrinsic antifungal activity. To follow up this research, this study aimed to improve the adhesiveness of respective fluconazole microemulsions using chitosan (a biopolymer with intrinsic antifungal activity) as gellator and to evaluate the formulation variables’ effect (composition and concentration of essential oil, sucrose ester structure) on the gel microemulsions’ (MEGELs) properties. All MEGELs were evaluated for drug content, pH, rheological behavior, viscosity, spreadability, in vitro drug release and skin permeation and antifungal activity. The results showed that formulation variables determined distinctive changes in the MEGELs’ properties, which were nevertheless in accordance with official requirements for semisolid preparations. The highest flux and release rate values and large diameters of the fungal growth inhibition zone were produced by formulations MEGEL-FZ-D1616-CIN 10%, MEGEL-FZ-D1216-CIN 10% and MEGEL-FZ-D1616-ORG 10%. In conclusion, these MEGELs were demonstrated to be effective platforms for fluconazole topical delivery.

To initiate our research into the development of biocompatiîle gelled-microemulsions based on essential oils (EOs) and sucrose esters (SEs) for the topical delivery of fluconazole, this formulation study investigated the usefulness of two relatively harmless natural non-ionic surfactants from the group of SEs (sucrose laurate and stearate) to form, in the presence of antifungal EOs, stable, isotropic microemulsions effective on fluconazole solubilization. Fluconazole’s solubility in EO significantly depended on their chemical composition, showing higher values for cinnamon, oregano and clove essential oils, further selected as oil phase components for microemulsion formulations. The phase behavior of several EO–isopropyl miristate/SE–isopropanol/water systems was assessed through pseudo-ternary phase diagrams constructed by microplate dilution technique. The hydrocarbon chain length of the SE and EO type strongly influenced the size of the microemulsion region in the pseudo-ternary phase diagrams. Ten microemulsion formulations containing 2% fluconazole, 6% or 10% oil mixture of EO–isopropyl myristate in 1:1 ratio, 45% SE-isopropanol mixture and water, were selected and evaluated for physicochemical properties (droplet size, polydispersity, viscosity, refractive index, zeta potential and pH). All formulations were physicochemically acceptable, but viscosity enhancement and further in vitro and in vivo tests are required for the development of biocompatible, clinically safe and effective fluconazole topical preparations.

The present paper deals with the correlation between intramolecular and intermolecular interactions of polycarboxybetaines. The degree of coupling between the opposite charges within the polycarboxybetaine molecules was varied by spacers of different length and by the substitution of additional alkyl chains at the quaternary nitrogen atom. In order to check intermolecular interactions between polycarboxybetaines, SANS measurements were carried out at aqueous polycarboxybetaines solutions. For getting information about the interaction with an oppositely charged polyelectrolyte, multilayers were formed by alternating adsorption of polystyrene sulfonate (PSS) and polycarboxybetaines from aqueous solutions. The occurrence of a structure peak in SANS spectra and the ability to form polyelectrolyte multilayers provide an indicator for the polyelectrolyte character of some of the studied polycarboxybetaines. Not only the charge but also the hydrophobicity of the polycarboxybetaines has a pronounced effect on the chain conformation and therefore on the thickness of the polyelectrolyte multilayers. The results show that small differences in molecular architecture lead to pronounced differences in intermolecular interactions.

Attractive smart and emissive nanomaterials are designed by embedding the methylene blue (MB) in the complex of pyrene labeled poly(acrylic acid) (PAA25Py3) and dodecyltrimethylammonium chloride (C12TAC) using the supramolecular host-guest strategy. The investigation methods were surface tension, UV–vis, steady-state fluorescence, electrokinetic potential, dynamic light scattering and microscopy. A comparative study about the adsorption at air/water interface of anionic polymer and oppositely charged surfactant complexes without (PS) and with MB (PS/MB) was made. The photophysical properties of PS and PS/MB assemblies were highlighted by both pyrene (Py) and MB. The self-aggregation and conformation of polymer with MB in the PS matrix were analyzed. At low surfactant concentration, small and well dispersed PS/MB complexes form hydrophobic environments as detected by Py label. The PS complexes quenched the MB emission. At high surfactant amounts, the Py label signaled an unusual micropolarity. Thus, the formation of iceberg-like environments due to the cation-л interactions in large aggregates of PS complexes was proved by polarity index. In these high polar and rigide nanoenvironments of PS aggregates, the dye fluorescence is enhanced. The obtained results have the potential applications in chemical sensing and imaging.

This chapter treats polymer-nonionic surfactant interactions, but focuses on systems of polyacids and ethoxy-type surfactants in aqueous solution. It covers only physico-chemical properties of interaction between typical water-soluble proteins and nonionic surfactants. The surfactant ion with its hydrophobic moiety is attracted more closely or bound to the polymers even in the form of micelles. It enhances its characteristic effect as a salt on the polymer at lower concentration than the ordinary salts. Hydrophobically modified water-soluble polymers are materials with hydrophobic groups either end-positioned or randomly substituted onto the hydrophilic backbone polymer chain. Nonionic surfactants are widely employed as mild processors in the extraction of native proteins from lipids and biomembranes. Physico-chemical studies on the interaction between proteins and nonionic surfactants are relatively rare compared with the number of studies on ionic surfactants. Carbomer, Carbopole is a water-dispersible polyacrylic acid loosely interlinked through polyalcohols. By neutralization with alkali an aqueous dispersion becomes transparent and viscous, forming a gel at high concentration.

This study was focused on creating a new and effective immobilization method for Trametes versicolor laccase (Lc) by using chitosan (CS) microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. The activation of the support alternated with immobilization of the enzyme, in repetitive procedures, led to obtaining three different products. Also, the physicochemical properties of the new products were investigated and compared with those of free laccase. The discoloration and reusability properties of the immobilized Lc were evaluated using indigo carmine (IC) as a model micropollutant. The ESEM and FT-IR methods demonstrated that the Lc was successfully immobilized. The relative reaction rate and the total amount of immobilized Lc were tripled using the iterative protocol as proved by specific and Bradford assays. The maximum amount of immobilized Lc was 8.4 mg Lc/g CS corresponding to the third immobilization procedure. Compared to the free Lc, the operational stability of the immobilized Lc was significantly improved, presenting a maximum activity plateau over a pH range of 3-5 and a temperature range of 25-50 °C. The thermal inactivation study at 55 °C proved that the immobilized enzyme is three times more stable than the free Lc. The isoconversional and Michaelis-Menten methods showed that the immobilization did not affect the enzyme catalytic properties. After 32 days of storage, the residual activities are 85% for the immobilized laccase and 40% for the free one. In similar conditions, the free and immobilized Lc (2.12 x 10-6 M) completely decolorized IC (7.15 x 10-5 M) within 14 min. The immobilized Lc activity remained almost constant (80%) during 10 reusability cycles. All these results highlight the substantial advantages of the new immobilization protocol and demonstrate that immobilized Lc can be used as a promising micropollutant removal from real wastewater.

This work was devoted to investigate the aggregation of methylene blue (MB) with pyrene labeled poly(acrylic acid) (PAA25Py3) by using the measurements of UV–vis absorption, steady-state and time-resolved fluorescence. For comparison, the effect of unlabeled poly(acrylic acid) (PAA25) on the self-association of MB was also evaluated. The spectral positions of the absorption and emission bands of MB as well as the pyrene monomer and excimer emissions were used to assess the local changes of polymer/MB microenvironment. The binding mechanism and thermodynamic analysis for the interaction between MB and pyrene labeled poly(acrylic acid) were evaluated by fluorescence quenching measurements. Moreover, the strategy of switching of pyrene excimer/monomer emission was used to manage the self-aggregation of the pH-responsive fluorescent polymer with phenothiazinium dye. The UV–vis absorption and fluorescence results showed that low amounts of polymers provoked the self-association of MB. At high concentrations of polymer, the MB monomer is stabilized. The labeling of polymer with pyrene induced a dramatic changing of optical properties suggesting that a peculiar process occurred between PAA25Py3 and MB. At low quencher concentrations, both steady-state and time-resolved fluorescence data indicated a static quenching process. The thermodynamic parameters (∆H, ∆S and ∆G) and the efficiency of pyrene excimer formation revealed that the association of MB with the fluorescent polymer occurred spontaneously due to non-covalent hetero π-π stacking, hydrophobic and electrostatic interactions. The study highlights the key contribution of the π-π stacking interactions in the capturing of methylene blue in pyrene labeled poly(acrylic acid). The outcome may be useful in biomedical applications or in wastewater treatment.

Novel results on combustible microemulsions prepared with diesel (D), blends of diesel and rapeseed oil (RSO), and mixtures of eco-friendly amphiphiles are presented. Water solubilization in oil/amphiphile systems was estimated by pseudo-ternary diagrams whereas the phase behavior by Winsor (W) diagrams. The extent of single-phase microemulsion (SPM) area depends on the amphiphile and oil phase composition. The presence of cosurfactant in the anionic-nonionic surfactant mixture increases very much the SPM area, but no effect is observed when half of D is replaced by RSO. In the pseudo-ternary phase diagram, the addition of organic electrolyte decreases the SPM areas. The microemulsions were characterized by the oil/water interfacial tension (gow), and the oil and water solubilization parameters (SPo) and (SPw). The results obtained reveal that the W III microemulsions have minimal goow values, whereas SPo and SPw are maximal. The work connects the phase behavior with the interfacial tension and the solubilization parameters of oil and water and is useful for obtaining and developing optimal microemulsions as alternative fuels.

The binding of drugs to serum proteins is governed by weak non-covalent forces. In this study, the nature and magnitude of the interactions between piroxicam (PRX) and bovine serum albumin (BSA) was assessed using spectroscopic, calorimetric and computational molecular methods. The fluorescence data revealed an atypical behavior during PRX and BSA interaction. The quenching process of tryptophan (Trp) by PRX is a dual one (approximately equal static and dynamic quenched components). The FRET results indicate that a non-radiative transfer of energy occurred. The association constant and the number of binding sites indicate moderate PRX and BSA binding. The competitive binding study indicates that PRX is bound to site I from the hydrophobic pocket of subdomain IIA of BSA. The synchronous spectra showed that the microenvironment around the BSA fluorophores and protein conformation do not change considerably. The Trp lifetimes revealed that PRX mainly quenches the fluorescence of Trp-213 situated in the hydrophobic domain. The CD and DSC investigation show that addition of PRX stabilizes the protein structure. ITC results revealed that BSA-PRX binding involves a combination of electrostatic, hydrophobic and hydrogen interactions. The analysis of the computational data is consistent with the experimental results. This thorough investigation of the PRX-BSA binding may provide support for other studies concerning moderate affinity drugs with serum protein. Communicated by Ramaswamy H. Sarma

Multilayer films from hydrophobically modified poly(acrylic acid) (HMPA) and their complexes with cationic surfactants were successfully prepared using the layer-by-layer (LbL) method. Alkyl trimethylammonium bromide derivatives with various lengths of the hydrophobic chain (C10–C18) were used to interact with the HMPA polymer, generating highly hydrophobic domains in the films and contributing to the antimicrobial properties of the prepared coating. The antimicrobial efficiency against common pathogens such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans was investigated in relationship with the morphology and composition of the thin films. The wettability and roughness of the multilayered systems were evaluated using atomic force microscopy (AFM) and contact angle measurements. The effects of the microbial exposure on the surface properties of the prepared films were investigated in order to assess the stability of the HMPA-deposited multilayers and the durability of the antimicrobial activity. The hydrophobically modified films exhibited antimicrobial activity against the studied pathogens. The best efficiency was registered in the case of S. aureus, which showed an inhibition of growth up to 100% after 2 h. C. albicans proved to be less sensitive to the effect of the multilayers deposited from HMPA–surfactant complexes. These results suggest that HMPA and HMPA–surfactant complex LbL multilayer films can be used as promising materials in antimicrobial surface coatings with increased resistance to pathogens during exposure.

Aqueous octaethylene glycol mono(n-dodecyl) ether (C12E8) solutions, in the absence and presence of poly(acrylic acid) (PAA) are studied by means of viscosity, pH, refractive index, static fluorescence and dynamic light scattering measurements. At high surfactant concentrations, these properties present inflection points. They are different by the classical critical points (critical micelle concentration and critical interaction concentrations) of such systems and appear at almost the same surfactant concentration, irrespective of the polymer presence. The results are interpreted in terms of micellar size and shape changes. Some images collected with two microscopes prove these changes and the coexistence of various shaped aggregates.

The present work investigates the influence of silica nanoparticles upon the wettability properties of hydrophobically modified poly(acrylate)-surfactant - silica films. The organicinorganic films were obtained via layer-by-layer method. The silica nanoparticles were synthesized by a sol-gel method using the Stober process with tetraethoxysilane (TEOS) and alkyltriethoxysilane (RTES). The size of silica nanoparticles was measured by dynamic light scattering (DLS) and environmental scanning electron microscopy (ESEM). The functionalization of silica nanoparticles was confirmed by Fourier transform infrared spectroscopy (FTIR). The experimental data show that the hydrophobically modified-poly(acrylate)-surfactant - silica films have a higher contact angle than those without silica nanoparticles.

Environmental decontamination requires strategies for removing organic contaminants from the ecosystem. Polycyclic aromatic hydrocarbons (PAHs) with toxic and carcinogenic properties are potentially hazardous pollutants. One suitable method for PAHs removal is their solubilization by micelles. This paper evaluates the effect of borax upon the aggregation ability of sodium dodecyl sulfate (SDS) with consequence over the micellar solubilization of naphthalene. Various techniques, such as micellar electrophoretic chromatography (MEKC), surface tension, UV-Vis and steady-state fluorescence were used to assess the micelle formation. The results show that borax decreases the critical micelle concentration of SDS and enhances the naphthalene solubilization. The work recommends borax as an efficient booster in the micellar decontamination strategy of PAHs.

Linear and hyperbranched polyglycidol (LPGL and HPGL) with average molecular weight of a few thousands were studied in water and surfactant solutions. The employed surfactants are hexaethyleneglycol mono n-dodecyl ether (C12E6), cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The working methods are surface tension, steady-state fluorescence, dynamic light scattering (DLS), electrokinetic potential and FTIR spectroscopy. The linear polyglycidols are weakly associative species, unlike the hyperbranched one which is more hydrophilic and harder associates. The linear polymers most efficiently interact with the anionic surfactant, followed by cationic and most weakly with the nonionic. The hydrodynamic diameters of the investigated polyglycidols depend on their structure and molecular weight. In the presence of SDS, the hydrodynamic diameters vary with surfactant concentration. The study reveals the solubilization of fluorescent probes (pyrene, naphthalene) inside the polyglycidol aggregates. Unlike the LPGL, the presence of cavities in HPGL macromolecule offers supplementary "pockets" for solubilization.

The oxidation of catechin in the presence of atmospheric oxygen in a methanol/buffer model solution was studied by investigating generated products using LC/MS and spectrophotometry.It was proved that catechin was slowly converted to dimeric species with similar structures and properties.The catechin autoxidation was investigated spectrophotometrically at different pH ranging between 5 and 10.Using the initial linear dependence of the kinetic curves [Dimers] = f(t) the initial reaction rates were estimated for the autoxidation of catechin in methanol/buffered solutions.It was found that the dimer formation is favored at pH 8.

The aim of this study was to develop and evaluate several microemulsion (ME) formulations as topical delivery systems for loratadine (LRT), a second-generation H1 antihistaminic drug, used for allergic skin manifestations treatment. The solubility of LRT in different oils, non-ionic surfactants and cosurfactants was determined to select the ME components. Establishment of pseudoternary phase diagrams, using a relatively new method (Phase Diagram by Micro Plate Dilution) for several systems, including the Captex 355/Cremophor Rh 40-Capryol 90/water system, was used to select the studied ME and gelME. The selected LRT-loaded ME were characterized for physicochemical properties and in vitro drug release through synthetic membrane. The results showed great impact of the ME components and their proportions on the mentioned characteristics. Three of the assessed ME, presenting permeation profiles best fitted with Korsmeyer-Peppas model, were suggested to be firstly evaluated for the in vitro drug release through a biological membrane model.