Search

[Display omitted] • ATR-FTIR difference spectroscopy enables identification of degradable substrates. • Standard spectra of individual substrates guide recognition of degraded components. • IR signals of major metabolites are highlighted by a double difference approach. • E. aerogenes, grown anaerobically, consumes glucose but cannot degrade maltose. • Main products of dark fermentation by E. aerogenes are H 2 , ethanol and 2,3-BD. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) difference spectroscopy has been employed for a variety of applications spanning from reaction mechanisms analysis to interface phenomena assessment. This technique is based on the detection of spectral changes induced by the chemical modification of the original sample. In the present study, we highlight the potential of the ATR-FTIR difference approach in the field of microbial biochemistry and biotechnology, reporting on the identification of main soluble species consumed and released by growing bacteria during the biohydrogen production process. Specifically, the mid-infrared spectrum of a model culture broth, composed of glucose, malt extract and yeast extract, was used as background to acquire the FTIR difference spectrum of the same broth as modified by Enterobacter aerogenes metabolism. The analysis of difference signals revealed that only glucose is degraded during hydrogen evolution in anaerobic conditions, while ethanol and 2,3-butanediol are the main soluble metabolites released with H 2. This fast and easy analytical approach can therefore represent a sustainable strategy to screen different bacterial strains and to select raw and waste materials to be employed in the field of biofuel production. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) is a hydrophobic polyphenol from the rhizome of Curcuma spp., while hydroxytyrosol (HT) is a water-soluble polyphenol from Olea europaea. Both show outstanding antioxidant properties but suffer from scarce bioavailability and low stability in biological fluids. In this work, the co-encapsulation of Cur and HT into liposomes was realized, and the liposomal formulation was improved using polymers to increase their survival in the gastrointestinal tract. Liposomes with different compositions were formulated: Type 1, composed of phospholipids and cholesterol; Type 2, also with a PEG coating; and Type 3 providing an additional shell of Eudragit® S100, a gastro-resistant polymer. Samples were characterized in terms of size, morphology, ζ-potential, encapsulation efficiency, and loading capacity. All samples were subjected to a simulated in vitro digestion and their stability was investigated. The Eudragit®S100 coating demonstrated prevention of early releases of HT in the mouth and gastric phases, while the PEG shell reduced bile salts and pancreatin effects during the intestinal digestion. In vitro antioxidant activity showed a cumulative effect for Cur and HT loaded in vesicles. Finally, liposomes with HT concentrations up to 40 μM and Cur up to 4.7 μM, alone or in combination, did not show cytotoxicity against Caco-2 cells. [ABSTRACT FROM AUTHOR]

Abstract: The potential of purple non-sulphur bacteria for bioremediation was assessed by investigating the ability of Rhodobacter sphaeroides strain R26.1 to grow photosynthetically in heavy metal contaminated environments. Bacterial cultures were carried out in artificially polluted media, enriched with the transition metal ions Hg2+, Cu2+, Fe2+, Ni2+, Co2+, , and in millimolar concentration range. For each investigated ion the effect on growth parameters was evaluated. The analysis of concentration–effect curves revealed a differentiated response, indicating that diverse mechanisms of tolerance and/or resistance are involved. Adaptation or selection procedures were not applied, leading to assess intrinsic abilities of coping with these contaminants. The microorganism proved to be highly tolerant to heavy metal exposure, especially towards Co2+, Fe2+ and . In addition Ni2+ and Co2+ were found to decrease the cellular content of light harvesting complexes. A characteristic behavior was observed with mercuric ions, which produced a significant increase of the lag-phase. [Copyright &y& Elsevier]

Redox transitions in a film of detergent-purified bovine cytochrome bc[sub 1] complex were investigated by perfusion-induced attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The technique provides a flexible method for generating redox-induced IR changes of components of bovine cytochrome bc[sub 1] complex at a high signal:noise ratio. These IR redox difference spectra arise from perturbations of prosthetic groups and surrounding protein. Visible difference spectra were recorded synchronously using a light beam reflected from the exposed prism surface and provided a quantitative means of determining the redox transitions that were occurring. IR and visible redox difference spectra of iron-sulfur protein/cytochrome c[sub 1], heme b[sub H], and heme b[sub L] were separated by selective reduction and/or oxidation that extends published data on the homologous bacterial enzyme. Several bands could be tentatively assigned to redox-sensitive modes of hemes and ubiquinone and changes in the surrounding protein by comparison with available data for bacterial bc[sub 1] complex, other related heme proteins, and model compounds. Some tentative assignments of further signals to specific amino acids are made on the basis of known crystal structures. [ABSTRACT FROM AUTHOR]

Radiotherapy (RT) involves delivering X-ray beams to the tumor site to trigger DNA damage. In this approach, it is fundamental to preserve healthy cells and to confine the X-ray beam only to the malignant cells. The integration of gold nanoparticles (AuNPs) in the X-ray methodology could be considered a powerful tool to improve the efficacy of RT. Indeed, AuNPs have proven to be excellent allies in contrasting tumor pathology upon RT due to their high photoelectric absorption coefficient and unique physiochemical properties. However, an analysis of their physical and morphological reaction to X-ray exposure is necessary to fully understand the AuNPs' behavior upon irradiation before treating the cells, since there are currently no studies on the evaluation of potential NP morphological changes upon specific irradiations. In this work, we synthesized two differently shaped AuNPs adopting two different techniques to achieve either spherical or star-shaped AuNPs. The spherical AuNPs were obtained with the Turkevich–Frens method, while the star-shaped AuNPs (AuNSs) involved a seed-mediated approach. We then characterized all AuNPs with Transmission Electron Microscopy (TEM), Uv-Vis spectroscopy, Dynamic Light Scattering (DLS), zeta potential and Fourier Transform Infrared (FTIR) spectroscopy. The next step involved the treatment of AuNPs with two different doses of X-radiation commonly used in RT, namely 1.8 Gy and 2 Gy, respectively. Following the X-rays' exposure, the AuNPs were further characterized to investigate their possible physicochemical and morphological alterations induced with the X-rays. We found that AuNPs do not undergo any alteration, concluding that they can be safely used in RT treatments. Lastly, the actin rearrangements of THP-1 monocytes treated with AuNPs were also assessed in terms of coherency. This is a key proof to evaluate the possible activation of an immune response, which still represents a big limitation for the clinical translation of NPs. [ABSTRACT FROM AUTHOR]

The impetuous development of nanotechnology over the past two decades has enabled the production of a plethora of nanomaterials with outstanding optical, magnetic, electrical, catalytic and mechanical properties. The versatility of these materials attracted attention from the very beginning in the most disparate sectors of science and technology. The application of nanomaterials in the biological and biomedical fields soon benefited from the interaction with liposomes, which increased their biocompatibility and biostability. Liposomes indeed are versatile self-assembling supramolecular (nano)structures constituted of an aqueous core enclosed by a lipid bilayer, able to host hydrophobic and hydrophilic cargo, and with superior biocompatibility and great similarity with the biological membranes. The result is the construction of hybrid nanoscale architectures, in which nanoparticles (NPs) are allocated either in the aqueous core, in the palisade of the lipid bilayer or on the outer surface of the vesicles. In the first part of this review, the principal methods for the preparation of NP-loaded liposomes are carefully illustrated in a tutorial manner. In the second part, an overview of the great potentialities deriving from the conjugation of liposomes with NPs is presented. In each paragraph, the main characteristics of the most notable classes of NPs, the related issues, and the advantages arising from their association with liposomes are shown. Here, the most significant research works in literature for each kind of system are presented. [Display omitted] • Current methods for incorporating NPs into liposomes are illustrated. • The advantages of incorporating NPs into liposomes are discussed. • A tutorial section for non-expert researchers in the field is included. • An updated review of the main hybrid NP-liposomes and their applications is shown. • The impacts in the field of innovative therapies, theranostics and sensing are shown. [ABSTRACT FROM AUTHOR]

Abstract: The interaction of cobalt (Co2+) and nickel (Ni2+) ions with whole cells of the photosynthetic purple bacterium Rhodobacter sphaeroides strain R26 was investigated. Active and passive uptakes were examined in cells grown in the presence of increasing amounts of Co2+ and Ni2+. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), pH titration, and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy were used to assess the role of cell envelope and metabolism in accumulating the two heavy metals. The chosen microorganism was able to uptake cobalt and nickel up to 2.2 and 0.25 mg per gram of dried cells respectively, with the largest part found bound to the cell surface. Carboxylate groups lying on the cell wall of this Gram-negative bacterium proved to be the major candidates for binding protons and metal cations. Co2+ was found to interfere with Mg2+ extracellular immobilization and transport across the membrane, indicating that these ions share binding sites on the cell envelope and ion transport systems. According to the presence of a competition mechanism, bacterial growth experiments showed that high Mg2+ concentrations are able to rescue R. sphaeroides from Co2+ toxicity. [Copyright &y& Elsevier]

The construction from scratch of artificial cells by means of a "bottom up" approach is one of the most ambitious challenges in synthetic biology. Artificial cells capable of imitating the light phase of photosynthesis can be considered photoautotrophs. In bacterial photosynthesis, the first step in the light energy transduction process is the enzymatic photo‐redox cycle catalysed by two membrane protein complexes, that is, the photosynthetic reaction centre (RC) and the ubiquinol oxidase (bc1B). In this work we studied this process in a micellar suspension of both proteins but coupling a bacterial RC with an ortholog bc1 extracted from mammalian mitochondria (bc1M). With this hybrid protein complex chain, the light transduction efficiency turns out to be enhanced up to 90 % by tuning the enzymatic level ratio of the two protein complexes. These results pave the way towards the reconstitution of the entire photosynthetic machinery in artificial membranes for the realization of photoautotrophic artificial cells. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) are renewable, sustainable and biocompatible nanomaterials, which have gained great attention in last years for their potentialities in several fields of application. With their polyelectrolyte behaviour, sulphated CNCs are suitable to produce multilayered architectures with cationic molecules. In this work, we have investigated the ability of anionic CNCs to assist the two-dimensional organization of two cationic fulleropyrrolidines at the air/water interface, leading to hybrid Langmuir-Schäfer films with improved (photo)electrical properties. We demonstrated that CNCs interact with the fulleropyrrolidines at the air/water interface, favouring the assembly of organized hybrid C 60 /CNC films. The transfer efficiency of Langmuir layers and the morphological regularity of supported films proved to be influenced by the extent of positive charge on the fullerene counterpart. Interestingly, the electrochemical characterization of hybrid films revealed that sulphated nanocellulose strongly improves the electrical properties of organized fullerene layers, by increasing their conductivity and favouring the hydrogen evolution reaction. Moreover, the well-established C 60 photoactivity proved to be enhanced by CNCs, as demonstrated by the higher intensity of photocurrents. This outstanding nanocellulose impact on fullerene film electrical properties paves the way to the development of more performing C 60 -based electrochemical devices, able to better exploit the unique properties of carbon nanostructures. Image 1 [ABSTRACT FROM AUTHOR]

Exposure to atmospheric particulate matter (PM) leads to adverse health effects although the exact mechanisms of toxicity are still poorly understood. Several studies suggested that a large number of PM health effects could be due to the oxidative potential (OP) of ambient particles leading to high concentrations of reactive oxygen species (ROS). The contribution to OP of specific anthropogenic sources like road traffic, biomass burning, and industrial emissions has been investigated in several sites. However, information about the OP of natural sources are scarce and no data is available regarding the OP during Saharan dust outbreaks (SDO) in Mediterranean regions. This work uses the a-cellular DTT (dithiothreitol) assay to evaluate OP of the water-soluble fraction of PM 2.5 and PM 10 collected at an urban background site in Southern Italy. OP values in three groups of samples were compared: standard characterised by concentrations similar to the yearly averages; high carbon samples associated to combustion sources (mainly road traffic and biomass burning) and SDO events. DTT activity normalised by sampled air volume (DTT V ), representative of personal exposure, and normalised by collected aerosol mass (DTT M ), representing source-specific characteristics, were investigated. The DTT V is larger for high PM concentrations. DTT V is well correlated with secondary organic carbon concentration. An increased DTT V response was found for PM 2.5 compared to the coarse fraction PM 2.5-10 . DTT V is larger for high carbon content samples but during SDO events is statistically comparable with that of standard samples. DTT M is larger for PM 2.5 compared to PM 10 and the relative difference between the two size fractions is maximised during SDO events. This indicates that Saharan dust advection is a natural source of particles having a lower specific OP with respect to the other sources acting on the area (for water-soluble fraction). OP should be taken into account in epidemiological studies to evaluate the potential health risks associated to ROS in regions affected by high pollution events due to Saharan dust advection. [ABSTRACT FROM AUTHOR]

Ultrasounds are used in many industrial, medical and research applications. Properties and function of proteins are strongly influenced by the interaction with the ultrasonic waves and their bioactivity can be lost because of alteration of protein structure. Surprisingly, to the best of our knowledge no study was carried out on Integral Membrane Proteins (IMPs), which are responsible for a variety of fundamental biological functions. In this work, the photosynthetic Reaction Center (RC) of the bacterium Rhodobacter sphaeroides has been used as a model for the study of the ultrasound-induced IMP denaturation. Purified RCs were suspended in i) detergent micelles, in ii) detergent-free buffer and iii) reconstituted in liposomes, and then treated with ultrasound at 30 W and 20 kHz at increasing times. The optical absorption spectra showed a progressive and irreversible denaturation in all cases, resulting from the perturbation of the protein scaffold structure, as confirmed by circular dichroism spectra that showed progressive alterations of the RC secondary structure. Charge recombination kinetics were studied to assess the protein photoactivity. The lifetime for the loss of RC photoactivity was 32 min in detergent micelles, ranged from 3.8 to 6.5 min in the different proteoliposomes formulations, and 5.5 min in detergent-free buffer. Atomic force microscopy revealed the formation of large RC aggregates related to the sonication-induced denaturation, in agreement with the scattering increase observed in solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni2+ extracellular uptake by Rhodobacter sphaeroides follows the Langmuir model. • Ni2+ fully displace alkali metal ions while Ca2+ and Mg2+ remain bound to the surface. • Single component XPS analysis enables assessing Ni2+-induced surface modifications. • Ni2+ binding causes stacking and/or packing of lipopolysaccharide moieties. The presence of anionic functional groups on the surface of microbial cells makes the bacterial biomass very attractive as metal cation removal tool for environmental bioremediation. To go insight to the heavy metal sorption abilities of Gram-negative bacteria, we characterized the extracellular uptake of Ni2+ ions by the phototrophic bacterium Rhodobacter sphaeroides , whose ability to sequester toxic metal ions has been widely documented. The sorption process proved to be well described by the Langmuir model, suggesting that the cell envelope behaves as an ideal adsorbent surface, showing a layer of chemically equivalent binding sites with high affinity for Ni2+. X-ray photoelectron spectroscopic data reveal that, at binding site saturation, Ni2+ ions fully displace alkali metal ions from the bacterial surface, while they are unable to displace Ca2+ and Mg2+ from their tight binding sites. The analysis of carbon, nitrogen and oxygen speciation, as arisen from high resolution spectra fitting, highlights that the Ni2+/K+ cation exchange affects the surface distribution of main chemical components, with increased contribution by peptides and phosphatidylcholines. A role of Ni2+ ions in favoring the stacking and/or packing of lipopolysaccharide sugar chains by interaction with carboxylate groups is proposed and discussed. [ABSTRACT FROM AUTHOR]

Semiquinone oscillations induced by light pulses in the presence of exogenous electron donors are a valuable source of information on the kinetics and thermodynamics of ubiquinone chemistry relevant to the Q site of the photosynthetic reaction center (RC). In previous attempts to achieve the quantitative interpretation of data, the ubiquinone concentration was considered constant during the experiment since it was much bigger than that of RC. In this work, we extended existing models to low ubiquinone concentrations revealing several hidden processes taking place during the ubiquinone photoreduction and enabling the evaluation of the ubiquinone binding constant K at the Q site. The proposed approach provides for the first time the evaluation of K without any preliminary treatment of ubiquinone extraction from the binding site, thereby better preserving its native structure. [ABSTRACT FROM AUTHOR]

Liposomes represent a versatile biomimetic environment for studying the interaction between integral membrane proteins and hydrophobic ligands. In this paper, the quinone binding to the Q-site of the photosynthetic reaction centers (RC) from Rhodobacter sphaeroides has been investigated in liposomes prepared with either the zwitterionic phosphatidylcholine (PC) or the negatively charged phosphatidylglycerol (PG) to highlight the role of the different phospholipid polar heads. Quinone binding ( K) and interquinone electron transfer ( L) equilibrium constants in the two type of liposomes were obtained by charge recombination reaction of Q-depleted RC in the presence of increasing amounts of ubiquinone-10 over the temperature interval 6-35 °C. The kinetic of the charge recombination reactions has been fitted by numerically solving the ordinary differential equations set associated with a detailed kinetic scheme involving electron transfer reactions coupled with quinone release and uptake. The entire set of traces at each temperature was accurately fitted using the sole quinone release constants (both in a neutral and a charge separated state) as adjustable parameters. The temperature dependence of the quinone exchange rate at the Q-site was, hence, obtained. It was found that the quinone exchange regime was always fast for PC while it switched from slow to fast in PG as the temperature rose above 20 °C. A new method was introduced in this paper for the evaluation of constant K using the area underneath the charge recombination traces as the indicator of the amount of quinone bound to the Q-site. [ABSTRACT FROM AUTHOR]

Osmotic shock was used as a tool to obtain cardiolipin (CL) enriched chromatophores of Rhodobacter sphaeroides. After incubation of cells in iso- and hyper-osmotic buffers both chromatophores with a physiological lipid profile (Control) and with an almost doubled amount of CL (CL enriched) were isolated. Spectroscopic properties, reaction centre (RC) and reducible cytochrome (cyt) contents in Control and CL enriched chromatophores were the same. The oxidoreductase activity was found higher for CL enriched than for Control chromatophores, raising from 60 ± 2 to 93 ± 3 mol cyt c s (mol total cyt c). Antymicin and myxothiazol were tested to prove that oxidoreductase activity thus measured was mainly attributable to the cyt bc complex. The enzyme was then purified from BH6 strain yielding a partially delipidated and almost inactive cyt bc complex, although the protein was found to maintain its structural integrity in terms of subunit composition. The ability of CL in restoring the activity of the partially delipidated cyt bc complex was proved in micellar systems by addition of exogenous CL. Results here reported indicate that CL affects oxidoreductase activity in the bacterium Rhodobacter sphaeroides both in chromatophore and in purified cyt bc complex. [ABSTRACT FROM AUTHOR]

Photosynthetic reaction center (RC) is the minimal nanoscopic photoconverter in the photosynthetic membrane that catalyzes the conversion of solar light to energy readily usable for the metabolism of the living organisms. After electronic excitation the energy of light is converted into chemical potential by the generation of a charge separated state accompanied by intraprotein and ultimately transmembrane proton movements. We designed a system which fulfills the minimum structural and functional requirements to investigate the physico/chemical conditions of the processes: RCs were reconstituted in closed lipid vesicles made of selected lipids entrapping a pH sensitive indicator, and electron donors (cytochrome c and K[Fe(CN)]) and acceptors (decylubiquinone) were added to sustain the photocycle. Thanks to the low proton permeability of our preparations, we could show the formation of a transmembrane proton gradient under illumination and low buffering conditions directly by measuring proton-related signals simultaneously inside and outside the vesicles. The effect of selected ionophores such as gramicidin, nigericin and valinomycin was used to gain more information on the transmembrane proton gradient driven by the RC photochemistry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluid mono and bilayers of POPC are affected by the presence of EE2. • At the air/water interface, EE2 penetrates on hydrophobic chain of POPC molecules. • The high membrane curvature degree of SUVs allowed the EE2 entrance in the vesicles. • EE2 strongly affects the morphology of POPC GUVs. The lack of studies involving the effects in human health associated with the chronic ingestion of pollutants lead to the path of investigating the action of these compounds in cell membrane models. We demonstrated the interaction (causes and consequences) of the hormone 17 α-ethinylestradiol (EE2) with lipid monolayers (prepared as Langmuir films) and bilayers prepared as small unilamellar vesicles (SUVs) and giant unilamellar vesicles (GUVs). Both fluidity and majority chemical composition of real plasma cell membrane were guaranteed using the phospholipid 1-palmitoil-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC). Surface pressure-mean molecular area (π-A) isotherms and PM-IRRAS measurements highlighted the strong interaction of EE2 with POPC monolayers, leading the hormone to remain at the air/water interface and promoting its penetration into the phospholipid hydrophobic chains. In the case of bilayers, the entrance of the hormone inside the SUV is likely facilitated by their high curvature. In GUVs, EE2 was responsible for changes in the spherical shape, forming structures like buds and lipid protrusions. The set of results indicates the strong effects of EE2 on fluid membranes, which is an important feature to predict its damage in human cells. [ABSTRACT FROM AUTHOR]

Abstract: The correlations between morphological features and field-effect properties of poly(alkoxyphenylene-thiophene) thin Langmuir–Schäfer film deposited on differently terminated gate dielectric surfaces, namely bare and methyl functionalized thermal silicon dioxide (t-SiO2), have been systematically studied. The film morphology has been investigated at different film thickness by Scanning Force Microscopy. Films thicker than a few layers show comparable morphology on both dielectric surfaces while differences are seen for the ultra-thin polymer deposit in close proximity to the substrate. Such deposit is notably more heterogeneous on bare t-SiO2, while a more compact and uniform nanogranular structure is observed on the silylated t-SiO2. As to the field-effect properties, the methyl-terminated gate dielectric surface leads to a two order of magnitude mobility enhancement along with a field-effect thickness independent conductance. [Copyright &y& Elsevier]

Abstract: The thermodynamics and kinetics of light-induced electron transfer in bacterial photosynthetic RCs are sensitive to physiologically important lipids (phosphatidylcholine, cardiolipin and phosphatidylglycerol) in the environment. The analysis of the temperature-dependence of the rate of the P+QA −QB→P+QAQB − interquinone electron transfer revealed high enthalpy change of activation in zwitterionic or neutral micelles and vesicles and low enthalpy change of activation in vesicles constituted of negatively charged phospholipids. The entropy change of activation was compensated by the changes of enthalpy, thus the free energy change of activation (≈ 500 meV) did not show large variation in vesicles of different lipids. [Copyright &y& Elsevier]

Cellulose nanomaterials have been widely investigated in the last decade, unveiling attractive properties for emerging applications. The ability of sulfated cellulose nanocrystals (CNCs) to guide the supramolecular organization of amphiphilic fullerene derivatives at the air/water interface has been recently highlighted. Here, we further investigated the assembly of Langmuir hybrid films that are based on the electrostatic interaction between cationic fulleropyrrolidines deposited at the air/water interface and anionic CNCs dispersed in the subphase, assessing the influence of additional negatively charged species that are dissolved in the water phase. By means of isotherm acquisition and spectroscopic measurements, we demonstrated that a tetra-sulfonated porphyrin, which was introduced in the subphase as anionic competitor, strongly inhibited the binding of CNCs to the floating fullerene layer. Nevertheless, despite the strong inhibition by anionic molecules, the mutual interaction between fulleropyrrolidines at the interface and the CNCs led to the assembly of robust hybrid films, which could be efficiently transferred onto solid substrates. Interestingly, ITO-electrodes that were modified with five-layer hybrid films exhibited enhanced electrical capacitance and produced anodic photocurrents at 0.4 V vs Ag/AgCl, whose intensity (230 nA/cm2) proved to be four times higher than the one that was observed with the sole fullerene derivative (60 nA/cm2). [ABSTRACT FROM AUTHOR]

The present study aimed to develop and optimize liposome formulation for the colonic delivery of biologically active compounds. A strategy to facilitate such targeting is to formulate liposomes with a polymer coating sensitive to the pH shifts in the gastrointestinal tract. To this end, liposomes encapsulating curcumin—chosen as the biologically active compound model—and coated with the pH-responsive polymer Eudragit S100 were prepared and characterized. Curcumin was encapsulated into small unilamellar vesicles (SUVs) by the micelle-to-vesicle transition method (MVT) in a simple and organic solvent-free way. Curcumin-loaded liposomes were coated with Eudragit S100 by a fast and easily scalable pH-driven method. The prepared liposomes were evaluated for size, surface morphology, entrapment efficiency, stability, in vitro drug release, and curcumin antioxidant activity. In particular, curcumin-loaded liposomes displayed size lower than 100 nm, encapsulation efficiency of 98%, high stability at both 4 °C and 25 °C, high in vitro antioxidant activity, and a cumulative release that was completed within 200 min. A good Eudragit S100 coating which did not alter the properties of the curcumin-loaded liposomes was obtained. The present work therefore provides a fast and solvent-free method to prepare pH-responsive polymer-coated liposomes for the colonic delivery of biologically active compounds. [ABSTRACT FROM AUTHOR]