Phenolic Compounds from Sour Cherry Pomace: Microencapsulation, in Vitro Digestion, and Cell Growth Activities.

The objective of this work was the valorisation of sour cherry (Prunus cerasus L.) pomace as a source of biologically active compounds. To formulate microcapsules, polyphenolic compounds were extracted and encapsulated with maltodextrin as wall material, by freeze-drying. An in vitro digestion study was carried out on obtained encapsulates but also on sour cherry pomace extract and sour cherry pomace freeze-dried powder. The results indicated that encapsulation, as well as freeze-drying, provided a good protective effect on bioactive compounds during digestion. Furthermore, the potential antiproliferative and cytotoxic activities of encapsulates and sour cherry pomace extract were evaluated using breast adenocarcinoma MCF7 cell lines, colon adenocarcinoma HT-29 cell lines, and noncancer cell line. Encapsulates and sour cherry pomace extract showed variable anti-proliferative activity towards all cell lines. Obtained results showed that encapsulation of sour cherry pomace could be useful for improving the stability of polyphenolic compounds in the gastrointestinal tract. The results highlight the bioactive potential of sour cherry pomace as a nutraceutical resource and the protective effects of microencapsulation on the digestion of bioactive compounds.

Application of the Ugi reaction for preparation of submicron capsules based on sugar beet pectin.

The Ugi four-component condensation in diluted liposomal suspensions was used to prepare pectin-based submicron capsules. A set of isocyanides and aldehydes was used to optimize the synthesis of capsule shells. Modified sugar beet pectin was selected as a natural polymer with pronounced surface activity to create a capsule shell. At first, liposomal composition was optimized in order to select suitable conditions for capsule formation. Then, the wide set of capsules constructed on modified sugar beet pectin scaffold has been synthesized. The choice was determined by level of substitution degree and possible chemical diversity of the modified surface. Detailed characterization of products has been performed for polysaccharide particles with liposomal core prepared with various processing parameters (concentration, cross-linking components, the density of linkage). The chemical structure, average size, polydispersity index, morphology, stability, and cytotoxicity of obtained particles have been investigated in dependence on the shell content. The obtained submicrometer cross-linked capsules (220-240 nm) with controlled colloidal properties showed high stability and low toxicity. Thus, the proposed carriers have a great potential as sustained drug delivery systems for different administration routes.

Keratin/alginate hybrid hydrogels filled with halloysite clay nanotubes for protective treatment of human hair.

Keratin/alginate hydrogels filled with halloysite nanotubes (HNTs) have been tested for the protective coating of human hair. Preliminary studies have been conducted on the aqueous colloidal systems and the corresponding hydrogels obtained by using Ca2+ ions as crosslinkers. Firstly, we have investigated the colloidal properties of keratin/alginate/HNTs dispersions to explore the specific interactions occurring between the biomacromolecules and the nanotubes. Then, the rheological properties of the hydrogels have been studied highlighting that the keratin/alginate interactions and the subsequent addition of HNTs facilitate the biopolymer crosslinking. Finally, human hair samples have been treated with the hydrogel systems by the dipping procedure. The protection efficiency of the hydrogels has been evaluated by studying the tensile properties of hair fibers exposed to UV irradiation. In conclusion, keratin/alginate hydrogel filled with halloysite represents a promising formulation for hair protective treatments due to the peculiar structural and rheological characteristics.

Conversion of Organic Dyes into Pigments: Extraction of Flavonoids from Blackberries (Rubus ulmifolius) and Stabilization.

The blackberry's color is composed mainly of natural dyes called anthocyanins. Their color is red-purple, and they can be used as a natural colorant. Anthocyanins are flavonoids, which are products of plants, and their colors range from orange and red to various shades of blue, purple and green, according to pH. In this study, the chemical composition of an extract obtained from blackberries was defined by LC-ESI/LTQOrbitrap/MS in positive and negative ionization mode. Furthermore, we investigated the adsorption process of blackberry extract using several inorganic fillers, such as metakaolin, silica, Lipari pumice, white pozzolan and alumina. The pigments exhibit different colors as a function of their interactions with the fillers. The analysis of the absorption data allowed the estimation of the maximum adsorbing capacity of each individual filler tested. Through thermogravimetric measurements (TGA), the thermal stability and the real adsorption of the organic extract were determined.

Pickering Emulsions Based on Wax and Halloysite Nanotubes: An Ecofriendly Protocol for the Treatment of Archeological Woods.

A novel green protocol for the consolidation and protection of waterlogged archeological woods with wax microparticles has been designed. First, we focused on the development of halloysite nanotubes (HNTs) based Pickering emulsions using wax as the inner phase of the oil-in-water droplets. The optimization of the preparation strategy was supported by both optical microscopy and scanning electron microscopy, which allowed us to show the morphological features of the prepared hybrid systems and their structural properties, i.e., the distribution of the clay at the interface. Also, the dependence of the overall dimensions of the prepared systems on the halloysite content was demonstrated. Microdifferential scanning calorimetry (µ-DSC) was conducted in order to assess whether the thermal properties of the wax are affected after its interaction with HNTs. Then, the Pickering emulsions were employed for the treatment of waterlogged wooden samples. Compared to the archeological woods treated with pure wax, the addition of nanotubes induced a remarkable improvement in the mechanical performance in terms of stiffness and flexural strength. The proposed protocol is environmentally friendly since water is the only solvent used throughout the entire procedure, even if wax is vehiculated into the pores at room temperature. As a consequence, the design of wax/halloysite Pickering emulsions represents a promising strategy for the preservation of wooden artworks, and it has a great potential to be scaled up, thus becoming also exploitable for the treatments of shipwrecks of large size.

Coffee grounds as filler for pectin: Green composites with competitive performances dependent on the UV irradiation.

Novel composite bioplastics were successfully prepared by filling pectin matrix with treated coffee grounds. The amount of coffee dispersed into the pectin was changed within a wide filler range. The morphology of the pectin/coffee hybrid films was studied by microscopic techniques in order to investigate their mesoscopic structure as well as the sizes distribution of the particles dispersed into the matrix. The micrographs showed that the coffee grounds are uniformly dispersed within the polymeric matrix. The morphological characteristics of the biocomposite films were correlated to their properties, such as wettability, water uptake, thermal behavior and mechanical performances. Dynamic mechanical test were conducted as a function of the humidity conditions. As a general result, a worsening of the mechanical performances was induced by the addition of the coffee grounds into the pectin. An additional UV curing treatment was conducted on the pectin/coffee films with the aim to improve their tensile and viscoelastic features. The cured films showed promising and tunable properties that are dependent on both the filler content and the UV irradiation. In particular, the presence of single coffee particles into the pectin matrix renders the UV curing treatment effective in the enhancement of the elasticity as well as the traction resistance, whereas the cured composite films containing coffee clusters showed only more elastic characteristics. With this study, we fabricated pectin/coffee bioplastics with controlled behavior appealing for specific application within the food packaging.

Effect of Morphology and Size of Halloysite Nanotubes on Functional Pectin Bionanocomposites for Food Packaging Applications.

Pectin bionanocomposite films filled with various concentrations of two different types of halloysite nanotubes were prepared and characterized in this study as potential films for food packaging applications. The two types of halloysite nanotubes were long and thin (patch) (200-30 000 nm length) and short and stubby (Matauri Bay) (50-3000 nm length) with different morphological, physical, and dispersibility properties. Both matrix (pectin) and reinforcer (halloysite nanotubes) used in this study are considered as biocompatible, natural, and low-cost materials. Various characterization tests including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, release kinetics, contact angle, and dynamic mechanical analysis were performed to evaluate the performance of the pectin films. Exceptional thermal, tensile, and contact angle properties have been achieved for films reinforced by patch halloysite nanotubes due to the patchy and lengthy nature of these tubes, which form a bird nest structure in the pectin matrix. Matauri Bay halloysite nanotubes were dispersed uniformly and individually in the matrix in low and even high halloysite nanotube concentrations. Furthermore, salicylic acid as a biocidal agent was encapsulated in the halloysite nanotubes lumen to control its release kinetics. On this basis, halloysite nanotubes/salicylic acid hybrids were dispersed into the pectin matrix to develop functional biofilms with antimicrobial properties that can be extended over time. Results revealed that shorter nanotubes (Matauri Bay) had better ability for the encapsulation of salicylic acid into their lumen, while patchy structure and longer tubes of patch halloysite nanotubes made the encapsulation process more difficult, as they might need more time and energy to be fully loaded by salicylic acid. Moreover, antimicrobial activity of the films against four different strains of Gram-positive and Gram-negative bacteria indicated the effective antimicrobial properties of pectin/halloysite functionalized films and their potential to be used for food packaging applications.

Development and characterization of co-loaded curcumin/triazole-halloysite systems and evaluation of their potential anticancer activity.

Positively charged halloysite nanotubes functionalized with triazolium salts (f-HNT) were employed as a carrier for curcumin molecules delivery. The synthesis of these f-HNT new materials is described. Their interaction with curcumin was evaluated by means dynamic light scattering (DLS) and UV-vis spectroscopy in comparison with pristine unmodified HNT (p-HNT). The curcumin load into HNT was estimated by thermogravimetric analysis (TGA) measurements, while the morphology was investigated by scanning electron microscopy (SEM) techniques. Release of curcumin from f-HNT, at three different pH values, by means of UV-vis spectroscopy was also studied. Furthermore, different cancer cell lines were used to evaluate the potential cytotoxic effect of HNT at different concentrations and culture times. The results indicated that the f-HNT drug carrier system improves the solubility of curcumin in water, and that the drug-loaded f-HNT exerted cytotoxic effects against different cell lines.

Dispersions of nanoclays of different shapes into aqueous and solid biopolymeric matrices. Extended physicochemical study.

Dispersions of nanofillers into aqueous and solid biopolymeric matrices were studied from the physicochemical viewpoint. This work was carried out based on the idea that the combination of biopolymers, derived from renewable resources, and nanofiller, environmentally friendly, may form a new generation of nanomaterials with excellent and unique properties at low cost. To this purpose, two pectins with different degrees of methyl esterification and nanoclays like halloysite and laponite RD were selected. The thermodynamic and structural studies on the aqueous mixtures of pectin and nanoclay were able to discriminate the interactions, which control the adsorption of pectin onto the filler and the aggregation of both pectin and clay particles. The gained insights were useful to interpret the mesoscopic structure of the nanocomposites (prepared from the aqueous mixtures by means of the casting method) evidenced by SEM, thermal stability, tensile properties, and transparency investigations. The attained knowledge represents a basic point for designing new hybrid nanostructures in both the aqueous and the solid phase for specific purposes.