Quercetin encapsulated polycaprolactone-polyvinylpyrrolidone electrospun membranes as a delivery system for wound healing applications.

The present work focuses on the production of electrospun membranes based on Poly(ε-caprolactone) (PCL) and Polyvinylpyrrolidone (PVP) for the topical release of Quercetin (Q). Membranes were prepared at 0.5, 1.0, 3.0, 7.0 and 15 % wt of Quercetin and studied from a morphological, physical, and biological point of view. The scanning electron microscopy (SEM) evidences micrometric dimensions of the fibres with a good dispersion of the functional molecule. The retention degree of liquids was evaluated by testing four different liquid media while the radical scavenging activity of Quercetin-loaded membranes was evaluated through DPPH analysis. The release kinetics of Quercetin highlights the presence of an initial burst followed by slower release up to attaining an equilibrium state, after roughly 50 h, showing the possibility of a fine-tuning of drug release. Diffusion coefficients were then evaluated by using Fick's law. Finally, to verify the actual biocompatibility of the systems produced and the possible application in the repair of tissue injury, the biological activity of Quercetin released from drug-loaded membranes was analysed in an immortalized human keratinocyte cell line HaCaT by a wound healing assay. So, the reported preliminary data confirm the possibility of applying the electrospun Quercetin-loaded PCL-PVP membranes for wound healing applications.

Alginate Microbeads Containing Halloysite and Layered Double Hydroxide as Efficient Carriers of Natural Antimicrobials.

The present paper describes the preparation and characterization of novel microbeads from alginate filled with nanoclay such as halloysite nanotubes (HNTs). HNTs were used as support for the growth of layered double hydroxide (LDH) crystals producing a flower-like structure (HNT@LDH). Such nanofiller was loaded with grapefruit seed oil (GO), an active compound with antimicrobial activity, up to 50% wt. For comparison, the beads were also loaded with HNT and LDH separately, and filled with the same amount of GO. The characterization of the filler was performed using XRD and ATR spectroscopy. The beads were analyzed through XRD, TGA, ATR and SEM. The functional properties of the beads, as nanocarriers of the active compound, were investigated using UV-vis spectroscopy. The release kinetics were recorded and modelled as a function of the structural characteristics of the nanofiller.

Supercritical Impregnation of Mesoglycan and Lactoferrin on Polyurethane Electrospun Fibers for Wound Healing Applications.

Fibrous membranes of thermoplastic polyurethane (TPU) were fabricated through a uni-axial electrospinning process. Fibers were then separately charged with two pharmacological agents, mesoglycan (MSG) and lactoferrin (LF), by supercritical CO2 impregnation. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis proved the formation of a micrometric structure with a homogeneous distribution of mesoglycan and lactoferrin. Besides, the degree of retention is calculated in four liquid media with different pHs. At the same time, angle contact analysis proved the formation of a hydrophobic membrane loaded with MSG and a hydrophilic LF-loaded one. The impregnation kinetics demonstrated a maximum loaded amount equal to 0.18 ± 0.20% and 0.07 ± 0.05% for MSG and LT, respectively. In vitro tests were performed using a Franz diffusion cell to simulate the contact with the human skin. The release of MSG reaches a plateau after about 28 h while LF release leveled off after 15 h. The in vitro compatibility of electrospun membranes has been evaluated on HaCaT and BJ cell lines, as human keratinocytes and fibroblasts, respectively. The reported data proved the potential application of fabricated membranes for wound healing.

Development and Characterization of Thermoformed Bilayer Trays of Paper and Renewable Succinic Acid Derived Biopolyester Blends and Their Application to Preserve Fresh Pasta.

The present study reports on the development by thermoforming of highly sustainable trays based on a bilayer structure composed of paper substrate and a film made of a blend of partially bio-based poly(butylene succinate) (PBS) and poly(butylene succinate-co-adipate) (PBSA). The incorporation of the renewable succinic acid derived biopolyester blend film slightly improved the thermal resistance and tensile strength of paper, whereas its flexural ductility and puncture resistance were notably enhanced. Furthermore, in terms of barrier properties, the incorporation of this biopolymer blend film reduced the water and aroma vapor permeances of paper by two orders of magnitude, while it endowed the paper structure with intermediate oxygen barrier properties. The resultant thermoformed bilayer trays were, thereafter, originally applied to preserve non-thermally treated Italian artisanal fresh pasta, "fusilli calabresi" type, which was stored under refrigeration conditions for 3 weeks. Shelf-life evaluation showed that the application of the PBS-PBSA film on the paper substrate delayed color changes and mold growth for 1 week, as well as reduced drying of fresh pasta, resulting in acceptable physicochemical quality parameters within 9 days of storage. Lastly, overall migration studies performed with two food simulants demonstrated that the newly developed paper/PBS-PBSA trays are safe since these successfully comply with current legislation on plastic materials and articles intended to come into contact with food.

Quercetin-Loaded Polycaprolactone-Polyvinylpyrrolidone Electrospun Membranes for Health Application: Design, Characterization, Modeling and Cytotoxicity Studies.

Fibrous membranes of polycaprolactone (PCL)-polyvinylpyrrolidone (PVP) encapsulating 15% wt of quercetin are fabricated by a uniaxial electrospinning technique. Morphological analysis of the electrospun systems proved the fabrication of micrometric fibers (1.58 µm for PCL/PVP and 2.34 µm for quercetin-loaded membrane). The liquid retention degree of the electrospun membranes is evaluated by testing four different liquid media. The contact angle estimation is performed by testing three liquids: phosphate buffer solution, basic solution (pH = 13) and acidic solution (pH = 3), showing high hydrophobicity degree (contact angles > 90°) in all cases. The release of quercetin from the nanofibers in PBS (phosphate buffer solution) and pH = 3 medium, modeled through different models, shows the possibility of a fine tuning of drug release (up to 7 days) for the produced materials. The release profiles attained a plateau regime after roughly 50 h up to 82% and 71% for PBS and pH = 3 media, respectively. Then, since quercetin is known to undergo photooxidation upon UV radiation, release tests after different UV treatment times are carried out and compared with the untreated membrane, demonstrating that the release of the active drug changes from 82% for no-irradiated sample up to 57% after 10 h of UV exposure. The biology activity of released quercetin is evaluated on two human cell lines. The reported results demonstrate the ability of the quercetin-loaded membranes to reduce cell viability of human cell lines in two different conditions: direct contact between cells and quercetin-loaded membranes and cells treatment with culture medium previously conditioned with quercetin-loaded membranes. Therefore, the reported preliminary data confirm the possibility of applying the electrospun quercetin-loaded PCL-PVP membranes for health applications.

Correction: Gorrasi et al. Fabrication and Characterization of Electrospun Membranes Based on "Poly(ε-caprolactone)", "Poly(3-hydroxybutyrate)" and Their Blend for Tunable Drug Delivery of Curcumin. Polymers 2020, 12, 2239.

In the original publication [...].

Encapsulation of Grape (Vitis vinifera L.) Pomace Polyphenols in Soybean Extract-Based Hydrogel Beads as Carriers of Polyphenols and pH-Monitoring Devices.

In this work, novel bio-based hydrogel beads were fabricated by using soybean extract as raw waste material loaded with Lambrusco extract, an Italian grape cultivar. The phenolic profile and the total amount of anthocyanins from the Lambrusco extract were evaluated before encapsulating it in soybean extract-based hydrogels produced through an ionotropic gelation technique. The physical properties of the produced hydrogel beads were then studied in terms of their morphological and spectroscopic properties. Swelling degree was evaluated in media with different pH levels. The release kinetics of Lambrusco extract were then studied over time as a function of pH of the release medium, corroborating that the acidity/basicity could affect the release rate of encapsulated molecules, as well as their counter-diffusion. The pH-sensitive properties of wine extract were studied through UV-Vis spectroscopy while the colorimetric responses of loaded hydrogel beads were investigated in acidic and basic solutions. Finally, in the framework of circular economy and sustainability, the obtained data open routes to the design and fabrication of active materials as pH-indicator devices from food industry by-products.

One-Pot Terpolymerization of Macrolactones with Limonene Oxide and Phtalic Anhydride to Produce di-Block Semi-Aromatic Polyesters.

The synthesis of novel block copolymers, namely poly(limonene-phthalate)-block-poly(pentadecalactone) and poly(limonene-phthalate)-block-poly(pentadecalactone) is here described. To achieve this synthesis, a bimetallic aluminum based complex (1) was used as catalyst in the combination of two distinct processes: the ring-opening polymerization (ROP) of macrolactones such as ω-pentadecalactone (PDL) and ω-6-hexadecenlactone (HDL) and the ring-opening copolymerization (ROCOP) of limonene oxide (LO) and phthalic anhydride (PA). The synthesis of di-block polyesters was performed in a one-pot procedure, where the semi-aromatic polyester block was firstly formed by ROCOP of LO and PA, followed by the polyethylene like portion produced by ROP of macrolactones (PDL or HDL). The obtained di-block semiaromatic polyesters were characterized by NMR and GPC. The structural organization was analyzed through XRD. Thermal properties were evaluated using differential thermal analysis (DSC) and thermogravimetric measurements (TGA) either in air or in nitrogen atmosphere.

Production of Mesoglycan/PCL Based Composites through Supercritical Impregnation.

The development of targeted therapies for wound repair is knowing a growing interest due to the increasing aging of the population and the incidence of chronic pathologies, mainly pressure ulcers. Among molecules recruiting cell populations and promoting the formation of new vital tissue, sodium mesoglycan (MSG) has been proven to be effective in wound healing. In this work, MSG impregnation of polymer matrices has been attempted by a supercritical carbon dioxide-based process. Polymeric matrices are composed of polycaprolactone blends, where water-soluble polymers, polyethylene glycol, polyvinyl pyrrolidone, gelatin, and thermoplastic starch, have been employed to modulate the MSG release, making the devices potentially suitable for topical administrations. Two different techniques have been used to obtain the films: the first one is compression molding, producing compact and continuous structures, and the second one is electrospinning, producing membrane-like designs. A higher amount of MSG can be loaded into the polymeric matrix in the membrane-like structures since, in these films, the impregnation process is faster than in the case of compression molded films, where the carbon dioxide has firstly diffused and then released the active molecule. The type of water-soluble polymer influences the drug release rate: the blend polycaprolactone-gelatin gives a prolonged release potentially suitable for topical administration.

Functional bioplastics from food residual: Potentiality and safety issues.

Plastic pollution and food waste are two global issues with much in common. Plastic containers were introduced as a practical and easy remedy to improve food preservation and reduce the risk of creating waste, but ironically, to address one problem, another has been made worse. The spread of single-use containers has dramatically increased the amount of plastic that has to be discarded, and the most urgent task is now to find a solution to what has become part of the problem. An innovative way around it consists of promoting the valorization of food residues by turning them into novel materials for packaging. Although the results are promising, the aim of completely replacing plastics with biodegradable materials still seems far from being achieved. This review illustrates the main strategies adopted thus far to produce new bioplastic materials and composites from waste resources and focuses on the pros and cons of the food recovery process to look for the aspects that represent an obstacle to the development of the circular food economy on an industrial scale.

Fabrication and Characterization of Bio-Nanocomposites Based on Halloysite-Encapsulating Grapefruit Seed Oil in a Pectin Matrix as a Novel Bio-Coating for Strawberry Protection.

In the framework of designing a novel bio-coating for the preservation of fresh fruits, this paper reports the design, preparation, and characterization of novel bio-nanocomposites based on pectin loaded with grapefruit seed oil (GO), a natural compound with antimicrobial properties, encapsulated into halloysite nanotubes (HNTs). The vacuum-based methodology was used for the encapsulation of the oil into the hollow area of the nanotubes, obtaining nano-hybrids (HNT-GO) with oil concentrations equal to 20, 30, and 50 wt%. Physical properties (thermal, mechanical, barrier, optical) were analyzed. Thermal properties were not significantly (p < 0.05) affected by the filler, while an improvement in mechanical performance (increase in elastic modulus, stress at breaking, and deformation at breaking up to 200%, 48%, and 39%, respectively, compared to pure pectin film) and barrier properties (increase in water permeability up to 480% with respect to pure pectin film) was observed. A slight increase in opacity was detected without significantly compromising the transparency of the films. The release of linoleic acid, the main component of GO, was followed for 21 days and was correlated with the amount of the hybrid filler, demonstrating the possibility of tailoring the release kinetic of active molecules. In order to evaluate the effectiveness of the prepared bio-composites as an active coating, fresh strawberries were coated and compared to uncoated fruit. Qualitative results showed that the fabricated novel bio-coating efficiently extended the preservation of fresh fruit.

The role of (bio)degradability on the management of petrochemical and bio-based plastic waste.

In order to mitigate the social and ecological impacts of post-consumer plastic made of conventional petrochemical polymers, the market of (bio)degradable plastics have recently become more widespread. Although (bio)degradable plastics could be an environmentally friendly substitute of petrochemical ones, the consequences of their presence in the waste management system and in the environment (if not correctly disposed) are not always positive and plastic pollution is not automatically solved. Consequently, this work aims to review how plastic (bio)degradability affects the municipal solid waste management cycle. To this end, the state-of-the-art of the intrinsic (bio)degradability of conventional and unconventional petrochemical and bio-based polymers has been discussed, focusing on the environment related to the waste management system. Then, the focus was on strategies to improve polymer (bio)degradability: different types of eco-design and pre-treatment approach for plastics has been investigated, differently from other works that focused only on specific topics. The information gathered was used to discuss three typical disposal/treatment routes for plastic waste. Despite many of the proposed materials in eco-design have increased the plastics (bio)degradability and pre-treatments have showed interesting results, these achievements are not always positive in the current MSW management system. The effect on mechanical recycling is negative in several cases but the enhanced (bio)degradability can help the treatment with organic waste. On the other hand, the current waste treatment facility is not capable to manage this waste, leading to the incineration the most promising options. In this way, the consumption of raw materials will persist even by using (bio)degradable plastics, which strength the doubt if the solution of plastic pollution leads really on these materials. The review also highlighted the need for further research on this topic that is currently limited by the still scarce amount of (bio)degradable plastics in input to full-scale waste treatment plants.

Hemp fibers modified with graphite oxide as green and efficient solution for water remediation: Application to methylene blue.

In this paper, the use of hemp fibers modified with graphite oxide for the removal of methylene blue (MB) from aqueous solutions was investigated. Parameters such as contact time, pH, temperature, initial concentration of dye and ionic strength were varied and their effects on the adsorption recovery were evaluated. The adsorption process attained the equilibrium within 30 min while the adsorption capacity was found to increase with increasing contact time. The experimental data were fitted through a pseudo-second order model. Maximum adsorption capacity slightly increases with temperature changing from 54 mg/g to 58 mg/g at pH = 7.5, from 37 mg/g to 45 mg/g at pH = 3 and from 44 mg/g to 49 mg/g at pH = 12, by increasing the temperature from 20 °C to 80 °C indicating that the process is slightly endothermic (ΔH = 3.43 kJ/mol). The thermodynamic parameters were even calculated demonstrating that the process is spontaneous (ΔG ≈ -4.4 J/mol K and ΔS = 3.16 J/mol K)). Finally, a mathematical algorithm was applied to forecast the response surface model. A second order model was chosen to fit the experimental data and the statistical effect of the process parameters were estimated. A numerical optimization was even performed to individuate the optimal set of process parameters (pH = 9.25, T = 53.8 °C and C0 = 13.2 mg/L) which maximizes the removal capacity. A possible adsorption mechanism was even presented. So, it was proved the efficiency of the adsorption of a novel, inexpensive and sustainable composite material obtained from agro-waste resources by performing reusability cycles.

EVA Films Loaded with Layered Double Hydroxide (LDH) Modified with Methacrylic Anion: Effect of the Nanohybrid Filler on the Photodegradation Phenomena.

The photo-oxidative studies of ethylene vinyl acetate copolymer (EVA) matrix, filled with Layered Double Hydroxide (LDH) modified with methacrylic anion (MA), were herein reported, together with gas permeation tests. The formulation of nano-hybrid LDHs was characterized using X-ray diffractometry (XRD) and thermogravimetric analysis (TGA), demonstrating the partial intercalation of the 30% of MA anion between the LDH's galleries. The as-modified filler was introduced into an EVA matrix by mechanical milling, producing free-standing films subjected to accelerated aging. Fourier transform infrared spectroscopy (FT-IR) results suggested that the nanohybrid presence determined a stabilizing effect up to 45 days of UV irradiation, especially if compared to the EVA/LDH references for all formulated EVA hybrid nanocomposites. Conversely, the presence of nanohybrid in the matrix did not significantly change the thermal stability of EVA samples. The dispersion of modified MA-LDH in the EVA matrix produces defect-free samples in the whole range of investigated loadings. The samples show a slight decrease in gas permeability, coupled with a substantial stabilization of the original CO2/O2 selectivity, which also proves the integrity of the films after 30 days of UV irradiation.

Degradable Elastomers: Is There a Future in Tyre Compound Formulation?

Problems related to non-biodegradable waste coming from vulcanized rubber represent one of the pre-eminent challenges for modern society. End-of-life tyres are an important source of this typology of waste and the increasingly high accumulation in the environment has contributed over the years to enhance land and water pollution. Moreover, the release into the environment of non-degradable micro-plastics and other chemicals as an effect of tyre abrasion is not negligible. Many solutions are currently applied to reuse end-of-life tyres as a raw material resource, such as pyrolysis, thermo-mechanical or chemical de-vulcanisation, and finally crumbing trough different technologies. An interesting approach to reduce the environmental impact of vulcanised rubber wastes is represented by the use of degradable thermoplastic elastomers (TPEs) in tyre compounds. In this thematic review, after a reviewing fossil fuel-based TPEs, an overview of the promising use of degradable TPEs in compound formulation for the tyre industry is presented. Specifically, after describing the properties of degradable elastomers that are favourable for tyres application in comparison to used ones, the real scenario and future perspectives related to the use of degradable polymers for new tyre compounds will be realized.

Antimicrobial and Antibiofilm Activity of Curcumin-Loaded Electrospun Nanofibers for the Prevention of the Biofilm-Associated Infections.

Curcumin extracted from the rhizome of Curcuma Longa has been used in therapeutic preparations for centuries in different parts of the world. However, its bioactivity is limited by chemical instability, water insolubility, low bioavailability, and extensive metabolism. In this study, the coaxial electrospinning technique was used to produce both poly (ε-caprolactone) (PCL)-curcumin and core-shell nanofibers composed of PCL and curcumin in the core and poly (lactic acid) (PLA) in the shell. Morphology and physical properties, as well as the release of curcumin were studied and compared with neat PCL, showing the formation of randomly oriented, defect-free cylindrical fibers with a narrow distribution of the dimensions. The antibacterial and antibiofilm potential, including the capacity to interfere with the quorum-sensing mechanism, was evaluated on Pseudomonas aeruginosa PAO1, and Streptococcus mutans, two opportunistic pathogenic bacteria frequently associated with infections. The reported results demonstrated the ability of the Curcumin-loading membranes to inhibit both PAO1 and S. mutans biofilm growth and activity, thus representing a promising solution for the prevention of biofilm-associated infections. Moreover, the high biocompatibility and the ability to control the oxidative stress of damaged tissue, make the synthesized membranes useful as scaffolds in tissue engineering regeneration, helping to accelerate the healing process.

Active Packaging Based on Coupled Nylon/PE Pouches Filled with Active Nano-Hybrid: Effect on the Shelf Life of Fresh Milk.

The study reports on the preparation and characterization of an active packaging based on pouches composed of a coupled system nylon/polyethylene (PE). The PE layer was filled with and active nano-hybrid of layered double hydroxide (LDH) on which it was anchored salicylate, as antimicrobial molecule. The release of the salicylate anchored to the LDH was compared to the release of the molecule free dispersed into the PE and resulted much slower. It was evaluated the efficiency of the active packaging to inhibit Pseudomonas aeruginosa, Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and Campylobacter. Global migration tests on the PE active layer, using ethanol (50% v/v) as food simulant, demonstrated the possibility of such active nanocomposite to be used for food contact being the migration limits in compliance with those imposed from the EU regulation. Fresh milk was packed into the active pouches and pouches with unfilled PE layer, as control. The pH reduction as function of the time, due to the production of lactic acid, resulted much slower in the active packaging. Total bacterial count (TBC) was evaluated on the milk, either packed into the active packaging or the control, up to 50 days of storage at 4 °C. Shelf life of the milk was evaluated using the Gompertz model. It was demonstrated an increasing of the shelf life of milk packaged in active pouches from 6 days up to 10 days.

Facile preparation of layered double hydroxide (LDH)-alginate beads as sustainable system for the triggered release of diclofenac: Effect of pH and temperature on release rate.

This paper concerns the facile preparation of alginate beads encapsulating layered double hydroxide (LDH) intercalated with diclofenac sodium as drug delivery systems. To better evaluate the effect of LDH carrier, alginate beads loaded with free diclofenac were also prepared. Composites hydrogel beads were ionotropically crosslinked in CaCl2 solution at 4 °C. Thermal and barrier properties were evaluated and correlated with the presence of the inorganic phase. Swelling behavior was investigated over time. Release kinetics of diclofenac at different pH and temperatures were evaluated. The diclofenac release behavior appeared to be affected by the presence of LDH, the pH of release medium and the temperature allowing for fabricating a sustainable composite characterized by a triggered drug release rate. Finally, empirical relationships correlating the drug diffusion as a function of temperature and pH were extrapolated.

Electromagnetically Stimuli-Responsive Nanoparticles-Based Systems for Biomedical Applications: Recent Advances and Future Perspectives.

Nanoparticles (NPs) in the biomedical field are known for many decades as carriers for drugs that are used to overcome biological barriers and reduce drug doses to be administrated. Some types of NPs can interact with external stimuli, such as electromagnetic radiations, promoting interesting effects (e.g., hyperthermia) or even modifying the interactions between electromagnetic field and the biological system (e.g., electroporation). For these reasons, at present these nanomaterial applications are intensively studied, especially for drugs that manifest relevant side effects, for which it is necessary to find alternatives in order to reduce the effective dose. In this review, the main electromagnetic-induced effects are deeply analyzed, with a particular focus on the activation of hyperthermia and electroporation phenomena, showing the enhanced biological performance resulting from an engineered/tailored design of the nanoparticle characteristics. Moreover, the possibility of integrating these nanofillers in polymeric matrices (e.g., electrospun membranes) is described and discussed in light of promising applications resulting from new transdermal drug delivery systems with controllable morphology and release kinetics controlled by a suitable stimulation of the interacting systems (nanofiller and interacting cells).