Evaluation of enzymatic stamp removal strategies on handmade (cellulose-based) and machine-made (lignin-containing) papers.

Two different biocleaning techniques for stamp removal from different paper samples (handmade and machine-made) were investigated. Cellulose is the main component of handmade paper, while higher concentration of lignin is present in machine-made paper. Biocleaning methods included the direct application on paper surfaces of the extracellular enzymatic mixture (EEM) extracted from the yeast Sporidiobolus metaroseus and the recombinant protein CthediskatG of Chaetomium thermophilum var. dissitum. The produced microbial enzymes (EEM or CthediskatG) were also combined with agarose hydrogels. The effectiveness of the cleaning ability of the individual methods was determined using different spectrophotometer measurements based on colorimetric analysis and by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). Some tested samples were also subjected to microstructural and chemical analysis using Scanning Electron Microscope-Energy-Dispersive X-ray spectroscopy (SEM-EDX). The analysis showed that the EEM-based approaches were the most suitable, mainly they are less time-consuming and easy to produce, and moreover slight differences were displayed between EEM and CthediskatG during the removal of the stamp by hydrogel-enzyme approaches. Both EEM applications (direct and hydrogel) speed up the stamp removal process from real paper samples. However, for the complete elimination of the stamp smears a quick N,N-dimethylformamide post-treatment is advised too.

Biodegradable Active Packaging Enriched with Essential Oils for Enhancing the Shelf Life of Strawberries.

The strawberry (Fragaria ananassa) is a nutrient-rich fruit with high content of health-beneficial compounds. However, strawberries are susceptible to mechanical damage and microbiological contamination which can cause changes in fruit sensory properties. These changes consequently effect on ripening and shelf life of the strawberry. In recent years, essential oils (EOs) have been famous for their antimicrobial and antioxidant properties and are promising ecological alternatives to chemical antimicrobial substances. Nowadays, active packaging is one of several techniques developed for slowing down the metabolic processes of fresh fruits. Poly(lactic acid) (PLA) is one of the several polymers suitable for encapsulation EOs, whereas at the same time represent non-toxic, biodegradable, and compostable polymer derived from renewable resources. Suitable packaging prolongs the shelf life of fruit, keeps the products at the highest possible nutrition level, improves quality, and attracts customer attention. In the current study, we encapsulated EOs (lemongrass and oregano) into a PLA and poly(3-hydroxybutyrate) (PHB) packaging film and explored their antimicrobial and antioxidant properties. Moreover, biochemical and quality parameters for strawberry preservation and shelf-life extension were also assessed. Our tested active packaging film with EOs was proven to be useful for postharvest quality maintenance and shelf-life extension of strawberries, with PLA/PHB/ATBC + 5% lemongrass EO being slightly better than PLA/PHB/ATBC + 5% oregano EO.

Electrospinning of Cyclodextrin-Oligolactide Derivatives.

The materials used for the preparation of electrospun mats exhibit a large variety. Among them, cyclodextrins (CDs) and their derivatives have received thorough attention. Herein, we focus on the preparation of electrospun fibers based on biodegradable cyclodextrin-oligolactide (CDLA) derivatives, which may be qualified as polymer-free cyclodextrin. CDLA was prepared by ring opening of L-lactide initiated by the ß-cyclodextrin. A clear structural image of the high-purity CDLA product was proved by MALDI MS. Preparation of the electrospun mats was optimized by taking into consideration the electrospinning parameters such as applied voltage, needle-to-collector distance, flow rate, the concentration of cyclodextrin solutions, and solvent type. The obtained electrospun fibers were morphologically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). SEM allowed the optimization of the electrospinning process to obtain beadless fibers with submicronic diameters. Further analysis by TEM and SAXS revealed the inner structural features of the CDLA-based filaments. Our results showed that the high purity CDLA materials, structurally well-defined at the molecular level, are suitable for the preparation of electrospun mats by using dimethylformamide or a water/acetonitrile mixture as electrospinning solvents, similar to lower molecular weight commercial cyclodextrin derivatives.

Electrospun Nisin-Loaded Poly(ε-caprolactone)-Based Active Food Packaging.

Packaging for fresh fruits and vegetables with additional properties such as inhibition of pathogens grown can reduce food waste. With its biodegradability, poly(ε-caprolactone) (PCL) is a good candidate for packaging material, especially in the form of an electrospun membrane. The preparation of nonwoven fabric of PCL loaded with food additive, antimicrobial nisin makes them an active packaging with antispoilage properties. During the investigation of the nonwoven fabric mats, different concentrations of nisin were obtained from the solution of PCL via the electrospinning technique. The obtained active porous PCL loaded with varying concentrations of nisin inhibited the growth of Staphylococcus aureus and Escherichia coli. Packages made of PCL and PCL/nisin fibrous mats demonstrated a prolongation of the fruits' freshness, improving their shelf life and, consequently, their safety.

Thermoplastic Starch-Based Composite Reinforced by Conductive Filler Networks: Physical Properties and Electrical Conductivity Changes during Cyclic Deformation.

Conductive polymer composites (CPC) from renewable resources exhibit many interesting characteristics due to their biodegradability and conductivity changes under mechanical, thermal, chemical, or electrical stress. This study is focused on investigating the physical properties of electroconductive thermoplastic starch (TPS)-based composites and changes in electroconductive paths during cyclic deformation. TPS-based composites filled with various carbon black (CB) contents were prepared through melt processing. The electrical conductivity and physicochemical properties of TPS-CB composites, including mechanical properties and rheological behavior, were evaluated. With increasing CB content, the tensile strength and Young's modulus were found to increase substantially. We found a percolation threshold for the CB loading of approximately 5.5 wt% based on the rheology and electrical conductivity. To observe the changing structure of the conductive CB paths during cyclic deformation, both the electrical conductivity and mechanical properties were recorded in parallel using online measurements. Moreover, the instant electrical conductivity measured online during mechanical deformation of the materials was taken as the parameter indirectly describing the structure of the conductive CB network. The electrical conductivity was found to increase during five runs of repeated cyclic mechanical deformations to constant deformation below strain at break, indicating good recovery of conductive paths and their new formation.

Electrospun Poly(ethylene Terephthalate)/Silk Fibroin Composite for Filtration Application.

In this study, fibrous membranes from recycled-poly(ethylene terephthalate)/silk fibroin (r-PSF) were prepared by electrospinning for filtration applications. The effect of silk fibroin on morphology, fibers diameters, pores size, wettability, chemical structure, thermo-mechanical properties, filtration efficiency, filtration performance, and comfort properties such as air and water vapor permeability was investigated. The filtration efficiency (FE) and quality factor (Qf), which represents filtration performance, were calculated from penetration through the membranes using aerosol particles ranging from 120 nm to 2.46 µm. The fiber diameter influenced both FE and Qf. However, the basis weight of the membranes has an effect, especially on the FE. The prepared membranes were classified according to EN149, and the most effective was assigned to the class FFP1 and according to EN1822 to the class H13. The impact of silk fibroin on the air permeability was assessed. Furthermore, the antibacterial activity against bacteria S. aureus and E. coli and biocompatibility were evaluated. It is discussed that antibacterial activity depends not only on the type of used materials but also on fibrous membranes' surface wettability. In vitro biocompatibility of the selected samples was studied, and it was proven to be of the non-cytotoxic effect of the keratinocytes (HaCaT) after 48 h of incubation.

Circulatory Management of Polymer Waste: Recycling into Fine Fibers and Their Applications.

In modern society, it is impossible to imagine life without polymeric materials. However, managing the waste composed of these materials is one of the most significant environmental issues confronting us in the present day. Recycling polymeric waste is the most important action currently available to reduce environmental impacts worldwide and is one of the most dynamic areas in industry today. Utilizing this waste could not only benefit the environment but also promote sustainable development and circular economy management. In its program statement, the European Union has committed to support the use of sorted polymeric waste. This study reviews recent attempts to recycle this waste and convert it by alternative technologies into fine, nano-, and microscale fibers using electrospinning, blowing, melt, or centrifugal spinning. This review provides information regarding applying reprocessed fine fibers in various areas and a concrete approach to mitigate the threat of pollution caused by polymeric materials.

Antibacterial Filtration Membranes Based on PVDF-co-HFP Nanofibers with the Addition of Medium-Chain 1-Monoacylglycerols.

The efficiency of filtration membranes is substantially lowered by bacterial attachments and potential fouling processes, which reduce their durability and lifecycle. The antibacterial and antifouling properties exhibited by the added materials play a substantial role in their application. We tested a material poly(vinylidene fluoride)-co-hexafluoropropylene (PDVF-co-HFP) based on an electrospun copolymer, where an agent was incorporated with a small amount of ester of glycerol consecutively with caprylic, capric, and lauric acids. Each of these three materials differing in the esters (1-monoacylglycerol, 1-MAG) used was prepared with three weighted concentrations of 1-MAG (1, 2, and 3 wt %). The presence of 1-MAG with an amphiphilic structure resulted in the hydrophilic character of the prepared materials that contributed to the filtration performance. The tested materials (membranes) were characterized with rheological, optical (scanning electron microscopy, SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and other methods to evaluate antibacterial and antifouling activities. The pure water flux was 6 times higher than that of the neat PVDF-co-HFP membrane when the added 1-MAG attained only 1 wt %. It was experimentally shown that the PVDF-co-HFP/1-MAG membrane with high wettability improved antibacterial activity and antifouling ability. This membrane is highly promising for water treatment due to the safety of antibacterial 1-MAG additives.

Fabrication, Modification, and Characterization of Lignin-Based Electrospun Fibers Derived from Distinctive Biomass Sources.

From the environmental point of view, there is high demand for the preparation of polymeric materials for various applications from renewable and/or waste sources. New lignin-based spun fibers were produced, characterized, and probed for use in methylene blue (MB) dye removal in this study. The lignin was extracted from palm fronds (PF) and banana bunch (BB) feedstock using catalytic organosolv treatment. Different polymer concentrations of either a plasticized blend of renewable polymers such as polylactic acid/polyhydroxybutyrate blend (PLA-PHB-ATBC) or polyethylene terephthalate (PET) as a potential waste material were used as matrices to generate lignin-based fibers by the electrospinning technique. The samples with the best fiber morphologies were further modified after iodine handling to ameliorate and expedite the thermostabilization process. To investigate the adsorption of MB dye from aqueous solution, two approaches of fiber modification were utilized. First, electrospun fibers were carbonized at 500 °C with aim of generating lignin-based carbon fibers with a smooth appearance. The second method used an in situ oxidative chemical polymerization of m-toluidine monomer to modify electrospun fibers, which were then nominated by hybrid composites. SEM, TGA, FT-IR, BET, elemental analysis, and tensile measurements were employed to evaluate the composition, morphology, and characteristics of manufactured fibers. The hybrid composite formed from an OBBL/PET fiber mat has been shown to be a promising adsorbent material with a capacity of 9 mg/g for MB dye removal.

Removal of overpainting from an historical painting of the XVIII Century: A yeast enzymatic approach.

Biocleaning of cultural heritage items is mainly performed using living microorganisms. Approaches utilizing the enzymes of isolated microorganisms have not been frequently investigated. To find an enzymatic alternative for the removal of an oil-based overpainting, we focused on the characterization and use of a yeast Extracellular Enzymatic Mixture (EEM). A historical silk yeast was selected for its lipolytic properties and its EEM was extracted after cultivation on a medium supplemented with linseed oil. The EEM protein content was visualized by SDS-PAGE, its concentration assessed by fluorimeter and the enzymatic activity evaluated by p-NPP spectrophotometric lipase assay. The yeast growth was suppressed by adding diverse metal ions (Cd, Zn, Cr and Cu) in Reasoner's 2A (R2A) broth, while the quantity and activity of EEM were affected by adding Fe and Pb. Various delivery systems (agar-agar, tylose and klucel G) alone or in a combination with EEM were assayed on the historical painting surface. The colorimetric measurements and the ATR-FTIR analysis indicated that the combinations tylose-EEM and klucel G-EEM can be easily and effectively applied as biocleaning procedures to remove oil-based overpainting from fragile and valuable historical painting surfaces.

The Drug-Loaded Electrospun Poly(ε-Caprolactone) Mats for Therapeutic Application.

Diclofenac sodium salt (DSS)-loaded electrospun nanofiber mats on the base of poly(ε-caprolactone) (PCL) were investigated as biocompatible nanofibrous mats for medical applications with the ability to inhibit bacterial infections. The paper presents the characteristics of fibrous mats made by electrospinning and determines the effect of medicament on the fiber morphology, chemical, mechanical and thermal properties, as well as wettability. PCL and DSS-loaded PCL nanofibrous mats were characterized using scanning electron microscopy, transmission electron microscopy, attenuated total reflectance-Fourier transform infrared spectrometry, dynamic mechanical analysis, and contact angle measurements. Electron paramagnetic resonance measurements confirmed the lifetime of DSS before and after application of high voltage during the electrospinning process. In vitro biocompatibility was studied, and it was proved to be of good viability with ~92% of the diploid human cells culture line composed of lung fibroblast (MRC 5) after 48 h of incubation. Moreover, the significant activity of DSS-loaded nanofibers against cancer cells, Ca Ski and HeLa, was established as well. It was shown that 12.5% (m/V) is the minimal concentration for antibacterial activity when more than 99% of Escherichia coli (Gram-negative) and 99% of Staphylococcus aureus (Gram-positive) have been exterminated.

Reuse of Textile Waste to Production of the Fibrous Antibacterial Membrane with Filtration Potential.

Wasted synthetic fabrics are a type of textile waste source; the reuse of them brings environmental protection and turns waste into a valuable material. In this work, the used nylon (polyamide) stockings were transmuted into a fine fibrous membrane via an electrospinning process. In addition, the safety antibacterial agent, monoacylglycerol (MAG), was incorporated into a recycled fibrous membrane. The results revealed that the neat, recycled polyamide (rPA) fibers with a hydrophobic surface could be converted into hydrophilic fibers by blending various amounts of MAG with rPA solution prior to electrospinning. The filtration efficiency and air/water vapor permeability of the two types of produced membranes, neat rPA, and rPA/MAG, were tested. Their filtration efficiency (E100) was more than 92% and 96%, respectively. The membranes were classified according to Standard EN1822, and therefore, the membranes rPA and rPA/MAG were assigned to the classes E10 and E11, respectively. The air permeability was not affected by the addition of MAG, and water vapor permeability was slightly enhanced. Based on the obtained data, prepared rPA/MAG fibrous membranes can be evaluated as antifouling against both tested bacterial strains and antimicrobial against S. aureus.

Properties and Degradation of Novel Fully Biodegradable PLA/PHB Blends Filled with Keratin.

The utilization of keratin waste in new materials formulations can prevent its environmental disposal problem. Here, novel composites based on biodegradable blends consisting of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) (PHB), and filled with hydrolyzed keratin with loading from 1 to 20 wt % were prepared and their properties were investigated. Mechanical and viscoelastic properties were characterized by tensile test, dynamic mechanical thermal analysis (DMTA) and rheology measurements. The addition of acetyltributyl citrate (ATBC) significantly affected the mechanical properties of the materials. It was found that the filled PLA/PHB/ATBC composite at the highest keratin loading exhibited similar shear moduli compared to the un-plasticized blend as a result of the much stronger interactions between the keratin and polymer matrix compared to composites with lower keratin content. The differences in dynamic moduli for PLA/PHB/ATBC blend filled with keratin depended extensively on the keratin content while loss the factor values progressively decreased with keratin loading. Softening interactions between the keratin and polymer matrix resulted in lower glass transitions temperature and reduced polymer chain mobility. The addition of keratin did not affect the extent of degradation of the PLA/PHB blend during melt blending. Fast hydrolysis at 60 °C was observed for composites with all keratin loadings. The developed keratin-based composites possess properties comparable to commonly used thermoplastics applicable for example as packaging materials.

Simple and Eco-Friendly Route from Agro-Food Waste to Water Pollutants Removal.

The current study reflects the demand to mitigate the environmental issues caused by the waste from the agriculture and food industry. The crops that do not meet the supply chain requirements and waste from their processing are overfilling landfills. The mentioned wastes contain cellulose, which is the most abundant carbon precursor. Therefore, one of the possibilities of returning such waste into the life cycle could be preparing the activated carbon through an eco-friendly and simple route. Herein, the carrot pulp from the waste was used. Techniques such as thermogravimetric analysis (TGA), elemental analysis (EA), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray diffraction (XRD) were used to investigate the thermal treatment effect during the carbon material preparation. The development of microstructure, phase formation, and chemical composition of prepared material was evaluated. The obtained carbon material was finally tested for water cleaning from a synthetic pollutant such as rhodamine B and phloxine B. An adsorption mechanism was proposed on the base of positron annihilation lifetime spectroscopy (PALS) results and attributed to the responsible interactions. It was shown that a significant carbon sorbent from the organic waste for water purification was obtained.

The Role of Electrical Polarity in Electrospinning and on the Mechanical and Structural Properties of As-Spun Fibers.

Electric field strength and polarity in electrospinning processes and their effect on process dynamics and the physical properties of as-spun fibers is studied. Using a solution of the neutral polymer such as poly(methyl methacrylate) (PMMA) we explored the electrospun jet motion issued from a Taylor cone. We focused on the straight jet section up to the incipient stage of the bending instability and on the radius of the disk of the fibers deposited on the collecting electrode. A new correlation formula using dimensionless parameters was found, characterizing the effect of the electric field on the length of the straight jet, L˜E~E˜0.55. This correlation was found to be valid when the spinneret was either negatively or positively charged and the electrode grounded. The fiber deposition radius was found to be independent of the electric field strength and polarity. When the spinneret was negatively charged, L˜E was longer, the as-spun fibers were wider. The positively charged setup resulted in fibers with enhanced mechanical properties and higher crystallinity. This work demonstrates that often-overlooked electrical polarity and field strength parameters influence the dynamics of fiber electrospinning, which is crucial for designing polymer fiber properties and optimizing their collection.

Diclofenac Embedded in Silk Fibroin Fibers as a Drug Delivery System.

Silk fibroin is a biocompatible, non-toxic, mechanically robust protein, and it is commonly used and studied as a material for biomedical applications. Silk fibroin also gained particular interest as a drug carrier vehicle, and numerous silk formats have been investigated for this purpose. Herein, we have prepared electrospun nanofibers from pure silk fibroin and blended silk fibroin/casein, followed by the incorporation of an anti-inflammatory drug, diclofenac. Casein serves as an excipient in pharmaceutical products and has a positive effect on the gradual release of drugs. The characteristics of the investigated composites were estimated by scanning electron microscope, transmission electron microscope, thermogravimetric analysis, and a lifetime of diclofenac by electron paramagnetic resonance analysis. The cumulative release in vitro of diclofenac sodium salt, together with the antiproliferative effect of diclofenac sodium salt-loaded silk nanofibers against the growth of two cancer cell lines, are presented and discussed.

Cyclodextrins tethered with oligolactides - green synthesis and structural assessment.

Biodegradable oligolactide derivatives based on α-, ß- and γ-cyclodextrins (CDs) were synthesized by a green procedure in which CDs play the role of both the initiator and the catalyst. The synthetic procedure in which CDs and L-lactide (L-LA) are reacting in bulk at relatively high temperature of 110 °C was investigated considering the structural composition of the products. The obtained products were thoroughly characterized via mass spectrometry methods with soft ionization like matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI). Liquid chromatography (LC) separation with evaporative light scattering detection (ELSD) and NMR analysis were employed in order to elucidate the structural profiles of the obtained mixtures. The results clearly demonstrate that the cyclodextrins were tethered with more than one short oligolactate chain per CD molecule, predominantly at the methylene group, through ring opening of L-LA initiated by primary OH groups.

Utilization of starch films plasticized with urea as fertilizer for improvement of plant growth.

The utilization of starch films, obtained by extrusion of potato starch with urea as plasticizer, for the fertilization of plants has been undertaken. Release rate of urea from the starch films was conducted in water conditions. The molecular weight distribution, surface erosion and weight loss of the starch samples have been determined. The evaluation of efficiency of urea as a fertilizer in the process of release from the starch films was performed under laboratory conditions based on the plant growth test proposed by OECD 208 Guideline and the PN-ISO International Standard using oat and common radish. Although among extruded starch-based films, those that contain the highest amount of fertilizer hold the most promise for a delayed release system, the time of release of fertilizer from obtained films in undertaken study was not satisfactory. All the same, in the present study effort has been made to utilize extruded samples as a fertilizer for agriculture or horticulture purposes. Urea-plasticized starch was successfully used as a fertilizer. Plant growth assessment, including determination of such parameters as fresh and dry matter of plants and their visual evaluation, has proved the stimulating effect of using extruded films on the growth and development of cultivated plants.

Liquid chromatography of synthetic polymers under critical conditions of enthalpic interactions 4: sample recovery.

Reduced sample recovery is a frequent feature of LC of macromolecules under critical conditions of enthalpic interactions (LC CC). Several methods of assessment of LC CC sample recovery are compared. A novel approach is based on an online combination of the. The LC CC column with a noninteractive SEC column. It provides not only the amount but also the molar mass of the eluted/withheld polymer. The procedure was tested with poly(methyl methacrylate), bare silica gel column packings, and "critical eluent" tetrahydrofuran/toluene. It was shown that macromolecules with higher molar masses were preferentially trapped within the LC CC column packing so that the eluted part of the sample was no longer representative. The incomplete polymer elution can make the LC CC polymer analyses susceptible to significant experimental errors.

LC-multistage mass spectrometry for the characterization of poly(butylene adipate-co-butylene terephthalate) copolyester.

A comprehensive study using liquid chromatography electrospray ionization multistage mass spectrometry (LC-ESI MS(n)) was performed to get detailed structural information on poly(butylene adipate-co-butylene terephthalate) co-polyester and its product of partial degradation. LC-MS and LC-MS(n) identified the existence of cyclic structures in the original samples that disappear completely during the degradation. The occurrence of methanol transesterification in the degradation process was confirmed. MS(2) on the first (13)C isotope peak helped to determine the elemental composition of the fragments and facilitated end group determination. The method can be used to provide an alternative for high mass accuracy MS(2) experiments. Sequence information was also revealed for certain copolymeric structures.