Effect of molecular structure on film blowing ability of thermoplastic zein

Nanofibers based on zein protein loaded with tungsten oxide for cancer therapy: fabrication, characterization and in vitro evaluation

Plant proteins have become attractive for biomedical applications such as wound dressing and drug delivery. In this research, nanofibers from pristine zein (plant protein) and zein loaded with tungsten oxide (WO3) were prepared (WO3@zein) using less toxic solvents (ethanol and acetic acid). Morphological and biological properties of the zein nanofiber were determined. Prepared nanofibers were defined by thermogravimetric analysis (TGA), X-ray diffraction (X-RD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy. The average fiber diameter was unchanged with an increase in WO3 concentration from 0.001 to 0.008%. FT-IR spectroscopy and X-RD indicated the presence of WO3 in WO3@zein nanofibers. In comparison to WO3-free, WO3@zein nanofibers showed higher safety and preserved the anticancer effect of WO3 against human melanoma cell line (A375) melanoma cells compared to WO3-free. Moreover, both WO3-free and WO3@zein caused a fourfold increase in the cellular proliferation of reactive oxygen species (ROS) in the treated A375 cells compared to untreated cells. ROS elevation led to apoptosis-dependent cell death of A375 cells as evidenced by up-regulating the expression of p53-downstream genes (p21 and Bax) (tumor-suppressor gene) while down-regulating the expression of key oncogenes (BCL2 and cyclin D). In conclusion, the prepared nanofiber represents a promising and safe candidate for anticancer applications.

Applications of Prolamin-Based Edible Coatings in Food Preservation: A Review

Foods are susceptible to deterioration and sour due to external environmental influences during production and storage. Coating can form a layer of physical barrier on the surface of foods to achieve the purpose of food preservation. Because of its good barrier properties and biocompatibility, prolamin-based film has been valued as a new green and environment-friendly material in the application of food preservation. Single prolamin-based film has weaknesses of poor toughness and stability, and it is necessary to select appropriate modification methods to improve the performance of film according to the application requirements. The practical application effect of film is not only affected by the raw materials and the properties of the film itself, but also affected by the selection of preparation methods and processing techniques of film-forming liquid. In this review, the properties and selection of prolamins, the forming mechanisms and processes of prolamin-based coatings, the coating techniques, and the modifications of prolamin-based coatings were systematically introduced from the perspective of food coating applications. Moreover, the defects and deficiencies in the research and development of prolamin-based coatings were also reviewed in order to provide a reference for the follow-up research on the application of prolamin-based coatings in food preservation.

Encapsulation of rosemary essential oil in zein by electrospinning technique

In this study, rosemary essential oil was encapsulated in zein-electrospun fibers at different concentrations of loading (0%, 2.5%, 5%, and 10% v/v). The chemical composition of rosemary essential oil was determined by GC-MS. The resultant zein-electrospun fibers were characterized by SEM, AFM, XRD, DSC, FTIR, and NMR. After being loaded with the essential oil, the fibers were evaluated for antimicrobial properties by the disc diffusion method against S. aureus (ATCC 1112) and E. coli (ATCC 1330). The release test was studied at pH values of 3 and 7.2 in phosphate buffer for 180 min. The GC-MS indicated that α-pinene occurred as a major compound in rosemary essential oil. Diameters of the zein-electrospun fibers increased in response to higher concentrations of rosemary essential oil. The AFM assay attributed a tubular morphology to the fibers. The physical status of rosemary essential oil in zein-electrospun fibers was determined by X-ray diffraction (XRD). DSC thermograms and FTIR spectra confirmed the existence of the rosemary essential oil in zein-electrospun fibers. FTIR spectra also indicated that adding rosemary essential oil to the fibers affected the secondary structure of zein protein. The NMR study showed that the electrospinning process did not change the secondary structure of zein. Disc diffusion indicated that zein-electrospun mats generated inhibition zones against S. aureus and E. coli. The release test revealed that pH values significantly affect the release of rosemary essential oil from fibers. The results demonstrated how loading zein-electrospun fibers with rosemary essential oil can benefit food packaging. PRACTICAL APPLICATION: In this study, electrospun fibers were produced from food-grade biopolymer to encapsulate rosemary essential oil. This product can be produced at industrial scale as an active food packaging/coating, controlled release, and delivery of the rosemary essential oil to food products and gastrointestinal. Also, it can be considered as a functional food to increase health.

Three-Dimensional Printing Using a Maize Protein: Zein-Based Inks in Biomedical Applications

The use of three-dimensional (3D) printing for biomedical applications has expanded exponentially in recent years. However, the current portfolio of 3D printable inks is still limited. For instance, only few protein matrices have been explored as printing/bioprinting materials. Here, we introduce the use of zein, the primary constitutive protein in maize seeds, as a 3D printable material. Zein-based inks were prepared by dissolving commercial zein powder in ethanol with or without polyethylene glycol (PEG400) as a plasticizer. The rheological characteristics of our materials, studied during 21 days of aging/maturation, showed an increase in the apparent viscosity as a function of time in all formulations. The addition of PEG400 decreased the apparent viscosity. Inks with and without PEG400 and at different maturation times were tested for printability in a BioX bioprinter. We optimized the 3D printing parameters for each ink formulation in terms of extrusion pressure and linear printing velocity. Higher fidelity structures were obtained with inks that had maturation times of 10 to 14 days. We present different proof-of-concept experiments to demonstrate the versatility of the engineered zein inks for diverse biomedical applications. These include printing of complex and/or free-standing 3D structures, tablets for controlled drug release, and scaffolds for cell culture.

Marine Collagen from Alternative and Sustainable Sources: Extraction, Processing and Applications

Due to its unique properties, collagen is used in the growing fields of pharmaceutical and biomedical devices, as well as in the fields of nutraceuticals, cosmeceuticals, food and beverages. Collagen also represents a valid resource for bioplastics and biomaterials, to be used in the emerging health sectors. Recently, marine organisms have been considered as promising sources of collagen, because they do not harbor transmissible disease. In particular, fish biomass as well as by-catch organisms, such as undersized fish, jellyfish, sharks, starfish, and sponges, possess a very high collagen content. The use of discarded and underused biomass could contribute to the development of a sustainable process for collagen extraction, with a significantly reduced environmental impact. This addresses the European zero-waste strategy, which supports all three generally accepted goals of sustainability: sustainable economic well-being, environmental protection, and social well-being. A zero-waste strategy would use far fewer new raw materials and send no waste materials to landfills. In this review, we present an overview of the studies carried out on collagen obtained from by-catch organisms and fish wastes. Additionally, we discuss novel technologies based on thermoplastic processes that could be applied, likewise, as marine collagen treatment.

A drug delivery system obtained by hot-melt processing of zein plasticized by a pharmaceutically active ionic liquid

Zein is extruded with [Lidocainium][Ibuprofenate] to obtain an amorphous drug delivery system.

Biodegradable zein film composites reinforced with chitosan nanoparticles and cinnamon essential oil: Physical, mechanical, structural and antimicrobial attributes

Natural bio-based zein films were prepared by incorporating cinnamon essential oil (CEO) and chitosan nanoparticles (CNPs) at 2% and 4% (w/w) amounts, respectively, in order to provide mechanical and antimicrobial functionalities. The physical, mechanical, structural and antibacterial properties of the enriched zein films were also scrutinized. The results showed that the combination of CEO-CNPs significantly improves the tensile strength and decreases the elongation of zein film composite. According to X-ray diffraction (XRD) results, zein film experienced more crystallinity in the presence of CNPs and also combination of CNPs-CEO. Nano-scale size of CNPs and their uniform distribution within the zein film were monitored by scanning electron microscopy (SEM) and proved by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The antimicrobial properties were investigated against Escherichia coli and Staphylococcus aureus, observing that their growth was considerably inhibited by addition of CEO alone and in combination with CNPs in zein films, while CNPs-loaded zein film had no significant effect on the growth of microorganisms. Thus, it can be concluded that the reinforced zein based composites could be suggested as potential degradable film-forming materials for food packaging applications.

Utilization of Lignin in Biopolymeric Packaging Films

Lignin is a byproduct of agricultural industries and only has limited applications. In this study, lignin was investigated for use in sustainable biopolymeric packaging film. Alkali lignin (AL) and lignosulfonate (LSS) were added to enzymatically modified soy protein isolate (SPI) biopolymeric film with different concentrations with the goal of improvement of film physical and functional properties. A radical scavenging activity test revealed that films containing LSS had values 28 and 6% higher than control and AL-based films, respectively; AL itself (not in films) had significantly higher radical scavenging activity than LSS. This indicates the activity of lignin is affected by interaction with SPI. The higher compatibility between LSS and enzymatically modified SPI resulted in a positive effect on surface smoothness, water absorption, and mechanical properties of LSS-based films. Films containing AL showed a high light absorption range in the UV region, and this UV-blocking ability increased with increasing level of lignin. Deconvoluted Fourier transform infrared spectra confirmed that the addition of lignin resulted in some changes in the secondary structure of the protein matrix, which were aligned with X-ray diffraction results. The addition of lignin improved tensile strength (TS) and thermal stability of films compared to the lignin-free control. This improvement in TS and thermal stability was probably a result of new intermolecular interactions between lignin and SPI. Water vapor permeability of the films containing lignin decreased to 50% of the control because lignin played a role as a filler in the matrix. On the basis of our observations, the incorporation of lignin into biopolymeric film is capable of providing additional benefits and solutions to various industries, such as food, packaging, agriculture, and pharmaceuticals.

Amyloids and prions in plants: Facts and perspectives

Amyloids represent protein fibrils that have highly ordered structure with unique physical and chemical properties. Amyloids have long been considered lethal pathogens that cause dozens of incurable diseases in humans and animals. Recent data show that amyloids may not only possess pathogenic properties but are also implicated in the essential biological processes in a variety of prokaryotes and eukaryotes. Functional amyloids have been identified in archaea, bacteria, fungi, and animals, including humans. Plants are one of the most poorly studied groups of organisms in the field of amyloid biology. Although amyloid properties have not been shown under native conditions for any plant protein, studies demonstrating amyloid properties for a set of plant proteins in vitro or in heterologous systems in vivo have been published in recent years. In this review, we systematize the data on the amyloidogenic proteins of plants and their functions and discuss the perspectives of identifying novel amyloids using bioinformatic and proteomic approaches.

Supercritical CO2 foaming of thermoplastic materials derived from maize: proof-of-concept use in mammalian cell culture applications

BACKGROUND

Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds.

METHODOLOGY/PRINCIPAL FINDINGS

We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively) and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively). Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3) and two different prostate cancer cell lines (22RV1, DU145) attached to and proliferated on zein foams.

CONCLUSIONS/SIGNIFICANCE

We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves). Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity) for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein foams for extended time periods.

Commercial potato protein concentrate as a novel source for thermoformed bio-based plastic films with unusual polymerisation and tensile properties

Films thermoformed from commercial potato protein concentrate exhibited a constant Young's modulus and increasing strain at break with increasing processing temperature, in contrast to the usually observed behaviour for protein-based materials.

Bio-hybrid foams by silsesquioxanes cross-linked thermoplastic zein films

Hybrid materials, a new class of materials obtained by sol-gel approach and based on the nanoscale interaction between inorganic and organic phases, have recently gained large scientific and industrial attention. In this work, the material designing of zein hybrid materials with tailored properties is addressed to the production of zein hybrid foams by both gas foaming and supercritical carbon dioxide, CO2 drying. Hybrid materials have been produced from thermoplastic zein and 3-glycidoxypropyltrimethoxysilane by a two-step procedure including reactive melt mixing and a simultaneous sol-gel approach. Protein structural changes have been investigated by infrared spectroscopy and correlated with thermomechanical properties. The hybrid foams have been analyzed by scanning electron microscopy in order to evaluate the effect of silsesquioxanes domains on the porous structure. Hybrid microcellular foams with homogeneous cellular structures have been obtained by both foaming approaches. A bimodal structure with bubbles characterized by micrometric and nanometric sizes was obtained in hybrid foams obtained with CO2 drying.

Effect of two kinds of lignins, alkaline lignin and sodium lignosulfonate, on the foamability of thermoplastic zein-based bionanocomposites

The aim of this study was to utilize zein, a protein from corn, to develop bioplastic formulations in combination with reactive additives based on ligninic compounds and to investigate the effects of these highly interactive additives on the foamability of zein. In particular, different amounts of alkaline lignin and sodium lignosulfonate were added to zein powder and poly(ethylene glycol) through melt mixing to achieve thermoplastic bio-polymers, which were subsequently foamed in a batch process, with a mixture of CO2 and N2 as blowing agent, in the temperature range 50–60°C. The materials before foaming were characterized by X-ray and Fourier transform infrared analysis to highlight the physico-chemical interactions and the eventual destructuration of the protein secondary structure. After foaming, density measurements, scanning electron microscopy and image analysis have been used in order to evaluate the porosity and the pore size distribution of the microstructure of the foams and to determine the effect of the ligninic compounds on the foamability of the bioplastic.

Effect of supramolecular structures on thermoplastic zein-lignin bionanocomposites

The effect of alkaline lignin (AL) and sodium lignosulfonate (LSS) on the structure of thermoplastic zein (TPZ) was studied. Protein structural changes and the nature of the physical interaction between lignin and zein were investigated by means of X-ray diffraction and Fourier transform infrared (FT-IR) spectroscopy and correlated with physical properties. Most relevant protein structural changes were observed at low AL concentration, where strong H-bondings between the functional groups of AL and the amino acids in zein induced a destructuring of inter- and intramolecular interactions in α-helix, β-sheet, and β-turn secondary structures. This destructuring allowed for an extensive protein conformational modification which, in turn, resulted in a strong improvement of the physical properties of the bionanocomposite.