Photo-degradable and recyclable starch/Fe3O4/TiO2 nanocomposites: feasibility of an approach to reduce the recycling labor cost in plastic waste management.

In this research, a biodegradable starch/Fe3O4/TiO2 bio-nanocomposites (SFT) were produced using different nano Fe3O4/TiO2 (FT) (3, 5, and 10 (wt% dry based)) contents. Mechanical properties, visual properties, moisture-sensitive parameters, magnetic properties, and physical properties of the film specimens were investigated. Photodegradability of film specimens was also evaluated under UV-A irradiation. The FT content increased the hydrophobicity of the film specimens. Tensile strength (TS) of SFT films was increased by increasing FT up to 3%. Elongation at break (EB) and tensile energy to break (TEB) were decreased by adding FT content up to 3% simultaneously. The film specimens' water vapor permeability (WVP) was decreased with increasing FT content. The intrinsic viscosity of SFT was decreased by increasing FT content. It confirms the enhancement of photodegradability of the specimens by increasing FT content. It seems the compatibility of FT with biopolymer has had great effects on these properties. Use of FT-based nanocomposites is an appropriate approach to developing magnetic-recyclable and photodegradable packaging materials.

Digital holographic microscopy for real-time investigation of 3D microstructural dynamics of starch-kefiran-based nanocomposite.

Investigating real-time phenomena in bio-polymers has received much attention because of their increasing demands in polymer substitution. The 3D morphometry of polymer surfaces may be very impactful in such studies. Here, digital holographic microscopy (DHM) is applied for quantitative measurement of the rare morphological changes of UV-A and UV-C exposed nanocomposites during their incubation with excess water. By reconstructing the recorded successive digital holograms, the time evolution of the swelled regions of the samples is derived. Our results clearly show that the higher water swelling of UV-A irradiated starch/kefiran/ZnO may be attributed to its higher hydrophilicity.

Kefiran ameliorates malfunctions in primary and functional immune cells caused by lipopolysaccharides.

Kefiran is a water-soluble polysaccharide well recognized as a bioactive ingredient to enhance nutritional and health-promoting features. Also, some therapeutic properties have made this macromolecule an active ingredient in ointments and oral anti-inflammatory drugs. However, the details of the molecular and cellular aspects of these effects have not been addressed. In this study, lipopolysaccharides (LPS)-induced monocytes, lymphocytes, and monocyte-derived dendritic cells (MDDCs) as representative cells for both innate and adaptive immunity were treated with kefiran for 2 h. Kefiran had an anti-inflammatory effect on monocytes to reduce pro-inflammatory cytokines, interleukin 1 ß (IL-1ß) & tumor necrosis factor α (TNF-α), as well as nuclear factor kappa b (NF-kb). However, it did not affect lymphocytes. Overexpression of Toll-like receptor 4 (TLR4) in LPS-induced cells was not reduced after kefiran treatment. Kefiran balanced MDDCs secretion of pro/anti-inflammatory cytokines by reducing and enhancing the expression of IL-1ß and interleukin 10 (IL-10), respectively. Also, kefiran decreased the number of apoptotic immature MDDCs and promoted dose-dependent phagocytosis capacity of MDDCs. According to the results of the current study, it may be concluded that the immunomodulatory effects of kefiran are due to antagonist against innate immune receptors especially TLR4. The results of this study can be used as a guide to developing kefiran-based non-aggressive anti-inflammatory drugs. Furthermore, understanding the immunobiological effects of kefiran on monocytes and lymphocytes was another outcome of this study.

Production of starch based biopolymer by green photochemical reaction at different UV region as a food packaging material: Physicochemical characterization.

In current study, the functional properties of modified starch solutions by photochemical reactions as a biodegradable food packaging material were investigated. Starch film-forming solutions were exposed to ultraviolet A (UV-A) and C (UV-C) over different time periods (1, 6, 12, and 24 h). A green method was used to prepare the modified starch films. Hydrophobicity, moisture sensitivity, and water vapor permeability of the starch films, decreased after exposure to UV irradiation up to 12 h. Tensile strength and Young's modulus of the specimens decreased by increasing UV exposure time. Elongation at break, and tensile energy to break of the film specimens were increased, simultaneously. Scanning electron microscopy images demonstrated that most of the films' physical properties were affected by their microstructures. UV-Vis spectrum of the specimens confirmed that UV-protective properties of the irradiated specimens in UV-A, UV-B, and UV-C region have changed in comparison with the control sample. According to the results, UV-irradiation could be considered as a green, easy, and accessible process for modification of starch-based films.

Using photo-modification to compatibilize nano-ZnO in development of starch-kefiran-ZnO green nanocomposite as food packaging material.

In this study, the effect of UV-C light on starch-kefiran-ZnO (1%) primary solution in different exposure times (1, 6, and 12 h) was investigated. Starch-kefiran-ZnO (SKZ) solution was modified by UV irradiation in different time periods. Also, nano-ZnO (ZN) was used as a photo-initiator and reinforcement agent, simultaneously. Mechanical properties of the films were affected after the UV treatment. The tensile strength increased because of the enhanced interaction between the biopolymer mixture and nano filler but elongation at break was decreased. WVP decreased about 16% and dwindled to 2.08 × 10-10 g m-1 s-1 Pa-1. Water related properties (i.e. moisture content, moisture absorption, and solubility in water) of the films decreased by UV-C exposure. On the other hand, UV absorption and water contact angle increased because of the better distribution of the ZNs in polymer matrix after the UV exposure. Better compatibility of the ZNs and the biopolymer matrix after UV treatment was confirmed by the SEM micrographs. Comparison of FTIR spectra before and after UV exposure showed slight shifts. It was due to some formed or deformed bonds inside of the nanocomposite matrix. The modified SKZ by UV could be an appropriate process to sanitizing and food packaging concurrently. As well as UV can be used as a nano-ZnO compatibilizer in food packaging materials.

Development of photo-modified starch/kefiran/TiO2 bio-nanocomposite as an environmentally-friendly food packaging material.

This paper reports on an experiment in which starch/kefiran/TiO2 (SKT)-based bio-nanocomposite films were developed and modified by photo-chemical reaction. In so doing, film-forming solutions were exposed to ultraviolet A (UV-A) for different times (1, 6, and 12 h). The obtained results indicated that increasing UV-A exposure time brought about an increase (≈14.9%) in the tensile strength of bio-nanocomposites. However, elongation at break and Young's modulus of irradiated film specimen decreased (≈32%, ≈12%, respectively) by increasing UV-A exposure time, and the moisture-sensitive parameters of specimen decreased using UV-A irradiation. According to the results, the functional properties of irradiated bio-nanocomposite are depended on the ratio of cross-linkages between polymer chains and the potentially produced mono and disaccharide by UV-A.

Photo-producible and photo-degradable starch/TiO2 bionanocomposite as a food packaging material: Development and characterization.

In current study, starch/TiO2 bionanocomposites were produced by photochemical reactions as a biodegradable food packaging material. Physical, mechanical, thermal and water-vapor permeability properties were investigated. Then, the photo-degradation properties of nanocomposite films were studied. This is the first report of the photo-producible and photo-degradable bionanocomposite as a food packaging material. Film-forming solutions were exposed to ultraviolet A (UV-A) for different times. Our results showed that UV-A irradiation increased the hydrophobicity of starch films. With increasing UV-A exposure time, tensile strength and Young's modulus of the specimens were decreased. On the other hand, elongation at break of the films was increased with increasing UV-A irradiation. The glass transition temperature and melting point of the films were increased by increasing UV-A exposure time. Nevertheless, the results showed that photo-degradation properties of photo-produced starch/TiO2 nanocomposite were significantly higher than virgin starch and virgin starch/TiO2 films. According to obtain results and bibliography a schema was developed to describe the mechanism of photo-production and photo-degradation of starch/TiO2 by UV-A ray. It can be concluded, the modification of starch based biopolymer by UV-A and nano-TiO2, is an easy and accessible process to improve the packaging properties and photo-degradability of biopolymer based films.

Eco-friendly soluble soybean polysaccharide/nanoclay Na+ bionanocomposite: Properties and characterization.

The impact of montmorillonite (MMT) as a nanofiller at different concentrations (5, 10, 15wt.%) on the physicochemical and functional properties of nanocomposite film based on soluble soybean polysaccharide (SSPS) was investigated. The results showed that an increase in MMT concentration was accompanied by a decrease in water solubility, thickness, and elongation at break. Furthermore, tensile strength increased when MMT concentration was increased to 10wt.%. Atomic force and scanning electron micrographs showed a significant agglomeration at MMT 15wt.%. With added MMT, the level of whiteness, greenness, and yellowness of SSPS film increased (P<0.05). Dynamic mechanical thermal analysis indicated that the storage modulus of nanocomposites increased when the MMT was increased to 10wt.%. Furthermore, Fourier transform infrared spectrophotometry demonstrated that no considerable changes occurred in the functional groups of the SSPS when MMT was added. Antimicrobial tests revealed that antibacterial and anti-mold activities were unlikely from reinforced nanocomposites.

Preparation of ecofriendly UV-protective food packaging material by starch/TiO2 bio-nanocomposite: Characterization.

In this study, ecofriendly starch/TiO2 bio-nanocomposites were produced using with different nano-TiO2 (TiO2) content (1, 3, and 5 (wt%)). Physical, mechanical, thermal, water-vapor permeability (WVP) properties and UV transmittance were investigated. Our results showed that the increasing TiO2 content increased the hydrophobicity of starch/TiO2 films. WVP of the bio-nanocomposites was reduced, simultaneously. With increasing TiO2 content, tensile strength and Young's modulus of the film specimens were reduced while elongation at break and tensile energy to break were increased. The thermal properties of specimens showed that glass transition temperature of the films increased but melting point of the specimen films was decreased by increasing TiO2 content. Scanning electron microscopy observations demonstrated, the most of films' physical properties were in relation to their microstructures. The starch/TiO2 nanocomposites effectively protect goods against UV light, and could potentially be applied as UV-shielding packaging materials.

Modification of functional properties of pullulan-whey protein bionanocomposite films with nanoclay.

In this study, biodegradable nanocomposite film composed of pullulan - whey protein isolate (WPI) - montmorillonite (MMT) were developed and characterized as a function of incorporating various amounts of MMT nanoparticles (0, 1, 3 and 5 % wt). Results showed that the water-vapor permeability, moisture content, moisture absorption and water solubility decreased when the nano-MMT content was increased. Tensile strength improved and elongation at break simultaneously decreased with increasing MMT content. The glass transition temperature (Tg(and melting-point temperature (Tm) increased with increasing nano-MMT content. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis revealed uniform distribution of MMT into the polymer matrix. Atomic force microscopy (AFM) showed enhancement of films' roughness with increasing MMT content.

Development of new active packaging film made from a soluble soybean polysaccharide incorporating ZnO nanoparticles.

This study aimed to develop a soluble soybean polysaccharide (SSPS) nanocomposite incorporating ZnO nanoparticles. The nanocomposites were prepared using the solvent-casting method. SEM, AFM, DSC and X-ray diffraction methods were applied to characterize the resulting films. Furthermore, the antibacterial and anti-mold activities of SSPS/ZN films were assessed against the selected microorganisms. The results indicated that incorporating ZNs into the SSPS film affected the tensile strength and elongation at break significantly. In addition, the antibacterial, antifungal and yeasticidal activities of ZnO/SSPS films have been approved. XRD results showed a crystal plane of hexagonal ZN, while SEM showed that there was not a good affinity between ZN and SSPS. Mono-dispersed particles with clearly spherical morphology and with no voids on the surface were observed using AFM. Fluctuation in Tg and Tm resulted from incorporating ZN. In summary, the potential of ZNs as a functional filler in SSPS film has been demonstrated.

Development of ecofriendly bionanocomposite: Whey protein isolate/pullulan films with nano-SiO2.

During the past decade, the limitation of petroleum based polymers, the high price of oil, and the environmental concern were attracted the attention of researchers to develop biobased polymers. The composition of different biopolymers and the reinforcement with nano filler are common methods to improve the drawbacks of biopolymers. In this study whey protein isolate/pullulan (WPI/PUL) films contain 1%, 3%, and 5% (w/w) nano-SiO2 (NS) were prepared by a casting method. Tensile strength of nanocomposite films increased after increasing NS content, but elongation at break decreased, simultaneously. Water absorption, moisture content, solubility in water improved in the wake of increasing NS content because NS increase the cohesiveness of the polymer matrix and improved the barrier and water resistance properties of the films. water vapor permeability of film specimens decreased by increasing NS content. Uniform distribution of NS into polymer matrix was confirmed by scanning electron microscopy (SEM). XRD pattern and thermal analysis revealed increasing crystallinity and increasing Tg of film specimens with increasing NS content, respectively. According to our result WPI/PUL/NS films possess potential to be used as environment friendly packaging films to improve shelf life of food and can be used as promising alternative to petroleum based packaging films.

Green bionanocomposite based on kefiran and cellulose nanocrystals produced from beer industrial residues.

Environmental concern about synthetic polymers and nanoparticles bring about development of the green bionanocomposite. Nanocellulose (NC) as safe nanofiller was prepared from beer industrial residues by acid hydrolysis in this study. ATR-FTIR spectrum showed no change in chemical structure of kefiran and NC after mixing. However, mechanical, visual, and WVP properties of kefiran/NC films improved with NC, but thermal properties and water sensitivity of them declined, simultaneously.

Effect of γ-irradiation on the physical and mechanical properties of kefiran biopolymer film.

In this study, the effect of different γ-ray dosages (3, 6, and 9 kGy) on the functional properties of kefiran biopolymer was investigated. The obtained results showed that increasing γ-ray dosage brought about an increase in the tensile strength of film specimens up to three-times. However, elongation at break, and tensile energy to break of γ-irradiated kefiran films decreased in the wake of increasing γ-ray dosage. γ-Irradiation could improve surface hydrophobicity, sensitivity of kefiran film specimens to water, and water vapor permeability, but yellowness of films increased, simultaneously. XRD spectrum confirmed increased crystallinity of γ-irradiated films. Melting point of films was constant but glass transition temperature decreased drastically at high γ-ray dosage (9 kGy). ATR-FTIR analysis confirmed that γ-ray engendered no changes in chemical functional groups. According to the result, a mechanism was proposed to percept the effects of γ-irradiation on kefiran biopolymer and its role on the functional properties of kefiran film. Hence, the functional properties of kefiran films were depend on the ratio of cross-linkages between polymer chains and produced mono and disaccharide by γ-irradiation.

Preparation of UV-protective kefiran/nano-ZnO nanocomposites: physical and mechanical properties.

In this study, we investigated the effect of ZnO nanoparticles (ZN) as a UV-protective agent of kefiran biopolymers. Our results showed that with increasing ZN content, the tensile strength, elongation at break, and tensile energy to break the kefiran film and nanocomposites also increased. Kefiran nanocomposites with a ZN content higher than 2% produced a UV-protective film with good visual properties, low sensibility to water, and low water-vapor permeability. The thermal properties of all specimens, analyzed by DSC, showed that the ZN content had a negative effect on Tg and a positive effect on nanocomposites' melting point. TEM, SEM micrography and XRD spectrum analysis confirmed the hypothesis that ZNs act like a ball bearing, making movement of kefiran chains easier and increasing elongation at break, while simultaneously decreasing the Tg of kefiran nanocomposites.