Development of Biodegradable Foamlike Materials Based on Casein and Sodium Montmorillonite Clay

A Survey on Detection of Plastic-Related Chemicals in Beer Packaged in PET Using FT-IR Technology

The emerging consciousness on nano- and microplastics in our environment raises questions on how to reduce and minimize its influence on human health. PET (polyethylene terephthalate) packaging is gaining popularity, and many traditional products end up in such packaging (vinegar, wine, beer). Currently, it is very hard to quantify the number of particles and their exact composition, but semi-quantitative techniques such as FT-IR (Fourier Transform Infrared Spectrophotometry) can give us an insight into the chemical composition of plastic bits in foods and beverages. Nowadays, beer is packed in PET packaging, since it provides a cheaper packaging material compared to glass and since it is safe to use at public manifestations, contrary to glass bottles, while providing a reasonable barrier for gas permeation (O2 and CO2). The aim of this paper was to provide a short overview of FT-IR-detected compounds in PET-packaged beer samples. The results indicate that many compounds can be found in beer, but those that were most commonly found in our research were β-cyclodextrin and L(-)-glyceraldehyde unnatural forms, two compounds designated as plastic-related compounds.

Aramid Pulp Reinforced Clay Aerogel Composites: Mechanical, Thermal and Combustion Behavior

In this work, we reported that aramid pulps (AP) reinforced clay aerogel composites with improved mechanical strength, good thermal insulation and fire resistance based on the combination of AP, Poly(vinyl alcohol) (PVA) and sodium montmorillonite (MMT), which present a promising prospect in the thermal insulation application. The PVA-MMT-AP_x (x: denotes the mass content of AP) aerogel composites present an isotropic “lamella-honeycomb” porous structure, which endows them with excellent comprehensive performance. With the AP content increasing, the extremely low density is kept, ranging between 67–73 mg/cm³, and the low thermal conductivity is maintained within 40.9–47.9 mW·m⁻¹·K⁻¹. The mechanical strength is significantly improved with the maximum compressive modulus increasing from 2.95 to 5.96 MPa and the specific modulus rising from 44.03 to 81.64 MPa∙cm³/g. Their detailed heat transfer process has been analyzed, which provides a deep understanding to the low thermal conductivity of the PVA-MMT-AP_x aerogel composites. Based on the combination of thermogravimetric analysis and combustion behavior, the PVA-MMT-AP_x aerogel composites are demonstrated to possess improved thermal stability and fire resistance. This study puts forward a facile approach to utilizing AP to reinforce clay aerogel composites, which provides new insight into the development of thermal-insulating, fire-safe and high-strength thermal insulation materials.

Wastewater Treatment and Biomedical Applications of Montmorillonite Based Nanocomposites: A Review

Background::

Rapid industrialisation, population growth and technological race worldwide have brought adverse consequences on water resources and as a result affect human health. Toxic metal ions, non-biodegradable dyes, organic pollutants, pesticides, pharmaceuticals are among the chief hazardous materials released into the water bodies from various sources. These hazardous contaminants drastically affect the flora and fauna globally leading to health deterioration there by giving rise to new biomedical challenges.

Hypothesis::

Montmorillonite based nanocomposites (MMTCs) have drawn an attention of the researchers to design environmental friendly, advanced and hygienic nanocomposites for wastewater treatment and biomedical purposes. Montmorillonite clay possesses peculiar physical and chemical properties that include enhanced surface reactivity, improved rheological performance, exorbitant miscibility in water due to which it shows highly favourable interactions with polymers, drugs, metals, mixed metals and metal oxides leading to the fabrication of different types of advanced montmorillonite based nanocomposites that have remarkable applications

Methodology::

Here we review the structural characteristics of montmorillonite clay, advances in the synthetic techniques involved in the fabrication of montmorillonite nanocomposites, their applications in waste water treatment and in bio medical field. The recently developed montmorillonite nanocomposites for (1) waste water treatment as nano-adsorbents for the elimination of toxic inorganic species such as metal ions and heterogeneous photo-catalysts for photo degradation of dyes, pesticides and pharmaceuticals (2) biomedical utilization viz drug delivery, wound amelioration, bone cement, tissue engineering etc. are presented

Conclusion::

The review exclusively focuses on recent research on montmorillonite based nanocomposites and their application in wastewater treatment and in biomedical field

Protein-Based Systems for Topical Antibacterial Therapy

Recently, proteins are gaining attention as potential materials for antibacterial therapy. Proteins possess beneficial properties such as biocompatibility, biodegradability, low immunogenic response, ability to control drug release, and can act as protein-mimics in wound healing. Different plant- and animal-derived proteins can be developed into formulations (films, hydrogels, scaffolds, mats) for topical antibacterial therapy. The application areas for topical antibacterial therapy can be wide including bacterial infections in the skin (e.g., acne, wounds), eyelids, mouth, lips, etc. One of the major challenges of the healthcare system is chronic wound infections. Conventional treatment strategies for topical antibacterial therapy of infected wounds are inadequate, and the development of newer and optimized formulations is warranted. Therefore, this review focuses on recent advances in protein-based systems for topical antibacterial therapy in infected wounds. The opportunities and challenges of such protein-based systems along with their future prospects are discussed.

pH-driven entrapment of enrofloxacin in casein-based nanoparticles for the enhancement of oral bioavailability

Enrofloxacin (ENR), a broad-spectrum antibacterial drug, has extremely poor water solubility contributing to low bioavailability, which prevents drug formulation design and limits its wide application in livestock farming and aquaculture. Compared to conventional formulations of ENR, casein (Cas)-based drug delivery system has been reported to have significant advantages in the improvement of solubility and bioavailability of drugs. In this paper, we report the preparation process of ENR-loaded Cas nanoparticles (ENR-Cas) using magnetic agitation without any organic agent and the optimization of the formulation. Transmission electron microscopy (TEM), dynamic light scattering (DLS), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR) were all adopted to characterize the ENR-Cas. Results showed that the obtained ENR-Cas were approximately spherical with a particle size of 171.6 ± 13.8 nm with a polydispersity index of 0.322 ± 0.053. In vitro release behavior of ENR-Cas showed a sustained release profile. Additionally, in vivo study in rats displayed that the mean plasma concentration of ENR after oral administration of ENR-Cas was significantly higher than that treated with ENR suspension. The mean residence time (MRT0-24) of ENR was enhanced by Cas nanoparticles from 9.287 ± 0.524 to 11.372 ± 1.139 hr in comparison with ENR suspension. Accordingly, the area under the curve (AUC0-24) of ENR-Cas was 80.521 ± 6.624 μg·hr/ml, 3.8-fold higher than that of ENR suspension (20.850 ± 1.715 μg·hr/ml). Therefore, it can be concluded that ENR-Cas enhanced the absorption, prolonged the retention time, and improved oral bioavailability of ENR. Taken the good oral safety of Cas into consideration, ENR-Cas should be a more promising oral preparation of ENR for clinical application.

Self-assembled caseinate-laponite® nanocomposites for curcumin delivery

In this study, novel self-assembled protein-clay nanocomposites were developed for curcumin delivery. Experimentally, curcumin was dissolved and deprotonated in sodium caseinate-laponite® (NaCas-LAP) dispersion at pH 12.0 for 30 min followed by neutralization to pH = 7. Due to the pH-mediated dissociation and re-association process, curcumin was successfully encapsulated into NaCas-LAP nanocomposites. The colloidal properties and encapsulation capabilities of NaCas-LAP nanocomposites were investigated, including particle size, zeta potential, encapsulation efficiency, release profile in simulated gastrointestinal tract, as well as nanoscale morphology. The results indicated that upon neutralization, NaCas-LAP nanocomposites were re-associated into smaller particles due to strong hydrophobic interactions among NaCas, LAP and curcumin. Specifically, 0.10% curcumin loaded nanocomposites prepared with 2% NaCas and 0.5% LAP showed improved encapsulation performance (73.4%) with smaller particle size (100 nm). The as-prepared protein-clay nanocomposites hold promising potential to deliver lipophilic bioactive compounds, such as curcumin.

Recent Developments in Nanocellulose-Based Aerogels in Thermal Applications: A Review

Naturally derived nanocellulose (NC) is a renewable, biodegradable nanomaterial with high strength, low density, high surface area, and tunable surface chemistry, which allows its interaction with other polymers and nanomaterials in a controlled manner. In recent years, NC aerogel has gathered a lot of attention due to environmental concerns. This review presents recent developments of NC-based aerogels and their controlled interactions with other polymers and nanomaterials for thermal applications that include electronic devices, the apparel industry, superinsulating materials, and flame-retardant smart building materials. After going through the distinctive properties of NC aerogels, they are orderly categorized and discussed as thermally insulated, thermally conductive, and flame-retardant materials.

The fabrication and characterization of casein/PEO nanofibrous yarn via electrospinning

Casein, a natural protein, has been used as a biopolymer-based resource for producing fiber. This fiber provides high comfort properties with a pH close to human skin. This study focused on evaluating the production feasibility of casein nanofiber twisted yarn with the highest protein content in the hybrid yarn, obtaining suitable spinning conditions and desirable properties of the produced yarn. The desirable yarn achieved by composing 90% casein and 10% polyethylene oxide. The yarn strengthened using several types of cross-linking methods and the best technique was obtained to spin an optimized engineered yarn. Consequently, the biodegrading test conducted on the optimized yarn (90% casein and 10% polyethylene oxide blend) in the presence of 40% di-isocyanate as strengthener additive. Observations showed that after ten days, the sample mostly degraded in the solvent and its strength massively reduced so it could be considered as an environmentally friendly, biodegradable fiber.

Recyclable Xanthan/TiO2 Composite Cryogels towards the Photodegradation of Cr(VI) Ions and Methylene Blue Dye

Composite cryogels were prepared from xanthan gum (XG) precursor gels at 20 g L-1 containing TiO2 load at 5, 10, and 20 wt% and citric acid, as crosslinker. The effect of the pH over precursor gel on the properties of the resulting cryogels was evaluated. The characterization of the XG/TiO2 cryogels comprised compression tests, swelling degree (SD) determination, Fourier transform infrared vibrational spectroscopy in the attenuated total reflectance mode (FTIR-ATR), scanning electron microscopy (SEM), and X-ray microtomography (CT) analyses. The largest compressive modulus (E) was observed for XG/TiO2 10% cryogels prepared at pH 4.0, which amounted to 100±7 kPa, whereas the E value determined for bare XG cryogels was 29±3 kPa. XG/TiO2 10% cryogels presented larger pores and thicker walls than bare XG cryogels, as evidenced by SEM and CT analyses. FTIR-ATR spectra evidenced the ester bonds stemming from the esterification among carboxylic acid groups and/or XG hydroxyl groups. XG/TiO2 10% cryogels presented SD of (61±2) gwater/gcryogel, long-term stability in water, and outstanding photocatalytic properties in the presence of Cr(VI) ions and methylene blue (MB). The photocatalytic processes for the reduction of Cr(VI) to Cr(III) and for the photobleaching of MB fitted the first-order kinetic model, yielding rate constants of 0.019 varying min-1 and 0.0096 min-1, respectively. For both processes, the XG/TiO2 10% cryogels could be recycled five times without losing shape or efficiency.

Preparation and characterization of homogeneous and enhanced casein protein-based composite films via incorporating cellulose microgel

Gelatin-coupled cellulose (GCC) microgel with whisker-like structure is prepared and used to incorporate into casein (CA) matrix to construct reinforced CA-based composite films by solution casting. The GCC microgel has excellent dispersibility and stability in water, which contributes to the hydrophobicity and significantly reduces the moisture absorption of the composite films, as well as a decrease in the water vapor permeability with an increase of GCC content at different relative humidity is also observed. Compared with pure casein material, the resultant CA-based composite films show more homogeneous and dense cross-sectional structure, and the cleavage temperature of the hydrogen bonds increases by 16 °C. In particular, their tensile strength and Young’s modulus increase by 6 and 3.5 times, respectively. These indicators are superior to that of the nanoparticle enhanced CA-based composite film. Moreover, the light transmittance of the CA-based films at 550 nm is about 88% when GCC content is higher than 9%. The above results could be attributed to the strong hydrogen bonds formed between GCC components and CA matrix, as further confirmed by fourier transform infrared spectra and X-ray diffraction analysis.

Electrospinning of casein nanofibers with silver nanoparticles for potential biomedical applications

Casein, a major protein content in the milk has been extensively used in drug delivery due to its unique structural features. Fabrication of nanofibers from casein along with nanoparticles for tissue engineering applications has been explored in this study. Nanofibers fabrication is achieved by co-electrospinning of casein with poly (ethylene oxide) in sodium dodecyl sulphate (SDS) aqueous solution. Stabilization of silver nanoparticles has been achieved by the presence of SDS in the nanofiber matrix. The influence of conductivity on the nanofiber fabrication has also been studied. The nanofibrous mats have been characterized using techniques such as scanning electron microscope (SEM) and high resolution-transmission electron microscope (HR-TEM). Antimicrobial properties of the nanofibers have been assessed and the cellular biocompatibility of the material has been evaluated using cultured fibroblast (NIH-3T3) cells. Silver nanoparticles incorporated nanofibers showed good antimicrobial property against both gram negative and gram positive bacteria. In addition, the nanofiber matrix exhibited good biocompatibility for the fibroblast cell proliferation. These results pave the way for extending the use of casein based nanofibers in the skin care applications.

The Relation between the Rheological Properties of Gels and the Mechanical Properties of Their Corresponding Aerogels

A series of low density, highly porous clay/poly(vinyl alcohol) composite aerogels, incorporating ammonium alginate, were fabricated via a convenient and eco-friendly freeze drying method. It is significant to understand rheological properties of precursor gels because they directly affect the form of aerogels and their processing behaviors. The introduction of ammonium alginate impacted the rheological properties of colloidal gels and improved the mechanical performance of the subject aerogels. The specific compositions and processing conditions applied to those colloidal gel systems brought about different aerogel morphologies, which in turn translated into the observed mechanical properties. The bridge between gel rheologies and aerogel structures are established in the present work.

Poly(Amide-imide) Aerogel Materials Produced via an Ice Templating Process

Low density composites of sodium montmorillonite and poly(amide-imide) polymers have been created using an ice templating method, which serves as an alternative to the often-difficult foaming of high temperature/high performance polymers. The starting polymer was received in the poly(amic acid) form which can be cured using heat, into a water insoluble amide-imide copolymer. The resulting materials have densities in the 0.05 g/cm³ range and have excellent mechanical properties. Using a tertiary amine as a processing aid provides for lower viscosity and allows more concentrated polymer solutions to be used. The concentration of the amine relative to the acid groups on the polymer backbone has been found to cause significant difference in the mechanical properties of the dried materials. The synthesis and characterization of low density versions of two poly(amide-imide) polymers and their composites with sodium montmorillonite clay are discussed in the present work.

Clay Aerogel Supported Palladium Nanoparticles as Catalysts

Highly porous, low density palladium nanoparticle/clay aerogel materials have been produced and demonstrated to possess significant catalytic activity for olefin hydrogenation and isomerization reactions at low/ambient pressures. This technology opens up a new route for the production of catalytic materials.

Poly(vinyl alcohol)/clay aerogel composites with enhanced flame retardancy

The effect of pentaerythritol octahydrogen tetraphosphate (PEPA) on the microstructure and properties of poly(vinyl alcohol) (PVOH)/clay aerogel composites was investigated.

Effects of Molecular Weight upon Irradiation-Cross-Linked Poly(vinyl alcohol)/Clay Aerogel Properties

Facile fabrication of mechanically strong poly(vinyl alcohol) (PVOH)/clay aerogel composites through a combination of increasing polymer molecular weights and gamma irradiation-cross-linking is reported herein. The aerogels produced from high polymer molecular weights exhibit significantly increased compressive moduli, similar to the effect of irradiation-induced cross-linking. The required irradiation dose for fabricating strong PVOH composite aerogels with dense microstructure decreased with increasing polymer molecular weight. Neither thermal stability nor flammability was significantly changed by altering the polymer molecular weight or by modest gamma irradiation, but they were highly dependent upon the polymer/clay ratio in the aerogel. Optimization of the mechanical, thermal, and flammability properties of these composite aerogels could therefore be obtained by using relatively low levels of polymer, with very high polymer molecular weight, or lower molecular weight coupled with moderate gamma irradiation. The facile preparation of strong, low flammability aerogels is an alternative to traditional polymer foams in applications where fire safety is important.

Effects of Fiber Reinforcement on Clay Aerogel Composites

Novel, low density structures which combine biologically-based fibers with clay aerogels are produced in an environmentally benign manner using water as solvent, and no additional processing chemicals. Three different reinforcing fibers, silk, soy silk, and hemp, are evaluated in combination with poly(vinyl alcohol) matrix polymer combined with montmorillonite clay. The mechanical properties of the aerogels are demonstrated to increase with reinforcing fiber length, in each case limited by a critical fiber length, beyond which mechanical properties decline due to maldistribution of filler, and disruption of the aerogel structure. Rather than the classical model for reinforced composite properties, the chemical compatibility of reinforcing fibers with the polymer/clay matrix dominated mechanical performance, along with the tendencies of the fibers to kink under compression.

Efficient approach to improving the flame retardancy of poly(vinyl alcohol)/clay aerogels: incorporating piperazine-modified ammonium polyphosphate

Ammonium polyphosphates (APP) modified with piperazine (PA-APP) was used to improve the flame retardancy of poly(vinyl alcohol) (PVA)/montmorillonite (MMT) aerogels, which were prepared via an environmentally friendly freeze-drying method. The thermal stabilities of the samples were evaluated by thermogravimetric analysis (TG); the flammability behaviors of samples were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter (CC) tests. TG test results showed that the 5% weight loss temperature (T5%) of PVA/MMT/PA-APP was 10 °C higher than that of PVA/MMT/APP. In combustion testing, all of PVA/MMT/PA-APP aerogels achieved V-0 ratings and have a higher LOI values than the unmodified PVA/MMT aerogel. Moreover, the aerogel with 1% PA-APP5, which means that the content of piperazine is 5% in PA-APP, decreased the cone calorimetry THR value to 5.71 MJ/m(2), and increased the char residue to 52%. The compressive modulus of PVA/MMT/PA-APP was increased by 93.4% compared with PVA/MMT/APP because of the increase in interfacial adhesion between matrix and PA-APP fillers. The densities of the PVA/MMT/PA-APP samples were slightly lower than those of the unmodified aerogels because of reduced shrinkage in the presence of PA-APP. All the tests results indicated that the incorporation of PA-APP not only improved the thermal stability and flame retardancy of aerogels but also maintained their mechanical properties.

Green bio-based aerogels prepared from recycled cellulose fiber suspensions

The flammability of green aerogels prepared using recycled cellulose fibres was improved by adding clay and ammonium polyphosphate.

Preparation and flammability of poly(vinyl alcohol) composite aerogels

Poly(vinyl alcohol) (PVOH)-based aerogel composites with nanoscale silica, halloysite, montmorillonite (MMT), and laponite were prepared via a freeze-drying method. The PVOH/MMT and PVOH/laponite composites exhibit higher compressive moduli than the PVOH/SiO2 or PVOH/halloysite samples. Layered microstructures were observed for the samples except with PVOH/laponite, which showed irregular network morphologies. Thermogravimetric analysis of the aerogel samples showed increased thermal stability with the addition of nanofillers. The heat release measured by cone calorimetry, smoke release, and carbon monoxide production of the aerogel composites are all significantly decreased with the addition of nanofillers; these values are much lower than those for commercial expanded polystyrene foam. The fillers did not lead to obvious increases in the limiting oxygen index values, and the corresponding time to ignition values decrease. The ability to adjust the nanofiller levels in these foamlike aerogel composites allows for specific tuning of these products for fire safety.

Polyvinyl alcohol-cellulose nanofibrils-graphene oxide hybrid organic aerogels

Hybrid organic aerogels consisting of polyvinyl alcohol (PVA), cellulose nanofibrils (CNFs), and graphene oxide nanosheets (GONSs) were prepared using an environmentally friendly freeze-drying process. The material properties of these fabricated aerogels were measured and analyzed using various characterization techniques including compression testing, scanning electron microscopy, thermogravimetric (TGA) analysis, Brunauer-Emmet-Teller (BET) surface area analysis, and contact angle measurements. These environmentally friendly, biobased hybrid organic aerogels exhibited a series of desirable properties including a high specific compressive strength and compressive failure strain, ultralow density and thermal conductivity, good thermal stability, and moisture resistance, making them potentially useful for a broad range of applications including thermal insulation.

Biodegradable pectin/clay aerogels

Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. The addition of multivalent cations (Ca(2+) and Al(3+)) resulted in apparent cross-linking of the polymer and enhancement of aerogel properties. The compressive properties increased as the solid contents (both pectin and clay) increased; moduli in the range of 0.04-114 MPa were obtained for materials with bulk densities ranging from 0.03 g/cm(3) to 0.19 g/cm(3), accompanied by microstructural changes from a lamellar structure to a cellular structure. Biodegradability of the aerogels was investigated by detecting CO2 release for 4 weeks in compost media. The results revealed that pectin aerogels possess higher biodegradation rates than wheat starch, which is often used as a standard for effective biodegradation. The addition of clay and multivalent cations surprisingly increased the biodegradation rates.

Ultrasound-assisted pullulan/montmorillonite bionanocomposite coating with high oxygen barrier properties

In this paper, the preparation and characterization of oxygen barrier pullulan sodium montmorillonite (Na(+)-MMT) nanocomposite coatings are presented for the first time. Full exfoliation of platelets during preparation of the coating water dispersions was mediated by ultrasonic treatment, which turned out to be a pivotal factor in the oxygen barrier performance of the final material even at high relative humidity (RH) conditions [oxygen permeability coefficients ~1.43 ± 0.39 and 258.05 ± 13.78 mL·μm·m(-2)·(24 h)(-1)·atm(-1) at 23 °C and 0% RH and 70% RH, respectively]. At the micro- and nanoscale, the reasons are discussed. The final morphology of the coatings revealed that clay lamellae were stacked on top of one another, probably due to the forced confinement of the platelets within the coating thickness after solvent evaporation. This was also confirmed by modeling the experimental oxygen permeability data with the well-known Nielsen and Cussler permeation theoretical models, which suggested a reasonable aspect ratio (α) of ~100. Electron microscopic analyses also disclosed a peculiar cell-like arrangement of the platelets. The stacking of the clay lamellae and the cell-like arrangement create the excellent oxygen barrier properties. Finally, we demonstrated that the slight haze increase in the bionanocomposite coating materials arising from the addition of the clays depends on the clay concentration but not so much on the sonication time, due to the balance of opposite effects after sonication (an increase in the number of scattering centers but a reduction in their size).