Rheological and thermo-mechanical evaluation of bio-based chitosan/pectin blends with tunable ionic cross-linking

Ionic-physical-chemical triple cross-linked all-biomass-based aerogel for thermal insulation applications

Aerogels, as a unique porous material, are expected to be used as insulation materials to solve the global environmental and energy crisis. Using chitosan, citric acid, pectin and phytic acid as raw materials, an all-biomass-based aerogel with high modulus was prepared by the triple strategy of ionic, physical and chemical cross-linking through directional freezing technique. Based on this three-dimensional network, the aerogel exhibited excellent compressive modulus (24.89 ± 1.76 MPa) over a wide temperature range and thermal insulation properties. In the presence of chitosan, citric acid and phytic acid, the aerogel obtained excellent fire safety (LOI value up to 31.2%) and antibacterial properties (antibacterial activity against Staphylococcus aureus and Escherichia coli reached 81.98% and 67.43%). In addition, the modified aerogel exhibited excellent hydrophobicity (hydrophobic angle of 146°) and oil-water separation properties. More importantly, the aerogel exhibited a biodegradation rate of up to 40.31% for 35 days due to its all-biomass nature. This work provides a green and sustainable strategy for the production of highly environmentally friendly thermal insulation materials with high strength, flame retardant, antibacterial and hydrophobic properties.

Novel films of pectin extracted from ambarella fruit peel and jackfruit seed slimy sheath: Effect of ionic crosslinking on the properties of pectin film

Here, we prepared ionically crosslinked films using pectin extracted from agro-wastes, specifically ambarella peels (AFP) and jackfruit seed slimy sheath (JFS). Physiochemical properties of pectins, including moisture content, molecular weight (Mw), degree of esterification (DE), and galacturonic acid (GA), were analyzed. Optimal extraction was determined, i.e., citric acid concentration 0.3 M, time 60 min, solid/liquid ratio 1:25, and temperature 90 °C for AFP or 85 °C for JFS. Pectin yields under these conditions were 29.67 % ± 0.35 % and 29.93 ± 0.49 %, respectively. AFP pectin revealed Mw, DE, and GA values of 533.20 kDa, 67.08 % ± 0.68 %, and 75.39 ± 0.82 %, while JFS pectin exhibited values of 859.94 kDa, 63.04 % ± 0.47 %, and 78.63 % ± 0.71 %, respectively. The pectin films crosslinked with Ca2+, Cu2+, Fe3+, or Zn2+ exhibited enhanced tensile strength and Young's modulus, along with reduced elongation at break, moisture content, water solubility, water vapor permeability, and oxygen permeability. Structural analyses indicated metal ions were effectively crosslinked with carboxyl groups of pectin. Notably, the Cu2+-crosslinked film demonstrated superior water resistance, mechanical properties, and exhibited the highest antioxidant and antibacterial activities among all tested films. Therefore, the pectin films represent a promising avenue to produce eco-friendly food packaging materials with excellent properties.

Electrospun Fe3O4-chitosan/polyvinyl alcohol nanofibrous film for improved capture and elimination of foodborne pathogens

This study developed a new "capture and killing" antibacterial approach for efficient elimination of foodborne pathogens. Fe3O4-Chitosan (CS)/polyvinyl alcohol (PVA) nanofibrous films with improved antibacterial and mechanical properties were fabricated by a simple, environmentally friendly, and cost-effective electrospinning technique. The relationship between the physical properties (viscosity, surface tension, and conductivity) and spinnability of CS/PVA as fiber forming matrix was explored. Electrospun Fe3O4-CS/PVA films (0.03-0.12 mm) with smooth and bead-free nanofibrous structures (145-169 nm) were successfully obtained. Compared with the film electrospun from neat CS/PVA, incorporating Fe3O4 nanoparticles (NPs) (1.25-5 wt%) in CS/PVA nanofibrous film promoted bacterial attachment and increased the final inactivated efficiency, showing a difference with Fe3O4 loading and bacterial strain, which had the highest value against Escherichia coli (E. coli) and Staphyloccus aureus (S. aureus) being 90 % and 66.30 %, respectively. The tensile strength and elongation at break of Fe3O4-CS/PVA films enhanced by 46-192 % and 92-141 %, respectively. Results of the cytotoxicity test indicated that the resulting films had high biocompatibility. These promising findings provide a novel strategy for effective foodborne pathogens elimination, which could apply to sterilizing and food packaging to extend the shelf life of liquid food.

Characteristics of Interpolyelectrolyte Complexes Based on Different Types of Pectin with Eudragit® EPO as Novel Carriers for Colon-Specific Drug Delivery

Given that pectin is a well-known substance used for drug delivery, we aimed to obtain and further examine the efficacy of interpolyelectrolyte complexes based on citrus or apple pectin and the Eudragit® EPO for using these carriers in oral drug delivery. To characterize the physicochemical properties of these compounds, turbidity, gravimetry, viscosity, elementary analysis, FTIR spectroscopy, and DSC analysis were utilized. Diffusion transport characteristics were evaluated to assess the swelling ability of the matrices and the release of diclofenac sodium. To examine the release parameters, mathematical modeling was performed by using the Korsmayer-Peppas and Logistic equations as well. During the turbidity study, stoichiometry compositions were selected for the developed IPECs EPO/PecA and EPO/PecC at pH values = 4.0, 5.0, 6.0, and 7.0. The FTIR spectra of the complexes were characterized by an increase in the intensity of the bands at 1610 cm-1 and 1400 cm-1. According to the DSC analysis, IPEC has a certain Tg = 57.3 °C. The highest release rates were obtained for IPEC EPO/PecC_1 and EPO/PecC_4. The mechanism of drug transport from the matrices IPEC EPO/PecC, IPEC EPO/PecA_3, and EPO/PecA_4 can be characterized as Super Case II. Anomalous release (non-Fickian release) is typical for IPEC EPO/PecA_1 and EPO/PecA_2. Thus, the resulting systems can be further used for the effective delivery of the drugs to the colon.

Zinc Oxide-Incorporated Chitosan-Poly(methacrylic Acid) Polyelectrolyte Complex as a Wound Healing Material

A novel type of porous films based on the ZnO-incorporated chitosan-poly(methacrylic acid) polyelectrolyte complex was developed as a wound healing material. The structure of porous films was established by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) analysis. Scanning electron microscope (SEM) and porosity studies revealed that the pore size and porosity of the developed films increased with the increase in zinc oxide (ZnO) concentration. The porous films with maximum ZnO content exhibited improved water swelling degree (1400%), controlled biodegradation (12%) for 28 days, a porosity of 64%, and a tensile strength of 0.47 MPa. Moreover, these films presented antibacterial activity toward Staphylococcus aureus and Micrococcus sp. due to the existence of ZnO particles. Cytotoxicity studies demonstrated that the developed films had no cytotoxicity against the mouse mesenchymal stem (C3H10T1/2) cell line. These results reveal that ZnO-incorporated chitosan-poly(methacrylic acid) films could be used as an ideal material for wound healing application.

Recent progress in pectin extraction and their applications in developing films and coatings for sustainable food packaging: A review

Perishable foods like fruits and vegetables, meat, fish, and dairy products have short shelf-life that causes significant postharvest losses, which poses a major challenge for food supply chains. Biopolymers have been extensively studied as sustainable alternatives to synthetic plastics, and pectin is one such biopolymer that has been used for packaging and preservation of foods. Pectin is obtained from abundantly available low-cost sources such as agricultural or food processing wastes and by products. This review is a complete account of pectin extraction from agro-wastes, development of pectin-based composite films and coatings, their characterizations, and their applications in food packaging and preservation. Compared to conventional chemical extraction, supercritical water, ultrasound, and microwave assisted extractions are a few examples of modern and more efficient pectin extraction processes that generate almost no hazardous effluents, and thus, such extraction techniques are more environment friendly. Pectin-based films and coatings can be functionalized with natural active agents such as essential oils and other phytochemicals to improve their moisture barrier, antimicrobial and antioxidant properties. Application of pectin-based active films and coatings effectively improved shelf-life of fresh cut-fruits, vegetables, meat, fish, poultry, milk, and other food perishable products.

From mango by-product to food packaging: Pectin-phenolic antioxidant films from mango peels

The objective of the study was to prepare active films based on pectin and polyphenol-rich extracts from Tommy Atkins mango peels. Aqueous and methanolic extracts showed a variety of phenolic compounds that were identified by UPLC-MS analysis, and a high content of total phenolics that were quantified by the Folin-Ciocalteau method. The methanolic extract showed better results in antioxidant tests and was more effective in inhibiting the growth of Gram-positive and Gram-negative bacteria. The pectin extracted from mango peels showed good thermal stability and a degree of methoxylation of 58.3% by ¹H NMR. The films containing the phenolic extracts showed lower water vapor permeability when compared to the control film (without any phenolic extracts). The incorporation of the extracts led to an increase in elongation (ε) and a decrease in tensile strength (σ) and modulus of elasticity (Y). The films with aqueous or methanolic extracts showed higher antioxidant activity in terms of inhibition of the DPPH radical. Therefore, the films developed in this work are presented as a promising alternative for food packaging and/or coating applications.

Bioactive pectic polysaccharides from bay tree pruning waste: Sequential subcritical water extraction and application in active food packaging

The potential isolation of bio-active polysaccharides from bay tree pruning waste was studied using sequential subcritical water extraction using different time-temperature combinations. The extracted polysaccharides were highly enriched in pectins while preserving their high molecular mass (10-100 kDa), presenting ideal properties for its application as additive in food packaging. Pectin-enriched chitosan films were prepared, improving the optical properties (≥95% UV-light barrier capacity), antioxidant capacity (˃95% radical scavenging activity) and water vapor permeability (≤14 g·Pa-1·s-1·m-1·10-7) in comparison with neat chitosan-based films. Furthermore, the antimicrobial activity of chitosan was maintained in the hybrid films. Addition of 10% of pectins improved mechanical properties, increasing the Young's modulus 12%, and the stress resistance in 51%. The application of pectin-rich fractions from bay tree pruning waste as an additive in active food packaging applications, with triple action as antioxidant, barrier, and antimicrobial has been demonstrated.

3D Printed Chitosan-Pectin Hydrogels: From Rheological Characterization to Scaffold Development and Assessment

Chitosan-pectin hydrogels were prepared, and their rheological properties were assessed in order to select the best system to develop scaffolds by 3D printing. Hydrogels showed a weak gel behavior with shear thinning flow properties, caused by the physical interactions formed between both polysaccharides, as observed by FTIR analysis. Since systems with high concentration of pectin showed aggregations, the system composed of 2 wt% chitosan and 2 wt% pectin (CHI2PEC2) was selected for 3D printing. 3D printed scaffolds showed good shape accuracy, and SEM and XRD analyses revealed a homogeneous and amorphous structure. Moreover, scaffolds were stable and kept their shape and size after a cycle of compression sweeps. Their integrity was also maintained after immersion in PBS at 37 °C, showing a high swelling capacity, suitable for exudate absorption in wound healing applications.

Multilayer Films Based on Chitosan/Pectin Polyelectrolyte Complexes as Novel Platforms for Buccal Administration of Clotrimazole

Buccal films are recognized as easily applicable, microbiologically stable drug dosage forms with good retentivity at the mucosa intended for the therapy of oromucosal conditions, especially infectious diseases. Multilayer films composed of layers of oppositely charged polymers separated by ionically interacting polymeric chains creating polyelectrolyte complexes represent very interesting and relatively poorly explored area. We aimed to develop the antifungal multilayer systems composed of cationic chitosan and anionic pectin as potential platforms for controlled delivery of clotrimazole. The systems were pharmaceutically characterized with regard to inter alia their release kinetics under different pH conditions, physicomechanical, or mucoadhesion properties with using an animal model of the buccal mucosa. The antifungal activity against selected Candida sp. and potential cytotoxicity with regard to human gingival fibroblasts were also evaluated. Interactions between polyions were characterized with Fourier transform infrared spectroscopy. Different clotrimazole distribution in the films layers highly affected their in vitro dissolution profile. The designed films were recognized as intelligent pH-responsive systems with strong antifungal effect and satisfactory safety profile. As addition of chitosan resulted in the improved antifungal behavior of the drug, the potential utilization of the films in resistant cases of oral candidiasis might be worth of further exploration.

Pectin in biomedical and drug delivery applications: A review

Natural macromolecules have attracted increasing attention due to their biocompatibility, low toxicity, and biodegradability. Pectin is one of the few polysaccharides with biomedical activity, consequently a candidate in biomedical and drug delivery Applications. Rhamnogalacturonan-II, a smaller component in pectin, plays a major role in biomedical activities. The ubiquitous presence of hydroxyl and carboxyl groups in pectin contribute to their hydrophilicity and, hence, to the favorable biocompatibility, low toxicity, and biodegradability. However, pure pectin-based materials present undesirable swelling and corrosion properties. The hydrophilic groups, via coordination, electrophilic addition, esterification, transesterification reactions, can contribute to pectin's physicochemical properties. Here the properties, extraction, and modification of pectin, which are fundamental to biomedical and drug delivery applications, are reviewed. Moreover, the synthesis, properties, and performance of pectin-based hybrid materials, composite materials, and emulsions are elaborated. The comprehensive review presented here can provide valuable information on pectin and its biomedical and drug delivery applications.

Tuning Functional Behavior of Humic Acids through Interactions with Stöber Silica Nanoparticles

Humic acids (HA) exhibit fascinating multifunctional features, yet degradation phenomena as well as poor stability in aqueous environments strongly limit their use. Inorganic nanoparticles are emerging as a powerful interface for the development of robust HA bio-hybrid materials with enhanced chemical stability and tunable properties. Hybrid organic-inorganic SiO2/HA nanostructures were synthesized via an in-situ sol-gel route, exploiting both physical entrapment and chemical coupling. The latter was achieved through amide bond formation between carboxyl groups of HA and the amino group of 3-aminopropyltriethoxysilane (APTS), as confirmed by Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. Monodisperse hybrid nanoparticles about 90 nm in diameter were obtained in both cases, yet Electron Paramagnetic Resonance (EPR) spectroscopy highlighted the different supramolecular organization of HA. The altered HA conformation was reflected in different antioxidant properties of the conjugated nanoparticles that, however, resulted in being higher than for pure HA. Our findings proved the key role of both components in defining the morphology of the final system, as well as the efficacy of the ceramic component in templating the HA supramolecular organization and consequently tuning their functional features, thus defining a green strategy for bio-waste valorization.