Preparation and characterization of 3D graphene oxide nanostructures embedded with nanocomplexes of chitosan- gum Arabic biopolymers

Shifting archetype to nature's hidden gems: from sources, purification to uncover the nutritional potential of bioactive peptides

Contemporary scientific findings revealed that our daily food stuffs are enriched by encrypted bioactive peptides (BPs), evolved by peptide linkage of amino acids or encrypted from the native protein structures. Remarkable to these BPs lies in their potential health benefiting biological activities to serve as nutraceuticals or a lead addition to the development of functional foods. The biological activities of BPs vary depending on the sequence as well as amino acid composition. Existing database records approximately 3000 peptide sequences which possess potential biological activities such as antioxidants, antihypertensive, antithrombotic, anti-adipogenics, anti-microbials, anti-inflammatory, and anti-cancerous. The growing evidences suggest that BPs have very low toxicity, higher accuracy, less tissue accretion, and are easily degraded in the disposed environment. BPs are nowadays evolved as biologically active molecules with potential scope to reduce microbial contamination as well as ward off oxidation of foods, amend diverse range of human diseases to enhance the overall quality of human life. Against the clinical and health perspectives of BPs, this review aimed to elaborate current evolution of nutritional potential of BPs, studies pertaining to overcome limitations with respect to special focus on emerging extraction, protection and delivery tools of BPs. In addition, the nano-delivery mechanism of BP and its clinical significance is detailed. The aim of current review is to augment the research in the field of BPs production, identification, characterisation and to speed up the investigation of the incredible potentials of BPs as potential nutritional and functional food ingredient.

Preparation of superhydrophobic, green, and eco-friendly modified polylactic acid foams for separation oil from water

Developing a facile and green strategy to fabricate polymer foams with super hydrophobicity and eco-friendliness for large-scale oil-water separation remains a challenge. In this study, biocompatible polylactic acid polymer foam modified by nanochitosan and stearic acid was used to remove petroleum and organic contaminants in water. All three materials used to prepare and modify this foam are green and inexpensive. F₄d foam (prepared by solvent displacement method) and F₈d foam (prepared by freeze dryer) can selectively remove oil pollutants in water with a contact angle of 164.01° and 168.51°, respectively. The maximum absorption capacity of oil pollutants by F₄d and F₈d are related to chloroform with values of 32.7 g/g and 48.51 g/g, respectively. Also, the minimum absorption capacity is related to n-hexane with values of 24.83 g/g and 32.06 g/g. The absorption percentage range of F₄d and F₈d foams after 15 cycles of absorption-desorption for chloroform is 82.56 % and 87.81 %, respectively, and for n-hexane, is 77.28 % and 85.99 %, respectively. During the continuous water-oil pumping test, the efficiency of foam can be maintained for >15 h, which shows promising hope for large-scale oil pollution cleaning.

Preparation, characterization and immune activity of Codonopsis pilosula polysaccharide loaded in chitosan-graphene oxide

The purpose of this study was to investigate the effects of chitosan graphene oxide Codonopsis pilosula polysaccharide (CS-GO-CPP) complex on the immune function of macrophage cells (RAW264.7). In this experiment, chitosan (CS) was combined with graphene oxide (GO) by electrostatic action to prepare CS-GO nanocomposites, and it was used as a carrier to load Codonopsis pilosula polysaccharide (CPP) onto CS-GO to prepare CS-GO-CPP. Using infrared spectroscopy detection, zeta potential detection, and thermogravimetric analysis, we conduct a preliminary analysis of the structure of CS-GO-CPP. Macrophages were employed to evaluate CS-GO-CPP immunomodulatory activity and the possible mechanism responsible for the activation of macrophages in vitro. The results showed that compared with CPP, CS-GO-CPP did not change the basic structure of polysaccharide, and its thermal stability was improved. 0.78- 12.5 μg·mL^-1 of CS-GO-CPP could significantly promote the phagocytic activity of RAW264.7 cells (P < 0.05) and significantly increase NO content, IL-4 and IFN-γ secretion, the expression of CD40, CD86, and F4/80 (P < 0.05). CS-GO-CPP might activate the NF-κB signaling pathway and induce the nuclear translocation of NF-κB p65. In conclusion, CS-GO-CPP has a capacity to activate RAW264.7 cells for an improvement of immunomodulation activities, which might be through NF-κB signaling pathway.

Performance of novel GO-Gly/HNTs and GO-GG/HNTs nanocomposites for removal of Pb(II) from water: optimization based on the RSM-CCD model

For the first time, in this study, two novel glycogen-graphene oxide/halloysite nanotubes (GO-Gly/HNTs) and guar gum-graphene oxide/halloysite nanotubes (GO-GG/HNTs) nanocomposites were synthesized as the adsorbents for removal of Pb(II) from water, and the ionic liquid was used in the synthesis as a green solvent. According to the SEM, TEM, EDS, BET, zeta potential, FTIR, and XRD results, GO-Gly/HNTs and GO-GG/HNTs were synthesized successfully. Response surface methodology (RSM) was applied to optimize the experimental conditions. Nanocomposites followed the Langmuir equilibrium model and were best fitted to the pseudo-second-order model. According to the thermodynamic model, the adsorption process was endothermic. Due to several features, these two novel nanocomposites can be considered the proper candidate for Pb(II) removal from water and wastewater. First, these nanocomposites have good adsorption capacity for Pb(II) removal, which is 219 mg/g for GO-Gly/HNTs and 315 mg/g for GO-GG/HNTs. Moreover, nanocomposites can be recycled with proper adsorption capacity after four repeated cycles. These materials can be used to remove Pb(II) from water in the presence of other contaminants because nanocomposites have selective tendency toward Pb(II) in the presence of other pollutants such as Cd²⁺, Cu²⁺, Cr²⁺, and Co²⁺. In addition, the presence of Ca²⁺, Mg²⁺, Na⁺, and K⁺ improve Pb(II) removal. Finally, possible mechanisms for each nanocomposite were represented.

Surface-decorated graphene oxide sheets with nanoparticles of chitosan-Arabic gum for the separation of bioactive compounds: A case study for adsorption of crocin from saffron extract

This work provides a new perception toward the application of the graphenic-biopolymeric composites as a solid-bed for separation and purification of bioactive compounds. Graphene oxide nanocomposites with functionalized sheets by soluble and insoluble nanocomplexes of chitosan and Arabic gum, were successfully synthesized and employed for the adsorption and purification of crocin, a nutraceutical from saffron. The composites exhibited a nanostructured scaffold with a particle size of 10 nm and experienced an unprecedented increase in the surface area by about 300% and improved d-spacing sheets by 17%. The optimum conditions for crocin separation were temperature = 318 K, stirring rate = 300 rpm, initial concentration = 100 mg L^-1 and pH = 6. Under these conditions, the nanocomposites separated 99.1% of crocin in an equilibrium time of 30 min. The adsorption data were best represented by Freundlich isotherm and pseudo-second-order kinetic models. The thermodynamic studies indicated that the crocin adsorption on nanocomposites was an endothermic, spontaneous and physisorption process. The high-performance liquid chromatography (HPLC) analysis revealed that produced nanocomposites adsorbed crocin efficiently from saffron extract with a purity similar to the standard sample. The possible interaction mechanisms between crocin and nanocomposites were electrostatic interactions and hydrogen bonding.

Evaluation on Structural Properties and Performances of Graphene Oxide Incorporated into Chitosan/Poly-Lactic Acid Composites: CS/PLA versus CS/PLA-GO

In this work, to fabricate a novel composite consisting of chitosan/poly-lactic acid doped with graphene oxide (CS/PLA-GO), composites were prepared via solution blending method to create various compositions of CS and PLA (90/10, 70/30 and 50/50CS/PLA-GO). Graphene oxide (GO) was added into a PLA solution prior to blending it with chitosan (CS). The surface morphology and structural properties of synthesized composites were characterized using FT-IR, SEM and XRD analysis. The performances of synthesized composites on thermal strength, mechanical strength, water absorption, and microbial activity were also evaluated through standard testing methods. The morphology of 70/30CS/PLA-GO became smoother with the addition of GO due to enhanced interfacial adhesion between CS, PLA and GO. The presence of GO has also improved the miscibility of CS and PLA and has superior properties compared to CS/PLA composites. Moreover, the addition of GO has boosted the thermal stability of the composite, with a significant enhancement of T_d and T_g. The highest T_d and T_g were accomplished at 389 °C and 76.88 °C, respectively, for the 70/30CS/PLA-GO composite in comparison to the CS and PLA that recorded T_d at 272 °C and 325 °C and T_g at 61 °C and 60 °C, respectively. In addition, as reinforcement, GO provided a significant influence on the tensile strength of composites where the tensile modulus showed remarkable improvement compared to pure CS and CS/PLA composites. Furthermore, CS/PLA-GO composites showed excellent water-barrier properties. Among other compositions, 70/30CS/PLA revealed the greatest decrement in water absorption. From the antibacterial results, it was observed that 90/10CS/PLA-GO and 70/30CS/PLA-GO showed an inhibitory effect and had wide inhibition zones which were 8.0 and 8.5 mm, respectively, against bacteria Bacillus Subtillis B29.

Bio-nanocomposites of graphene with biopolymers; fabrication, properties, and applications

The unique properties of graphene and graphene oxide (GO) nanocomposites make them suitable for a wide range of medical, industrial, and agricultural applications. The addition of graphene or GO to a polymeric matrix can ameliorate its thermo-mechanical, electrical, and barrier characteristics. The present paper reviews the literature on graphene/GO-based bio-nanocomposites and examines the various fabrication methods, such as chemical vapor deposition, chemical synthesis, microwave synthesis, the solvothermal method, molecular beam epitaxy, and colloidal suspension. Each procedure potentially has its disadvantages, especially for mass production. Therefore, introducing an effective method for fabricating graphene on a large scale with high quality is essential. Recent studies have shown that graphene-based bio-nanocomposites are promising materials given their excellent performance in the development of biosensors, drug delivery systems, antimicrobials, modified electrodes, and energy storage systems among other applications. In this review, we evaluate the various procedures used for developing graphene/GO-based bio-nanocomposites and examine the features and applications of the related products. Furthermore, the toxicity of these compounds and attempts to uncover the optimal combinations of biopolymers and carbon nanomaterials for industrial applications will be discussed.

Two Fascinating Polysaccharides: Chitosan and Starch. Some Prominent Characterizations for Applying as Eco-Friendly Food Packaging and Pollutant Remover in Aqueous Medium. Progress in Recent Years: A Review

The call to use biodegradable, eco-friendly materials is urgent. The use of biopolymers as a replacement for the classic petroleum-based materials is increasing. Chitosan and starch have been widely studied with this purpose: to be part of this replacement. The importance of proper physical characterization of these biopolymers is essential for the intended application. This review focuses on characterizations of chitosan and starch, approximately from 2017 to date, in one of their most-used applications: food packaging for chitosan and as an adsorbent agent of pollutants in aqueous medium for starch.