Electrospinning of commercial guar-gum: Effects of purification and filtration

A comprehensive review on guar gum and its modified biopolymers: Their potential applications in tissue engineering

Guar gum (GG), as a non-exudate gum, is extracted from the seed's embryos of Cyamopsis tetragonoloba (a member of Leguminosae family). Recently, this biopolymer has received extensive attention due to its low cost, notable properties, non-toxic biodegradation, ease of availability, and biocompatibility. However, disadvantages such as uncontrolled hydration rate and susceptibility to microbial attack have led many researchers to further modification of guar gum. Further modifications of guar gum heteropolysaccharide have been performed to improve properties and explore and expand its potential. The favorable biostability, improved solubility, and swelling, increased pH sensitivity, and good antibacterial and antioxidant properties indicate the significant advantages of the modified gum structures with different functional groups. In this review, the rapid growth in research on GG derivatives-based materials has been discovered. Besides, the production methods of GG and its derivatives have been discussed in tissue engineering and regenerative medical. Consequently, this review highlights the advances in the production of guar-based products to outline a promising future for this biopolymer by changing its properties and expanding its applications in potential targets.

Green fabrication of hierarchical pore starch with controllable pore size and shape based on different amylose-amylopectin ratios

Porous starch (PS) was widely prepared for its large effective surface area, pore volume, and superior hydrophilic property, but its application is limited by enzyme and chemical use. In this study, a novel method to prepare PS with controllable hierarchical pores through ultrasound-ethanol precipitation and different amylose-amylopectin ratios is proposed. As shown in porous morphology and parameters, there were macropores, mesopores and micropores in the formed PS. Moreover, we found that the content of amylose (AM) was negatively related with the total pore volume and pore diameter in PS. The different surface tensions created through ethanol evaporation and water migration during oven drying are the main mechanisms of forming pores with controllable sizes. Based on the molecular information and the long-/short-range orders reflected by crystalline pattern, lamellas, and single-/double-helices, we conclude that AM is easier to form V-type inclusion complexes with ethanol. More single helix of V-amylose was transformed from B-type polymorph after ethanol exchange, which had significantly broadened dLozentz in PS. The TG spectra proved that the novel PS has the stable thermodynamic property. Overall, the finding of an objective regular between AM and pore sizes of PS in this study may support the other work related to PS.

Fabrication, Characterization, and Microbial Biodegradation of Transparent Nanodehydrated Bioplastic (NDB) Membranes Using Novel Casting, Dehydration, and Peeling Techniques

NDBs were fabricated from gum Arabic (GA) and polyvinyl alcohol (PVA) in different ratios using novel techniques (casting, dehydration, and peeling). The GA/PVA blends were cast with a novel vibration-free horizontal flow (VFHF) technique, producing membranes free of air bubble defects with a homogenous texture, smooth surface, and constant thickness. The casting process was achieved on a self-electrostatic template (SET) made of poly-(methyl methacrylate), which made peeling the final product membranes easy due to its non-stick behavior. After settling the casting of the membranous, while blind, the sheets were dried using nanometric dehydration under a mild vacuum stream using a novel stratified nano-dehydrator (SND) loaded with P2O5. After drying the NDB, the dry, smooth membranes were peeled easily without scratching defects. The physicochemical properties of the NDBs were investigated using FTIR, XRD, TGA, DTA, and AFM to ensure that the novel techniques did not distort the product quality. The NDBs retained their virgin characteristics, namely, their chemical functional groups (FTIR results), crystallinity index (XRD data), thermal stability (TGA and DTA), and ultrastructural features (surface roughness and permeability), as well as their microbial biodegradation ability. Adding PVA enhanced the membrane's properties except for mass loss, whereby increasing the GA allocation in the NDB blend reduces its mass loss at elevated temperatures. The produced bioplastic membranes showed suitable mechanical properties for food packaging applications and in the pharmaceutical industry for the controlled release of drugs. In comparison to control samples, the separated bacteria and fungi destroyed the bioplastic membranes. Pseudomonas spp. and Bacillus spp. were the two main strains of isolated bacteria, and Rhizobus spp. was the main fungus. The nano-dehydration method gave the best solution for the prompt drying of water-based biopolymers free of manufacturing defects, with simple and easily acquired machinery required for the casting and peeling tasks, in addition to its wonderful biodegradation behavior when buried in wet soil.

Properties of galactomannans and their textile-related applications-A concise review

Galactomannans are reserve carbohydrates in legume plants and are primarily extracted from their seeds. They contain galactose side chains throughout the mannose backbone and have unique features such as emulsifying, thickening, and gelling together with biodegradability, biocompatibility, and non-toxicity, which make them an appealing material. Guar gum and locust bean gum mainly are used in all galactomannan needed applications. Nonetheless, tara gum and fenugreek gum have also attracted considerable attention in recent decades. Despite the increased usage of galactomannans in the textile-related fields in recent years, there is no review article published yet. To fill this gap and to demonstrate the striking and increasing importance of galactomannans, a concise summary of the properties of common galactomannans and their comparisons is given first, followed by an account of recent developments and applications of galactomannans in the textile-related fields. The associated potential opportunities are also provided at the end of this review.

In Situ Synthesis of AZO-Np in Guar Gum/PVOH Composite Fiber Mats for Potential Bactericidal Release

Since the number of antibiotic-resistant bacterial infections is growing and cases are getting worse every year, the search for new alternative bactericidal wound dressing treatments is becoming crucial. Within this context, the use of polysaccharides from plants and seeds in innovative biopolymer technologies is of key importance. In this work, bio-nano-composite guar gum/polyvinyl alcohol (PVOH) membranes loaded with aluminum-doped zinc oxide nanoparticles were produced via electrospinning. Citric acid was added to the mixture to increase spinnability. However, depending on the pH, zinc oxide nanoparticles are partially dissociated, decreasing their bactericidal efficiency. Thus, a second successful alkaline thermo-chemical regrowth step was added to the process to treat the obtained fibers. This alkaline thermo-chemical treatment reconstituted both the nanoparticles and their bactericidal properties. The Staphylococcus aureus antibacterial assay results show that the membranes obtained after the alkaline thermo-chemical treatment presented a 57% increase in growth inhibition.

Morphological study of electrospun chitosan/poly(vinyl alcohol)/glycerol nanofibres for skin care applications

This study aimed to evaluate the influence of formulation and procedure parameters in obtaining thick and continuous chitosan/PVA/glycerol nanofibres to be applied in skin care. For that, the polymers were characterized by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and size-exclusion chromatography. After this, 96 chitosan/PVA/glycerol nanofibre scaffolds were prepared by electrospinning method, using factorial designs. The independent variables were crude and pure chitosan, 2 brands of PVA, 2 needle gauges, high and low polymer concentration, high and low glycerol concentration, and final solution with and without ultrafiltration. Morphological analysis was performed by scanning electron microscopy, atomic force microscopy, and confocal microscopy. The best sample (NF67) presented an average thickness of 268.3 nm, uniform distribution, and high yield. It was obtained at a 1:3.5 (crude chitosan: PVA with lower molecular weight, but more hydrolysed) ratio and lower glycerol concentration, suggesting that the degree of hydrolysis of the PVA is more important than its molecular weight for obtaining better quality nanofibres and that the glycerol also makes the electrospinning process difficult. Thus, it was possible to choose parameters that provide scaffolds that could be applied as a matrix extracellular-like material in wound healing.

Bio nanocomposites of graphene oxide with carboxymethyl guargum: fabrication and characterization and application for type 1 diabetes

Islet cells transplantation has limitations like low survivability, which can be overcome by using extracellular matrix mimicking three-dimensional (3D) scaffolds, which supports the growth and proliferation of seeded cells. This study was aimed to investigate the role of novel 3D carboxymethyl guargum (CMGG) nanocomposite with reduced graphene oxide (rGO) for proliferation of pancreatic islet cells (RIN-5F) and rate of insulin secretion of RIN-5F cells. Scanning electron microscope and Fourier transform infrared results have demonstrated good porosity and the chemical interactions between CMGG and rGO. Mechanical testing and thermogravimetric analysis of nanofibers have shown good tensile strength and thermal stability with rGO in the nanocomposite. These scaffolds demonstratedin vitrobiocompatibility with acceptable ranges of biodegradability and hemocompatibility. Thein vitrocell proliferation and viability of RIN-5F cells on 3D CMGG nanofibers have significantly increased compared to two-dimensional (2D) cell control. Moreover, the glucose dependent insulin secretion of RIN-5F cells on CMGG nanocomposite has significantly increased upto 4-5 folds than cells on 2D cell control. The biomaterials used in this 3D nanofiber scaffold have shown to be biodegradable and hemocompatible and can be a promising platform for the proliferation and secretion of insulin from beta cells and can be effectively used in transplantation type-1 diabetes.

Electrospun fibers based on carbohydrate gum polymers and their multifaceted applications

Electrospinning has garnered significant attention in view of its many advantages such as feasibility for various polymers, scalability required for mass production, and ease of processing. Extensive studies have been devoted to the use of electrospinning to fabricate various electrospun nanofibers derived from carbohydrate gum polymers in combination with synthetic polymers and/or additives of inorganic or organic materials with gums. In view of the versatility and the widespread choice of precursors that can be deployed for electrospinning, various gums from both, the plants and microbial-based gum carbohydrates are holistically and/or partially included in the electrospinning solution for the preparation of functional composite nanofibers. Moreover, our strategy encompasses a combination of natural gums with other polymers/inorganic or nanoparticles to ensue distinct properties. This early established milestone in functional carbohydrate gum polymer-based composite nanofibers may be deployed by specialized researchers in the field of nanoscience and technology, and especially for exploiting electrospinning of natural gums composites for diverse applications.

Gum-based nanocarriers for the protection and delivery of food bioactive compounds

Gums, which for the most part are water-soluble polysaccharides, can interact with water to form viscous solutions, emulsions or gels. Their desirable properties, such as flexibility, biocompatibility, biodegradability, availability of reactive sites for molecular interactions and ease of use have led to their extremely large and broad applications in formation of nanostructures (nanoemulsions, nanoparticles, nanocomplexes, and nanofibers) and have already served as important wall materials for a variety of nano encapsulated food ingredients including flavoring agents, vitamins, minerals and essential fatty acids. The most common gums used in nano encapsulation systems include Arabic gum, carrageenan, xanthan, tragacanth plus some new sources of non-traditional gums, such as cress seed gum and Persian/or Angum gum identified as potential building blocks for nanostructured systems. New preparation techniques and sources of non-traditional gums are still being examined for commercialization in the food nanotechnology area as low-cost and reproducible sources. In this study, different nanostructures of gums and their preparation methods have been discussed along with a review of gum nanostructure applications for various food bioactive ingredients.

Fabrication of Guar-Only Electrospun Nanofibers by Exploiting a High- and Low-Molecular Weight Blend

We present a facile approach to electrospin nanofibers of guar galactomannan by blending high- and low-molecular weights (MWs) of guar. We discover that while neither native high MW guar nor hydrolyzed low MW guar is electrospinnable on its own, their combination leads to synergism in producing defect-free nanofibers. Such an approach of fabricating nanofibers from blending multiple MWs of the same polymer may provide an easy route to produce nanofibers of biopolymers which are typically hard to electrospin. Rheological studies reveal that a limiting amount of native guar is needed for electrospinnability, and for those systems that have the proportionate amount of native guar, there is a critical total concentration above which fibers form. Interestingly, a plot of blend viscosity versus guar concentration reveals two power-law regimes with an inflection point, above which fiber formation can be achieved akin to the behavior observed for pure (i.e., nonblend) polymers.

Incorporation of Tannic Acid in Food-Grade Guar Gum Fibrous Mats by Electrospinning Technique

The use of polysaccharides to produce functional micro- or nanoscale fibrous mats has attracted growing interest for their food-grade applications. In this study, the characterization and electro-spinnability of guar gum (GG) solutions loaded with tannic acid (TA) was demonstrated. Food-grade antioxidant materials were successfully produced by electrospinning while incorporating different loads of TA into GG fibers. Bead-free GG-TA fibers could be fabricated from GG solution (2 wt %) with 10 wt % TA. Increasing the amount of TA led to fibers with defects and larger diameter sizes. Fourier Transformed Infrared Spectroscopy and X-ray Diffraction of neat GG and TA loaded GG fibrous mats suggested that inclusion of TA interrupted the hydrogen bonding and that a higher density of the ordered junction zones formed with the increased TA. The high TA incorporation efficiency and retained antioxidant activity of the fibrous mats afford a potential application in active edible film or drug delivery system.

Production of electrospun nanofibers based on graphene oxide/gum Arabic

Over the last few years, the electrospinning technique has attracted significant attention for the production of novel nanofibrous materials. At the same time, the use of graphene oxide and the natural products extracted from plants and/or trees have become very popular in various fields of science. In this work, a new method for the production of nanofibers based on a combination of Gum Arabic (GA), as a natural tree gum exudate, PVA, as an environmentally-friendly stabilizer, and graphene oxide (GO) has been developed and characterized. SEM analysis showed fundamental differences on the surface of bare nanofibers with and without GO, and also significantly smaller fiber diameters in the case of the presence of GO (fibers <100 nm present). Raman spectroscopy confirmed and TGA analysis approximated the content of GO in the nanofibers. Adsorption of methylene blue on the produced nanofibrous membrane was about 50% higher in the presence of GO, which opens the possibility to use GO/GA/PVA fibers in several applications, for example for the removal of dyes.

Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields

The prospective uses of tree gum polysaccharides and their nanostructures in various aspects of food, water, energy, biotechnology, environment and medicine industries, have garnered a great deal of attention recently. In addition to extensive applications of tree gums in food, there are substantial non-food applications of these commercial gums, which have gained widespread attention due to their availability, structural diversity and remarkable properties as 'green' bio-based renewable materials. Tree gums are obtainable as natural polysaccharides from various tree genera possessing exceptional properties, including their renewable, biocompatible, biodegradable, and non-toxic nature and their ability to undergo easy chemical modifications. This review focuses on non-food applications of several important commercially available gums (arabic, karaya, tragacanth, ghatti and kondagogu) for the greener synthesis and stabilization of metal/metal oxide NPs, production of electrospun fibers, environmental bioremediation, bio-catalysis, biosensors, coordination complexes of metal-hydrogels, and for antimicrobial and biomedical applications. Furthermore, polysaccharides acquired from botanical, seaweed, animal, and microbial origins are briefly compared with the characteristics of tree gum exudates.

Fabricated approach for an effective wound dressing material based on a natural gum impregnated with Acalypha indica extract

Although acute wounds are common, treatment for a scarless condition remains limited and ineffective as medicated dressings act only as an epidermal coverage and no interdermal interactions happen. This study examined the benefit of Acalypha indica, a traditionally acclaimed plant for wound healing, as a three-dimensional nanofibrous dressing. guar gum, a natural polysaccharide, was chosen as the raw material, in combination with a synthetic copolymer polyvinyl alcohol. A series of polymer blend nanofibers made of 3:7 of 1% wt guar and 10% wt polyvinyl alcohol along with varied ratios of A. indica were prepared using electrospinning. The effect of cross-linking by citric acid on the nanofibers was studied using Fourier transform infrared. A 5% wt A. indica content was optimized in the electrospun solution to get nanosized morphology, roughness, water absorbing capacity, thermal stability, and tensile strength. The composite material was found inhibitory to both Gram-positive and Gram-negative strains as measured by zone of inhibition. The ability of the dressing to support and proliferate human dermal fibroblasts was evaluated by cell proliferation assay and Calcein acetomethyl (AM) staining assay. The results confirmed that the composite dressing could support long-term cell growth in the 9-day cell culture study. The incorporation of A. indica to guar/polyvinyl alcohol composite nanofibers has thus resulted in a wound dressing material with nanosized morphology for mimicking the extracellular matrix, surface roughness for the absorbtion of proteins, swelling capacity for the absorption of exudates, antimicrobial activity for prevention of microbial infections, and cell proliferation activity for the complete wound closure. The electrospun guar/polyvinyl alcohol/ A. indica composite which proved to be a suitable dressing for acute wounds when ascertained in vitro can surely be developed as an ethical plant bioactive wound healant.

Thermal stability and haemolytic effects of depolymerized guar gum derivatives

The purpose of current study was to purify and partially depolymerize guar gum by β-mannanase, HCl, Ba(OH)₂ actions and subjected to inspect compositional, thermogravimetric analysis (TGA) and haemolytic activity. Chemical composition revealed mannose and galactose ratio remained un-altered even after process of purification and hydrolysis. TGA thermograms affirmed initial and final decomposition temperature in various zones. Major decomposition stages apparently revealed partially hydrolyzed guar gum (PHGG) exhibited better heat stable properties having more zones of degradation than crude one. Furthermore, all guar fractions (2.5-250 mg/mL) were subjected to haemolysis to evaluate toxic effects during process of hydrolysis. The crude and hydrolyzed guar galactomannans exhibited minor haemolytic activity (1.9 ± 0.03-7.24 ± 0.02%) when compared to 0.1% Triton-X 100 (100% haemolysis) showing no toxic effects to human RBC's. Conclusively, hydrolyzed guar-galactomannans are safe and can be used in food products with improved heat stability.

Characterization of Fractional Polysaccharides from Gleditsia sinensis and Gleditsia microphylla Gums

The seeds of Gleditsia sinensis and Gleditsia microphylla, widespread in China, are an important source of galactomannans. G. sinensis gum (GSG) and G. microphylla gum (GMG) were purified and precipitated using different concentrations of ethanol and isopropanol. The GSG and GMG, precipitated in different stages, presented different characteristics, including polymer recovery, mannose/galactose ratio, chemical composition, molecular weight, and morphological appearance. The galactomannan recovery of GSG and GMG in 33.3% ethanol was 81.7% and 82.5%, respectively, while that in 28.8% isopropanol was 81.3% and 82.9%, respectively. To achieve similar precipitation efficiency, the amount of isopropanol should be lower than that of ethanol because of the lower dielectric constant of isopropanol (20 vs. 25 for ethanol). The precipitation behavior of galactomannans in polar organic solvents was dependent on the molecular structures and properties of the solvent. A higher mannose/galactose ratio and a higher molecular weight was obtained in a lower concentration of alcohols.

TEMPO-mediated oxidation on galactomannan: Gal/Man ratio and chain flexibility dependence

Guar (GG) and locust bean (LBG) galactomannans (GMs) oxidation at C-6 was performed with catalyst TEMPO, in which the reaction progress was monitored by consume of NaOH solution. The products were characterized by spectroscopic analysis, infrared, and (1)H-nuclear magnetic resonance, confirming the presence of aldehydes groups as intermediate of reaction to carboxylic acid. From high performance anion exchange chromatography with pulsed amperometric detection Man/Gal molar ratio was determined and demonstrated a preference to oxidize Man during the reaction on both GMs, following a first order kinetics of oxidation. The comparative macromolecular behavior of native and oxidized GMs was obtained through the analysis by high performance size exclusion chromatography, and the persistence length (Lp) was 6nm and 4nm to native LBG and GG, respectively. A more accessible OH-6 at mannose residue in LBG could be related with a two times faster reaction than GG. The selective oxidation with catalyst TEMPO proved to be efficient to increase the flexibility of the GMs during oxidation. Short reaction time and β-elimination process were mainly observed to LBG, probably due to a more favorable oxidation access to the polysaccharide main chain.

Electrospun fibers based on Arabic, karaya and kondagogu gums

Nanofibers of natural tree polysaccharides based on three gums namely Arabic (GA), karaya (GK) and kondagogu (KG) have been prepared for the first time using electrospinning. Electrospinning solutions were prepared by mixing gum solutions of GA, GK & KG with eco-friendly polymers such as polyvinyl alcohol (PVA) or polyethylene oxide (PEO). The present study focuses on the effect of electrospinning blended solutions of GA, GK or KG with PVA or PEO, additives which influence system parameters and process parameters. This has important effects on the electrospinning process and the resulting fibers whose morphology and physicochemical properties were evaluated. The mass ratios of 70:30 to 90:10 for PVA: GA, PVA: GK and PVA: KG were observed to establish an optimum blend solution ratio in order to fabricate uniform beadless nanofibers with an average diameter of 240±50, 220±40 and 210±30nm, respectively. Various structural and physicochemical properties of the electrospun fibers were investigated. Furthermore, the comparisons of various functionalities of the untreated and plasma treated electrospun fibers were assessed. The methane plasma treated nanofibers were shown to be of extremely specific surface area, improved water contact angle, high surface porosity and roughness and superior hydrophobic properties compared to untreated fibers.

Tuning Fe3O4 nanoparticle dispersion through pH in PVA/guar gum/electrospun membranes

Polyvinyl Alcohol (PVA)/guar gum (GG) membranes with different loads of paramagnetic iron oxide Fe3O4 nanoparticles were successfully electrospun using both non-alkaline and alkaline stock solutions. The nanoparticle homogeneity distribution was clearly enhanced in fibers obtained from alkaline stock solutions. This is mainly due to the interaction between GG and the metallic ion, which also leads to further dispersion of remained uncoated nanoparticles in the mixture. It was also noticed that GG favors nanoparticle stability in the mixture and contributes to nanoparticle encapsulation. X-ray results showed that all membranes were semi-crystalline. FTIR-ATR spectra showed that Fe-O absorption band intensity improved with increasing nanoparticle load, reaching saturation at 3.5mg/ml Fe3O4 concentration under alkaline conditions. VSM analyses showed that the nanoparticles are paramagnetic and were successfully incorporated by the fibers. In vitro biocompatibility tests using L929 cells indicates adequate levels of cytotoxicity and cell adhesion/proliferation assays for both membranes obtained from non-alkaline and alkaline stock solutions. Therefore, they have potential for biomedical applications as biodegradable wound dressing.

Poly (vinyl alcohol)/gum karaya electrospun plasma treated membrane for the removal of nanoparticles (Au, Ag, Pt, CuO and Fe3O4) from aqueous solutions

In the present work, nanofibre membranes composed of polyvinyl alcohol (PVA) and a natural gum karaya (GK) hydrocolloid were prepared using electrospinning. The electrospun membranes of PVA/GK were cross-linked with heat treatment and later methane plasma was used to obtain a hydrophobic membrane. The morphology, characterization and adsorption ability of P-NFM was assessed using scanning electron microscopy, UV-vis spectroscopy, ATR-FTIR techniques, water contact angle and ICP-MS analytical methods. The membrane was employed for the extraction of nanoparticles (Ag, Au, Pt, CuO and Fe3O4) from water. The nanoparticle extraction kinetic and adsorption isotherm perform the pseudo-second-order model and Langmuir isotherm model, respectively. The adsorption capacities of the membrane for the removal of NPs from water diverge in the order Pt>Au>Ag>CuO>Fe3O4. The high adsorption efficiency for the removal of NPs from water was compared with an untreated membrane. Physisorption, functional group interactions, complexation reactions between metal/metal oxide nanoparticles with various functional groups present in NFM and modified surface properties such as the balance of hydrophilicity/hydrophobicity, surface free energy, and the high surface area of the plasma treated membrane were possible mechanisms of NPs adsorption onto NFM. The regeneration and reusability were tested in five consecutive adsorption/desorption cycles.

Characterization and evaluation of curcumin loaded guar gum/polyhydroxyalkanoates blend films for wound healing applications

Schematic representation of the blockage of UV rays and controlled release of curcumin on a wound.