Methyl cellulose solutions and gels: fibril formation and gelation properties

Artificial intelligence-based prediction of the rheological properties of hydrocolloids for plant-based meat analogues

BACKGROUND

Methylcellulose has been applied as a primary binding agent to control the quality attributes of plant-based meat analogues. H owever, a great deal of effort has been made to search for hydrocolloids to replace methylcellulose because of increasing awareness of clean labels. In this study, a machine learning framework was proposed in order to describe and predict the flow behavior of six hydrocolloid solutions, and the predicted viscosities were correlated with the textural features of their corresponding plant-based meat analogues.

RESULTS

Different shear-thinning and Newtonian behaviors were observed depending on the type of hydrocolloid and the shear rate. Methylcellulose exhibited an increasing viscosity pattern with increasing temperature, compared to the other hydrocolloids. The machine learning algorithms (random forest and multilayer perceptron models) showed a better viscosity fitting performance than the constitutive equations (power law and Cross models). In addition, three hyperparameters of the multilayer perceptron model (optimizer, learning rate, and the number of hidden layers) were tuned using the Bayesian optimization algorithm.

CONCLUSION

The optimized multilayer perceptron model exhibited superior performance in viscosity prediction (R2 = 0.9944-0.9961/RMSE = 0.0545-0.0708). Furthermore, the machine learning-predicted viscosities overall showed similar patterns to the textural parameters of the meat analogues. © 2024 Society of Chemical Industry.

Combined experiments and molecular simulations for understanding the thermo-responsive behavior and gelation of methylated glucans with different glycosidic linkages

HYPOTHESIS

Elucidation of the micro-mechanisms of sol-gel transition of gelling glucans with different glycosidic linkages is crucial for understanding their structure-property relationship and for various applications. Glucans with distinct molecular chain structures exhibit unique gelation behaviors. The disparate gelation phenomena observed in two methylated glucans, methylated (1,3)-β-d-glucan of curdlan (MECD) and methylated (1,4)-β-d-glucan of cellulose (MC), notwithstanding their equivalent degrees of substitution, are intricately linked to their unique molecular architectures and interactions between glucan and water.

EXPERIMENTS

Density functional theory and molecular dynamics simulations focused on the electronic property distinctions between MECD and MC, alongside conformational variations during thermal gelation. Inline attenuated total reflection Fourier transform infrared spectroscopy tracked secondary structure alterations in MECD and MC. To corroborate the simulation results, additional analyses including circular dichroism, rheology, and micro-differential scanning calorimetry were performed.

FINDINGS

Despite having similar thermally induced gel networks, MECD and MC display distinct physical gelation patterns and molecular-level conformational changes during gelation. The network of MC gel was formed via a "coil-to-ring" transition, followed by ring stacking. In contrast, the MECD gel comprised compact irregular helices accompanied by notable volume shrinkage. These variations in gelation behavior are ascribed to heightened hydrophobic interactions and diminished hydrogen bonding in both systems upon heating, resulting in gelation. These findings provide valuable insights into the microstructural changes during gelation and the thermo-gelation mechanisms of structurally similar polysaccharides.

Injectable in situ gelling methylcellulose-based hydrogels for bone tissue regeneration

Injectable bone substitutes (IBSs) represent a compelling choice for bone tissue regeneration, as they can be exploited to optimally fill complex bone defects in a minimally invasive manner. In this context, in situ gelling methylcellulose (MC) hydrogels may be engineered to be free-flowing injectable solutions at room temperature and gels upon exposure to body temperature. Moreover, incorporating a suitable inorganic phase can further enhance the mechanical properties of MC hydrogels and promote mineralization, thus assisting early cell adhesion to the hydrogel and effectively guiding bone tissue regeneration. In this work, thermo-responsive IBSs were designed selecting MC as the organic matrix and calcium phosphate (CaP) or CaP modified with graphene oxide (CaPGO) as the inorganic component. The resulting biocomposites displayed a transition temperature around body temperature, preserved injectability even after loading with the inorganic components, and exhibited adequate retention on an ex vivo calf femoral bone defect model. The addition of CaP and CaPGO promoted the in vitro mineralization process already 14 days after immersion in simulated body fluid. Interestingly, combined X-ray diffraction and solid state nuclear magnetic resonance characterizations revealed that the formed biomimetic phase was constituted by crystalline hydroxyapatite and amorphous calcium phosphate. In vitro biological characterization revealed the beneficial impact of CaP and CaPGO, indicating their potential in promoting cell adhesion, proliferation and osteogenic differentiation. Remarkably, the addition of GO, which is very attractive for its bioactive properties, did not negatively affect the injectability of the hydrogel nor the mineralization process, but had a positive impact on cell growth and osteogenic differentiation on both pre-differentiated and undifferentiated cells. Overall, the proposed formulations represent potential candidates for use as IBSs for application in bone regeneration both under physiological and pathological conditions.

Characterization, Biocompatibility and Antioxidant Activity of Hydrogels Containing Propolis Extract as an Alternative Treatment in Wound Healing

Hydrogels consist of a network of highly porous polymeric chains with the potential for use as a wound dressing. Propolis is a natural product with several biological properties including anti-inflammatory, antibacterial and antioxidant activities. This study was aimed at synthesizing and characterizing a polyacrylamide/methylcellulose hydrogel containing propolis as an active ingredient, to serve as a wound dressing alternative, for the treatment of skin lesions. The hydrogels were prepared using free radical polymerization, and were characterized using scanning electron microscopy, infrared spectroscopy, thermogravimetry, differential scanning calorimetry, swelling capacity, mechanical and rheological properties, UV-Vis spectroscopy, antioxidant activity by the DPPH, ABTS and FRAP assays and biocompatibility determined in Vero cells and J774 macrophages by the MTT assay. Hydrogels showed a porous and foliaceous structure with a well-defined network, a good ability to absorb water and aqueous solutions simulating body fluids as well as desirable mechanical properties and pseudoplastic behavior. In hydrogels containing 1.0 and 2.5% propolis, the contents of total polyphenols were 24.74 ± 1.71 mg GAE/g and 32.10 ± 1.01 mg GAE/g and those of total flavonoids 8.01 ± 0.99 mg QE/g and 13.81 ± 0.71 mg QE/g, respectively, in addition to good antioxidant activity determined with all three methods used. Therefore, hydrogels containing propolis extract, may serve as a promising alternative wound dressing for the treatment of skin lesions, due to their anti-oxidant properties, low cost and availability.

Reductive amination of oxidized hydroxypropyl cellulose with ω-aminoalkanoic acids as an efficient route to zwitterionic derivatives

Zwitterionic polymers, with their equal amounts of cationic and anionic functional groups, have found widespread utility including as non-fouling coatings, hydrogel materials, stabilizers, antifreeze materials, and drug carriers. Polysaccharide-derived zwitterionic polymers are attractive because of their sustainable origin, potential for lower toxicity, and possible biodegradability, but previous methods for synthesis of zwitterionic polysaccharide derivatives have been limited in terms of flexibility and attainable degree of substitution (DS) of charged entities. We report herein successful design and synthesis of zwitterionic polysaccharide derivatives, in this case based on cellulose, by reductive amination of oxidized 2-hydroxypropyl cellulose (Ox-HPC) with ω-aminoalkanoic acids. Reductive amination products could be readily obtained with DS(cation) (= DS(anion)) up to 1.6. Adduct hydrophilic/hydrophobic balance (amphiphilicity) can be influenced by selecting the appropriate chain length of the ω-aminoalkanoic acid. This strategy is shown to produce a range of amphiphilic, water-soluble, moderately high glass transition temperature (Tg) polysaccharide derivatives in just a couple of efficient steps from commercially available building blocks. The adducts were evaluated as crystallization inhibitors. They are strong inhibitors of crystallization even for the challenging, poorly soluble, fast-crystallizing prostate cancer drug enzalutamide, as supported by surface tension and Flory-Huggins interaction parameter results.

Understanding Self-Assembly and Molecular Packing in Methylcellulose Aqueous Solutions Using Multiscale Modeling and Simulations

We present a multiscale molecular dynamics (MD) simulation study on self-assembly in methylcellulose (MC) aqueous solutions. First, using MD simulations with a new coarse-grained (CG) model of MC chains in implicit water, we establish how the MC chains self-assemble to form fibrils and fibrillar networks and elucidate the MC chains' packing within the assembled fibrils. The CG model for MC is extended from a previously developed model for unsubstituted cellulose and captures the directionality of H-bonding interactions between the -OH groups. The choice and placement of the CG beads within each monomer facilitates explicit modeling of the exact degree and position of methoxy substitutions in the monomers along the MC chain. CG MD simulations show that with increasing hydrophobic effect and/or increasing H-bonding strength, the commercial MC chains (with degree of methoxy substitution, DS, ∼1.8) assemble from a random dispersed configuration into fibrils. The assembled fibrils exhibit consistent fibril diameters regardless of the molecular weight and concentration of MC chains, in agreement with past experiments. Most MC chains' axes are aligned with the fibril axis, and some MC chains exhibit twisted conformations in the fibril. To understand the molecular driving force for the twist, we conduct atomistic simulations of MC chains preassembled in fibrils (without any chain twists) in explicit water at 300 and 348 K. These atomistic simulations also show that at DS = 1.8, MC chains adopt twisted conformations, with these twists being more prominent at higher temperatures, likely as a result of shielding of hydrophobic methyl groups from water. For MC chains with varying DS, at 348 K, atomistic simulations show a nonmonotonic effect of DS on water-monomer contacts. For 0.0 < DS < 0.6, the MC monomers have more water contacts than at DS = 0.0 or DS > 0.6, suggesting that with few methoxy substitutions, the MC chains are effectively hydrophilic, letting the water molecules diffuse into the fibril to participate in H-bonds with the MC chains' remaining -OH groups. At DS > 0.6, the MC monomers become increasingly hydrophobic, as seen by decreasing water contacts around each monomer. We conclude based on the atomistic observations that MC chains with lower degrees of substitutions (DS ≤ 0.6) should exhibit solubility in water over broader temperature ranges than DS ∼ 1.8 chains.

Formulation of Budesonide-Loaded Polymeric Nanoparticles into Hydrogels for Local Therapy of Atopic Dermatitis

Budesonide is a mineral corticoid applied in the local therapy of pediatric atopic dermatitis. Unfortunately, its dermal administration is hindered by the concomitant adverse effects and its physicochemical properties. The characteristic pH change in the atopic lesions can be utilized for the preparation of a pH-sensitive nanocarrier. In this view, the formulation of Eudragit L 100 nanoparticles as a budesonide delivery platform could provide more efficient release to the desired site, improve its penetration, and subsequently lower the undesired effects. In this study, budesonide-loaded Eudragit L100 nanoparticles were prepared via the nanoprecipitation method (mean diameter 57 nm, -31.2 mV, and approx. 90% encapsulation efficiency). Their safety was proven by cytotoxicity assays on the HaCaT keratinocyte cell line. Further, the drug-loaded nanoparticles were incorporated into two types of hydrogels based on methylcellulose or Pluronic F127. The formulated hydrogels were characterized with respect to their pH, occlusion, rheology, penetration, spreadability, and drug release. In conclusion, the developed hydrogels containing budesonide-loaded nanoparticles showed promising potential for the pediatric treatment of atopic dermatitis.

Rigid Rod-like Viscoelastic Behaviors of Methyl Cellulose Samples with a Wide Range of Molar Masses Dissolved in Aqueous Solutions

The viscoelastic behaviors of aqueous solutions of commercially available methyl cellulose (MC) samples with a degree of substitution of 1.8 and a wide range of weight average molar masses (Mw) were investigated over a wide concentration (c) range at some temperatures from -10 to 25 °C. The viscoelastic parameters useful to discuss the structure and dynamics of MC-forming particles in aqueous solutions were precisely determined, such as the zero-shear viscosity (η0), the steady-state compliance (Je), the average relaxation time (τw), and the activation energy (E*) of τw. Because previously obtained scattering and intrinsic viscosity ([η]) data revealed that the MC samples possess a rigid rod-like structure in dilute aqueous solutions over the entire Mw range examined, the viscoelastic data obtained in this study were discussed in detail based on the concept of rigid rod particle suspension rheology. The obtained Je-1 was proportional to the number density of sample molecules (ν = cNAMw-1, where NA means the Avogadro's constant) over the ν range examined irrespective of Mw. The reduced relaxation time (4NAτw(3νJe [η]ηmMw)-1), where ηm means the medium viscosity, was proportional to (νL3)2, L; the average particle length depending on Mw for each sample was determined in a previous study; and the reduced specific viscosity (ηspNAL3(Mw [η])-1), where ηsp means the specific viscosity, was proportional to (νL3)3 in a range of νL3 < 3 × 102. These findings were typical characteristics of the rigid rod suspension rheology. Therefore, the MC samples behave as entangling rigid rod particles in the νL3 range from rheological points of view. A stepwise increase in E* was clearly observed in a c range higher than the [η]-1 value irrespective of Mw. This observation proposes that contact or entanglement formation between particles formed by MC molecules results in an increase in E*.

Methylcellulose as a non-bonding gelling agent for calcium chloride methanol fuel gels

Carbohydrate-based fuel gels find diverse applications across industries ranging from renewable energy and transportation to military and emergency preparedness. This study investigates the thermal properties, gel characteristics, combustion performance, micro-, and nano-scale structure of methylcellulose (MC) in methanol and the effect of calcium chloride (CaCl2) addition. The results show that MC exhibits viscoelastic phase separation due to the lower critical solution temperature, resulting in gelation at the 22 wt%. Thermogravimetric analysis reveals good thermal stability of MC in methanol, with a single decomposition stage. Adding CaCl2 modifies rheological behavior and enhances the thermal properties of the MC/methanol gel, with improved combustion and ignition performance due to the formation of CaCl2-methanolates. Small-angle X-ray scattering analysis indicates changes in nanoscale aggregates, correlation length, and fractal dimension with increasing CaCl2 content. This study provides valuable insights into the properties of MC-based fuel gels and their potential applications.

Methyl cellulose/okra mucilage composite films, functionalized with Hypericum perforatum oil and gentamicin, as a potential wound dressing

There is a growing demand for the development of functional wound dressings enriched with bioactive natural compounds to improve the quality of life of the population by accelerating the healing process of chronic wounds. In this regard, a functional composite film of okra mucilage (OM) and methylcellulose (MC) incorporated with Hypericum perforatum oil (Hp) and gentamicin (G) was prepared and characterized as a wound dressing. Increasing Hp resulted in improved film properties with a more porous structure, higher WVTR, and lower surface hydrophobicity. Furthermore, incorporating Hp into OM:MC films led to increased elongation at the break while reducing the tensile strength of the films. The highest values of total antioxidant capacity (1.09-1.16 mM trolox equivalent) and total phenolic content (13.76-16.94 μg GA equivalent mL-1) were measured in the composite films containing the highest Hp concentration (1.5 %). In addition, OM:MC/HpG composite films exhibited significant antibacterial activity against both E. coli and S. aureus and prevented the transmission of these bacteria through the films. Hp incorporation reduced the cytotoxic effects of OM:MC films on BJ cells and increased the wound closure rate in vitro. In conclusion, the developed OM:MC/HpG composite film can be a promising candidate as a novel wound dressing with its superior properties.

A systematic approach to improve printability and cell viability of methylcellulose-based bioinks

Printability in 3D extrusion bioprinting encompasses extrudability, filament formation, and shape fidelity. Rheological properties can predict the shape fidelity of printed hydrogels. In particular, tan(δ), the ratio between loss (G'') and storage (G') modulus (G''/G'), is a powerful indicator of printability. This study explores the effect of different salt, sucrose, and MC concentrations on tan(δ), and therefore the printability of methylcellulose (MC) hydrogels. Salt and sucrose increased G', lowering tan(δ) and enabling printing of scaffolds with high shape fidelity. Conversely, MC concentration increased G'' and G', having a lesser effect on tan(δ). Shape fidelity of three formulations with similar G' but varying tan(δ) values were compared. Higher tan(δ) led to reduced height, while lower tan(δ) improved shape fidelity. Cell viability increased when reducing MC content, extrusion rate, and nozzle gauge. Higher MC concentration (G' > 1.5 kPa) increased the influence of needle size and extrusion rate on cell viability. Hydrogels with G' < 1 kPa could be extruded at high rates with small nozzles, minimally affecting cell viability. This work shows a direct relationship between tan(δ) and printability of MC-based hydrogels. Lowering the complex modulus of hydrogels, mitigates extrusion stress, thus improving cell survival.

High Viscosity Slows the Utilization of Rapidly Fermentable Dietary Fiber by Human Gut Microbiota

In the present study, the influence of viscosity on the fermentation characteristics of fructooligosaccharides (FOS) by gut microbiota was examined. Different concentrations of methylcellulose (MC) were added to create varying viscosities and the mixture was fermented with FOS by gut microbiota. The results demonstrated that higher viscosity had a significant impact on slowing down the fermentation rate of FOS. Specifically, the addition of 2.5 wt% MC, which had the highest viscosity, resulted in the lowest and slowest production of gas and short-chain fatty acids (SCFAs), indicating that increased viscosity could hinder the breakdown of FOS by gut microbiota. Additionally, the slower fermentation of FOS did not significantly alter the structure of the gut microbiota community compared to that of FOS alone, suggesting that MC could be used in combination with FOS to achieve similar prebiotic effects and promote gut health while exhibiting a slower fermentation rate.

Cellulosic Textiles-An Appealing Trend for Different Pharmaceutical Applications

Cellulose, the most abundant biopolymer in nature, is derived from various sources. The production of pharmaceutical textiles based on cellulose represents a growing sector. In medicated textiles, textile and pharmaceutical sciences are integrated to develop new healthcare approaches aiming to improve patient compliance. Through the possibility of cellulose functionalization, pharmaceutical textiles can broaden the applications of cellulose in the biomedical field. This narrative review aims to illustrate both the methods of extraction and preparation of cellulose fibers, with a particular focus on nanocellulose, and diverse pharmaceutical applications like tissue restoration and antimicrobial, antiviral, and wound healing applications. Additionally, the merging between fabricated cellulosic textiles with drugs, metal nanoparticles, and plant-derived and synthetic materials are also illustrated. Moreover, new emerging technologies and the use of smart medicated textiles (3D and 4D cellulosic textiles) are not far from those within the review scope. In each section, the review outlines some of the limitations in the use of cellulose textiles, indicating scientific research that provides significant contributions to overcome them. This review also points out the faced challenges and possible solutions in a trial to present an overview on all issues related to the use of cellulose for the production of pharmaceutical textiles.

Thermo-Responsive Hydrogels Coupled with Photothermal Agents for Biomedical Applications

Intelligent hydrogels are materials with abilities to change their chemical nature or physical structure in response to external stimuli showing promising potential in multitudinous applications. Especially, photo-thermo coupled responsive hydrogels that are prepared by encapsulating photothermal agents into thermo-responsive hydrogel matrix exhibit more attractive advantages in biomedical applications owing to their spatiotemporal control and precise therapy. This work summarizes the latest progress of the photo-thermo coupled responsive hydrogel in biomedical applications. Three major elements of the photo-thermo coupled responsive hydrogel, i.e., thermo-responsive hydrogel matrix, photothermal agents, and construction methods are introduced. Furthermore, the recent developments of these hydrogels for biomedical applications are described with some selected examples. Finally, the challenges and future perspectives for photo-thermo coupled responsive hydrogels are outlined.

Orthogonal Gelations to Synthesize Core-Shell Hydrogels Loaded with Nanoemulsion-Templated Drug Nanoparticles for Versatile Oral Drug Delivery

Hydrophobic active pharmaceutical ingredients (APIs) are ubiquitous in the drug development pipeline, but their poor bioavailability often prevents their translation into drug products. Industrial processes to formulate hydrophobic APIs are expensive, difficult to optimize, and not flexible enough to incorporate customizable drug release profiles into drug products. Here, a novel, dual-responsive gelation process that exploits orthogonal thermo-responsive and ion-responsive gelations is introduced. This one-step "dual gelation" synthesizes core-shell (methylcellulose-alginate) hydrogel particles and encapsulates drug-laden nanoemulsions in the hydrogel matrices. In situ crystallization templates drug nanocrystals inside the polymeric core, while a kinetically stable amorphous solid dispersion is templated in the shell. Drug release is explored as a function of particle geometry, and programmable release is demonstrated for various therapeutic applications including delayed pulsatile release and sequential release of a model fixed-dose combination drug product of ibuprofen and fenofibrate. Independent control over drug loading between the shell and the core is demonstrated. This formulation approach is shown to be a flexible process to develop drug products with biocompatible materials, facile synthesis, and precise drug release performance. This work suggests and applies a novel method to leverage orthogonal gel chemistries to generate functional core-shell hydrogel particles.

The level of sulfate substitution of polysaccharide regulates thermal-induced egg white protein gel properties: The characterization of gel structure and intermolecular forces

Sulfated polysaccharides exhibit great potential for regulating protein-protein interactions. In the present study, three sulfated microcrystalline cellulose (MCS) with different degrees of sulfate substitution (DSS: 0.33, 0.51, 0.61) were synthesized and the effects of DSS on the regulation of egg white protein (EWP) aggregation and gelation properties were investigated. The results found that the improvement of protein mechanical properties by MCS is closely related to the level of sulfate substitution. The higher the DSS, the more ordered protein aggregates and compact gel network formed during heating as compared to that of pure EWP. Lower DSS (0.33) shows little effect on the mechanical properties of EWP. Furthermore, all the MCSs could significantly destroy the tertiary structure of protein molecules during heating, while for the secondary structure, MCS with higher DSS (0.51 and 0.61) could effectively control the decreasing tendency of α-helix and increasing tendency of β-sheet. Hydrophobic interactions were recognized as the major intermolecular force in the compact mixed gels (EWP/MCS2 and EWP/MCS3 gels, DSS was 0.51 and 0.61, respectively). These findings provide a vital understanding of the gelling mechanism of the protein-polysaccharide system and the application of sulfated polysaccharides in protein-based food products.

Modulation of surface properties of cellulose nanocrystals through adsorption of tannic acid and alkyl cellulose derivatives

Cellulose nanocrystals (CNCs) are hydrophilic nanoparticles that cannot be dispersed in non-polar solvents or hydrophobic polymer matrices. Here, we demonstrate the tunable modification of CNC surfaces by physical adsorption of tannic acid (TA) and two alkyl cellulose derivatives (ACDs), methyl cellulose (MC) and ethyl cellulose (EC), while maintaining their sustainable nature. We compare the impact of ACD adsorption when mixed with CNCs to CNCs precoated with tannic acid (CNC@TA), varying ACD weight fractions in CNC suspensions. Our results show that CNC@ACD and CNC@TA@ACD aqueous suspensions display good colloidal stability in water, while their surface properties are altered. We use a wide range of analytical techniques to characterize these suspensions, with a focus on their interaction with water. The two selected ACDs adsorb on both CNCs and CNC@TA at low fractions (ACD ≤ 10 % w/w), followed by an intermediate region of saturation between 10 % and 30 % w/w. At fractions above 30 % w/w, we observe the formation of CNC- or CNC@TA-reinforced ACD composites. Most samples can be redispersed in water upon freeze-drying, except for EC-rich samples redispersible in toluene. Our facile method for preparing ACD-coated CNCs allows for the creation of a range of nanomaterials with modulable wetting and emulsification properties.

Crosslinking strategies in modulating methylcellulose hydrogel properties

Methylcellulose (MC) hydrogels are ideal materials for the design of thermo-responsive platforms capable of exploiting the environment temperature as a driving force to activate their smart transition. However, MC hydrogels usually show reduced stability in an aqueous environment and low mechanical properties, limiting their applications' breadth. A possible approach intended to overcome these limitations is chemical crosslinking, which represents a simple yet effective strategy to modify the MC hydrogels' properties (e.g., physicochemical, mechanical, and biological). In this regard, understanding the selected crosslinking method's role in modulating the MC hydrogels' properties is a key factor in their design. This review offers a perspective on the main MC chemical crosslinking approaches reported in the literature. Three main categories can be distinguished: (i) small molecule crosslinkers, (ii) crosslinking by high-energy radiation, and (iii) crosslinking via MC chemical modification. The advantages and limitations of each approach are elucidated, and special consideration is paid to the thermo-responsive properties after crosslinking towards the development of MC hydrogels with enhanced physical stability and mechanical performance, preserving the thermo-responsive behavior.

Structure and Conformation of Hydroxypropylmethyl Cellulose with a Wide Range of Molar Masses in Aqueous Solution─Effects of Hydroxypropyl Group Addition

The structure of hydroxypropylmethyl cellulose (HpMC) samples with a wide range of weight average molar masses (Mw) from 23 to 5000 kg mol-1, a controlled degree of substitution (DS) of 1.9 by methyl groups, and a molar substitution number (MS) of 0.25 by hydroxypropyl groups dissolved in aqueous solution was examined using static light scattering (SLS), dynamic light scattering (DLS), small-to-wide angle neutron scattering (S-WANS) techniques, and intrinsic viscosity ([η]) measurements. The determined Mw and the radius of gyration (Rg) showed the relationships Rg ∝ Mw1.0 and [η] ∝ Mw1.7 in a range of Mw < 100 kg mol-1, similar to rigid rod molecules in solution. However, exponents in the relationships decreased gradually with increasing Mw and reached ∼0.5 in a high Mw region, which is a typical value of flexible chain molecules for both Rg and [η]. These observations suggest that the HpMC samples behave as semiflexible rods with a certain persistence length (lp). The ratios of the hydrodynamic radius via DLS measurements to Rg also supported semiflexible rod behavior. Particle form factors and the average lengths (L) resulting from SLS and S-WANS experiments are well described with rigid rod particles in the range of Mw < 100 kg mol-1 and semiflexible rods with lp ∼ 100 nm in Mw > 100 kg mol-1. Because the average contour length (lc) calculated from Mw is approximately twice as long as L in the Mw range < 100 kg mol-1, the formed HpMC particles possess a folded hairpin-like elongated rigid rod structure. However, the lc/L value increases gradually in the range Mw > 200 kg mol-1, where the formed HpMC particles behave as semiflexible rods. The formed particle structure was substantially different from that found in methyl cellulose samples with a similar DS value, which showed rod-like behavior over a wide Mw range. The addition of hydroxypropyl groups only at MS = 0.25 effectively changed the formed particle structure.

Bioinks for Space Missions: The Influence of Long-Term Storage of Alginate-Methylcellulose-Based Bioinks on Printability as well as Cell Viability and Function

Bioprinting is considered a key technology for future space missions and is currently being established on the International Space Station (ISS). With the aim to perform bioink production as a critical and resource-consuming preparatory step already on Earth and transport a bioink cartridge "ready to use" to the ISS, the storability of bioinks is investigated. Hydrogel blends based on alginate and methylcellulose are laden with either green microalgae of the species Chlorella vulgaris or with different human cell lines including immortilized human mesenchymal stem cells, SaOS-2 and HepG2, as well as with primary human dental pulp stem cells. The bioinks are filled into printing cartridges and stored at 4°C for up to four weeks. Printability of the bioinks is maintained after storage. Viability and function of the cells embedded in constructs bioprinted from the stored bioinks are investigated during subsequent cultivation: The microalgae survive the storage period very well and show no loss of growth and functionality, however a significant decrease is visible for human cells, varying between the different cell types. The study demonstrates that storage of bioinks is in principle possible and is a promising starting point for future research, making complex printing processes more effective and reproducible.

Legume protein/polysaccharide food hydrogels: Preparation methods, improvement strategies and applications

For the development of innovative foods and nutritional fortification, research into food gel is essential. As two types of rich natural gel material, both legume proteins and polysaccharides have high nutritional value and excellent application potential, attracting wide attention worldwide. Research has focused on combining legume proteins with polysaccharides to form hybrid hydrogels as their combinations show improved texture and water retention compared to single legume protein or single polysaccharide gels, and these properties can be tailored for specific applications. This article reviews hydrogels of common legume proteins and discusses heat induction, pH induction, salt ion induction, and enzyme-induced assembly of legume protein/polysaccharide mixtures. The applications of these hydrogels in fat replacement, satiety enhancement, and delivery of bioactive ingredients are discussed. Challenges for future work are also highlighted.

Cellulose-Based Scaffolds: A Comparative Study for Potential Application in Articular Cartilage

Osteoarthritis is a highly prevalent disease worldwide that leads to cartilage loss. Tissue engineering, involving scaffolds, cells, and stimuli, has shown to be a promising strategy for its repair. Thus, this study aims to manufacture and characterise different scaffolds with poly(ε-caprolactone) (PCL) with commercial cellulose (microcrystalline (McC) and methyl cellulose (MC) or cellulose from agro-industrial residues (corncob (CcC)) and at different percentages, 1%, 2%, and 3%. PCL scaffolds were used as a control. Morphologically, the produced scaffolds presented porosities within the desired for cell incorporation (57% to 65%). When submitted to mechanical tests, the incorporation of cellulose affects the compression resistance of the majority of scaffolds. Regarding tensile strength, McC2% showed the highest values. It was proven that all manufactured scaffolds suffered degradation after 7 days of testing because of enzymatic reactions. This degradation may be due to the dissolution of PCL in the organic solvent. Biological tests revealed that PCL, CcC1%, and McC3% are the best materials to combine with human dental pulp stem/stromal cells. Overall, results suggest that cellulose incorporation in PCL scaffolds promotes cellular adhesion/proliferation. Methyl cellulose scaffolds demonstrated some advantageous compressive properties (closer to native cartilaginous tissue) to proceed to further studies for application in cartilage repair.

Introduction of Curdlan Optimizes the Comprehensive Properties of Methyl Cellulose Films

The good oxygen barrier and hydrophobic properties of curdlan (CL) film might be suitable complements for MC film, and its similar glucose unit and thermal-gel character might endow the methyl cellulose (MC)/CL blended system with compatibility and good comprehensive properties. Thus, MC/CL blended films were developed. The effects of MC/CL blend ratios on the microstructures and physical properties of the blends were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), oxygen and water vapor permeability testing, dynamic mechanical analysis (DMA), light transmittance testing, tensile testing, hydrophilic property testing, and water solubility testing. The introduction of CL affected the molecular aggregation and crystallization of the MC molecules, suggesting MC-CL molecular interactions. The cross-sectional roughness of the MC/CL film increased with an increase in CL content, while the surface of the MC/CL 5:5 film was smoother than those of the MC/CL 7:3 and 3:7 films. Only one glass transition temperature, which was between that of the MC and CL films, was observed for the MC/CL 7:3 and MC/CL 5:5 films, indicating the good compatibility of the MC and CL molecules at these two blend ratios. The hydrophobicity and water insolubility increased with the CL content, which was due to the combined effects of more hydrophobic cavities in the CL triple-helix and increased surface roughness. Increased oxygen barrier properties with increasing CL content might be a combined effect of the increased hydrogen bonds and hydrophilic ektexines of the CL triple-helix. The elongations of the blended films were higher than those of the MC film, which might be related to its increased water content. The MC/CL 7:3 and MC/CL 5:5 films retained the good light transmittance and tensile strength of the MC film, which corresponded well to their good compatibility and might be due to the effects of the MC-CL molecular interactions and the relative smooth morphologies. MC/CL 5:5 showed improved water vapor barrier properties, which might be due to its smooth surface morphologies. This research offers new MC based films with improved properties and good compatibility, providing great potential for use as edible coatings, capsules, and packaging materials.

Mucoadhesive chitosan-methylcellulose oral patches for the treatment of local mouth bacterial infections

Mucoadhesive buccal patches are dosage forms promising for successful drug delivery. They show the distinctive advantages of long residence time on the oral mucosa and increased in situ drug bioavailability. In this context, electrophoretic deposition (EPD) of chitosan (CS) has been demonstrated as a simple and easily tunable technique to produce mucoadhesive buccal patches. However, CS-based buccal patches may suffer from weak mucoadhesion, which can impair their therapeutic effect. In this work, methylcellulose (MC), a widely investigated biopolymer in the biomedical area, was exploited to increase the mucoadhesive characteristic of pristine CS patches. CS-MC patches were obtained in a one-pot process via EPD, and the possibility of incorporating gentamicin sulfate (GS) as a model of a broad-spectrum antibiotic in the so-obtained patches was investigated. The resulting CS-MC patches showed high stability in a water environment and superior mucoadhesive characteristic (σ_adh = 0.85 ± 0.26 kPa, W_adh = 1192.28 ± 602.36 Pa mm) when compared with the CS control samples (σ_adh = 0.42 ± 0.22 kPa, W_adh = 343.13 ± 268.89 Pa mm), due to both the control of the patch porosity and the bioadhesive nature of MC. Furthermore, GS-loaded patches showed no in vitro cytotoxic effects by challenging L929 cells with material extracts and noteworthy antibacterial activity on both Gram-positive and Gram-negative bacterial strains.

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery-A Bibliometric Review

Food hydrogels are biopolymeric materials made from food-grade biopolymers with gelling properties (proteins and polysaccharides) and a 3D network capable of incorporating large amounts of water. They have sparked considerable interest because of their potential and broad application range in the biomedical and pharmaceutical sectors. However, hydrogel research in the field of food science is still limited. This knowledge gap provides numerous opportunities for implementing their unique properties, such as high water-holding capacity, moderated texture, compatibility with other substances, cell biocompatibility, biodegradability, and high resemblance to living tissues, for the development of novel, functional food matrices. For that reason, this article includes a bibliometric analysis characterizing research trends in food protein-polysaccharide hydrogels (over the last ten years). Additionally, it characterizes the most recent developments in hydrogel induction methods and the most recent application progress of hydrogels as food matrices as carriers for the targeted delivery of bioactive compounds. Finally, this article provides a future perspective on the need to evaluate the feasibility of using plant-based proteins and polysaccharides to develop food matrices that protect nutrients, including bioactive substances, throughout processing, storage, and digestion until they reach the specific targeted area of the digestive system.

A methylcellulose/agarose hydrogel as an innovative scaffold for tissue engineering

In situ crosslinked materials are the main interests of both scientific and industrial research. Methylcellulose (MC) aqueous solution is one of the representatives that belongs to this family of thermosensitive materials. At room temperature, MC is a liquid whereupon during temperature increase up to 37 °C, it crosslinks physically and turns into a hydrogel. This feature makes it unique, especially for tissue engineering applications. However, the crosslinking rate of MC alone is relatively slow considering tissue engineering expectations. According to these expectations, the crosslinking should take place slowly enough to allow for complete injection and fill the injury avoiding clogging in the needle, and simultanously, it should be sufficiently fast to prevent it from relocation from the lesion. One of the methods to overcome this problem is MC blending with another substance that increases the crosslinking rate of MC. In these studies, we used agarose (AGR). These studies aim to investigate the effect of different AGR amounts on MC crosslinking kinetics, and thermal, viscoelastic, and biological properties. Differential Scanning Calorimetry (DSC) and dynamic mechanical analysis (DMA) measurements proved that AGR addition accelerates the beginning of MC crosslinking. This phenomenon resulted from AGR's greater affinity to water, which is crucial in this particular crosslinking part. In vitro tests, carried out using the L929 fibroblast line and mesenchymal stem cells (MSCs), confirmed that most of the hydrogel samples were non-cytotoxic in contact with extracts and directly with cells. Not only does this type of thermosensitive hydrogel system provide excellent mechanical and biological cues but also its stimuli-responsive character provides more novel functionalities for designing innovative scaffold/cell delivery systems for tissue engineering applications.

Hysteresis in the thermally induced phase transition of cellulose ethers

Functionalized cellulosics have shown promise as naturally derived thermoresponsive gelling agents. However, the dynamics of thermally induced phase transitions of these polymers at the lower critical solution temperature (LCST) are not fully understood. Here, with experiments and theoretical considerations, we address how molecular architecture dictates the mechanisms and dynamics of phase transitions for cellulose ethers. Above the LCST, we show that hydroxypropyl substituents favor the spontaneous formation of liquid droplets, whereas methyl substituents induce fibril formation through diffusive growth. In celluloses which contain both methyl and hydroxypropyl substituents, fibrillation initiates after liquid droplet formation, suppressing the fibril growth to a sub-diffusive rate. Unlike for liquid droplets, the dissolution of fibrils back into the solvated state occurs with significant thermal hysteresis. We tune this hysteresis by altering the content of substituted hydroxypropyl moieties. This work provides a systematic study to decouple competing mechanisms during the phase transition of multi-functionalized macromolecules.

Elongated Rodlike Particle Formation of Methyl Cellulose in Aqueous Solution

The conformation and structure of methyl cellulose (MC) ether samples dissolved in pure water under dilute conditions were carefully reconsidered based on the results obtained using small-to-wide-angle neutron scattering (S-WANS), static light scattering (SLS), dynamic light scattering (DLS), and viscometric techniques. The examined MC samples possessed an average degree of substitution by methyl groups per glucose unit of ca 1.8 and weight average molar masses (M _w), ranging from 23 to 790 kg mol^-1. S-WANS experiments clearly demonstrated that the samples possess highly elongated rigid rodlike local structures in deuterium oxide solutions with weak periodicities of ca 0.4 and 1.0 nm on a length scale, which correspond to the average intermolecular distance between molecular chain portions facing each other in the formed rodlike structure and the repeating length of the monomeric cellobiose unit of molecular chains, respectively. Ratios of the particle length (L) to the radius of gyration (R _g) determined by SLS techniques approximately showed the relationship LR _g ^-1 = holding in rigid rods over the entire M _w range examined in this study. However, the folding number, defined as the ratio of the average molecular contour length (l) to L, remained at the value of lL ^-1 ∼ 2, representing an elongated one-folded hairpin structure, until M _w ∼ 300 kg mol^-1 and increased substantially up to ca 4.9 at the highest M _w of 790 kg mol^-1. The observed increase in the lL ^-1 value corresponded well with an increase in the diameter of the formed rod with increasing M _w observed in the S-WANS data. The M _w dependencies of the translational diffusion coefficient determined via DLS measurements and that of the intrinsic viscosity detected via viscometric techniques also distinctly demonstrated that particles formed by the MC samples dissolved in aqueous solution behave as elongated rigid rods irrespective of M _w.

Injectable light-assisted thermo-responsive methylcellulose-sodium humate hydrogel proposed for photothermal ablation and localized delivery of cisplatin

This study aimed to develop injectable light-assisted thermo-responsive methylcellulose hydrogels filled with sodium humate, which were proposed for photothermal ablation and localized cisplatin delivery. Sodium humate converts light energy from laser beams into thermal energy, which causes methylcellulose to gel, thereby controlling the release of chemotherapy agents. Meanwhile, light emission causes to the photothermal ablation of tumor cells. For determining the optimal production conditions, different concentrations of sodium humate and light emission times were investigated. Results show that hydrogel uniformity is highly dependent on variables. An increase in sodium humate concentration and emission time resulted in a slight reduction in swelling ratio and an increase in durability. According to the simulation conditions, the cisplatin release profile was consistent with a non-Fickian mechanism with a predominant erosion contribution. In conjugation with increasing light emission time and sodium humate content, the storage modulus and viscosity increased, demonstrating hydrogel’s sol-gel transition and long-lasting durability. The intrinsic fluorescence spectroscopy study revealed that the hydrogel-model protein complex empowered hydrogel bio-performance. Laser emission and cisplatin release synergistically reduced the number of viable osteosarcoma cell lines, suggesting the possibility of tumor ablation. This study describes the potential of simultaneous photothermal therapy and chemotherapy in osteosarcoma treatment, laying the groundwork for future preclinical and clinical trials.

Leveraging the gel-to-sol transition of physically crosslinked thermoresponsive polymer hydrogels to enable reactions induced by lowering temperature

Much work has been done on the use of heating to trigger reactions via the temperature-dependent removal of a barrier or constraint separating reagents. Far less work, however, has been done on the use of cooling to achieve a similar goal. Numerous applications, such as those involving components or materials susceptible to persistent low temperatures and cases in which energy for heating is not available, would benefit from this inverse approach. Hence, in this study we explore whether physically crosslinked hydrogels can be reliably used as thermoresponsive constraints that allow reagents to react only upon cooling. We achieve this by loading reagents into adjacent blocks of thermoresponsive hydrogel and showing that these reagents can only react with each other after the temperature of the hydrogel falls below its lower critical solution temperature (LCST). Above the LCST, the reagents remain sequestered in separate gels and no reaction occurs; this "OFF" state is stable for extended periods. When the system is allowed to cool, the hydrogels liquify and flow into each other, allowing mixing of the embedded reagents ("ON" state). We tune the hydrogels' LCSTs using NaCl, quantify the NaCl's tuning effect using rheometry, and determine that reactions are triggered reproducibly at temperatures similar to the tuned LCSTs. We also demonstrate generalizability of the concept by exploring situations involving radically different reaction types. This concept therefore constitutes a new approach to autonomous material behavior based on cooling.

Toward a Better Understanding of the Gelation Mechanism of Methylcellulose via Systematic DSC Studies

A methylcellulose (MC) is one of the materials representatives performing unique thermal-responsive properties. While reaching a critical temperature upon heating MC undergoes a physical sol-gel transition and consequently becomes a gel. The MC has been studied for many years and researchers agree that the MC gelation is related to the lower critical solution temperature (LCST). Nevertheless, a precise description of the MC gelation mechanism remains under discussion. In this study, we explained the MC gelation mechanism through examination of a wide range of MC concentrations via differential scanning calorimetry (DSC). The results evidenced that MC gelation is a multistep thermoreversible process, manifested by three and two endotherms depending on MC concentration. The occurrence of the three endotherms for low MC concentrations during heating has not been reported in the literature before. We justify this phenomenon by manifestation of three various transitions. The first one manifests water–water interactions, i.e., spanning water network breakdown into small water clusters. It is clearly evidenced by additional normalization to the water content. The second effect corresponds to polymer–water interactions, i.e., breakdown of water cages surrounded methoxy groups of MC. The last one is related to the polymer–polymer interactions, i.e., fibril hydrophobic domain formation. Not only did these results clarify the MC crosslinking mechanism, but also in the future will help to assess MC relevance for various potential application fields.

Gelation under stress: impact of shear flow on the formation and mechanical properties of methylcellulose hydrogels

We demonstrate that small unidirectional applied-stresses during temperature-induced gelation dramatically change the gel temperature and the resulting mechanical properties and structure of aqueous methylcellulose (MC), a material that forms a brittle gel with a fibrillar microstructure at elevated temperatures. Applied stress makes gelation more difficult, evidenced by an increased gelation temperature, and weakens mechanical properties of the hot gel, evidenced by a decreased elastic modulus and decreased apparent failure stress. In extreme cases, formation of a fully percolated polymer network is inhibited and a soft granular yield-stress fluid is formed. We quantify the effects of the applied stress using a filament-based mechanical model to relate the measured properties to the structural features of the fibril network. The dramatic changes in the gel temperature and hot gel properties give more design freedom to processing-dependent rheology, but could be detrimental to coating applications where gravitational stress during gelation is unavoidable.

Hydroxypropyl methylcellulose-controlled in vitro calcium phosphate biomineralization

Scanning pyroelectric microscopy of DCPD single crystals.

An Overview of Cellulose Derivatives-Based Dressings for Wound-Healing Management

Presently, notwithstanding the progress regarding wound-healing management, the treatment of the majority of skin lesions still represents a serious challenge for biomedical and pharmaceutical industries. Thus, the attention of the researchers has turned to the development of novel materials based on cellulose derivatives. Cellulose derivatives are semi-synthetic biopolymers, which exhibit high solubility in water and represent an advantageous alternative to water-insoluble cellulose. These biopolymers possess excellent properties, such as biocompatibility, biodegradability, sustainability, non-toxicity, non-immunogenicity, thermo-gelling behavior, mechanical strength, abundance, low costs, antibacterial effect, and high hydrophilicity. They have an efficient ability to absorb and retain a large quantity of wound exudates in the interstitial sites of their networks and can maintain optimal local moisture. Cellulose derivatives also represent a proper scaffold to incorporate various bioactive agents with beneficial therapeutic effects on skin tissue restoration. Due to these suitable and versatile characteristics, cellulose derivatives are attractive and captivating materials for wound-healing applications. This review presents an extensive overview of recent research regarding promising cellulose derivatives-based materials for the development of multiple biomedical and pharmaceutical applications, such as wound dressings, drug delivery devices, and tissue engineering.

Methylcellulose-Cellulose Nanocrystal Composites for Optomechanically Tunable Hydrogels and Fibers

Chemical modification of cellulose offers routes for structurally and functionally diverse biopolymer derivatives for numerous industrial applications. Among cellulose derivatives, cellulose ethers have found extensive use, such as emulsifiers, in food industries and biotechnology. Methylcellulose, one of the simplest cellulose derivatives, has been utilized for biomedical, construction materials and cell culture applications. Its improved water solubility, thermoresponsive gelation, and the ability to act as a matrix for various dopants also offer routes for cellulose-based functional materials. There has been a renewed interest in understanding the structural, mechanical, and optical properties of methylcellulose and its composites. This review focuses on the recent development in optically and mechanically tunable hydrogels derived from methylcellulose and methylcellulose-cellulose nanocrystal composites. We further discuss the application of the gels for preparing highly ductile and strong fibers. Finally, the emerging application of methylcellulose-based fibers as optical fibers and their application potentials are discussed.

Frying Conditions, Methyl Cellulose, and K-Carrageenan Edible Coatings: Useful Strategies to Reduce Oil Uptake in Fried Mushrooms

Despite being widely consumed and appreciated, fried food has the unhealthy characteristic of high final oil content. Therefore, alternatives to reduce the oil uptake of fried products are being researched. The aim of this study was to investigate the effect of 0.5% methyl cellulose and 0.5% kappa-carrageenan edible films, as well as different frying procedure parameters, such as oil temperatures (from 150 to 180 °C), and thickness of slices (from 2 to 6 mm) on the oil uptake of whole fried mushrooms and their parts. The results showed a lower final oil content when lower frying temperature and thicker slices are applied. Hydrocolloid suspensions of methyl cellulose and kappa-carrageenan, used as edible coatings, were effective at reducing moisture evaporation and, consequently, oil uptake independently of the hydrocolloid temperature. A reduction of 10–22% in the final oil content was achieved. Adjusting the frying parameters and the use of methyl cellulose or kappa-carrageenan as an edible coating were useful strategies to reduce the oil uptake in fried products.

Injectable Thermogel Generated by the "Block Blend" Strategy as a Biomaterial for Endoscopic Submucosal Dissection

Endoscopic submucosal dissection is an established method for the removal of early cancers and large lesions from the gastrointestinal tract but is faced with the risk of perforation. To decrease this risk, a submucosal fluid cushion (SFC) is needed clinically by submucosal injection of saline and so on to lift and separate the lesion from the muscular layer. Some materials have been tried as the SFC so far with disadvantages. Here, we proposed a thermogel generated by the "block blend" strategy as an SFC. This system was composed of two amphiphilic block copolymers in water, so it was called a "block blend". We synthesized two non-thermogellable copolymers poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) and blended them in water to achieve a sol-gel transition upon heating in both pure water and physiological saline. We explored the internal structure of the resultant thermogel with transmission electron microscopy, three-dimensional light scattering, ¹³C NMR, fluorescence resonance energy transfer, and rheological measurements, which indicated a percolated micelle network. The biosafety of the synthesized copolymer was preliminarily confirmed in vitro. The main necessary functions as an SFC, namely, injectability of a sol and the maintained mucosal elevation as a gel after injection, were verified ex vivo. This study has revealed the internal structure of the block blend thermogel and illustrated its potential application as a biomaterial. This work might be stimulating for investigations and applications of intelligent materials with both injectability and thermogellability of tunable phase-transition temperatures.