Methylcellulose Gels Research Articles

Evaluation of the printability of agar and hydroxypropyl methylcellulose gels as gummy formulations: Insights from rheological properties

The trial-and-error method currently used to create formulations with excellent printability demands considerable time and resources, primarily due to the increasing number of variables involved. Rheology serves as a relatively rapid and highly beneficial method for assessing materials and evaluating their effectiveness as 3D constructs. However, the data obtained can be overwhelming, especially for users lacking experience in this field. This study examined the rheological properties of formulations of agar, hydroxypropyl methylcellulose, and the model drug caffeine, alongside exploring their printability as gummy formulations. The gels’ rheological properties were characterized using oscillatory and rotational experiments. The correlation between these gels’ rheological properties and their printability was established, and three clusters were formed based on the rheological properties and printability of the samples using principal component analysis. Furthermore, the printability was predicted using the sample’s rheological property that correlated most with printability, the phase angle δ, and the regression models resulted in an accuracy of over 80%. Although these relationships merit confirmation in later studies, this study suggests a quantitative definition of the relationship between printability and one rheological property and can be used for the development of formulations destined for extrusion 3D printing.

Ionic liquids based on carboxylate anions: Auto and hetero assembly with methylcellulose in diluted and semi-diluted regime

This study explores the impact of carboxylate ionic liquids (ILs) on the phase transition properties of methylcellulose (MC) in the diluted and semi-diluted regime. Conductivity measurements were used to examine the aggregation of ILs 1-decyl-3-methylimidazolium butanoate ([C10MIM][BUT]), 1-decyl-3-methylimidazolium crotonate ([C10MIM][CRO]), and 1-decyl-3-methylimidazolium pentanoate ([C10MIM][PEN]) in the presence and absence of MC. The interaction between ILs and MC was confirmed using 1H NMR spectroscopy. The effect of ILs on the phase transition of MC was investigated through UV–vis spectroscopy and oscillatory rheometry. Results indicated that the carboxylate ILs studied tend to interact with MC, reducing polymer-polymer interactions and the apparent viscosity of MC solutions. Furthermore, carboxylate ILs were observed to modulate the sol-gel transition temperature of MC to higher temperatures, while weakening the resulting gel compared to pure MC gels.

Methylcellulose-Encapsulated Carbon Nanotubes as Biosensing Implants

While single-walled carbon nanotubes (SWCNTs) have shown functionality in vivo for monitoring drugs and cancer biomarkers via their near-infrared fluorescence in the tissue transparent window, there is not yet a widely-used non-invasive method for implanting such devices. We developed an injectable methylcellulose (MC)-based polymer system, with demonstrated biocompatibility and in-situ gelling, for encapsulating SWCNTs. Oligonucleotide-wrapped SWCNTs were added to methacrylated MC polymer solutions, which were then crosslinked by free radical polymerization using redox initiators. Encapsulation in MC gels did not adversely impact SWCNT fluorescence for at least 149 days in vitro. The resulting nanocomposite gels were then exposed to varying concentrations of bovine serum albumin (BSA) as a model globular protein analyte, which caused SWCNT fluorescence to red-shift in a quantitative, concentration-dependent fashion from 0.1 to 150 µM. Separately, SWCNT response to the chemotherapeutic doxorubicin was also evaluated. This interaction quenched the fluorescence of MC-encapsulated SWCNTs with similar concentration dependence above 200 nM as has previously been found for in vivo implantable devices. We anticipate that this MC system will be a valuable tool for minimally-invasive delivery of SWCNT-based sensors for future in vivo experiments and potentially for use in the clinic.

High-thermopower polarized electrolytes enabled by methylcellulose for low-grade heat harvesting.

Low-grade heat exists ubiquitously in the environment. Thermogalvanic cells (TGCs) are promising for converting the widespread low-grade heat directly into electricity owing to relatively high thermopowers of redox reactions. This work reports polarized electrolytes with ultrahigh thermopowers of −8.18 mV K−1 for n-type and 9.62 mV K−1 for p-type. The electrolyte consists of I−/I3− redox couple, methylcellulose, and KCl. Thermoresponsive methylcellulose leads to polarization switching from n-type to p-type above a transition temperature due to the strong hydrophobic interaction between methylcellulose and I3− ions. The giant thermopowers can be attributed to the simultaneously enhanced entropy change and concentration difference of redox couple enabled by the gelation of methylcellulose and KCl-induced complexation. The p-type TGC with the optimized electrolyte achieves a normalized maximum power density of 0.36 mW m−2 K−2, which is far superior to other reported I−/I3−-based TGCs. This work demonstrates cost-effective, high-thermopower polarized electrolytes for low-grade heat harvesting.

BEHAVIOUR OF METHYLCELLULOSE GEL AT HIGHER CONCENTRATIONS FOR CLEANING OF ACRYLIC PAINTED SURFACES

This research demonstrates the application of methylcellulose (MC) as a gelator for cleaning acrylic painted surfaces. Highly thickened methylcellulose gels were predominantly tested to investigate the residue left after cleaning. The function of methylcellulose as a molecular trap was also assessed to minimize the clearance issue. The presence of residue, the efficacy of the methylcellulose as a cleaning agent and its physical impact on the paint surfaces were investigated using a digital microscope in normal, raking, and ultraviolet lights. Scanning electron microscopy (SEM), coupled with energy-dispersive X-ray spectroscopy (EDS) was used to study the compositional and topographical changes on the paint surface. Fourier transform infrared spectroscopy (FTIR) was performed in attenuated total reflectance (ATR) mode to observe the presence of residues after complete removal of the gelling agent. The experimental results indicated a minimum interaction of methylcellulose on the paint surface as the concentration increases in the gel formulation. The super-thickened hydrogels also worked like molecular traps useful for removal of soiling from the painted surfaces.

Operational Variables on the Processing of Porous Titanium Bodies by Gelation of Slurries with an Expansive Porogen

Colloidal processing techniques, based on the suspension of powders in a liquid, are very versatile techniques to fabricate porous structures. They can provide customized pores, shapes and surfaces through the control of operational parameters, being the base of the alternative additive manufacture processes. In this work disperse and stable titanium aqueous slurries has been formulated in order to process porous materials by the incorporation of methylcellulose (MC) as a gelation agent and ammonium bicarbonate as an expansive porogen. After casting the slurries and heating at mild temperatures (60–80 °C) the methylcellulose gels and traps the gas bubbles generated by the ammonium bicarbonate decomposition to finally obtain stiff porous green structures. Using an experimental design method, the influence of the temperature as well as the concentration of gelation agent and porogen on the viscosity, apparent density and pore size distribution is analyzed by a second-order polynomial function in order to identifying the influence of the operating variables in the green titanium porous compact. After sintering at 1100 °C under high vacuum, titanium sponges with 39% of open porosity and almost no close porosity were obtained.

Development of a novel polymer-based carrier for deformable liposomes for the controlled dermal delivery of naringenin

In recent years, the incidence of skin cancer has increased worldwide, presenting a significant burden on healthcare services. Chemotherapy intervention is often not appropriate for all patients due to localized adverse effects on skin physiology. The aim of this study was, therefore, to consider the development of a novel phytochemical-based deformable liposomal formulation suspended in an aqueous gel for the controlled-release of naringenin. Naringenin is an antioxidant, free radical scavenger, anti-inflammatory agent, and immune system modulator thus may be potentially useful as a pharmacological anti-cancer agent. Formulated liposomes incorporating an increasing loading of Tween 20 (from 0% w/w to 10% w/w) demonstrated a significant decrease in deformability index (DI) (80.71 ± 2.02–59.17 ± 4.42 %), indicating an increase in elasticity. The release of naringenin over 24 h was directly affected by Tween-20 concentration, decreasing from 100.72%±4.98% to 79.53%±3.68% for 0% and 2% w/w Tween 20, respectively. Further, the incorporation of deformable liposomes into hydroxyethylcellulose (HEC) and hydroxypropyl methylcellulose (HPMC) gels resulting in a further retardation of naringenin release, 23.21%±1.17% and 19.83%±1.50%, respectively, over 24 h. Incubation of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate-loaded liposomes with human dermal fibroblast (HDF) and keratinocyte cells demonstrated intracellular accumulation within 2 h, confirming deformable liposomes may be beneficial in improving drug penetration across dermal cells and would be valuable in emerging controlled-release formulations.

Acid-induced mixed methylcellulose and casein gels: Structures, physical properties and formation mechanism

In this study, caseins and methylcellulose (MC) were selected as building materials to prepare a class of mixed gels by adding glucono-δ-lactone (GDL) to induce the gelation of composite MC/casein systems, where the casein concentration was fixed at 8.0% (w/v) and the MC concentration varied from 0 to 1.0% (w/v). It was found that with increasing amount of MC addition (0–0.4%), the mixed gels exhibited a structural conversion from a casein-dominant gel network to a “water-in-water emulsion structure”, with the caseins as the continuous gelling phase and the MC as the dispersed phase; further MC addition (0.4–1.0%, w/v) caused a more significant phase separation phenomenon. The structural conversion was in consistent with the determination result of gel hardness. Furthermore, by a combination of confocal laser scanning microscope (CLSM) and rheological studies, the structural evolution process of the mixed gels was revealed to explore the underlying formation mechanism of the mixed gels.

Rheological and Conformational Studies of Methylcellulose Gels in an Aqueous Medium

The gelation behavior of methylcellulose (MC) was studied by the dynamic mechanical analysis and UV-spectroscopy. To investigate the chain elastic response the dynamic strain experiment is performed at various temperatures, where the decrease in the peak heights with an increase in temperature reveals the increase in rigidity of the sol-gel network. The continuous rotation of functional groups induces turbidity in MC, therefore the association of –OCH3 groups or appearance of cloud point occurs earlier to the gel point. The area under the various curves also signifies the bridging percolated network of the MC aqueous system. Further, the mechanism of gelation is described as an equilibrium among the trans- and gauche-conformations. Computationally, various angles in the cyclic monomeric units of MC and the torsional angles in adjacent monomeric units are reconnoitered to describe the stability of the helical structure of MC.

Etodolac nanosuspension based gel for enhanced dermal delivery: in vitro and in vivo evaluation

Aim The objective of this study was to develop dermal nanosuspension (NS) based gel formulation of etodolac (ETD). Methods Etodolac nanosuspension (ETD-NS) was prepared by wet milling method and dispersed in hydroxypropyl methylcellulose (NS-HPMC) or hydroxyethyl cellulose (NS-HEC) gels. Rheologic and mechanical properties were investigated. In vitro and ex vivo permeability studies were performed. Topical anti-inflammatory and analgesic activity were evaluated in regard to carrageenan-induced inflammatory paw oedema and radiant heat tail-flick method, respectively. Results The ETD-NS with approximately 190 nm particle size (PS), 0.16 polydispersity index (PDI), and −15 mV zeta potential (ZP) values were obtained. The work of bioadhesion values of NS-HEC and NS-HPMC gels were 0.229 mJ/cm2 for both gels. Dermal permeation of ETD from NS-HEC gel (7.18%) was found significantly higher than the NS-HPMC gel (4.56%). Enhanced anti-inflammatory and analgesic activity of NS-HEC gels were observed in comparison with micronised ETD. Conclusions ETD-NS based gel formulation is promising for topical delivery of ETD.

Self-crosslinked chitosan/dialdehyde xanthan gum blended hypromellose hydrogel for the controlled delivery of ampicillin, minocycline and rifampicin

The design of improved biopolymeric based hydrogel materials with high load-capacity to serve as biocompatible drug carriers is a challenging task with vital implications in health sciences. In this work, chitosan crosslinked dialdehyde xanthan gum interpenetrated hydroxypropyl methylcellulose gels were developed for the controlled delivery of different antibiotic drugs including ampicillin, minocycline and rifampicin. The prepared hydrogel scaffolds were characterized by rheology method, FTIR, SEM, TGA and compression analysis. In addition, gelation kinetics, swelling, in vitro degradation and drug release rate were studied under simulated gastrointestinal fluid conditions of pH 2.0 and 7.4 at 37 °C. Results demonstrated the gel composition and structure affected drug release kinetics. The release study showed more than 50% cumulative release within 24 h for all investigated antibiotic drugs. In vitro cell cytocompatibility using mouse embryonic fibroblast cell lines depicted ≥80% cell viability, indicating the gels are non-toxic. Finally, the antibacterial activity of loaded gels was evaluated against Gram-negative and positive bacteria (Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia), which correlated well with swelling and drug release results. Overall, the present study demonstrated that the produced hydrogel scaffolds serves as promising material for controlled antibiotic delivery towards microbial growth inhibition.

Shock attenuation characteristics of methylcellulose hydrogels: Phenomenological modeling

The shock attenuation characteristics of aqueous methylcellulose (MC) gels were characterized experimentally and modeled towards their application in bodily protection systems against traumatic injury. The attenuation of MC gel with 4 different thicknesses (4, 7, 10 and 20 mm) and 3 concentrations (5, 10 and 15%Wt) was measured, using an instrumented (Hopkinson) bar and piezoresistive sensors for direct force sensing on the gel. First, the impulse attenuation was systematically characterized for all combinations of thickness and composition, and the results were analyzed statistically. The impulse attenuation increases with both thickness and MC concentration. A non-linear function was then fitted to the experimental results. The fitted functions increase monotonically with both the thickness and the concentration of the gel layer. However, the slope of each function decreases gradually with the thickness of the layer, thereby indicating an effective thickness beyond which shock attenuation efficiency does not increase significantly. The frequency dependence of the attenuation was determined next and found to be relatively independent of both thickness and gel concentration up to 100 kHz. A phenomenological expression was developed and validated for the shock attenuation of MC gels as a function of their composition, thickness and spectral content of the shock.

Microwave assisted freezing part 1: Experimental investigation and numerical modeling

The aim of this study was to develop an innovative process dedicated to enhancing the quality of frozen food using microwaves. A microwave assisted freezing device was designed at the laboratory scale to perform experiments in controlled conditions. Small samples of methylcellulose gels were frozen using nitrogen gas in a TE10 waveguide, where microwaves at 2.45 GHz were emitted intermittently or continuously. A numerical model was also developed to obtain results difficult to measure such as the local electric field and the corresponding energy density. The phase change part of the model was based on an enthalpy formulation and on the growth of spherical ice crystals. An original “hybrid 2D-3D” solving methodology was used to reduce the duration of the simulations. Favourable comparisons between the predicted temperatures and the experimental data highlighted the relevance of the models used for the thermophysical and dielectric properties. The analysis of the interactions between microwaves and matter, performed with numerical simulations, revealed the role of the freezing front as a boundary. The strong influence of sample size and of dielectric properties on the power density distribution were also illustrated when comparing our results with those published previously. The scientific knowledge obtained through this study and the original structure of the numerical model will be used to optimize microwave assisted freezing and link the process parameters to the reduction of ice crystal size highlighted in the companion paper. Industrial relevanceMicrowave assistance during freezing can improve frozen product quality by reducing ice crystal size. This innovative and promising process has not yet been given much attention. Developing an accurate model which describes microwave – matter interactions during phase change permits numerical simulations that can facilitate the design of industrial equipment, and determine optimal product dimensions.

Formulation and Comparative Characterization of Methylcellulose, Carbomer and Petrolatum Gels for Topical and Transdermal Delivery of Zosyn (Piperacillin/Tazobactam) Antibiotics

Formulation and Comparative Characterization of Methylcellulose, Carbomer and Petrolatum Gels for Topical and Transdermal Delivery of Zosyn (Piperacillin/Tazobactam) Antibiotics

Selective cell propagation via micropatterning of a thermally-activated hydrogel.

The ability to selectively propagate specific cells is fundamentally important to the development of clonal cell populations. Current methods rely on techniques such as limiting dilution, colony picking, and flow cytometry to transfer single cells into single wells, resulting in workflows that are low-throughput, slowed by propagation kinetics, and susceptible to contamination. Here, we developed a method, called selective laser gelation (SLG), to micropattern hydrogels in cell culture media in order to encapsulate specific cells to selectively arrest their growth. This process relies on the inverse gelation of methylcellulose, which forms a hydrogel when heated rather than cooled. Local heating using an infrared laser enables hydrogel micropatterning, while phase transition hysteresis retains the hydrogel after laser excitation. As a demonstration, we used this approach to selectively propagate transgenic CHO cells with increased antibody productivity. More generally, hydrogel micropatterning provides a simple and non-contact method for selective propagation of cells based on features identified by imaging.

Methylcellulose fibrils: a mini review

AbstractThis review covers the recently discovered methylcellulose (MC) fibrils and their impact on MC thermogelation and overall gel strength. The thermogelation of MC aqueous solutions has been studied for nearly 100 years, but it has only recently been attributed to fibril formation at elevated temperatures. The assembly of a fibrillar network explains the general features of MC gels: the unusually high modulus, the turbidity, and the nonlinear rheological behavior at high strains. Recent scattering, atomic force microscopy (AFM) and cryogenic transmission electron microscopy (cryo‐TEM) experimental efforts have led to critical discoveries about the fibril structure. MC fibrils are 60% water by volume when in solution. The length of the fibrils, especially for shorter chains, is closely correlated with the MC chain contour length. On the other hand, the fibril radius does not depend on the temperature, molecular weight or concentration of MC chains but does seem to be correlated with chain stiffness. The discovery of MC fibrils represents a significant departure from the entanglement of polymer chains and localized phase separation based physical model of MC gelation, opens new questions about the mechanism of fibril formation and presents new pathways for stimulus responsive material design. © 2019 Society of Chemical Industry

Properties of Chemically Cross-Linked Methylcellulose Gels

Methylcellulose (MC) is widely used as a rheology modifier because, upon heating in aqueous solutions, MC reversibly self-assembles into ∼7–10 nm radius fibrils that percolate into a network, resulting in physical gelation. Here, we have chemically cross-linked both MC solutions at room temperature and MC physical fibril gels at 80 °C and compared the swelling and shear modulus properties of both materials. To achieve this, hydroxyl moieties on MC (Mw ≈ 150 kDa) were substituted with allyl groups, with a degree of substitution of about one pendant carbon–carbon double bond per nine anhydroglucose repeat units. The allyl groups undergo cross-linking in the presence of a photoinitiator and UV light. Chemically cross-linking MC fibril gels (“xfib-MC”) at 80 °C results in opaque solid materials and locks in the fibril structure, which persists even on cooling back to room temperature. From small-angle X-ray scattering analysis, the fibril radius is larger at room temperature ∼20 nm and decreases to ∼10 nm at ...

Studies on rheological, thermal, and morphological properties of methylcellulose gel in aqueous medium

The rheological, morphological, and thermal behavior of aqueous methylcellulose (MC) gels was investigated by optical microscope, dynamic mechanical analyzer (DMA), and differential scanning calorimeter. The double crossover between the storage modulus and loss modulus during the frequency scan in DMA suggests the transition from gel to sol state. These gel networks are comprised of bead‐rod structures, which is visible under the optical microscope. Furthermore, the degelation mechanism of gels comprises of the thermodynamic viable bead burst phenomenon. The reheated samples of MC under dynamic compression show partial irreversibility of the MC aqueous system, indicating the possible presence of weakly coupled random coils and helix. The phenomenon of turbidity of MC aqueous gels is discussed with the help of a large bead model, in which the small‐sized beads present in aqueous solution collide with each other to form large beads. POLYM. ENG. SCI., 59:2024–2031, 2019. © 2019 Society of Plastics Engineers

Effect of mono- and dicationic ionic liquids on the viscosity and thermogelation of methylcellulose in the semi-diluted regime

Thermoreversible hydrogels are suitable in food products in order to improve texture and in biomedical applications as drug delivery vehicles. The properties of hydrogels affect their performance in those applications. In this paper, it is presented the effect of mono- (CnMIMBr) and dicationic (Cn(MIM)2Br2) imidazolium ionic liquids (ILs) on the viscosity and gelation of methylcellulose (MC) using rheology, micro differential scanning calorimetric and small angle X-ray scattering (SAXS) techniques. Results show that the ILs affect the pattern of the sol-gel transition and display transition from the salt-out to the salt-in on the gelation temperature, decrease the gel strength and increase viscosity of MC solutions. This behavior can be explained by hydrophobic interaction between the ILs and the MC, which depends of the alkyl chain length of the ILs, type of ILs (conventional or bolaform) and the range of ILs concentration. In general, the presence of ILs decrease the MC gel strength, while dicationic ILs hampers their association on MC in comparison with monocationic ones. The findings highlight the role of ILs on gelation of MC opening possibilities for the design of new complex formulations.

Formulation and evaluation of oxymetazoline hydrochloride nasal gels

The main intend of the implement sniff out formulate and evaluate oxymetazoline nasal gels. To achieve more persistent blood levels with decrease dosage of medicine by extended drug evidence and by passing hepatic initially cross metabolism and body including inferable disgrace. Mod FTIR & DSC spectra there is not any discrepancein the seam clean medicine, polymers & lipids. The Carbopol consisting of reinforce precail eventual scintillating moreover transparent Poloxamer, Hydroxy Propyl Methyl cellulose gels crop up prospective lucent as a consequence frosted slimy. The pH value of all developed formulations of gels (ONGF1-ONGF8) was in the range of 6.2 to 6.9. Spreadability of gels was in the range 19.51 - 33.91 g.cm/sec, The Viscosity of various formulated gels was found in range of 8628 to 9622 centipoises. The percentage drug content of all prepared gel formulations were found to be in the range of 78.53 to 98.56 %. The gel strength of all prepared formulations of gels was found to be in the range of 69 to 96 %. In-vitro diffusion drug release of Oxymetazoline Hydrochloride of nasal gels ONGF1 shows the 95% drug release. The release order kinetics shows all the formulations ONGF1 to ONGF8 formulations were followed Korsemeyer-Peppas with correlation coefficient R2=0.8969 & 0.2692 respectively. ONGF1 formulation follows both Zero order and Korsmeyer-Peppas models, it indicates diffusion release mechanism followed by non-fickian transport.
 Keywords: Nasal, gels, Oxymetazoline, In vitro diffusion, Carbopol.