Development of an online optical prototype for the simultaneous analysis of defects or gels in industrially synthesized polypropylene films. Part 1: Comparison with ASTM D 3351-93 methods

Polypropylene (PP) films are crucial in various industrial applications, from packaging to medical products. However, a common challenge in PP manufacturing is the presence of gel-like defects. These gels are minor defects on the surface of the films that significantly affect the physicochemical, mechanical, and organoleptic properties of the films, compromising the quality of the final product. This first research focuses on developing and validating an in-line optical method to replace the international method ASTM D 3351-93. The main objective was to create a methodology that has the same scope and analytical performance as those reported by ASTM D 3351-93 in such a way that it can compete with it in terms of precision and accuracy, thus allowing end users to this ASTM, such as PP producers, PP marketers, PP film producers, among others internationally, can use this new methodology with necessary analytical support. This analytical methodology integrates the PP extrusion zones, the film processing stages, and the optical zone for reading and processing analytical data. Additionally, it has the advantage of working with a sample size that is even more representative of the population and has less human error since only one operator is required to carry out the test; this method also has much shorter response times. The developed prototype had 14 online stages that allowed representative quantities of samples to be taken and processed thermally and mechanically for ideal optical measurement. For the online method, a 6-point calibration curve is carried out at concentrations of 40, 10, 5, 2, 1 and 0 ppm for the gel or defect sizes of 200, 400, 500, 600, 700, 800 and 900 µm, showing excellent linearity where the correlation coefficient varied between 0.997 and 0.999, the limits of detection (LOD) varied between 0.85 and 2.61 and the limits of quantification (LOQ) ranged between 2.82 and 8.71. The statistical analyzes by ANOVA of the comparison between the ASTM D 3351-93 method and the proposed simultaneous method indicate that the p value of the evaluation of the means was 0.946, which suggests that the means are not statistically different. To complement, the Tukey test was carried out at 95 %, indicating that the methods have statistical equivalence.•Process optimization•Determination of defects or imperfections in PP films.

Tailoring the Properties of Gel Polymer Electrolytes for Sodium-Ion Batteries Using Ionic Liquids: A Review

Ionic liquids are an extraordinary group of compounds, fully ionic in structure like inorganic salts but with low melting points, that resemble organic molecular solvents. Their chemical, electrochemical, and thermal stability is what draws the attention and enables their use in many applications, including electrochemical power sources. Even though they are no longer considered eco-friendly because of nonnegligible toxicity and long bioaccumulation, they can still be efficiently recovered, purified, and reused. These attributes can be harvested to enhance the properties of gel polymer electrolytes for the emerging sodium-ion batteries. The variety of anions and cations for ILs and their influence on the final properties of the compound opens the road to tuning the properties of gel polymer electrolytes. Ionic liquids as plasticizers constitute a major part of gel polymer electrolytes (average of 70 wt%) and hence, they affect the fundamental properties of gel electrolytes like ionic conductivity and electrochemical window. They also improve the safety features of sodium-ion batteries, which is relevant for their anticipated applications in stationary energy storage and electric vehicles. The presented review paper aims to explain the relationship between the cation and anion in ionic liquid and the properties of gel electrolytes for sodium-ion batteries.

Rutin-loaded zein gel as a green biocompatible formulation for wound healing application

Wound healing is a challenging clinical problem and efficient wound management is essential to prevent infection. This is best done by utilizing biocompatible materials in order to complete the healing in a rapid manner, with functional and esthetic outcomes. In this context, the zein protein fulfills the criteria of the ideal wound dressing which include non-toxicity and non-inflammatory stimulation. Zein gels containing rutin were prepared without any chemical refinement or addition of gelling agents in order to obtain a natural formulation characterized by antioxidant and anti-inflammatory properties to be proposed for the treatment of burns and sores. In vitro scratch assay showed that the proposed gel formulations promoted cell migration and a rapid gap closure within 24 h (~90 %). In addition, the in vivo activities of rutin-loaded zein gel showed a greater therapeutic efficacy in Wistar rats, with a decrease of the wound area of about 90 % at day 10 with respect to the free form of the bioactive and to DuoDERM®. The evaluation of various markers (TNF-α, IL-1β, IL-6, IL-10) confirmed the anti-inflammatory effect of the proposed formulation. The results illustrate the feasibility of exploiting the peculiar features of rutin-loaded zein gels for wound-healing purposes.

Thermoreversible gels of hollow silica nanorod dispersions

Colloidal suspensions of anisotropic particles are ubiquitous in particle-based industries. Consequently, there is a need to quantify the effects of particle shape on equilibrium phases and kinetic state transitions, particularly at lower aspect ratios (L/D ≈ 1-10). We present a new, colloidal system comprised of hollow, octadecyl-coated silica rods with 40 nm diameter with controlled aspect ratio and thermoreversible short-range attractions. Rheology and dynamic light scattering measurements on suspensions of these hollow adhesive hard rods with nominal aspect ratio ≈3 suspended in tetradecane exhibit thermoreversible gelation without complicating effects of gravitational settling. Small angle neutron scattering measurements of the microstructure are analyzed to determine the effective strength of attraction in the form of Baxter sticky parameter. Quantitative agreement is found with simulation predictions of the thermoreversible gel transition as a function of volume fraction, further validating a universal state diagram and providing guidance for the effects of aspect ratio on gelation.

Luminescent Supramolecular Metallogels: Drug Loading and Eu(III) as Structural Probe

Supramolecular metallogels combine the rheological properties of gels with the color, magnetism, and other properties of metal ions. Lanthanide ions such as Eu(III) can be valuable components of metallogels due to their fascinating luminescence. In this work, we combine Eu(III) and iminodiacetic acid (IDA) into luminescent hydrogels. We investigate the tailoring of the rheological properties of these gels by changes in their metal:ligand ratio. Further, we use the highly sensitive Eu(III) luminescence to obtain information about the chemical structure of the materials. In special, we take advantage of computational calculations to employ an indirect method for structural elucidation, in which the simulated luminescent properties of candidate structures are matched to the experimental data. With this strategy, we can propose molecular structures for different EuIDA gels. We also explore the usage of these gels for the loading of bioactive molecules such as OXA, observing that its aldose reductase activity remains present in the gel. We envision that the findings from this work could inspire the development of luminescent hydrogels with tunable rheology for applications such as 3D printing and imaging-guided drug delivery platforms. Finally, Eu(III) emission-based structural elucidation could be a powerful tool in the characterization of advanced materials.

Chocolates, compounds and spreads: A review on the use of oleogels, hydrogels and hybrid gels to reduce saturated fat content

This study is a bibliometric analysis and literature review on the use of oleogels (OGs), hydrogels (HGs) and hybrid gels (HYGs) in chocolate, compounds and spreads with the aim of reducing the saturated fat in these products. The articles were selected by analyzing titles, keywords and abstracts in the Web of Science (WoS), Scopus and Google Scholar databases. Supplementary documents were obtained from government sources, including patent registrations. The theoretical and practical aspects were critically analyzed, highlighting the main points of agreement and disagreement between the authors. The results revealed a lack of regulations and official guidelines that widely allow the use of OGs, HGs and HYGs in chocolate confectionery products. The type and characteristics of raw materials affect the properties of products. Replacing cocoa butter (CB) with OGs, HGs or HYGs also affects texture, melting point and behavior, and nutritional aspects. These substitutions can result in products with better sensory acceptance and health benefits, such as reducing saturated fat and promoting cardiovascular health. However, it is important to find the ideal combination and proportions of components to obtain the desired properties in the final products.

Development and Evaluation of Tacrolimus Loaded Nano-Transferosomes for Skin Targeting and Dermatitis Treatment

Tacrolimus (TRL) is used for the treatment of atopic dermatitis (AD) due to its T-cell stimulation effect. However, its significantly poor water solubility, low penetration and cytotoxicity have reduced its topical applications. Herein, tacrolimus loaded nano transfersomes (TRL-NTs) were prepared, followed by their incorporation into chitosan gel to prepare tacrolimus loaded nano transfersomal gel (TRL-NTsG). TEM analysis of the TRL-NTs was performed to check their morphology. DSC, XRD and FTIR analysis of the TRL-NTs were executed after lyophilization. Similarly, rheology, spreadability and deformability of the TRL-NTsG were investigated. In vitro release, ex vivo permeation and in vitro interaction of TRL-NTsG with keratinocytes and fibroblasts as well as their co-cultures were investigated along with their in vitro cell viability analysis. Moreover, in vivo skin deposition, ear thickness, histopathology and IgE level were also determined. Besides, 6 months stability study was also performed. Results demonstrated the uniformly distributed negatively charged nanovesicles with a mean particle size distribution of 163 nm and zeta potential of -27 mV. DSC and XRD exhibited the thermal stability and amorphous form of the drug, respectively. The TRL-NTsG showed excellent deformability, spreadability and rheological behavior. In vitro release studies exhibited an 8-fold better release of TRL from the TRL-NTsG. Similarly, 6-fold better permeation and stability of the TRL-NTsG with keratinocytes and fibroblasts as well as their co-cultures was observed. Furthermore, the ear thickness (0.6 mm) of the TRL-NTsG was found significantly reduced when compared with the untreated (1.7 mm) and TRL conventional gel treated mice (1.3 mm). The H&E staining showed no toxicity of the TRL-NTsG with significantly reduced IgE levels (120 ng/mL). The formulation was found stable for at least 6 months. These results suggested the efficacy of TRL in AD-induced animal models most importantly when incorporated in NTsG.

Insights into starch-based gels: Selection, fabrication, and application

Starch a natural polymer, has made significant advancements in recent decades, offering superior performance and versatility compared to synthetic materials. This review discusses up-to-date diverse applications of starch gels, their fabrication techniques, and their advantages over synthetic materials. Starch gels renewability, biocompatibility, biodegradability, scalability, and affordability make them attractive. Also, advanced theoretical foundations and emerging industrial technologies could further expand their scope and functions inspiring new applications.

Molybdenum disulfide nanoflowers - doped sodium alginate/polyvinyl alcohol porous xerogel for methylene blue and copper ion adsorption

In order to improve the adsorption performance of MoS2, as well as to solve the problems of MoS2-powder in adsorption, which is prone to agglomeration and difficulty to be recycled, we prepared MoS2-nanoflowers(MoS2-NFs), and mixed them with sodium alginate/polyvinyl alcohol(SA/PVA) to prepare MoS2-NFs/SA/PVA xerogel(MSP) by freezing-lyophilization. Then two forms of xerogels - block-MSP(MSPB) and spherical-MSP(MSPS) were prepared, and they were used as methylene blue(MB) and Cu2+ adsorbent. It was found that MoS2-NFs were evenly dispersed inside the SA/PVA with no agglomeration, while the interior of MSPB/MSPS showed the structure of parallel-pores and radial-pores, respectively. The adsorption capacity of MSPB/MSPS on MB can reach 233 mg/g, which is five times higher than SA/PVA-gel, showing excellent synergistic-adsorption effect, and the adsorption capacity for Cu2+ reaches 271 mg/g. The adsorption mechanism indicated that the adsorption of MB by MSPB/MSPS conformed to pseudo-first-order model, with electrostatic force as the main force. And their adsorption of Cu2+ conformed to pseudo-second-order model and was dominated by Lewis acid/base soft-soft interactions. Notably, after long-term adsorption, MSPB/MSPS maintains its shape and more than 90 % of the adsorption capacity, ensuring the recovery and reuse of materials. So, MSPB/MSPS has great potential in adsorption, providing a new solution for sewage purification.

Substituent alkyl-chain-dependent supramolecular chirality, tunable chiroptical property, and dye adsorption in azobenzene-glutamide-amphiphile based hydrogel

Controlling the supramolecular chirality of a self-assembly system by molecular structure design and external stimuli in aqueous solution is significant but challenging. Here, we design and synthesize several glutamide-azobenzene-based amphiphiles with different length alkyl chains. The amphiphiles can form self-assemblies in aqueous solution and show CD signals. As the number of the alkyl chain of amphiphiles increases, the CD signals of the assemblies can be enhanced. However, the long alkyl chains conversely restrict the isomerization of the azobenzene and the corresponding chiroptical property. Moreover, the alkyl length can determine the nanostructure of the assemblies and exert critical influence on the dye adsorption efficiency. This work exhibits some insights into the tunable chiroptical property of the self-assembly by delicate molecular design and external stimuli, and emphasizes the molecular structure can determine the corresponding application.

Saltiness perception in gel-based food systems (gels and emulsion-filled gels)

Reducing salt in food without compromising its quality is a huge challenge. Some review articles have been recently published on saltiness perception in some colloidal systems such as emulsions. However, no published reviews are available on saltiness perceptions of gel-based matrices, even though salt release and perception in these systems have been extensively studied. This article reviews the recent advances in salt perception in gel-based systems and provides a detailed analysis of the main factors affecting salt release. Strategies to enhance saltiness perception in gels and emulsion-filled gels are also reviewed. Saltiness perception can be improved through addition of biopolymers (proteins and polysaccharides) due to their ability to modulate texture and/or to adhere to or penetrate through the mucosal membrane on the tongue to prolong sodium retention. The composition of the product and the distribution of salt within the matrix are the two main factors affecting the perception of salty taste. Food structure re-design can lead to control the level of interaction between the salt and other components and change the structure, which in turn affects the mobility and release of the salt. The change of ingredients/matrix can affect the texture of the product, highlighting the importance of sensory evaluation.

Oleogel-based drug delivery for the treatment of periodontitis: current strategies and future perspectives

Periodontitis is the chronic inflammation of tooth-supporting tissues that leads to loss of tooth support if untreated. Conventional therapy for periodontitis (mechanical removal of microbial biofilm and oral hygiene enforcement) is augmented by anti-microbial and anti-inflammatory drugs. These drugs are frequently delivered locally into the periodontal pocket for maximum efficiency and minimum adverse effects. The potential of oleogels for periodontal drug delivery has been discussed and further, the future scope of oleogel-based drug delivery systems in dentistry. An oleogel-based local drug delivery system offers several advantages over other systems. Superior mechanical properties (firmness and compressibility), muco-adhesion, shear thinning, thixotropy, controlled drug release and the ability to incorporate water-insoluble drugs clearly distinguish and highlight the potential of oleogels as periodontal local drug delivery systems. Bigels can combine the qualities of both hydrogels and oleogels to provide a more promising option for drug delivery. However, there is limited evidence concerning oleogels as local drug delivery agents in periodontics. Further studies are needed to discern the clinical efficacy of oleogel-based drug delivery systems.

Thermal Gelation of Proteins from Cajanus cajan Influenced by pH and Ionic Strength

Cajanus cajan [pigeon pea (PP)] is an important legume crop for subsistence agriculture and its seeds are an alternative plant-based protein source. PP protein isolates (PPI) are able to form heat-induced gels that could be used for food applications. The aim of this work was to study the influence of pH (2.1, 3.9, 6.3, and 8.3) and ionic strength (μ) (0.10 and 0.54) on thermal stability and thermal gelation of PPI obtained by alkaline extraction (pH 8.0) and isoelectric precipitation. Thermal stability of PPI changed with pH variation at low ionic strength (μ = 0.10), decreasing this dependence with the increase of ionic strength (μ = 0.54). At μ = 0.10, gelation capacity of PPI was lower at pH 2.1 and pH 3.9. These gels presented a coarse network, which entails low WHC. At pH 6.3 and pH 8.3, gels showed a solid-like character with a compact and homogeneous matrix, with better WHC. At μ = 0.54, gel formation was favoured at pH 2.1 and pH 3.9. G'20/G'95 ratio values and differential solubility results suggest that hydrogen bonds and electrostatic interactions could play an important role in gel formation at pH 6.3 and pH 8.3.

Amphiphilic Polymer Hydrogel-supported Catalysts: Tuning the Accessibility to the Catalytic Site by Molecular Jacketing

Amphiphilic hydrogels, prepared using a peripherally clickable hyperbranched polyester (HBP) and PEG-diazides of different molecular weights, were used to ligate Cu utilizing the triazole rings formed by the alkyne-azide click reaction. Since only a fraction of the peripheral propargyl groups in the HB polyester are needed to generate the crosslinked polymer, the remaining were clicked with different types of azides, such as MPEG azide, decyl azide or 4-methylbenzyl azide, to create a molecular jacket around the catalytic sites that can potentially influence the catalytic activity and reaction outcome. The crosslinked films ligated with Cu functioned very effectively to catalyse alkyne-azide click reactions, both in water and in organic solvents; the nature of the molecular jacket around the catalytic site has a clear influence the reaction rate, which depended upon the relative solubilities of the reactants. The gel-supported catalysts films can be recycled multiple times with little loss in catalytic activity.

Gelation behaviors and mechanism of a new pectic polysaccharide from apple pomace as a potential gelatin substitute

In this study, we reported a pectic polysaccharide industrially obtained from apple pomace by metal ion precipitation technique showing an unexpected gelation behavior. Structurally, this apple pectin (AP) is a macromolecular polymer with a weight-average molecular weight (Mw) of 361.7 kDa, and DM (degree of methoxylation) of 12.5 %, comprising 60.38 % glucose, 19.41 % mannose, 17.60 % galactose and 1.00 % rhamnose and 1.61 % glucuronic acid. The low acidic sugar percentage relative to the total monosaccharide amount indicated a high branching structure of AP. On addition of Ca²⁺ ions, AP exhibited a remarkable gelling ability upon cooling its heat solution to low temperature (e.g., 4 °C). However, at room temperature (e.g., 25 °C) or in the absence of Ca²⁺, no gel was formed. At a fixed pectin concentration (0.5 %, w/v), AP showed increasing gel hardness and gelation temperature (T_gel) with CaCl₂ concentration increasing to 0.05 % (w/v); however, further addition of CaCl₂ weakened AP gels and even abolished the gelation. On reheating, all gels melted below 35 °C, which suggests the potential use of AP as a gelatin substitute. The gelation mechanism was explained as an intricate balance of the synchronous formation of hydrogen bond and Ca²⁺ crosslinks between AP molecules during cooling.

Transform commercial magnetic materials into injectable gel for magnetic hyperthermia therapy in vivo

Magnetic hyperthermia therapy of tumors employing magnetic materials has been greatly developed due to their low invasiveness, high specificity, few side effects and no limitation of tissue penetration depth. However, traditional nanoscale magnetocaloric materials exhibited the disadvantages of low tumor enrichment efficiency, complex preparation process and difficulty in large-scale production. While eddy current loss-based magnetic hyperthermia tumor ablation with metal implants faces shortcomings such as high invasiveness and low selectivity of tumor shape and volume. Herein, we developed injectable magnetic gels by adding commercial magnetic metal or metal oxide powders (CMMPs) into alginate-Ca²⁺ (ALG-Ca²⁺) gel through an ultra-simple mixing strategy for magneto-thermal therapy of tumors in vivo. The ALG-Ca²⁺ gel can not only turn the water-insoluble CMMPs into injectable gel, but also retain the inherent magnetic loss-based heating capacity. Besides, CMMPs in the gels are easily retained at the tumor site after peritumoral injection because of their large size and strong hydrophobicity, which benefits the efficiency and accuracy of the treatment and reduces side effects to the surrounding tissues. The prepared ALG-Ca²⁺-CMMPs give full play to the inherent magneto-thermal capacity of CMMPs, which possesses super high loading ability (>100 mg magnetic materials/mL), superior large-scale production capability (>1 kg in laboratory synthesis), low cost, satisfactory syringeability and biological safety. Collectively, this study provides a convenient and universal strategy for the construction of magnetocaloric materials for biological applications.

Near-infrared light accelerated glucose oxidase-MoS2 cascade catalytic chemodynamic therapy in synergistic cationic polymer hydrogels to combate multibacterial infection

Given the poor antibacterial activity of hydrogels, a multimodal synergistic antibacterial hydrogel based on dopamine-modified oxidized hyaluronic acid was developed, and its antibacterial activity and biocompatibility were demonstrated. First, dopamine-modified oxidized hyaluronic acid (OHA-DA) was used as the hydrogel backbone. A dual-dynamically cross-linked injectable hydrogel was constructed by mixing OHA-DA, Fe3+ with cationic antimicrobial peptide polylysine (EPL) via Schiff base and coordination complexation. Next, glucose oxidase-loaded MoS2 nanosheets were synthesized through electrostatic interaction and loaded into the hydrogel through physical mixing. Finally, a multimodal synergistic antibacterial hydrogel OD/EPL/GM was obtained. Antibacterial experiments show that the hydrogel has good antibacterial activity against E. coli and S. aureus, and the antibacterial rate can reach 99.99%.

Advancing textural heterogeneity: Effect of manipulating multi-component model foods on the perception of textural complexity

The aim of this study was to identify the individual and interacting effects of varying the mechanical properties of two inserts (к-carrageenan beads; 1, 2 and 4% w/w and/or agar-based disks; 0.3, 1.2 and 3% w/w) in pectin-based gels on the perception of textural complexity. A full factorial design was utilised, 16 samples were characterised with sensory and instrumental tests. Rate-All-That-Apply (RATA) was performed by 50 untrained participants. RATA selection frequency provided different information to attribute intensity regarding the detection of low yield stress inserts. In the two-component samples, the perception of textural complexity (n = 89) increased with insert yield stress for both к-carrageenan beads and agar disks. However, with the addition of medium and high yield stress к-carrageenan beads to three-component samples, the increases in perceived textural complexity caused by increased agar yield stress were eliminated. The definition of textural complexity, the number and intensity of texture sensations, as well as their interactions and contrasts, was in line with the results, and the hypothesis that not only mechanical properties but also the interaction of components play a key role in the perception of textural complexity.

Swelling-induced Mechanochromism in Multinetwork Polymers

We report a novel and versatile approach to achieving swelling-induced mechanochemistry using a multinetwork (MN) strategy that enables polymer networks to repeatedly swell with monomers and solvents. The isotropic expansion of the first network (FN) provides sufficient force to drive the mechanochemical scission of a radical-based mechanophore, difluorenylsuccinonitrile (DFSN). Although prompt recombination generally occurs in such highly mobile environments, the resulting pink radicals are kinetically stabilized in the gels, probably due to limited diffusion in the extended polymer chains. Moreover, the DFSN embedded in the isotropically strained chain exhibits increased thermal reactivity, which can be reasonably explained by an entropic contribution of the FN to the dissociation. The utility of the MN polymers is demonstrated not only in terms of swelling-force-induced network modification, but also in the context of tunable reactivity of the dissociative unit through proper design of the hierarchical network architecture.

ROS-Triggered Gel-Sol Transition and Kinetics-Controlled Cargo Release by Methionine-Containing Peptides

Gel-sol transition of self-assembling peptides is a useful switch for environment-dependent drug release. For their applications, kinetics control of the responses is important for matching the releasing velocity to the target biological events. Here we demonstrate a chemical control of redox-triggered gel-sol transition kinetics of self-assembling peptides by the amino acid sequence. Amphiphilic peptides with different methionine positions were developed, where the methionine residue locates at the center of JigSAP-IMI, whereas JigSAP-MII possesses the methionine residue near the N-terminus. Both peptides formed hydrogels in a physiological condition by forming β-sheet-based supramolecular nanofibers. In contrast, the oxidized forms retained solution states under identical conditions by adopting α-helix-rich secondary structures. Upon oxidation with H2O2, a reactive oxygen species, JigSAP-MII showed faster gel-to-sol transition and cargo-releasing than JigSAP-IMI, indicating that the phase-transition and releasing kinetics of self-assembling peptides can be rationally controlled by the position of the reactive amino acid residue.

Regulating the Mechanical and Optical Properties of Polymer-based Nanocomposites by Sub-Nanowires

Sub-nanowires (SNWs) exhibit great potential applications in nanocomposites owing to their high specific surface area, high flexibility, and similarity to polymer chains in dimension, which are a good entry point to bridge inorganic materials and polymer materials. Herein, we synthesized hydroxyapatite sub-nanowires (HAP SNWs) and engineered hydroxyapatite sub-nanowires/polyimide (HSP) gels and films by simple mixing of HAP SNWs and polyimide (PI). Benefiting from the interactions between HAP SNWs and PI, these nanocomposites were a continuous hybrid network. As the increase of HAP SNWs contents, the viscosity and modulus of HSP gels were greatly improved by one or two orders of magnitude compared with PI gel. HSP films not only maintained high transparency but also gained high haze, as well as exhibited enhanced Young's modulus. Thus, both HSP gels and films developed in this work are promising for various applications in coatings and high-performance films.

Liquid crystal phase formation and non-Newtonian behavior of oligonucleotide formulations

Viscosity behavior of liquid oligonucleotide therapeutics and its dependence on formulation properties has been poorly studied to date. We observed a high increase in viscosity and solidification of therapeutic oligonucleotide formulations with increasing oligonucleotide concentration creating challenges during drug product manufacturing. In this study, we characterized the viscosity behavior of three different single strand DNA oligonucleotides based on oligonucleotide concentration and formulation composition. We subsequently studied the underlying mechanism for increased viscosity at higher oligonucleotide concentrations by dynamic light scattering (DLS), 1H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and polarized light microscopy. Viscosity was highly dependent on formulation composition, oligonucleotide sequence, and concentration, and especially dependent on the presence and combination of different individual ions, such as the presence of sodium chloride in the formulation. In samples with elevated viscosity, the viscosity behavior was characterized by non-Newtonian, shear-thinning flow behavior. We further studied these samples by DLS and 1H NMR, which revealed the presence of supra-molecular assemblies, and further characterization by polarized light and DSC characterized these assemblies as liquid crystals in the formulation. The present study links the macroscopic viscosity behavior of oligonucleotide formulations to the formation of supra-molecular assemblies and to the presence of liquid crystals, and highlights the importance of formulation composition selection for these therapeutics.

A Hierarchical (Macro)molecular Assembly Assisted by Donor-Acceptor Charge-Transfer Interactions Exhibiting Room-Temperature Ferroelectricity

This communication reveals co-assembly of an electron-deficient naphthalene-diimide (NDI)-appended polyurethane (P1) and electron-rich pyrene (Py), forming an organogel with prominent room-temperature ferroelectricity. In a non-polar medium, intra-chain hydrogen-bonding among the urethane groups of P1 produces a folded structure with an array of the NDIs in the periphery, which intercalate Py by charge-transfer (CT)-interaction. Such CT-complexation enables slow crystallization of the peripheral hydrocarbons, causing gelation with nanotubular morphology, in which the wall consists of the alternating NDI-Py stack. Such D-A assembly exhibits ferroelectricity (saturation polarization P_s ≈0.8 μC cm^-2 and coercive field E_c ≈8 kV cm^-1 at 500 V and 10 Hz frequency) with Curie temperature (T_c ) of ≈350 K, which can be related to the disassembly of the CT-complex. In the absence of Py, P1 forms spherical aggregates, showing dielectric behaviour.

Stearoylamido-D-Glucamine Hydrogelators for Thixotropic Molecular Gels with Tunable Softness by Chemical Modification

Low-molecular-weight hydrogelators containing stearoyl, glycine, and D-glucamine moieties with or without methyl groups were synthesized to prepare chemically tuned molecular hydrogels. To evaluate the role of hydrogen bonding of hydrogelators in molecular hydrogel formation, the author has newly synthesized hydrogelators with or without methyl groups at their N-H in amide groups, contributing to the hydrogen bond formation in fiber in molecular hydrogels. The obtained hydrogels exhibited improved thixotropic performance with tunable softness, exhibiting pseudo-reversible thixotropic cycles that depended on the methyl substitution positions in the hydrogelators. To change the hydrogen bonds' positions by chemical modification has made it possible to tune the mechanical properties of molecular gels.

Dynamic Covalent Cross-linked Nanogel-stabilized Pickering Emulsion for Responsive Microstructures

Designing new dynamic matrices in combination with a highly diverse material formation approach as Pickering emulsionsprovides us with the tools to engineer innovative dynamic porous microstructures in a highly controllable fashion. Here we make use of nanogels (nGels), which exhibits dynamic covalent cross-linking capabilities, as surface stabilizing agents in view of their highly controllable physiochemical properties. The method provides successful formation of dynamic covalent cross-linked hydrogel microstructures based on ketone and amine functionalized nGels using Pickering emulsions was shown. In this system we incorporated a pH-triggerable responsive behavior. The physiochemical properties of the resulting microstructure can be further tailored by modifying the intramolecular interactions at the interface, making this systems interesting for a wide range of applications. This article is protected by copyright. All rights reserved.

Sugar reduction methods and their application in confections: a review

Many American adults consume almost double the daily recommended amount of sugar. With excess consumption of sugar and consequential health problems arising, food manufacturers are investigating methods to reduce sugar while maintaining similar functional and sensory properties. The body of literature was searched for papers regarding sugar reduction, and the main methods of sugar reduction are summarized herein with a specific focus on high sugar products. Reducing sugar in confections is possible; however, the challenge is maintaining the balance between texture and sweetness perception. Texture plays a large role in the sweetness perception of confections, with firmer products often being perceived as less sweet. Depending on the method, 20-40% of sugar can be removed from confections without sacrificing sensory acceptance, often replaced with multiple ingredients. Further investigation is needed on confection models and how the emerging health trends set the foundation for sugar reduction.

Rheological and gelling properties of Nicandra physalodes (Linn.) Gaertn. pectin in acidic media

Nicandra physalodes (Linn.) Gaertn. polysaccharide (NPGP) was previously recognized as a pectic polysaccharide, with a high galacturonic acid content (87.8%) and a low methoxylation degree (28%). In the present study, it was found that NPGP can form self-supporting gels when cooling its heated solutions (2.0%, w/v) acidified by citric acid. It was demonstrated that the decrease in pH led to the suppression in electrostatic repulsions between the pectin chains, thereby promoting pectin chain-chain association mainly through hydrogen bonding. As the pH decreased from 3.2 to 2.4, the gel strength and gel thermal stability were continuously increased. Moreover, it was shown that sucrose addition slightly promoted the gelation and gel thermal stability of NPGP, but the effect of monovalent ions (Na⁺) and divalent ions (Ca²⁺) was not significant. Conclusively, our results indicate that NPGP is a new gelling polysaccharide that shows great potential in formulation of acidic gel foods.

A 4arm-PEG macromolecule crosslinked chitosan hydrogels as antibacterial wound dressing

In order to develop better wound dressings, a novel chitosan hydrogel (Cn-Nm gel) was designed and fabricated by using aldehyde-4-arm polyethylene glycol (4r-PEG-CHO) to crosslink the chitosan dissolved in alkaline solution, amino-4-arm polyethylene glycol (4r-PEG-NH₂) was chosen as the additive simultaneously. The special dissolution technique and macromolecular crosslinking structure endows the Cn-Nm gels with better performance than that of gels prepared by acid dissolving method with micromolecule crosslinker. First, Cn-Nm gels own strong toughness with 500 kPa tensile strength and 1000% elongation, about 400% swelling ratio and fast water absorption rate. Second, about 300 kPa adhesive strength and strippability between the gels and skin is achieved. More importantly, Cn-Nm gels show nearly 100% antibacterial rate towards Escherichia coli and Staphylococcus aureus. Excellent biocompatibility is also proved by the mouse fibroblasts tests. All of the performance makes this developed chitosan-based gel be the potential candidate as a wound dressing.

Rheological properties of cellulosic thickeners in hydro-alcoholic media: The science behind the formulation of hand sanitizer gels

Cellulosic-based thickeners are commonly used in the preparation of hydro-alcoholic hand sanitisers. Yet, little is known about the behaviour of these polymeric dispersions in hydro-alcoholic mixtures. Here, we studied the dispersion ability and rheology of hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose and sodium carboxymethyl cellulose in water-ethanol mixtures. Hydroxypropyl cellulose formed transparent dispersions across the entire range of ethanol concentrations, while a critical ethanol concentration (CEC), above which dispersions became turbid, was found for all the other polymers. At and below the CEC, all the rheological parameters followed a bell-like shape profile as a function of ethanol concentration. Moreover, the molecular weight and degree of substitution of the polymers influenced the rheological properties. The CEC and rheological behaviour of the dispersions were both dependent on the ethanol/polymer and water/polymer interactions. As hand disinfectants should contain 60-95% ethanol, polymers of higher CEC, such as hydroxypropyl cellulose and hydroxypropyl methylcellulose, are recommended.

Cellulose nanocrystal/low methoxyl pectin gels produced by internal ionotropic gelation

The biotechnological applications of cellulose nanocrystals (CNCs) continue to grow due to their sustainable nature, impressive mechanical, rheological, and emulsifying properties, upscaled production capacity, and compatibility with other materials, such as protein and polysaccharides. In this study, hydrogels from CNCs and pectin, a plant cell wall polysaccharide broadly used in food and pharma, were produced by calcium ion-mediated internal ionotropic gelation (IG). In the absence of pectin, a minimum of 4 wt% CNC was needed to produce self-supporting gels by internal IG, whereas the addition of pectin at 0.5 wt% enabled hydrogel formation at CNC contents as low as 0.5 wt%. Experimental data indicate that CNCs and pectin interact to give robust and self-supporting hydrogels at solid contents below 2.5 %. Potential applications of these gels could be as carriers for controlled release, scaffolds for cell growth, or wherever else distinct and porous network morphologies are required.

Gelation of amphiphilic janus particles in an apolar medium

HYPOTHESIS

The anisotropic nature of colloidal particles results in orientation-dependent interactions that organize the particles into peculiar structures different from those formed by isotropic colloids. Particles with a hydrophilic hemisphere are expected to assemble in hydrophobic solvents due to the contribution of hydrophobic interactions as observed for molecular amphiphiles.

EXPERIMENTS

Asymmetrically decorated silica-based Janus particles are dispersed in an apolar solvent, chloroform, and their structure and dynamics are studied by light scattering and compared with computer simulations.

FINDINGS

Gelation of amphiphilic Janus particles with asymmetric surface decoration is observed in a hydrophobic medium. The influence of particle asymmetry on gel structure and dynamics is discussed. Unlike particles with long-range repulsive interactions in water, these systems rapidly form rather compact structures that are nevertheless more ramified than those made of isotropic hydrophobic particles. Comparison with computer simulations allows visualization of the gel and reveals a contribution of asymmetric short-range attractions and cross-term repulsions to the net effective interaction potential.

Oscillatory rheology of carboxymethyl cellulose gels: Influence of concentration and pH

The flow properties of ionic polysaccharides are determined by the interplay of electrostatic and hydrophobic interactions, which depend on the ionic strength and pH of the solvent. We explore the LVE and LAOS rheology of carboxymethyl cellulose (CMC) in aqueous media, focusing on its gelling behaviour. We find that addition of HCl promotes gel formation and addition of NaOH suppresses it. The former effect is interpreted as being caused by a decrease of the charge density of the polymer, which facilitates interchain associations and the later effect can be assigned to solubilisation of cellulose backbone by NaOH. Our results along with a review of the literature allow us to establish the concentration regimes and associated properties of physical gels of carboxymethyl cellulose. At neutral pH, the storage modulus of NaCMC gels of varying molecular weight and DS at a given concentration does not vary by more than a factor 5.

Porous Colloidal Hydrogels Formed by Coordination-Driven Self-Assembly of Charged Metal-Organic Polyhedra

Introduction of porosity into supramolecular gels endows soft materials with functionalities for molecular encapsulation, release, separation and conversion. Metal-organic polyhedra (MOPs), discrete coordination cages containing an internal cavity, have recently been employed as building blocks to construct polymeric gel networks with potential porosity. However, most of the materials can only be synthesized in organic solvents, and the examples of porous, MOP-based hydrogels are scarce. Here, we demonstrate the fabrication of porous hydrogels based on [Rh₂ (OH-bdc)₂ ]₁₂ , a rhodium-based MOP containing hydroxyl groups on its periphery (OH-bdc=5-hydroxy-1,3-benzenedicarboxylate). By simply deprotonating [Rh₂ (OH-bdc)₂ ]₁₂ with the base NaOH, the supramolecular polymerization between MOPs and organic linkers can be induced in the aqueous solution, leading to the kinetically controllable formation of hydrogels with hierarchical colloidal networks. When heating the deprotonated MOP, Na_x [Rh₂₄ (O-bdc)_x (OH-bdc)_24-x ], to induce gelation, the MOP was found to partially decompose, affecting the mechanical property of the resulting gels. By applying a post-synthetic deprotonation strategy, we show that the deprotonation degree of the MOP can be altered after the gel formation without serious decomposition of the MOPs. Gas sorption measurements confirmed the permanent porosity of the corresponding aerogels obtained from these MOP-based hydrogels, showing potentials for applications in gas sorption and catalysis.

Improving gelling properties of diluted whole hen eggs with sodium chloride and sodium tripolyphosphate: Study on intermolecular forces, water state and microstructure

Individual and synergistic effects of sodium chloride (NaCl) and sodium tripolyphosphate (STPP) on the physicochemical and gelling properties of highly diluted liquid whole eggs were studied. Results showed that NaCl and STPP acted differently whereby NaCl addition increased the surface hydrophobicity of the egg proteins and STPP addition increased the protein solubility and the negative surface charge. When combined together, these changes led to a significant increase in a number of intermolecular forces after heat treatment, including hydrophobic interactions, disulfide bonds, and hydrogen bonds, contributing to the best structure and texture of the whole egg gels enriched with binary salts. The amount of the free water in the heat-induced gel products with the addition of both NaCl and STPP were the least as compared to systems with single salt addition, which was related to the coarse and dense network microstructure.

3D printing performance of gels from wheat starch, flour and whole meal

The effects of material composition on the quality of 3D-printed food using wheat starch, flour and whole meal were explored. Results showed that samples molded by wheat starch and whole meal obtained a more accurate and better quality printing than wheat flour. Wheat flour had the worst printable capacity as it gets stuck easily to the wall of the printer. Starch-protein complexes appeared in the samples of wheat flour and whole meal. Whole meal constituted protein, fat, fiber and starch to form various complexes, which strengthen the gel network cross-linking, retard starch aging significantly, and enhance the water binding capacity than just the starch only sample. Printed samples using whole meal still possess a soft and elastic texture after long-time storage. Overall, whole meal with higher protein, fat and fiber content was better for food 3D printing than wheat starch and flour.

Flavour distribution and release from gelatine-starch matrices

Microstructure design of protein-polysaccharide phase separated gels has been suggested as a strategy to nutritionally improve food products. Varying the phase volumes of a phase separated matrix may affect texture and overall flavour balance of the final product, which are both important for consumer acceptance. The aims of this study were to investigate how modifying the phase volumes of a gelatine-starch biphasic mixture affected aroma release, and how addition of sucrose affects phase separation, flavour distribution and aroma release. Biphasic gels of different microstructures with the same effective concentration of gelatine and starch in each phase were developed. Microstructure significantly affected aroma release in vitro but not in vivo when panellists (n = 5) chewed and swallowed the sample. Addition of sucrose (0-60%) to the biphasic mixture significantly reduced water activity, affected the microstructure and affected aroma distribution in each phase and subsequent release rates depending on the physicochemical properties of the aroma volatile. In general, affinity for the gelatine phase for the less hydrophobic, more volatile compounds was not significantly affected by sucrose concentration. Whereas an increased affinity for the starch phase for the more hydrophobic, less volatile compounds was observed with increased sucrose as the starch phase becomes more dispersed at sucrose concentrations between 40 and 60%. The results of this study may be of interest to researchers and industry to enable prediction of how reformulation, such as reduction of sucrose, to meet nutritional guidelines may affect the overall aroma balance of a phase separated food matrix.

Probing gels and emulsions using large-amplitude oscillatory shear and frictional studies with soft substrate skin surrogates

Water swellable crosslinked polymers are widely used in oil-in-water emulsions for the healthcare and cosmetic industries due to their thickening properties. In this study, we investigate the rheological and lubrication behavior of a microgel-forming polymer, a lightly-crosslinked hydrophobically modified polyacrylic acid (HMPAA), in an aqueous medium and in an emulsion. Hydrogenated phosphatidylcholine, a class of phospholipids, is used as a surfactant in the emulsions composed of different oil content. Rheological behavior is probed both in the linear and non-linear regimes using small strain amplitude and large amplitude oscillatory shear (LAOS) experiments, respectively. We observe all systems to exhibit gel-like behavior with the elastic modulus (G') dominating and being frequency independent. Lissajous-Bowditch plots and nonlinear parameters obtained under large deformation show that the emulsions can resist greater deformations with smaller increase in the viscous dissipation when compared to a HMPAA gel. For tribology experiments, friction curves in a range of entrainment speeds are examined using substrates to mimic the skin surface (PDMS and Bioskin®). The role of polymer hydrophobicity on the different substrates are also explored by comparing the behavior of HMPAA to that of its hydrophilic analog, a polyacrylic acid highly crosslinked. We find the friction coefficient to be dependent on the hydrophobicity of the substrate and the polymer as well as the substrate roughness. These results taken together provide insights in the formulation of skincare products with efficient lubrication properties for different skin characteristics.

Blocking intruders: inducible physico-chemical barriers against plant vascular wilt pathogens

Xylem vascular wilt pathogens cause devastating diseases in plants. Proliferation of these pathogens in the xylem causes massive disruption of water and mineral transport, resulting in severe wilting and death of the infected plants. Upon reaching the xylem vascular tissue, these pathogens multiply profusely, spreading vertically within the xylem sap, and horizontally between vessels and to the surrounding tissues. Plant resistance to these pathogens is very complex. One of the most effective defense responses in resistant plants is the formation of physico-chemical barriers in the xylem tissue. Vertical spread within the vessel lumen is restricted by structural barriers, namely, tyloses and gels. Horizontal spread to the apoplast and surrounding healthy vessels and tissues is prevented by vascular coating of the colonized vessels with lignin and suberin. Both vertical and horizontal barriers compartmentalize the pathogen at the infection site and contribute to their elimination. Induction of these defenses are tightly coordinated, both temporally and spatially, to avoid detrimental consequences such as cavitation and embolism. We discuss current knowledge on mechanisms underlying plant-inducible structural barriers against major xylem-colonizing pathogens. This knowledge may be applied to engineer metabolic pathways of vascular coating compounds in specific cells, to produce plants resistant towards xylem colonizers.

Formulation, validation and evaluation studies on metaxalone and diclofenac potassium topical gel

Twenty different batches of gels containing metaxalone and diclofenac potassium were prepared for topical application. These drugs act synergistically in the management of pain and inflammation. Gels were prepared by varying the type of gelling agent (ten batches each of hydroxyl propyl methyl cellulose and carbopol 934). The prepared gels were characterized and evaluated. Batch F7 emerged as the best batch on the basis of favourable pH, high drug content, homogeneity and drug release. HPLC (High-performance liquid chromatography) method validation of gel formulation was also carried out and the developed and validated method was found to be robust and accurate.

Dentifrices or gels containing MMP inhibitors prevent dentine loss: in situ studies

OBJECTIVES

Evaluate the effect of dentifrices or gels containing MMP inhibitors on dentine loss in situ.

MATERIALS AND METHODS

Acrylic palatal appliances containing bovine dentine blocks were divided into two rows, corresponding to the groups erosion (ERO) and erosion associated with abrasion (ERO+ABR). For ERO, the appliances were immersed in a cola drink for 5 min, 4 times/day, while for ERO+ABR, the blocks were brushed for 15 sec with a dentifrice slurry after the second and third erosive challenges. Ten volunteers took part in study 1 (S1), where the dentifrices evaluated contained 1100 ppm fluoride as NaF, 0.61% green tea extract, or 0.012% chlorhexidine digluconate. Thirteen volunteers participated in study 2 (S2), in which the treatment was performed only once (1 min) with gels containing 400 μM EGCG (EGCG400), 0.012% chlorhexidine, 1 mM FeSO₄, 1.23% F (NaF), placebo, or received no treatment. Dentine loss was analyzed by profilometry (μm).

RESULTS

Regarding S1, ERO+ABR induced significantly higher dentine loss compared with ERO and all dentifrices tested led to significantly lower dentine loss when compared with placebo. For S2, regardless of the conditions or times of evaluation, gels containing EGCG, CHX, or FeSO₄ led to significantly less wear compared with the other groups.

CONCLUSION

Both dentifrices and gels containing MMP inhibitors significantly reduced dentine loss.

CLINICAL RELEVANCE

Dentifrices and gels containing MMP inhibitors are able to increase the protection against dentine wear, although gels have a better effect when compared with fluoride gel, lasting up to 10 days after a single application.

Comparison of Fluoride Ion Release from Fluoride Gel in Various Solvents

OBJECTIVE

The aim of this study was to determine the concentration of fluoride ions present in various solvent solutions and compare it to the label amount of fluoride concentration.

MATERIAL AND METHODS

The gel containing amine fluoride and sodium fluoride was compared to gel containing sodium fluoride only. The solvents used in this study were distilled water, redistilled water, tap water, 0.9% sodium chloride solution and the artificial saliva. The amount of fluoride ion (F^-) was determined by the use of fluoride ion-selective electrode. The ANOVA and the Post hoc Tukey's test were used. The significance level was α = 5%.

RESULTS

The differences between F^- ion release in various solvents were statistically significant (p < 0.05). The F^- ion concentrations measured in both gels' redistilled water solutions were higher than the label concentration. There was a significant difference in fluoride ion release in sodium fluoride only gel solutions. Fluoride ion release was significantly different in combined fluoride gel solutions.

CONCLUSIONS

Amine fluorides do not interact with other ions present in the solution, whereas F^- ion release from sodium fluoride alters when other ions are dissolved in the same solution. Amine fluorides deliver F^- ions for caries prevention more efficiently.

Morphology, gelation and cytotoxicity evaluation of D-α-Tocopheryl polyethylene glycol succinate (TPGS) - Tetronic mixed micelles

HYPOTHESIS

The combination of polymeric surfactants into mixed micelles is expected to improve properties relevant to their use in drug delivery, such as micellar size, gelation, and toxicity. We investigated synergistic effects in mixtures of D-α-Tocopheryl polyethylene glycol succinate (TPGS), an FDA-approved PEGylated derivative of vitamin E, and Tetronic surfactants, pH-responsive and thermogelling polyethylene oxide (PEO)-polypropylene oxide (PPO) 4-arm block copolymers. We hypothesized that mixed micelles would form under specific conditions and provide a handle to tune formulation characteristics.

EXPERIMENTS

We examined the morphology of the self-assembled structures in mixtures of TPGS with two Tetronic: T1107 and T908, using a combination of dynamic light scattering (DLS), small-angle neutron scattering (SANS), NMR spectroscopy (NOESY and diffusion NMR) and oscillatory rheology, over a range of compositions, temperatures and pH. Cell viability was assessed in NIH/3T3 fibroblasts.

FINDINGS

The combination of TPGS with either of the two Tetronic produces spherical core-shell micelles that comprise both surfactants in their structure (mixed micelles). T1107 unimers incorporate into TPGS aggregates below the critical micelle temperature of the poloxamine, while mixed micelles only form under limited conditions with T908. At high concentration/temperature, small proportions of TPGS extend the gel phase, more markedly with T1107, with similar elastic moduli (30-50 kPa) and a BCC crystalline structure. Cell viability of NIH/3T3 fibroblasts grown in the hydrogels increases significantly when the poloxamine gels are doped with TPGS, making the combination of poloxamines and TPGS a promising platform for drug delivery.

[Effect of Tongluo Zhitong (, TLZT) gel preparation on p53 /miR-502-5p /NF-κBp65 in synovial tissue of knee osteoarthritis]

OBJECTIVE

To observe effects of Tongluo Zhitong (, TLZT) gel preparation on p53, miR-502-5p, NF-κBp65 in synovial tissue of knee osteoarthritis (KOA), and to explore mechanism of TLZT gel preparation in treating KOA.

METHODS

Thirthy-six Wistar rats aged 8 weeks and weighed 200 to 220 g (meaned 208 g) were randomly divided into normal group, model group and traditional Chinese medicine (TCM) group, 12 rats in each group. KOA model was established by modified Hulth method. After 4 weeks of modeling, TCM group treated with TLZT gel preparation for external use, 3 times daily for 2 weeks;normal group and model group were fed normally without intervention. After treatment, morphological changes of specimens in each group were observed, changes of miR-502-5p in synovial tissue were detected by qPCR, and contents of p53, NF-κBp65, IL-1β, TNF-α, MMP-13 in synovial tissue were detected by qPCR and Western Blot respectively.

RESULTS

(1)Morphological observation of specimens showed that the articular cartilage in model group was hyaline and uneven, the synovial membranes were hypertrophic and proliferative with a large number of inflammatory cells infiltrating, the joint fluid was thicker in texture;the articular cartilage in TCM group was more transparent and smooth, synovial hyperplasia was mild with a small amount of inflammatory cell infiltration, the texture of articular fluid was clear and sparse. (2) Compared with normal group, content of miR-502-5p of synovial tissue in model and TCM group were increased, mRNA and expression of p53 decreased, expression of NF-κBp65, IL-1β, TNF-α, MMP-13 increased. (3)Compared with model group, content of miR-502-5p in synovial tissue of TCM group decreased (P<0.05), mRNA and protein expression of p53 increased (P<0.05), mRNA and protein expression of NF-κBp65, IL-1β, TNF-α, MMP-13 decreased (P<0.05).

CONCLUSION

Expression of p53, miR-502 -5p, NF -κBp65 in synovial tissue is closely related to synovial hyperplasia and inflammatory reaction, TLZT gel preparation may reduce proliferation and inflammatory reaction of KOA synovium by regulating the expression of p53, miR- 502-5p, NF-κBp65 in synovial tissues.

Influence of TMAO as co-solvent on the gelation of silica-PNIPAm core-shell nanogels at intermediate volume fractions

We study the structure and dynamics of poly(N-isopropylacrylamide) (PNIPAm) core-shell nanogels dispersed in aqueous trimethylamine N-oxide (TMAO) solutions by means of small-angle X-ray scattering and X-ray photon correlation spectroscopy (XPCS). Upon increasing the temperature above the lower critical solution temperature of PNIPAm at 33 °C, a colloidal gel is formed as identified by an increase of I(q) at small q as well as a slowing down of sample dynamics by various orders of magnitude. With increasing TMAO concentration the gelation transition shifts linearly to lower temperatures. Above a TMAO concentration of approximately 0.40 mol/L corresponding to a 1 : 1 ratio of TMAO and NIPAm groups, collapsed PNIPAm states are found for all temperatures without any gelation transition. This suggests that reduction of PNIPAm-water hydrogen bonds due to the presence of TMAO results in a stabilisation of the collapsed PNIPAm state and suppresses gelation of the nanogel.

A new approach to construct and modulate G-quadruplex by cationic surfactant

HYPOTHESIS

G-quadruplex structure has raised increasing attention in supramolecular chemistry as an effective template for ordered functional materials. Thus, it is of practical significance to advance our understanding regarding G-quadruplex structures. Typically, G-quadruplex structures are formed in the presence of suitable metal ions. New methods to construct such structures need to be explored.

EXPERIMENTS

The supramolecular assembly between CTAB and a guanosine derivative at different molar ratios was systematically studied, including assembly mechanisms, morphology, and macroscopic properties. Cationic surfactants with different alkyl chains were studied as control experiments.

FINDINGS

A novel strategy to construct G-quadruplex with the promotion of the cationic surfactant CTAB is presented in this work. The structure-property relationships of G-quadruplex gels are characterized by rheology and shrinkage ratio experiments. MacKintosh's theory was used to rationalize the relationship between gel elasticity and water content. The transition of G-quadruplex structures could be easily enabled by modulating CTAB concentration, which promotes the phase transition from gel/sol biphase to homogeneous sol phase. This work will provide a new viewpoint for the construction and modulation of G-quadruplex structures.

Self-assembled small molecule natural product gel for drug delivery: a breakthrough in new application of small molecule natural products

Natural products, as a gift of nature to humanity, have long been used as drugs or pharmacological actives to help people cure various diseases. Yet we still know comparatively little about their ability to be materials. In recent years, some small molecule natural products isolated from traditional Chinese medicines have been found to have new features, namely, self-assembly to form gels (i.e., natural product gels, NPG). However, the application development of these natural products is seriously lacking, which greatly weakens their practical value and delays the maturity of the field. Here, a series of self-assembled triterpenoid natural products are used as materials (gel scaffolds) to construct drug delivery systems. Surprisingly, these NPG not only exhibit the excellent self-healing, controlled gelation, good safety and sustained release, but also achieve synergistic treatment of tumors through bioactive natural products. Compared with non-bioactive gel scaffolds, NPG scaffolds show great advantages in tumor therapy, including optimal tumor inhibition, preferable health, better body recovery, stronger immune function, less toxic side effects and longer survival. The successful construction of NPG scaffolds not only takes full advantage of the self-assembled natural products, but also takes an important step in the development of new applications for natural products.

Structural characterization by scattering and spectroscopic methods and biological evaluation of polymeric micelles of poloxamines and TPGS as nanocarriers for miltefosine delivery

Miltefosine (MF), an alkylphospholipid originally developed for breast cancer treatment, is a highly active drug for the treatment against leishmaniasis, a neglected tropical disease considered the world's second leading cause of death by a parasitic agent after malaria. MF exhibits dose-limiting gastrointestinal side effects in patients and its penetration through lipophilic barriers is reduced. In this work we propose a reformulation of MF by incorporating the drug to poly(ethylene)oxide (PEO)-based polymeric micelles, specifically, D-α-tocopheryl polyethylene glycol succinate (TPGS) and Tetronic block copolymers (T904 and T1107). A full structural characterization of the aggregates has been carried out by SANS (small-angle neutron scattering) and dynamic light scattering (DLS), in combination with proton 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, to determine the precise location of the drug. The structure of MF micelles has been characterized as a function of the temperature and concentration. In the presence of the block-copolymers, MF forms mixed micelles in a wide range of temperatures, TPGS being the co-surfactant that incorporates more MF unimers. The hydrophobic tail of MF and those of the block copolymers are in close contact within the micelles, which present a core-shell structure with a hydrophilic corona formed by the PEG blocks of the TPGS and the zwitterion head group of the MF. In order to identify the best carrier, the antileishmanicidal activity of MF in the different formulations has been tested on macrophages, promastigotes and intracellular amastigotes. The combination of the three vehicles with MF makes the formulated drug more active than MF alone against L. major promastigotes, however, only the combination with T904 increases the MF activity against intracellular amastigotes. With the aim of exploring gel-based formulations of the drug, the combination of MF and T1107 under gelation conditions has also been investigated.

Fabrication of calcium phosphate composite polymer/SLS-stabilized emulsion-based bioactive gels and their application for dentine tubule occlusion

OBJECTIVES

Calcium phosphate/SLS/P123 composite bioactive gels were prepared to achieve dentine tubule occlusion.

METHODS

Gels containing calcium phosphate particles were prepared in a water-in-oil microemulsion system with a mixture of triblock copolymer pluronic (P123) as a co-surfactant and sodium lauryl sulfate (SLS) as a surfactant in cyclohexane. Subsequently, calcium chloride dihydrate and sodium hydrogen phosphate aqueous solutions were added in a water phase. Finally, slow evaporation of the oil phase at room temperature was performed to produce a hybrid gel. The obtained gels were investigated for their toxicity by the sulforhodamine B (SRB) assay and applied on human dentine specimens to examine their ability to occlude dentine tubules.

RESULTS

The size and morphology of the calcium phosphate particles embedded in the gel depended on the concentration of P123 and SLS, which were used as a template for mineral precipitation. The prepared calcium phosphate particles (200-500 nm in diameter) with the maximum polymer and surfactant content exhibited spherical shapes. Further, on reducing their content twice and tenfold yields micro-particles with flower-like shapes. These bioactive gels were able to occlude into dentine tubules after 3 days of application with a plugging rate of 79.22% when using the smallest particles. In addition, calcium phosphate nanorods were transformed into dentine tubules with a maximum depth of 6 μm on increasing the amount of gel.

CONCLUSIONS

The bioactive gels were effectively used as bioactive fillers to occlude exposed human dentine tubules.

Coordination of tongue pressure production, hyoid movement, and suprahyoid muscle activity during squeezing of gels

OBJECTIVE

The aim of this study was to evaluate tongue movement and its biomechanical effects during squeezing, one of the oral strategies for processing soft foods, by tongue pressure sensors, videofluorography, and surface electromyography.

DESIGN

Fifteen healthy men (mean age, 31.0 ± 4.1 years) without dysphagia were recruited. A 0.1-mm-thick pressure sensor sheet with five measuring points, videofluorography, and surface electromyography were used for synchronous measurements of tongue pressure, hyoid movement, and suprahyoid muscles activity, respectively, while squeezing 5 mL of gels. Amplitude, duration, area, and their sequential order during initial squeezing were analyzed. Differences in hyoid position at the onset, peak, and offset of hyoid movement were also analyzed.

RESULTS

At the beginning of initial squeezing, tongue pressure at the middle area of the hard palate, hyoid movement, and suprahyoid muscle activity appeared simultaneously, followed by tongue pressure at the anterior area and then at the posterior area. When the hyoid was in an elevated position, the amplitude of suprahyoid muscle activity and tongue pressure peaked. At the end of initial squeezing, the hyoid position at the offset of hyoid excursion was superior to that at the onset. All evaluation items of tongue pressure, hyoid movement, and suprahyoid muscle activity were modulated according to the texture of gels.

CONCLUSIONS

During initial squeezing, tongue pressure, hyoid movement, and suprahyoid muscle activity were coordinated while being modulated by the food texture. At the end of initial squeezing, the hyoid was maintained in an elevated position, which might be beneficial for subsequent squeezing.

Gelation on demand using switchable double emulsions: A potential strategy for the in situ immobilization of organic contaminants

Switchable double emulsions (water in oil in water, W/O/W) are proposed for the in situ immobilization of subsurface organic contaminants such as toluene, hexane or benzene. Primary W/O emulsions were prepared by emulsifying 250 mL of 0.36 M CaCl₂ aqueous solutions in 1 L of canola oil (with 12.5 g/L of ethylcellulose, EC, and 2.5 g/L of calcium stearate). In the primary W/O emulsion the water droplets in oil were ≈8 μm, as observed using an optical and a confocal microscope. EC and calcium stearate adsorbed at the oil water interface (as demonstrated by interfacial tension measurements), forming films which stabilized the W/O emulsions (as verified with bottle tests). Experiments conducted using a Langmuir trough suggest that EC and calcium stearate films did not desorb from the oil-water interface upon compression. Crumpling tests and optical microscopy observations indicate that EC and calcium stearate films were skin-like, and buckled when deformed. To obtain double W/O/W emulsions the primary emulsions were emulsified in a 0.75 wt% solution of sodium alginate, with 2 mL/L of Tween 20 and 10 g/L of NaCl. The formation of W/O/W emulsions was verified through optical microscopy and confocal microscopy observations. In the absence of the contaminants the double emulsions were stable, as observed by resting them on the bench over three days and agitating them with a multi-action wrist shaker for 30 min. Also, they had low shear elastic (G' = 2.67 ± 0.58 Pa) and viscous (G″ = 1.69 ± 0.24 Pa) moduli, which should facilitate their transport through geological media (e.g. soil) to polluted areas. Upon mixing with toluene, hexane or benzene at concentrations ranging from 5% to 17%, the double emulsions were destabilized. Emulsion destabilization caused the release of CaCl₂, which crosslinked sodium alginate and formed gels in which the contaminants were incorporated. The gelation rate and the magnitude of the viscoelastic moduli depended on the contaminant type and concentration, and on the mixing time. Gelation occurred fastest with the highest toluene concentrations tested (9% to 17%), but the highest elastic moduli were measured with 9% toluene concentrations for the longest mixing times tested (90 s). Gelation occurred slowest with hexane, likely due to the poor solubility of EC in hexane. Because of their ability to gel exclusively in contaminant proximity, the double emulsions studied offer a potential strategy to control the migration of plumes of contaminants such as toluene, hexane or benzene.