Cross-linked Gel Research Articles

Preparation and properties of the crosslinked poly(L-lactide) with high crystallinity and high gel content

Poly(L-lactide) (PLA) is the most important biobased polymer and is widely used in various fields. However, its application is still greatly limited by the distinct disadvantage such as poor thermal resistance. In this study, in order to improve the thermal properties, crosslinked PLA with high crystallinity (44 %) and high gel content (91 %) is prepared by the UV irradiation of its semicrystalline films by the loading of certain photoinitiators and curing agents. The structure and properties of the obtained films are systematically investigated with NMR, DSC, DMA, TG and WAXD. It is found that the crosslinking of the semicrystalline PLA film is more difficult than that of the amorphous in the absence of crosslinker. However, the combinations of 2phr photoinitiator such as 4,4′-dichloro benzophenone (DCB) and 2 phr crosslinker of 1,3,5-triallylisocyanurate (TAIC) can effectively trigger the crosslinking and high gel content up to 91 % can be achieved. Corresponding to the high density crosslinking, an increase of the glass transition temperature from 66.6 °C to 75.5 °C is observed for crystallized PLA, indicating an obvious improvement in thermal resistance. More interestingly, it is found that this crosslinked PLA with high crystallinity and high gel content still possesses high crystallizability.

The electron beam induced cross-linking of bovine collagen gels with various concentrations: The mechanical properties and secondary structure

This study considered the examination of the influence of electron beam irradiation (2 and 100 kGy) on bovine collagen gels with various concentrations (3, 6 and 8 wt%). The impact of irradiation was verified via the analysis of the mechanical properties and the secondary structure of the collagen. The irradiated collagen gels behaved non-linearly and stiffened with increasing strain in contrast to the non-irradiated state in which they softened with increasing strain. The impact of irradiation was reflected by an increase in the tensile modulus and strain energy density. The observed increase was greater the higher the water content of the collagen gels. The impact of irradiation on the secondary structure was less clear; infrared spectrometry revealed that the events that take place are complex, with the occurrence of cross-linking, partial denaturation and other structural changes. The electron beam irradiated collagen gels continued to exhibit collagenous polymeric structures and integrity.

Single fibre coating of cellulose acetate fibres for hydrophilic modification using carboxymethylated starch

Hydrophilic bio-based and biodegradable fabrics and fibres can be an alternative to petroleum-based fabrics and fibres. Hydrophilic modifications of conventional textile structures by compositing can be introduced on a fabric as well as on a fibre level. Here, the coating of hydrophobic cellulose acetate multifilaments with carboxymethylated starch (CMS) pastes is reported. The CA fibres were drawn through starch preparations with varying degrees of substitution for coating. To ensure CMS anchorage, citric acid was added to cross-link the hydrophilic starch preparation itself and to the substrate. Cross-linking and CMS gel viscoelasticity were determined using a heated FT-IR stage and a rheometer respectively. The composites were also characterised for citric acid elution, as their degree of swelling in water vapour. As the amount of crosslinker increased, the gel viscoelasticity increased, but so did the citric acid elution in swelling media. Through several drying and swelling steps, the hydrophilic CMS structures lose their swelling ability. Coated fibres were also tested in a fine wash. The hydrophilic coating is depleted.An estimate of the chemical consumption for the production of such composites is given and compared with related approaches. As the chemical modification only affects the sheath, the chemical consumption can be reduced.

Preparation of crosslinked starches with enhanced and tunable gel properties by the cooperative crosslinking-extrusion combined modification

Due to its safety and palatability, the citric acid crosslinking modification is an excellent way to modify the properties of starch gels. However, the application of this method is restricted by the low degree of crosslinking of gels produced by this method in the hydrogel system. To produce citric acid-crosslinked starch with improved strength and tunable gel characteristics, a novel ion-esterification cooperative crosslinking-extrusion combined (CCEC) modification approach is presented in this study. The linear and nonlinear rheological characteristics of the samples were measured to evaluate the effectiveness of CCEC modification. Findings disclosed that at 0.1 % strain, the elastic modulus of the CCEC-modified starch (SC-0.5Zn2+, G' = 1522.29 ± 36.31) exhibited a significant rise of 387.27 % as compared to the elastic modulus of citric acid-crosslinked starch (SC, G' = 318.29 ± 11.62). Furthermore, changing the cation concentration allowed for efficient control of the gel's rheological characteristics. The samples were characterized by SEM, FTIR, XRD, and XPS. The CCEC-modified gels had a smaller pore size distribution and a denser honeycomb porous structure. The CCEC modification reaction involves ester bonds and electrostatic attraction. This research is essential to elucidate how coupled physicochemical modification techniques affect the manipulation of starch gel characteristics.

Fast and efficient adsorptive capture of Congo red and Erythromycin pollutants by a novel nanobiosorbent from crosslinked nanosilica with nanobiochar and chitosan

Dyes and pharmaceuticals in wastewater are categorized as serious hazardous pollutants due to their nonbiodegradability and therefore, must be removed before discharge in water resources. In this work, a novel nanobiosorbent was fabricated via microwave crosslinking of nanosilica gel with banana peels nanobiochar (BPNB) and chitosan hydrogel (Chit Hgel) to produce BPNB-NSiO2-Chit Hgel nanobiosorbent (22.48–26.23 nm). The effects of nanobiosorbent dosage (1–50 mg), pH (2–12), shaking time (1– 45 min), pollutant concentration (5–100 mg/L), temperature (288–333 K), and interfering salts on the adsorption of Erythromycin antibiotic (ERM) and Congo red dye (CRD) pollutants were investigated and optimized. Pseudo-second-order model revealed a perfect fitting to the experimental data, while Langmuir model achieved (R2 = 0.997 for ERM and R2 = 0.992 for CRD) as the highest correlation coefficients. Moreover, adsorptive capture reactions of ERM and CRD onto BPNB-NSiO2-Chit Hgel were classified as spontaneous and endothermic. The removal of ERM (92.80–96.50 %) and CRD (92.80–95.0 %) from tap, sea, and wastewater was successfully established to confirm the validity and capability of the investigated BPNB-NSiO2-Chit Hgel nanobiosorbent in removal of these two pollutants from polluted water samples.

Chitin nanocrystals as natural gel modifier for yielding stronger acid-induced soy protein isolate gel

This study aimed to enhance the rheological properties and thermal stability of acid-induced soy protein isolate (SPI) gels by incorporating chitin nanocrystals (ChNCs) and proposing a gelation mechanism. SPI gels exhibited pseudo-plastic behavior. Increasing ChNCs concentration from 0.00 % to 1.00 % improved G' values, recovery rate, and initial degradation temperature: from 75.6 Pa to 1024.3 Pa, 80.27 % to 85.47 %, and 261.5 °C to 275.8 °C, respectively. FTIR analysis confirmed electrostatic and hydrogen bonding interactions between SPI and ChNCs. Adding 1.00 % ChNCs reduced α-helix content from 19.7 % to 12.1 % while increasing β-sheet content from 46.5 % to 52.6 %. This led to protein unfolding, exposure of Trp residues, and orderly aggregation, forming a dense cross-linked gel network. Gel particle size increased from 185.5 nm (no ChNCs) to 504.4 nm (1.00 % ChNCs), with reduced surface charges. Hydrophobic and electrostatic interactions were key forces stabilizing SPI-ChNCs gels. These findings offer a practical approach to enhancing traditional acid-induced protein gel-based functional foods using naturally sourced chitin nanocrystals.

Thermoresponsive DNA hydrogels through hydrophilic pre-polymer cross-linker and self-assembly

Denatured DNA molecules were used as building blocks to fabricate thermoresponsive hydrogels by cross-linking DNA strands with an isocyanate (NCO) end-capped star-shaped poly(EO-stat-PO) cross-linker. The NCO groups reacted with the amine groups of DNA’s bases through urea links while base pairing between the matching strands of DNA led to the self-assembly of DNA into a three-dimensional hydrogel network. Analysis of the ultrastructure by scanning force microscopy (SFM) revealed the temperature-mediated transition from the rod-to-coil structure as a result of the destabilization of double-stranded DNA (dsDNA) to form a single-stranded DNA (ssDNA), which eventually resulted in a DNA network due to base pairing, along with hairpin loops due to mismatches between nucleotides. Dynamic oscillatory and large deformation creep tests, as well as stress relaxation tests, revealed the formation of robust cross-linked gels: A ten-fold rise in the elastic modulus was observed for the covalent DNA gel compared to the physical gel at the identical DNA concentration. The thermoresponsiveness of the hydrogels was confirmed by a heating–cooling cycle while the non-porous internal morphology of the hydrogel was demonstrated through scanning electron microscopic analysis. Overall, this is the first study showing the fabrication of covalent DNA hydrogels using an NCO-end-capped hydrophilic prepolymer. Such gels have a high potential to be exploited in many fields to benefit from the structural properties of DNA molecules.

Dual-type gel polymer electrolyte for high-voltage lithium metal batteries with excellent cycle life

The most attractive approach for maximizing the energy density of rechargeable lithium batteries is to combine a lithium metal anode with a high-voltage cathode. However, the dendritic formation of lithium at the anode and the highly oxidizing conditions that cause electrolyte decomposition at the cathode have hindered the practical development of lithium metal batteries (LMBs). In this study, we report a dual-type gel polymer electrolyte (GPE) composed of an anolyte and a catholyte that can address the drawbacks of both the anode and cathode sides. The anolyte is a poly(ethylene oxide)-based composite solid polymer electrolyte that is chemically stable with lithium metal and has a high mechanical strength for suppressing lithium dendrite growth. A cross-linked gel polymer electrolyte with high lithium-ion conductivity and oxidative stability was used as the catholyte. The Li/LiCoO2 cell assembled with a dual-type GPE exhibited a high discharge capacity of 181.1 mAh g−1 (areal capacity: 3.15 mAh cm−2) in the voltage range of 3.0–4.5 V and excellent cycle life, with a capacity retention of 74 % after 700 cycles at 25 °C and 0.5 C rate. Our study proposes a promising electrolyte system for LMBs with high energy density and good cycle life.

Clinical evaluation of sodium hypochlorite/amino acids and cross-linked hyaluronic acid adjunctive to non-surgical periodontal treatment: a randomized controlled clinical trial

ObjectivesTo compare the clinical outcomes obtained with either mechanical subgingival debridement in conjunction with a sodium hypochlorite and amino acids containing gel followed by subsequent application of a cross-linked hyaluronic acid gel (xHyA) gel, or with mechanical debridement alone.Materials and MethodsFourty-eight patients diagnosed with stages II-III (Grades A/B) generalised periodontitis were randomly treated with either scaling and root planing (SRP) (control) or SRP plus adjunctive sodium hypochlorite/amino acid and xHyA gels (test). The primary outcome variable was reduction of probing depth (PD), while changes in clinical attachment level (CAL), bleeding on probing (BOP) and plaque index (PI) were secondary outcomes. The outcomes were assessed at baseline, at 3 and 6 months following therapy.ResultsAll patients completed the 6 months evaluation. At 6 months, the test group showed statistically significantly better results in terms of mean PD reduction (2.9 ± 0.4 vs 1.8 ± 0.6 mm, p < 0.001). Similarly, mean CAL gain was statistically higher in the test group compared to the control one (test: 2.6 ± 0.5 vs control: 1.6 ± 0.6 mm, p < 0.001). Mean BOP decreased from 81.8 ± 16.2% to 48.9 ± 14.5% in control (p < 0.001) and from 83.2 ± 15.5% to 17.6 ± 11.5% in test (p < 0.001) groups with a statistically significant difference favouring the test group (p < 0.001). Mean PI scores were reduced statistically significantly in both groups (from 38.8 ± 26% to 26.5 ± 20.5% in control (p = 0.039) and from 60.6 ± 10.9% to 12.7 ± 8.9% in test group (p < 0.001)), with a statistically significant difference between the groups (p < 0.001). The number of moderate pockets (4–6 mm) were reduced from 1518 (41.2%) to 803 (22.6%) in the control and from 1803 (48.6%) to 234 (7.7%) in the test group with a statistically significant difference between the groups (p < 0.001), while the number of deep pockets (≥ 7 mm) changed from 277 (7.6%) to 35 (1.0%) in the control and from 298 (8.7%) to 4 (0.1%) in test group (p = 0.003).ConclusionWithin their limits the present data indicate that: a) both treatments resulted in statistically significant improvements in all evaluated clinical parameters, and b) the adjunctive subgingival application of sodium hypochlorite/amino acid and xHyA to SRP yielded statistically significantly higher improvements compared to SRP alone.Clinical relevanceThe combination of sodium hypochlorite/amino acid and xHyA gels to subgingival mechanical debridement appears to represent a valuable approach to additionally improve the outcomes of non-surgical periodontal treatment.Clinical Trial Registration Number NCT04662216 (ClinicalTrials.gov).

Mercury selective hydrogelation of a pyridinyl substituted terpyridine ligand

We report the addition of aqueous solution of different divalent transition metal ions M2+ (M = Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg) to a dilute acidic solution of 4′-(pyridin-2-yl)-2,2′:6′,2″-terpyridine (L). An irreversible, translucent, and thixotropic hydrogel was selectively produced in the case of Hg(II). FESEM and HR-TEM images of Hg(II)-hydrogel showed non-uniform, fibrous, and cross-linked gel morphology. Further, the hydrogel was treated with sodium salts of different anions (F−, I−, Br−, Cl−, SO42−, NO3−, HCO3−, SO32−) in water. The iodide ion showed unusual behavior by forming a yellow precipitate of the hydrogel with a plate-like structure, as observed from FESEM images. DFT study has also been conducted to understand the aggregation behavior in Hg(II) based hydrogel. We also synthesized the mercury complex HgCl2L and characterized it by 1H NMR, elemental analysis, and mass spectrometry.

Influence of Blast Furnace Slag on Pore Structure and Transport Characteristics in Low-Calcium Fly-Ash-Based Geopolymer Concrete

Alkali-activated fly ash slag (AAFS) has emerged as a novel and environmentally sustainable construction material, garnering substantial attention due to its commendable mechanical attributes and minimal ecological footprint. This investigation delves into the influence of slag incorporation on the strength, pore structure, and transport characteristics of AAFS, encompassing various levels of fly ash replacement with slag. To assess the mechanical properties of AAFS concrete, unconfined compression and ultrasonic pulse velocity tests were conducted. Meanwhile, microstructural and mineralogical alterations were scrutinized through porosity, N2-adsorption/desorption, and SEM/EDX assessments. In addition, transport properties were gauged using electrical surface resistivity, water permeability, and water vapor permeability tests. According to the results, a remarkable refinement in the pore volume was found by increasing the slag content. The volume of the gel pores and surface area increased significantly associated with the increase in tortuosity. Accordingly, Ca inclusion in the cross-linked sodium aluminosilicate hydrate gel remarkably reduced the transport properties.

In situ composite of graphene oxide in polyacrylamide to enhance strength of hydrogel with polyethyleneimine as crosslinker

Polymer gel was widely used in the petroleum industry for water shutoffs to enhance oil recovery or for plugging to control lost circulation events. By free radical polymerization of acrylamide monomers in presence of graphene oxide (GO) nano sheets, polyacrylamide graphene oxide composite (PAMGO) was synthesized and used to prepare high strength hydrogel with polyethyleneimine (PEI) as crosslinker. The gelation time of gel was determined with viscosity test and gel strength was evaluated with rheological measurements and sand pack breakthrough pressure test. ATR-FTIR and SEM test was adopted to characterize the structure and morphology of the gel. The results showed that compared to polyacrylamide (PAM) gel, gelation time of composite gel decreased while gel elasticity modulus increased. The breakthrough pressure of composite gel is 21.71 MPa and increased by 20.71%. However, the mixing of graphene oxide in PAM gelling solution causes detrimental effects on gel strength and the breakthrough pressure of the mixture gel is only 3.72 MPa. The ATR-FTIR spectroscopy confirmed that the type of hydrogen bonding in the composite gel was different from that in the PAM GO mixture gel. The hydrogen bonding between N, O in composite and hydrogen atom on GO in the composite gel can enhance gel strength with reducing porosity and more crosslinking density of gel while the hydrogen bonding for H of NH2 in PAM with oxygen atom on GO in the mixture gel can occupy the crosslinking points, resulting in less crosslinking density and gel strength.

Clinical Evaluation of a Novel Combination of Sodium Hypochlorite/Amino Acid and Cross-linked Hyaluronic Acid Adjunctive to Non-surgical Periodontal Treatment: A Case Series.

The adjunctive subgingival application of sodium hypochlorite/amino acid and a mixture of natural and cross-linked hyaluronic acid gels (high molecular weight) has been recently proposed as a novel modality to enhance the outcomes of non-surgical periodontal therapy. The aim of this prospective case series was to evaluate the clinical outcomes obtained following the subgingival application of a combination of sodium hypochlorite/amino acid and a mixture of natural and cross-linked hyaluronic acid (high molecular) gels in conjunction with non-surgical periodontal therapy. Twenty-one systemically healthy, non-smoking patients diagnosed with stage II-III, grade A/B periodontitis underwent full-mouth subgingival debridement (SD) performed with ultrasonic and hand instruments. All sites with probing depths (PD) ≥ 4 mm were treated with additional repeated (i.e., 2-3 times) instillation of sodium hypochlorite/amino acid gel in the periodontal pockets prior to and during SRP. Following mechanical debridement, a mixture of natural and cross-linked hyaluronic acid (high molecular) gel was applied in the pockets. The primary outcome variable was PD reduction; changes in clinical attachment level (CAL) and bleeding on probing (BOP) were the secondary outcomes. The clinical parameters were assessed at baseline, 3 and 6 months after therapy. Compared to baseline, a statistically significant mean reduction of PD values was obtained after 3 and 6 months, amounting to 2.6 ± 0.4 mm, and 2.9 ± 0.4 mm, respectively (p < 0.001). Mean CAL gain measured 2.3 ± 0.5 mm at 3 months and 2.6 ± 0.5 mm at 6 months in comparison to baseline (p < 0.001). Mean reduction of BOP values was 54.9 ± 16.9 % at 3 months and 65.6 ± 16.4 % at 6 months (p < 0.001). The number of moderate pockets (4-5 mm) decreased from 1808 at baseline to 274 at the 6-month evaluation, and the number of deep (≥ 6 mm) pockets dropped from 319 to 3, respectively. The combination of sodium hypochlorite/amino acid and a mixture of natural and cross-linked hyaluronic acid (high molecular) adjunctive to subgingival debridement may represent a valuable approach to improve the outcomes of non-surgical periodontal treatment.

Investigation of the relationship between gel strength and microstructure of surimi gel induced by dense phase carbon dioxide based on quantitative analysis

The microstructure of a surimi product determines its quality. Dense phase carbon dioxide (DPCD) can induce surimi gel formation, and the gel strength of the product are significantly better than that of heat-induced gels. The study analysed the changes of the surimi from golden pompano gel strength during the process of DPCD-induced gelation, and the changes of microstructure based on quantitative analysis of scanning electron microscope (SEM) image using ImageJ 1.42 software. The correlations between gel strength and microstructure was investigated. The results showed that the DPCD treatment significantly increased the cross-linking degree (CLD) and gel strength of surimi, compared with the raw surimi. The CLD and gel strength of surimi increased with the increase of DPCD treatment pressure, temperature and time. Quantitative microscopic analysis revealed that the number of pores (n) in the surimi gels increased and then decreased. The apparent porosity (ƞa), average pore area (Aa), average pore perimeter (Pa), fractal dimension (Df) and pore equivalent diameter (d) increased with the increase of DPCD treatment pressure, temperature and time. Correlation analysis showed that the CLD, ƞa, Aa, Pa, Df, d and median pore perimeter (Pc-50) were strongly positively correlated with the gel strength. In contrast, lacunarity (L) is strongly negatively correlated with the gel strength. The linear correlation coefficients between the CLD, ƞa and Df and the gel strength are 0.97, 0.95 and 0.96, respectively. These results provide a technical basis for DPCD to process high-quality surimi products. These findings also offer a novel approach for the testing and evaluating of the quality of surimi products.

Self-healable, mechanically durable and cold-resistant integrated supercapacitor enabled by dual metallic redox-mediated multiple cross-linking gel polymer electrolyte

Flexible supercapacitor is an important energy supply source for wearable electronic devices. Herein, an integrated supercapacitor with exceptional electrochemical performance is successfully constructed based on a novel dual redox-mediated double network (DN) gel polymer electrolyte (GPE). Thanks to the synergistic effect of DN structure and multiple physical interactions (hydrophobic association, hydrogen bond and ionic coordination), the polyacrylic acid/lauryl methacrylate/sodium carboxymethyl cellulose/H2SO4/CuSO4_FeSO4 GPE possesses exceptional mechanical properties and rapid self-healing ability. In addition to being ionic cross-linking agents, CuSO4_FeSO4 can also serve as carrier donors and anti-freezing agents, endowing the GPE with excellent conductivity (0.17 S/cm) and low temperature adaptability. The GPE-based integrated supercapacitor demonstrates an outstanding specific capacitance of 414.96 mF/cm2 and a high energy density of 84.21 μWh/cm2, benefiting from redox reactions of Cu2+/Cu+ and Fe2+/Fe3+ at the electrode/electrolyte interface. Due to the seamless gradient structure, the interfacial resistance is reduced and the relative slippage is overcome, resulting in splendid capacitance retention of the supercapacitor under various mechanical deformations. Moreover, the device demonstrates promising self-healing ability even at −20 °C. This work provides a novel strategy for designing and fabricating the supercapacitor with self-healing, arbitrary deformability and anti-freezing in next-generation electronic devices.

Dual cross-linked gellan gum/gelatin-based multifunctional nanocomposite hydrogel scaffold for full-thickness wound healing

Biological macromolecules are excellent materials for wound dressing owing to their similar structure to the extracellular matrix and adjustable physicochemical properties. This research focuses on fabricating biological macromolecule-based hydrogel with desirable antibacterial, antioxidant, controlled drug release, cytocompatibility, and wound healing properties. Herein, different concentrations of nanoceria (NC) and flurbiprofen (FLU) drug-loaded gellan gum/gelatin (GG/Ge) based dual crosslinked (Ionic and EDC/NHS coupling) hydrogels were engineered.All fabricated hydrogels were hydrophilic, biodegradable, good strength, porous, antioxidant, hemocompatible and cytocompatible. Among all, hydrogel loaded with 500 μg/ml NC (GG/Ge/NC@FLU) exhibited desirable antioxidant, antibacterial (killed Staphylococcus aureus and Escherichia coli within 12 h), hemocompatible, cytocompatible, supports oxidative-stressed L929 cell growth and acted as a controlled release matrix for FLU, following Fickian diffusion, Peppas Sahlin and Korsmeyer-Peppas drug release models.Furthermore, nanocomposite hydrogel (GG/Ge/NC@FLU)-treated wounds of rats on day 14 demonstrated significantly higher collagen synthesis, nearly 100 % wound contractions, and efficiently decreased the expression of TNF-α and IL-1 while increasing the production of IL-10 and TNF-ß3, indicating antiinflammatory activity, and effectively reduced the expression of VEGF gene indicating effective angiogenesis than all other controls. In conclusion, the fabricated multifunctional GG/Ge/NC@FLU nanocomposite hydrogel shows promising potential for effectively treating full-thickness wound healing in a rat model.

Nanocomposite hydrogels: an optimistic insight towards the treatments of ocular disorders.

The distinct anatomy and physiology of the eye represent it as a specialized organ. The noumenal physiological barriers, whose prominent role is to prevent the entrance of extracellular substances, reduce the bioavailability of medicines taken locally. Nanocarriers offer many advantages, such as site-specific drug delivery, reduced dose-related side effects, more drug loading capacity, etc. Nanoparticles, nano micelles, Nanostructured Lipid Carriers (NLCs), Solid Lipid Nanoparticles (SLNs), liposomes, polymeric nanoparticles, microspheres, microemulsions, etc., have all undergone significant analysis to overcome numerous static and dynamic obstacles. Among the several methods of delivering drugs, one of the most captivating and demanding is ocular drug delivery (ODD). The intent of developing formulations for an extended period can be partially achieved via thermoresponsive hydrogels. It is feasible to store fluids inside a cross-linked gel system for efficient long-term administration owing to hydrogels, which are hydrophilic polymeric networks with excellent three-dimensional structures and water or biological fluid absorption capacities. Hydrogels can be incorporated into nanocarriers to achieve site-specific action and prolonged release. Related patents and research reports with various platforms like Science Direct, Springer, PubMed, Google Scholar, Shodhganga, and Patseer were used to gather the data, and a search methodology was availed. The paper thoroughly summarizes the strategies for incorporating drugs with hydrogel into a nanocarrier to provide sustained release and prolonged therapeutic effects. According to the comprehensive review of literature and patents like (US2015374633A1), (US10980882B2), and (WO2011018800A2), nanocarrier-loaded thermoresponsive hydrogels show promising results. Due to their propensity to alter state in reaction to temperature changes, thermoresponsive hydrogels can improve medication bioavailability. Intervening nanocarriers loaded hydrogels directly on the targeted site displays local intervention and site-specificity. Thus, the use of nanocarriers in ocular drug delivery is encouraging.

Mechanical Properties of Alginate Hydrogels Cross-Linked with Multivalent Cations.

Ionically, cross-linked alginate gels have a potential to be used in a wide range of biomedical, environmental and catalytic applications. The study deals with preparation of alginate hydrogels cross-linked with various cations and the analysis of their equilibrium swelling and mechanical properties. It is shown that the type of cations used in the cross-linking process affects the elastic moduli and the equilibrium degree of swelling of the gels. The experimental data in small-amplitude oscillatory tests are fitted with a model that involves two material parameters: the elastic modulus of a polymer network and a measure of its inhomogeneity. The influence of cations on these quantities is studied numerically. It is revealed that the dependence of the elastic modulus of ionically cross-linked alginate gels on their equilibrium degree of swelling differs from that predicted by the conventional theory for covalently cross-linked gels.

Deformation characteristics of hydrogel products based on cross-linked hyaluronic acid.

The cross-linked hyaluronic acid (HA) fillers are the viscoelastic hydrogel with a dominant elasticity rather than a viscosity as a useful medical device in the soft tissue augmentation. These HA fillers undergo deformation to begin the biodegradation by the biochemical and physical environment of the body, and result of deformations are closely related to clinical performance. The specific equation of molding index is newly generated and proved with Collin's equation, which is used for strong elastomers, for selecting optimal product in facial treatment. In this study, the results of amplitude sweep test from five marketed HA fillers were mathematically demonstrated for the proper clinical application. The increment of loss modulus by deformation was evaluated as a useful factor for the maintenance of optimal shape molding performance and resistance to external deformation of the cross-linked HA gel. From this study, the equation of molding index for weak viscoelastic hydrogels like HA products can be applied for choosing which products even in aesthetic plastic field. This molding index equation is compared to Collins' equation that index of deformation as elastomer like rubber and then found the positive correlation between two equations. This study could provide a basic theory that achieve useful clinical performance according to characteristics among many types of medical devices based on the molding index.

Texturing of Soy Yoghurt Alternatives: Pectin Microgel Particles Serve as Inactive Fillers and Weaken the Soy Protein Gel Structure.

Soy-based yoghurt alternatives were highly requested by consumers over the last few years. However, their texture does not always fulfil consumers' demands as such yoghurt alternatives are often perceived as too firm or too soft, sandy, or fibrous. In order to improve the texture, fibres, for example, in the form of microgel particles (MGP), can be added to the soy matrix. MGP are expected to interact with soy proteins, creating different microstructures and, thus, different gel properties after fermentation. In this study, pectin-based MGP were added in different sizes and concentrations, and the soy gel properties after fermentation were characterised. It was found that the addition of 1 wt.% MGP influenced neither the flow behaviour nor the tribological/lubrication properties of the soy matrix, regardless of the MGP size. However, at higher MGP concentrations (3 and 5 wt.%), the viscosity and yield stress were reduced, the gel strength and cross-linking density decreased, and the water-holding capacity was reduced. At 5 wt.%, strong and visible phase separation occurred. Thus, it can be concluded that apple pectin-based MGP serve as inactive fillers in fermented soy protein matrices. They can, therefore, be used to weaken the gel matrix purposely to create novel microstructures.