Degrees Of Modification Research Articles

Does Transglutaminase Crosslinking Reduce the Antibody Recognition Capacity of β-Lactoglobulin: An Analysis from Conformational Perspective

Food allergies are a global concern, with β-lactoglobulin (β-LG) in bovine milk being a major allergenic protein. This study investigated the effects of transglutaminase (TGase)-mediated crosslinking on the antibody recognition capacity (ARC) and structural properties of β-LG, with the aim of developing hypoallergenic dairy products. β-LG solutions were treated with TGase at varying concentrations (0, 5, 10, 15, and 20 U/g) and durations (0, 6, 18, 24, and 42 h), followed by analysis using electrophoresis, enzyme-linked immunosorbent assay (ELISA), and spectroscopy. The results demonstrated that treatment with TGase at 20 U/g significantly reduced the ARC and immunoglobulin E (IgE) binding capacity of β-LG to 90.0 ± 0.4% and 58.4 ± 1.0%, respectively, with the optimal ARC reduction observed after 6 h of treatment (86.7 ± 1.2%, p < 0.05). Although electrophoresis did not reveal significant crosslinking of β-LG, ultraviolet absorption, fluorescence intensity, and hydrophobicity all increased with prolonged crosslinking time, while sulfhydryl content fluctuated irregularly. These findings suggest that β-LG underwent varying degrees of structural modification, which led to the masking of antigenic epitopes during the early stages (0–24 h), followed by their re-exposure at the later stage (42 h). Overall, these results highlight the potential of TGase to reduce β-LG potential allergenicity, presenting a promising strategy for the development of hypoallergenic dairy products.

The Effect of Unbalance Supply on the Three- Phase Synchronous Motor Performance in the Laboratory

A detrimental worldwide phenomena that affects the output of three-phase synchronous motors is voltage unbalance. There are several ways that a three-phase source voltage can become unbalanced. A motor may be practically impacted by imbalanced instances that vary in several ranges. The goal of this work is to assess the operations using relevant hypotheses. To understand the degree of such modifications, this paper examines balanced and imbalanced situations practically in relation to their mechanical and electrical performance. This performance entails the currents of stator, total harmonics distortion, the speed of the motor, and the efficiency. The experiment was conduct laboratory on three phase synchronous motor.

Toward Intracellular Delivery: Aliphatic Polycarbonates with Pendant Thiol-Reactive Thiosulfonates for Reversible Postpolymerization Modification.

Postpolymerization modifications are valuable techniques for creating functional polymers that are challenging to synthesize directly. This study presents aliphatic polycarbonates with pendant thiol-reactive groups for disulfide formation with mercaptans. The reductive responsive nature of this reaction allows for reversible postpolymerization modifications on biodegradable scaffolds. Six-membered cyclic carbonate monomers with pendant thiosulfonate groups were synthesized and polymerized using controlled organocatalytic ring-opening polymerization, yielding polymers with narrow molecular weight dispersities (Đ = 1.2) and intact reactive thiosulfonate side chains. Reversible modification with benzyl mercaptans achieved high degrees of disulfide modification. Additionally, thiol-reactive carbonate monomers were block-copolymerized onto polyethylene glycol (mPEG113) and then converted into benzyl disulfides, while the block copolymers' hydroxyl end groups remained available for fluorescent dye labeling. The amphiphilic block copolymers self-assembled in water into micelles (∼33 nm diameter), capable of encapsulating hydrophobic molecules. These micelles successfully delivered hydrophobic dyes into macrophages, indicating the potential for intracellular drug delivery.

Mapping of Western Valles Marineris Light-Toned Layered Deposits and Newly Classified Rim Deposits.

Layered deposits are found on the plateaus surrounding the western portion of Valles Marineris, mantling the chasmata rims. These rim deposits exhibit intricate layering and are described as light-toned layered deposits (LLDs) in previous studies. Light-toned layered deposits are thought to be composed of pyroclastic ash that was emplaced during volcanic eruptions and later chemically altered. Using Shallow Radar (SHARAD) observations to map radar reflections from what appears to be the base of these deposits, we discovered two additional types of rim deposits that are contiguous with the well-known LLDs; weakly layered deposits (WLDs) that exhibit less obvious stratification and completely unstratified deposits designated as nonlayered deposits (NDs). Complementing the SHARAD data with imagery from Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE)and Context Camera (CTX) and with narrow-angle imagery from the Mars Global Surveyor Mars Observer Camera (MOC-NA), we mapped the full extent of all rim deposits and present the finished map within this study. We hypothesize that all three deposits originate from pyroclastic ashfall but experienced different degrees of modification due to the variable presence of liquid water. This hypothesis requires a source of volcanic depositional material and past aqueous environments in regions with LLDs and WLDs. We discuss the potential for several large Tharsis volcanoes and a hypothesized degraded volcano within Noctis Labyrinthus as sources of the ash, and we examine the evidence for past aqueous environments.

Polymer powerhouse: Methyl methacrylate – A breakthrough blend for superior adhesion to gingiva

The goal of this study was to develop a new poly(methyl methacrylate) (PMMA)-based conjugate with enhanced mucoadhesive features for gingiva. Five MMA-based conjugates with varying amounts of hydroxyethyl maleimide (HEM) and poly(ethylene glycol) (PEG) were synthesized and characterized using infrared spectroscopy and proton nuclear magnetic resonance. Quantification of attached HEM and PEG was performed using assay kits and established protocols. Mucoadhesiveness was tested through rheological measurements, retention time, and tensile strength studies. Results showed successful unification of MMA with HEM and PEG, with varying degrees of modification and no toxic effects. Dynamic viscosity was enhanced up to 13-fold for MMA-100Mal, decreasing incrementally for MMA-75Mal, MMA-50Mal, MMA-25Mal, and MMA-0Mal. Retention time improved up to 120-fold for MMA-100Mal, decreasing to 37.5-fold for MMA-0Mal. Mucoadhesiveness followed the order: MMA-100Mal > MMA-75Mal > MMA-50Mal > MMA-25Mal > MMA-0Mal. In conclusion, the novel modification of MMA with increased mucoadhesive features to buccal gingiva suggests its potential as a long-term total denture base material, paving the way for more patient-friendly prostheses.

Synthesis and characterization of photopolymerizable piezoelectric KNN-based methacrylated hyaluronic acid hydrogel scaffolds

The use of methacrylated hyaluronic acid hydrogel (MeHA) has tremendous promise for regeneration purposes, while potassium sodium niobate (KNN) exhibits biocompatibility properties that make it suitable for biomedical applications. This study examined the synthesis and characterization of hybrid scaffolds composed of MeHA and KNN. The investigation focused on various aspects, including gelation time, micromorphology, topographic analysis, swelling behavior, changes in volume and degradation profiles, as well as mechanical properties, compared to MeHA alone scaffolds, along with the synthesis and characterization of KNN. The findings demonstrated that the incorporation of KNN into MeHA influenced some properties, including shorter gelation time and partial pore development. Nevertheless, a few notable differences between hybrid scaffolds and MeHA alone scaffolds were observed, while there were no substantial disparities overall. As a result, integrating KNN into MeHA has the potential to lead to further investigation, such as biological testing using different degrees of modification of MeHA, crosslinking systems, and KNN with variable sizes and piezoelectricity.

Submicron-sized anhydrous crystalline silicates and their relation to amorphous silicate in the matrix of Acfer 094

The study of pristine chondrites provides insight into nebular processes that occurred prior to the accretion of small-sized parent bodies. The interchondrule matrix of the primitive chondrite Acfer 094 is characterized by the presence of submicron-sized anhydrous crystalline aggregates embedded in a silicate groundmass that is mostly amorphous. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDXS) were employed to investigate the matrix of Acfer 094 and its components.The amorphous silicate groundmass is homogeneous in composition and exhibits a Mg depletion relative to the solar value. It embeds Fe-Ni nanosulfides, whose typical size is a few tens of nanometers. Nanometer-sized fibrous silicates are rare in the groundmass indicating a low degree of aqueous alteration. Submicron-sized Mg-rich crystalline silicates (olivine and pyroxene) occur either as isolated grains or as aggregates. These submicron-sized crystalline silicates occupy around 25 % of the matrix volume. The isolated grains display a wide range of shapes, from rounded to irregularly angular, and could have originated from the fragmentation of type I chondrules or from nebular condensation. The aggregates exhibit variable morphologies and grain sizes (typically a few tens of nm). They are chemically equilibrated, and likely formed by solid-state thermal annealing of amorphous precursors.The Acfer 094 matrix contains a range of components that have undergone varying degrees of thermal modification. A significant proportion of a precursor material (i.e. nebular dust) resembling matrix is likely to have undergone one or more brief and intense thermal events, potentially associated with the process of chondrule formation. These events resulted in the formation of magnesium-rich anhydrous silicates (forsterite and enstatite) at high temperatures that were embedded in the matrix of Acfer 094 as isolated grains and crystalline aggregates.

Life After Death: Re‐Purposing End‐of‐Life Supercapacitors for Electrochemical Water Desalination

AbstractThis study explores the potential of re‐purposing end‐of‐life commercial supercapacitors as electrochemical desalination cells, aligning with circular economy principles. A commercial 500‐Farad supercapacitor was disassembled, and its carbon electrodes underwent various degrees of modification. The most straightforward modification involved NaOH‐etching of the aluminum current collector to produce free‐standing carbon films. More advanced modifications included CO2 activation and binder‐added wet processing of the electrodes. When evaluated as electrodes for electrochemical desalination via capacitive deionization of low‐salinity (20 mM) NaCl solutions, the minimally modified NaOH‐etched carbon electrodes achieved an average desalination capacity of 5.8 mg g−1 and a charge efficiency of 80 %. In contrast, the CO2‐activated, wet‐processed electrodes demonstrated an improved desalination capacity of 7.9 mg g−1 and a charge efficiency above 90 % with stable performance over 20 cycles. These findings highlight the feasibility and effectiveness of recycling supercapacitors for sustainable water desalination applications, offering a promising avenue for resource recovery and re‐purposing in pursuing environmental sustainability.

Innovative modified pectins enriched with galactose: Preparation, characterization, and gel-based properties of curcumin-delivered hydrogel beads

Gelling and thickening are the most important properties of pectin, and these properties are dependent on the molecule's structure. In this study, new types of pectin with varying degrees of modification were prepared by reducing the methyl ester groups on the galacturonic acid residues in pectin to hydroxyl groups using NaBH4, thereby converting methylated galacturonic acid to galactose. The physicochemical properties, rheological behavior, and gelling properties of the modified pectins were investigated. Galacturonic acid levels gradually decreased from 68.98% ± 0.40%–7.49% ± 0.09%, whereas galactose levels increased from 10.29% ± 0.48%–72.26% ± 0.62% with increasing degree of modification. The molecular weight exceeded 500 kDa, and solubility was high. The novel modified pectins underwent gelation without requiring sucrose addition and were calcium and pH sensitive. A higher degree of modification promoted gelation at higher temperatures. Addition of Ca2+ at 60 mg/g caused R-55 to gel at 37 °C and pH 2 but disintegrate at pH 6. Three types of R-55 hydrogel beads encapsulating curcumin were prepared. These beads effectively protected curcumin in the stomach; two allowed for its rapid and slow release in the small intestine, whereas one allowed for its release in the colon. Thus, R-55 can be used as a carrier for the targeted delivery of drugs to the small intestine and colon. The modified pectins are suitable for innovative applications in the food and pharmaceutical fields.

Temporal Shifts in Flower-Visiting Butterfly Communities and Their Floral Resources along a Vegetation Type Altered by Anthropogenic Factors

Habitat disturbance driven by human activities poses a major threat to biodiversity and can disrupt ecological interactions. Butterfly–plant mutualisms represent an ideal model system to study such anthropogenic impacts, as butterflies exhibit intimate dependencies on larval host plants and adult nectar sources, rendering them highly sensitive to habitat changes affecting the availability of these floral resources. This study examined flower-visiting butterfly communities and their associations with flowering plants in a landscape altered by anthropogenic factors in central Mexico. The study area encompassed a mosaic of vegetation types, including native juniper forests, agricultural lands, and introduced eucalyptus plantations, representing different degrees of human-induced habitat modification. Monthly surveys were conducted over a single year, covering both rainy and dry seasons, to analyze butterfly and plant diversity, community composition, and interactions. Results showed the highest diversity in juniper forests, followed by eucalyptus and agricultural sites. Seasonal turnover was the primary driver of community changes, with habitat-based segregation persisting within seasons. Butterfly diversity strongly correlated with flower abundance, while plant richness played a secondary role. SIMPER and indicator species analyses identified key taxa contributing to compositional dissimilarities among habitats and associated with specific vegetation types and seasons. Our research provides insights into temporal dynamics structuring butterfly–plant interactions across this forest disturbance spectrum, highlighting how habitat changes and seasonality shape these mutualistic communities in changing landscapes.

Knowing (or not knowing) their own socio-cognitive abilities

Metacognition, the ability to monitor and regulate one's own cognitive processes, is subject to varying degrees of modification in patients suffering from neurodegenerative diseases. The literature suggests the existence of dissociations within metacognitive abilities, with some patients exhibiting, for example, specific impairments in self-assessing their memory (and not other cognitive domains). The specific assessment of metacognition in patients' social-cognitive abilities is underdeveloped, although it has significant implications for both clinical and theoretical purposes. This narrative review aims to (i) list the main tools for assessing metacognition, underlining the presence (or absence) of social cognition items in particular; (ii) highlight the issues involved in this type of assessment, both from a clinical point of view, to support patients and their families, and from a theoretical perspective, concerning advances in cognitive modeling. Recommendations regarding the most appropriate tools for clinical practice are formulated and perspectives are discussed.

Interfacial Rheological Investigation of Modified Silica Nanoparticles with Different Alkyl Chain Lengths at the n-Octane/Water Interface.

The interfacial dilational rheology of silica nanoparticles (NPs) directly reflects the relationship between surface structure and interfacial behaviors in NPs, which has attracted significant attention in various industrial fields. In this work, modified silica nanoparticles (MNPs) with various alkyl chain lengths were synthesized and systematically characterized using Fourier transform infrared spectra, Zeta potential, and water contact angle measurements. It was found that the MNPs were successfully fabricated with similar degrees of modification. Subsequently, the interfacial behaviors of the MNPs in an n-octane/water system were investigated through interfacial dilational rheological experiments. The length of the modified alkyl chain dominated the hydrophilic-lipophile balance and the interfacial activity of the MNPs, evaluated by the equilibrium interfacial tension (IFT) variation and dilational elasticity modulus. In the large amplitude compression experiment, the balance between the electrostatic repulsion and interfacial activity in the MNPs was responsible for their ordered interfacial arrangement. The MNPs with the hexyl alkyl chain (M6C) presented the optimal amphipathy and could partly overcome the repulsion, causing a dramatic change in surface pressure. This was further confirmed by the variations in IFT and dilational elasticity during the compression path. The study provides novel insights into the interfacial rheology and interactions of functionally modified NPs.

Effect of Different Wheat Sprouting Conditions on the Characteristics of Whole-Wheat Flour.

Controlled sprouting promotes physiological and biochemical changes in whole grains, improves their nutritional value and offers technological advantages for breadmaking as an alternative to traditional whole grains. The aim of this study is to find sprouting conditions for the grains of Klein Valor wheat variety (Triticum aestivum L.) that would increase the nutritional value without significantly affecting the gluten proteins, which are essential in wholegrain baked goods. The chemical and nutritional composition, enzymatic activity and pasting properties of the suspensions of unsprouted and sprouted whole-wheat flour were evaluated. This bioprocess allowed us to obtain sprouted whole-wheat flour with different degrees of modification in its chemical composition. Sprouting at 25 °C resulted in an observable increase in enzymatic activity and metabolic processes, particularly α-amylases, which significantly affect the starch matrix and the associated pasting properties. Additionally, there was a smaller but still notable effect on the structure of the cell walls and the protein matrix due to the activation of endoxylanases and proteases. In contrast, sprouting at 15 and 20 °C for 24 h allowed for better process control as it resulted in nutritional improvements such as a higher content of free amino acid groups, free phenolic compounds and antioxidant capacity, as well as a lower content of phytates. In addition, it provided techno-functional advantages due to the moderate activation of α-amylase and xylanase. A moderate decrease in peak viscosity of sprouted whole-wheat flour suspensions was observed compared to the control flour, while protein degradation was not significantly prolonged. Sprouted whole-wheat flour obtained under milder sprouting conditions with moderate enzymatic activity could be a promising and interesting ingredient for wholegrain baked goods with improved nutritional values and techno-functional properties. This approach could avoid the use of conventional flour improvers and thus have a positive impact on consumer acceptance and enable the labelling of the product with a clean label.

What remains to be discovered: A global assessment of tree species inventory completeness

AbstractAimRecent unprecedented efforts to digitise and mobilise biodiversity data have resulted in the generation of ‘biodiversity big data’, enabling ecological research at scales previously not possible. However, gaps, biases and uncertainties in these data influence analytical outcomes and the validity of scientific research and conservation actions. Here, we estimated tree species inventory completeness globally and identified where future surveys should focus to maximise regional inventories.LocationGlobal.MethodsWe analysed spatial patterns in sampling effort of tree species occurrence records from the Global Biodiversity and Information Facility (GBIF) and estimated global tree species inventory completeness for 100 × 100 km grid cells (sampling units) and ecoregions. We also identified forested areas for future botanical exploration, by examining the spatial overlap between inventory completeness, remaining natural habitat and protected areas and degrees of forest modification by anthropogenic pressure (forest integrity).ResultsSpatial patterns in sampling effort and tree species inventory completeness were unevenly distributed around the world. Only 35% of ecoregions and 18% of sampling units can be considered well surveyed, most of which were concentrated in the Global North, including Europe, North America and Australia. Large areas in species‐rich tropical regions, especially in Southeast Asia, remained poorly documented. Moreover, our results showed that many areas with low inventory completeness overlapped with ecoregions retaining less than 50% of natural habitat and protected land area, as well as sampling units with low forest integrity.Main ConclusionsDue to limitations in biodiversity data, simply sampling more will not necessarily lead to increasing knowledge. We illustrated how gaps in these data can be used to improve existing knowledge by identifying priority areas for future surveys. With ongoing anthropogenic impacts and escalating rates of biodiversity loss, limited resources should be allocated to strategically survey regions likely to yield new knowledge and improve biodiversity representativeness.

Differential Epigenetic Regulation in Uninfected and Tuberculosis-Human Immunodeficiency Virus Co-Infected Patients.

This study aimed to compare the degree of epigenetic modifications between a TB-HIV co-infected cohort and uninfected subjects. Formalin-fixed paraffin-embedded (FFPE) tissues were retrieved from 45 TB-HIV co-infected and 45 control individuals. Real-time PCR was applied to compare the level of expression of genes involved in epigenetic regulation. The protein multiplex assay was used to assess the degree of protein modification. DNA sequencing was used to determine the evolutionary relationships between the infecting HIV and Mtb strains. Our results indicated a significant increase in the expression of the five candidate genes in the patients with TB-HIV relative to the control cohort. A sharp increase in the degree of histone methylation, acetylation and phosphorylation was observed in TB-HIV co-infected patients. The phylogenetic analysis classified the strains into three distinct HIV clusters and five Mtb clusters. The disparities in the expression profiles of our candidate genes between the TB-HIV cohort and non-TB-HIV group highlights the important role played by various TB and HIV strains in regulating the host gene expression landscape.

The infectivity of AAV9 is influenced by the specific location and extent of chemically modified capsid residues

BackgroundSeveral treatments for genetic diseases utilizing recombinant adeno-associated viruses (AAVs) have recently gained approval. However, the development of a greater number of therapeutic AAVs is constrained by certain limitations. While extensive efforts have concentrated on screening AAV genetic libraries, an alternative strategy involves modifying the AAV capsid by attaching various moieties. The capsid of AAV plays a pivotal role in transducing target cells and evading immune responses, making modifications a key avenue for engineering improved variants.ResultsIn our study, we replaced specific AAV9 capsid residues with an unnatural amino acid bearing a bioorthogonal group, identifying four positions with no adverse impact on production. Utilizing click chemistry, we attached varying proportions of Cy5.5 to these positions, allowing us to assess the impact of these modifications on AAV9 infectivity in cultured cells. Our findings reveal that both the position and degree of capsid modification significantly affect AAV transduction. While higher amounts of attached molecules lead to an increased number of AAV genomes within cells, this does not positively impact transgene expression. Conversely, a negative impact on transgene expression is observed when the AAV capsid is highly modified, with the degree of this effect associated with the modified residue.ConclusionCareful control of both the degree and specific position of capsid modifications is crucial for optimizing transduction efficiency and minimizing undesired effects on transgene expression. These results underscore the importance of precision in AAV capsid modification to achieve optimal transduction efficiency while mitigating potential drawbacks on transgene expression.

Fiber welded EDTA-modified cellulose for remediation of heavy metal ions

Ethylenediaminetetraacetic acid (EDTA) is a well-known metal chelator and an attractive ligand for covalently modifying adsorbents for bioremediation. Cellulose, a naturally occurring biopolymer, has immense potential as an inexpensive, earth abundant, biocompatible scaffold for EDTA-facilitated environmental remediation; however, pretreatment of the material is required to achieve sufficient degrees of chemical modification. In this study, Natural Fiber Welding (NFW) is used to prepare commercial cotton Aida cloth for EDTA functionalization. Following NFW, the cotton scaffold was covalently modified with up to 0.56 mmol of EDTA per gram of adsorbent, a nearly 2.5-fold increase over native material. The welded EDTA-modified substrates were tested qualitatively against cobalt and quantitatively against nickel, reaching equilibrium binding capacities (qe) of up to 46 mg metal per g of adsorbent, on par with capacities reported from past work on EDTA-modified cellulose. In addition, adsorbent material could be regenerated using mild acid treatment with no significant loss in qe. Unlike the controls, the fiber-welded EDTA-Aida did not fray even after 3 chelation cycles, indicating enhanced textile robustness afforded through NFW treatment. Overall, NFW offers a new approach to converting commercially available, sustainable biomaterials into robust adsorbents for environmental remediation.

Interfacial Behaviors and Oil Detachment Mechanisms by Modified Silica Nanoparticles: Insights from Molecular Simulations.

Surfactant flooding has been considered as a promising approach for chemically enhanced oil recovery (EOR). However, this technique encounters several limitations, such as high costs, environmental concerns, and reduced efficiency under high-temperature and high-salinity reservoir conditions. Recently, nanoparticles have also been proposed as an alternative for EOR due to their superior properties compared with surfactants. This research employs molecular dynamics simulations to explore the impact of modified SiO2 nanoparticles on oil-water interfacial behaviors and the detachment of oil droplets from an oil-wet surface. The simulation results reveal that modified nanoparticles, featuring hydrophilic and hydrophobic functional groups, have slight impacts on interfacial tension reduction of the oil-water interface. Nanoparticles with varying degrees of modification exhibit distinct positions within the interface, consequently influencing the thickness of the interfacial layer. Notably, the interactions among the nanoparticles, oil molecules, and surface facilitate the formation of a water channel, thereby enhancing the process of oil detachment. Comparative analysis indicates that in terms of oil displacement efficiency, the thickness of the interfacial layer has a more significant impact than interfacial tension reduction. Furthermore, to elucidate the mechanisms of modified nanoparticles enhancing the oil recovery rate, the interaction energies among the oil droplet, nanoparticles, water, and surface are analyzed. The molecular-level insights derived from this investigation could provide valuable guidance for the design of modified nanoparticles tailored to EOR applications.

Unique Method for Facile Postsynthetic Modification of Nonisocyanate Polyurethanes.

Nonisocyanate polyurethanes (NIPUs) are broadly investigated as a potential replacement for conventional polyurethanes (PUs) to eliminate the use of toxic isocyanates and reduce occupational hazards. One of the most popular approaches to NIPU synthesis is the polyaddition of cyclic bis(carbonate)s and diamines to form poly(hydroxyurethane)s (PHUs). However, such PHUs are highly hydrophilic due to the presence of two hydroxyl groups per repeat unit, and the resulting moisture absorption significantly degrades their thermomechanical performance and physical stability upon exposure to humidity, thus limiting their utility. Here, we introduce a simple and scalable approach for the modification of PHUs to increase hydrophobicity and adjust their properties. The proposed reaction between aldehydes and appropriately spaced hydroxyl groups in the polymer backbone resulted in high degrees of modification (up to 84%) and up to 3-fold reductions in water uptake at 85% RH. Furthermore, the use of aromatic aldehydes in particular enabled the retention of mechanical properties over a wide range of humidity levels, resulting in performance comparable to conventional PUs. Finally, we note that this approach is not limited to reducing moisture sensitivity alone and provides ample opportunities for imparting a broad range of novel properties to PHUs through an appropriate selection of functional aldehydes.

Dual Cross-Linked Stimuli-Responsive Alginate-Based Hydrogels.

Sodium alginate with different molecular weights (55, 170, and 320 kg mol-1) were chemically modified by grafting methacrylic moieties onto the hydroxyl groups of the alginate backbone. The methacrylation was optimized to obtain different degrees of modification. Chemically cross-linked hydrogels were obtained following UV-light irradiation in the presence of a photoinitiator. The swelling behavior and the mechanical properties were observed to depend on both the degree of methacrylation and the alginate molecular weight. Due to the chain entanglement present in high-viscosity sodium alginate, lower degrees of modification were required to tune the hydrogel properties. Moreover, in the presence of Ca2+, secondary cross-linking was introduced by the coordination of the alginate guluronate moieties with the Ca2+ ions. The addition of this secondary cross-linking caused fast volume shrinkage and a reinforcement of the mechanical properties. The secondary cross-linking was reversible, and the hydrogels regained their original shape for at least three cycles. Additionally, the dual cross-linked network can be used to induce adhesion between hydrogels and serve as a building block for self-folding actuators.