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Spider silk proteins (spidroins) have garnered attention in biomaterials research due to their ability to self-assemble into hydrogels. However, reported spidroin hydrogels require high protein concentration and prolonged gelation time. Our study engineered an artificial spidroin that exhibits unprecedented rapid self-assembly into hydrogels at physiologically relevant conditions, achieving gelation at a low concentration of 6 mg/mL at 37 °C without external additives. Remarkably, at a 30 mg/mL concentration, our engineered protein forms hydrogels within 30 s, a feature we termed "superfast gelation". This rapid formation is modulated by ions, pH, and temperature, offering versatility in biomedical applications. The hydrogel's capacity to encapsulate proteins and support E. coli growth while inducing RFP expression provides a novel platform for drug delivery and bioengineering applications. Our findings introduce a superfast, highly adaptable, and cytocompatible hydrogel that self-assembles under mild conditions, underscoring the practical implication of rapid gelation in biomedical research and clinical applications. [ABSTRACT FROM AUTHOR]

pH-sensitive degradable hydrogels are smart materials that can cleave covalent bonds upon pH variation, leading to their degradation. Their development led to many applications for drug delivery, where drugs can be released in a pH-dependent manner. Crosslinking hyperbranched polyglycerol (HPG), a biocompatible building block bearing high end-group functionality, using oxalic acid (OA), a diacid that can be synthesized from CO2 and form highly activated ester bonds, can generate this type of smart hydrogel. Aiming to understand the process of developing this novel material and its drug release for oral administration, its formation was studied by varying reactant stoichiometry, concentration and cure procedure and temperature; it was characterized regarding gel percent (%gel), swelling degree (%S), FTIR and thermal behavior; impregnated using ibuprofen, as a model drug, and a release study was carried out at pH 2 and 7. Hydrogel formation was evidenced by its insolubility, FTIR spectra and an increase in Td and Tg; a pre-cure step was shown to be crucial for its formation and an increase in the concentration of the reactants led to higher %gel and lower %S. The impregnation resulted in a matrix-encapsulated system; and the ibuprofen release was negligible at pH 2 but completed at pH 7 due to the hydrolysis of the matrix. A pH-sensitive degradable HPG-OA hydrogel was obtained and it can largely be beneficial in controlled drug release applications. [ABSTRACT FROM AUTHOR]

Spider silk proteins (spidroins) have garnered attention in biomaterials research due to their ability to self-assemble into hydrogels. However, reported spidroin hydrogels require high protein concentration and prolonged gelation time. Our study engineered an artificial spidroin that exhibits unprecedented rapid self-assembly into hydrogels at physiologically relevant conditions, achieving gelation at a low concentration of 6 mg/mL at 37 °C without external additives. Remarkably, at a 30 mg/mL concentration, our engineered protein forms hydrogels within 30 s, a feature we termed “superfast gelation”. This rapid formation is modulated by ions, pH, and temperature, offering versatility in biomedical applications. The hydrogel’s capacity to encapsulate proteins and support E. coli growth while inducing RFP expression provides a novel platform for drug delivery and bioengineering applications. Our findings introduce a superfast, highly adaptable, and cytocompatible hydrogel that self-assembles under mild conditions, underscoring the practical implication of rapid gelation in biomedical research and clinical applications.

Biopolymers and their derivatives are materials with increasing interest for industry and especially for sustainable engineering development. Among such kind of materials, carbohydrate polymer like highly deacetylated chitin (chitosan) is widely used for a wide range of applications, including material and biomedical developments. The majority of industrially produced chitosan is based on chitin extracted from crustacean exoskeleton. However, with increase of interest on this material, chitosan's production will rapidly become insufficient and other species should be investigated as new sources of chitosan. In the present work, we focus on the preparation of chitosan from giant dung beetles (Genus Heliocopris , Hope, 1838). This genus was chosen to show the possibility to take animals that develop and leave near dejection and valuate them for material applications. This work includes all the chitosan extraction procedures, chitosan characterisation IR, SEM, NMR, ash content, and deacetylation degree. Finally, the prepared carbohydrate polymer is used to form hydrogel. The prepared gel has been characterised and used for 3D printing, to show the compatibility of extracted chitosan with biomaterial application. [Display omitted] [ABSTRACT FROM AUTHOR]

Naturally derived polymers, such as cellulose or chitin, are materials with increasing interest for a sustainable future. Considering the pollution associated with plastics recycling, natural and fully biocompatible materials like cellulose and chitin are becoming increasingly more relevant for sustainable engineering applications. Chitin and highly deacetylated chitin (chitosan) are already implemented in a wide range of materials applications, especially in biomedical fields. One interesting aspect of chitin is that the majority of industrially produced chitin is extracted from shrimp exoskeleton. However, other arthropods can also be investigated as a source of chitin. In this work, we focus on the extraction of chitin and preparation of chitosan from a beetle specie: Mecynorhina torquata. This includes characterization of the native Mecynorhina torquata surfaces and all intermediate surfaces throughout the chitosan extraction procedure. The final product, prepared chitosan, is also characterized using IR, SEM, ash content, and deacetylation degree. In addition, spectacular iridescent surfaces of Mecynorhina torquata are highlighted at the intermediate steps during chitin extraction. Finally, as proof of concept, the isolated chitosan is used to form hydrogel. Unlabelled Image [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer’s backbone. An alternative modification of the vicinal diol of the glucuronic acid is oxidation with sodium periodate to generate dialdehydes via a ring opening mechanism that can subsequently be further modified or crosslinked via Schiff base chemistry. Since this oxidation causes a structural destruction of the polysaccharide backbone, it was our intention to study a novel synthesis protocol frequently applied to selectively oxidize the C6 hydroxyl group of saccharides. On the basis of this TEMPO/TCC oxidation, we studied an alternative hydrogel platform based on oxidized HA crosslinked using adipic acid dihydrazide as the crosslinker.

The majority of studies have focused on the industrial exploitation of marine fisheries waste through the production of natural bioactive bioploymeres such as chitin and chitosan. However, in recent years, beetles are increasingly attracting the interest of scientists as a source of chitin and chitosan for the preparation of hydrogels for sustainable engineering development. In the present work, we focus on the study for the first time a new Moroccan species of beetle (Akis granulifera Sahlberg, 1823), for the extraction of chitin and the elaboration of chitosan. A chemical extraction process was used. Then, physicochemical characterizations by FT-IR, SEM, XRD, 1H NMR, TGA/DSC, Potentiometry, Viscosimetry, and elemental analysis were performed. In addition, to evaluate its physicochemical quality, the elaborated chitosan is combined with alginate to form a hydrogel. This hydrogel was effectively characterized by SEM, DRX and FTIR to show the potential of chitosan from Akis granulifera in biomaterial applications. [ABSTRACT FROM AUTHOR]

Highlights • A precise and fast measurement for alginate hydrogel formation with CaCl 2 is proposed. • The measurement principle is based on the gel inhomogeneity (core/shell). • The method can supplement high temperature NMR analysis of G/M ratio. Abstract Although alginate-based hydrogels are widely used, determining their mechanical properties and explaining their ability to form a hydrogel in situ remains a challenge. A new method of external gelation using calcium chloride (CaCl 2) is proposed to quantify the formation of alginate hydrogel and its mechanical properties as well as to observe its temporal behaviour. To this end, small inhomogeneous alginate beads were formed, which comprised a shell and a core. The bead's shell consisted of calcium alginate hydrogel, while its core was sodium alginate sol. The beads were mechanically tested with a texture analyser to provide a detailed description of the structure. Different alginate samples could be clearly identified, and the M(mannuron)/G(guluron) acid ratios could be extrapolated quickly and easily from the test results if calibrated by NMR. This enables a fast and cost-effective characterisation of different alginates with regard to their composition and gel formation properties. [ABSTRACT FROM AUTHOR]

Nucleotide polymerization occurs by the nucleophilic attack of 3′-oxygen of the 3′-terminal nucleotide on the α-phosphorus of the incoming nucleotide 5′-triphosphate. The π-stacking of mononucleotides is an important factor for prebiotic RNA polymerization in terms of attaining the proximity of two reacting moieties. Adenosine and adenosine 5′-monophosphate (AMP) are known to form hydrogel in the presence of cyanuric acid at neutral pH. However, we observed that other canonical ribonucleotides did not gel under the same condition. The π-stacking-induced hydrogel formation of AMP was destroyed at pH 2.0, suggesting that the protonation of N at position 1 of adenine abolished hydrogen bonding with the NH of cyanuric acid and resulted in the deformation of the hexad of adenine and cyanuric acid. A liquid-like gel was formed in the case of adenosine with cyanuric acid and boric acid, whereas AMP caused the formation of a solid gel, implying that the negative charge inherent to AMP prevented the formation of esters of boric acid with the cis-diols of ribose. Cyanuric acid-driven oligomerizations of AMP might have been the first crucial event in the foundation of the RNA world. [ABSTRACT FROM AUTHOR]

Main conclusion : RG-I and AGP, but not XG, are associated to the building of the peculiar mechanical properties of tension wood. Hardwood trees produce tension wood (TW) with specific mechanical properties to cope with environmental cues. Poplar TW fibers have an additional cell wall layer, the G-layer responsible for TW mechanical properties. We investigated, in two poplar hybrid species, the molecules potentially involved in the building of TW mechanical properties. First, we evaluated the distribution of the different classes of non-cellulosic polysaccharides during xylem fiber differentiation, using immunolocalization. In parallel, G-layers were isolated and their polysaccharide composition determined. These complementary approaches provided information on the occurrence of non-cellulosic polysaccharides during G-fiber differentiation. We found no evidence of the presence of xyloglucan (XG) in poplar G-layers, whereas arabinogalactan proteins (AGP) and rhamnogalacturonan type I pectins (RG-I) were abundant, with an apparent progressive loss of RG-I side chains during G-layer maturation. Similarly, the intensity of immunolabeling signals specific for glucomannans and glucuronoxylans varies during G-layer maturation. RG-I and AGP are best candidate matrix components to be responsible for TW mechanical properties. [ABSTRACT FROM AUTHOR]

ABA block-type copolymers with poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) as the middle B segment and poly(glycidyl methacrylate(GMA)) as the A segments (PM b G) were synthesized by an activator regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP). The PM b Gs were reactive copolymers, as the epoxide group available in the poly(GMA) segment could be chemically modified by nucleophilic addition reactions, which allowed the functionalization of PM b G with a wide range of functional groups for various purposes. The PM b Gs had narrow molecular weight distributions with predetermined chain lengths, while the length of the middle poly(MPC) segment could be designed and synthesized with a fixed degree of polymerization of both poly(GMA) segments in a single polymer chain. The functionalization of PM b Gs by 3-aminophenylboronic acid allowed the preparation of a phenylboronic acid moiety connecting ABA block-type copolymers (PM b Bs). The PM b Gs were also reacted with diethanolamine (DEA) to introduce hydroxyl groups. The DEA-functionalized copolymers (PM b Ds) could interact with PM b Bs in aqueous media, forming hydrogels spontaneously. As the reactive groups were separated by the poly(MPC) segment, the network structure depended on the polymerization degree of the poly(MPC) segment. The diffusivity of various proteins in the PM b B/PM b D hydrogels depended on the molecular weight of these proteins and was regulated by adjusting the chain length of poly(MPC) between cross-linking positions of the hydrogel network, that is, the polymerization degree of the poly(MPC) segment. [ABSTRACT FROM AUTHOR]

pH- and thermo-sensitive hydrogels based on chitosan cross-linked with terephthaloyl diazide were synthesized. A new formulation of the polysaccharide modified with taxifolin (dihydroquercetin) was obtained by nucleophylic addition reaction resulting in the formation of urea and urethane bonds with a 1,4-phenylenediamine spacer. Sustained release of the effective agent (flavonoid) upon action of trypsin, which is one of the enzymes of the gastrointestinal tract, was observed. [ABSTRACT FROM AUTHOR]

Abstract: In order to study the impact of the amino acid sequence on the morphology of peptide-based nanostructures and their hydrogel formation, we designed a series of analogs of a milk-derived octapeptide (OP), mainly using strategic amino acid substitutions. Electronic transmission microscopy (TEM) and circular dichroism (CD) spectropolarimetry were used to analyze the nanostructures formed, and to characterize some structural features of the modified peptides. Further, the potential to form hydrogels was investigated for all of the analogous peptides. We learned that those able to undergo secondary structure transition to β-sheet conformation form strong gels. The results reported highlight some key structural properties that explain the self-assembly propensity of Peptide OP. [Copyright &y& Elsevier]

Kinetics of isothermal formation of poly (acrylic acid) (PAA) hydrogels through polymerization of acrylic acid and crosslinking of the PAA formed in a conventionally heated reaction system and in a microwave heated reaction system were investigated. It was found that in the microwave heated system the reaction rate constant of PAA hydrogel formation significantly increased (from 32 to 43 times) when compared with the conventionally heated system. The isothermal kinetics of the PAA hydrogel formation during the microwave process could be described by the so-called first-order chemical reaction kinetics model. In contrast, the so-called second-order chemical reaction rate model could best describe the isothermal kinetics of the PAA hydrogel formation during the conventionally heated process. Also, in the microwave heated system, the reaction kinetics of the PAA hydrogel formation and its kinetic parameters changed, that is, the activation energy (Ea) decreased by about 19% and the pre-exponential factor (lnA) decreased by 2.2 times. The decrease in activation energy, change in entropy of activation energy, and decrease in the pre-exponential value of PAA hydrogel formation under microwave heating are caused with increased energy of the reactive species when compared with their energy in thermal activation. Increased energy of the reactive species is a consequence of rapid transfer and absorption of the energy of microwave field to the existing reactive species. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

Abstract: Controlled release (CR) dosage forms are often based on polymeric matrices, e.g., sustained-release tablets and capsules. It is crucial to visualise and quantify processes of the hydrogel formation during the standard dissolution study. A method for imaging of CR, polymer-based dosage forms during dissolution study in vitro is presented. Imaging was performed in a non-invasive way by means of the magnetic resonance imaging (MRI). This study was designed to simulate in vivo conditions regarding temperature, volume, state and composition of dissolution media. Two formulations of hydrodynamically balanced systems (HBS) were chosen as model CR dosage forms. HBS release active substance in stomach while floating on the surface of the gastric content. Time evolutions of the diffusion region, hydrogel formation region and “dry core” region were obtained during a dissolution study of L-dopa as a model drug in two simulated gastric fluids (i.e. in fed and fasted state). This method seems to be a very promising tool for examining properties of new formulations of CR, polymer-based dosage forms or for comparison of generic and originator dosage forms before carrying out bioequivalence studies. [Copyright &y& Elsevier]

Formation and characterization of hydrogel of a hydrophilic polymer in a wide range of gamma absorbed doses is reported. An aqueous solution contains 2% polyvinyl alcohol (PVA) by mass irradiated under gamma rays of Co was chosen for study. The hydrogel was synthesized without using any additives. It was found that gel fraction is an exponential saturation function that increases with an increase of absorbed dose while swelling ratio is an exponential saturation function that decreases with an increase of absorbed dose. The results are described by energy transfer model. [ABSTRACT FROM AUTHOR]

The present contribution deals with the synthesis and characterization of N-isopropyl chitosan in which the introduction of hydrophobic groups leads to an increased flexibility of the polysaccharide backbone. The isopropyl groups extend the solubility of the modified-chitosan samples and render the modified chitosan a pH- and thermo-sensitive system for hydrogel formation. Indeed, upon varying the pH of the system and/or its temperature within a range compatible with biological applications, a non-reversible sol-gel transition occurs, as determined through extended rheological analyses. The modified chitosan samples show a very good biocompatibility as determined through preliminary viability and cell growth experiments., (Copyright © 2019 Elsevier Ltd. All rights reserved.)