Amino Acid-Based Hydrogel with Interpenetrating Gelatin and Cross-Linked by Metal Ions, Providing High Stretchability and Motion Sensitivity

A double network structure with metal ions was created to enhance the mechanical stability of the hydrogels and increase their low conductivity. For this purpose, the P(AM_AcOr_Gelatin) hydrogel was synthesized by combining gelatin, a biocompatible polymer, N-δ-acryloyl-ornithine (AcOr), an amino acid derivative, and acrylamide (AM). Because the amino acid-based monomer added charged groups to the hydrogel network, the hydrogel exhibited improved conductivity and motion sensitivity properties compared with polyacrylamide (PAM) hydrogels. Furthermore, we altered the P(AM_AcOr_Gelatin) hydrogel by introducing the Fe3+ and Cu2+ ions, resulting in the formation of the P(AM_AcOr_Gelatin)-Fe3+ and P(AM_AcOr_Gelatin)-Cu2+ hydrogels. The hydrogels containing metal ions had coordination bonds between the ions, gelatin, and AcOr. Additionally, there were other noncovalent bonds present, resulting in further increased conductivity (approximately 95% improvement) and stretchability (more than double). The conductivity and resistance of the hydrogels changed, depending on the bending position and strain applied to the hydrogel layer. The results demonstrated that the hydrogel layer had good strain sensitivity, with an enhanced gauge factor (GF) of approximately 1.7 (at 250% strain) and a conductivity ranging from 3355 to 4387 μS·cm-1.

Composite barrier membrane for bone regeneration: advancing biomaterial strategies in defect repair

Bone defects represent a significant challenge in clinical practice, driving the need for innovative solutions that effectively support bone regeneration. Barrier membranes, due to playing a critical role in creating an environment conducive to bone regeneration by preventing the infiltration of non-osteogenic tissues, are widely applied to bone repair. However, inadequate spatial stability and osteogenesis-promoting ability often limit current barrier membranes. In response to these challenges, we have developed an advanced gelatin methacrylate/hydroxyapatite/hydroxyapatite membrane (GelMA/HAp/HAM) composite biomaterial designed as a barrier membrane with superior spatial stability and optimal degradation properties. The GelMA/HAp/HAM composite features a bilayer structure, with each layer possessing distinct properties: the dense hydroxyapatite membrane (HAM) acts as a barrier to prevent connective tissue infiltration. In contrast, the porous gelatin methacrylate/hydroxyapatite (GelMA/HAp) hydrogel layer promotes osteogenesis. Studies have demonstrated the composite's excellent biocompatibility and its significant osteogenic differentiation enhancement. This composite membrane holds great promise for clinical applications in bone defect repair, providing a new avenue for improving patient outcomes in regenerative medicine.

Amino Acid-Derived Supramolecular Assembly and Soft Materials

Amino acids (AAs), serving as the primary monomer of peptides and proteins, are widely present in nature. Benefiting from their inherent advantages, such as chemical diversity, low cost, ease of modification, chirality, biosafety, and bio-absorbability, AAs have been extensively exploited to create self-assembled nanostructures and supramolecular soft materials. In this review article, we systematically describe the recent progress regarding amino acid-derived assembly and functional soft materials. A brief background and several classified assemblies of AAs and their derivatives (chemically modified AAs) are summarized. The key non-covalent interactions to drive the assembly of AAs are emphasized based on the reported systems of self-assembled and co-assembled AAs. We discuss the molecular design of AAs and the general rules behind the hierarchical nanostructures. The resulting soft materials with interesting properties and potential applications are demonstrated. The conclusion and remarks on AA-based supramolecular assemblies are also presented from the viewpoint of chemistry, materials, and bio-applications.

Smart Hydrogel Based on Derivatives of Natural α-Amino Acids for Efficient Removal of Metal Ions from Wastewater

A novel class of hydrogels, rich in a variety of functional groups capable of interacting/complexing with metal ions was successfully synthesized. This was achieved by using acryloyl derivatives of natural α-amino acids, specifically ornithine and cystine. The δ-amino group of ornithine was modified with an acryloyl group to facilitate its attachment to the polymer chain. Additionally, N,N'-bisacryloylcystine, derived from cystine, was employed as the cross-linker. The hydrogel was obtained through a process of free radical polymerization. This hydrogel, composed only from derivatives of natural amino acids, has proven to be a competitive sorbent and has been effectively used to remove heavy metal pollutants, mainly lead, copper, and silver ions, from aqueous media. The maximum sorption capacities were ca. 155 mg·g-1, 90 mg·g-1, and 215 mg·g-1, respectively for Pb(II), Cu(II), and Ag(I). The material was characterized by effective regeneration, maintaining the sorption capacity at around 80%, 85%, and 90% for Cu(II), Ag(I), and Pb(II), respectively, even after five cycles. The properties of sorption materials, such as sorption kinetics and the effect of pH on sorption, as well as the influence of the concentration of the examined metal ions on the swelling ratio and morphology of the gel, were investigated. The EDS technique was employed to investigate the composition and element distribution in the dry gel samples. Additionally, IR spectroscopy was used to identify the functional groups responsible for binding the studied metal ions, providing insights into their specific interactions with the hydrogel.

Tough polyvinyl alcohol-gelatin biological macromolecules ionic hydrogel temperature, humidity, stress and strain, sensors

High strength, high toughness and high sensitivity were some of the most popular characteristics of flexible sensors. However, the mechanical properties and reproducibility of current single biomacromolecule gelatin hydrogel sensors are lower, and few hydrogel sensors have been able to provide excellent mechanical properties and flexibility at the same time so far. To address this challenge, a simple method to prepare tough polyvinyl alcohol (PVA) and gelatin hydrogel was proposed in this study. The PVA-gelatin-Fe3+ biological macromolecules hydrogel was prepared by a freeze-casting-assisted solution substitution method, which exhibited high strength (2.5 MPa), toughness (7.22 MJ m-3), and excellent temperature, humidity, stress, strain, and human motion sensing properties. This combination of mechanical properties and flexibility makes PVA-gelatin biological macromolecules hydrogel a promising material for flexible sensing. In addition, an ionic immersion strategy could also impart multiple functions to the hydrogel and be applied to various hydrogel sensor materials. Thus, this work provided an all-around solution for the preparation of advanced and robust sensors with good application prospects.

Thermodynamic parameters of phenylglycine interaction with UO22+, La3+ and Zr4

Phenylglycine interactions with (UO₂²⁺, La³⁺ and Zr⁴⁺) transition metal ions were studied at different ionic strengths and different temperature degrees applying Bjerrum's method. The work determine and discuss both the thermodynamic stabilities and the degree of interactions [Formula: see text]. Also the work calculate and discuss the thermodynamic parameters of interactions of phenylglycine with (UO₂²⁺, La³⁺ and Zr⁴⁺). The variables that govern the interaction between phenylglycine and the metal ions under investigation were related to the nature of the amino acid reactive species as well as to the nature of M⁺ such as the valence and radius of the ion. It was observed that reactions between the M⁺ and L^- were the most likely to occur. It was determined that the pH values affect the degree of complex formation [Formula: see text] as well as the production of various reactive spices. When the range of degree of interaction was more than 0.5 and less than 1.15, forming 1:1 stoichiometric complex. Additionally, it was shown that the stability of the complexes produced between phenylglycine and M^Z+ increased in the subsequent order, which was in good accord with the Irving-Williams order.

Thermodynamic Parameters of Phenylglycine Interaction with UO22+, La3+ and Zr4+.. [DOI: 10.21203/rs.3.rs-1881732/v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The interactions between phenylglycine and some transition metal ions (UO22+,La3+ and Zr4+) were studied at three ionic strengths [(µ = 0.05, 0.10 and 0.15) M KNO3] and three temperatures [(25, 35 and 45) ºC] in aqueous media by using Bjerrum’s potentiometric technique. The stoichiometric and thermodynamic stability constants as well as the degree of complexation for all studied systems (\(\stackrel{-}{\text{n}}\)) were determined and discussed. The standard thermodynamic parameters (Δ pKº and Δlog Kº) and the thermodynamic parameter differences (ΔGº, ΔΔGº, ΔHº, ΔΔHº, ΔSº, and ΔΔSº) were calculated for all possible reactions. Advanced discussions of these functions as well as the factors that may control the complexation processes from the thermodynamic point of view have been reported.