by Keyword: biopolymers

Ramirez-Alba, Maria Dolores, Molins-Martinez, Marta, Garcia-Torres, Jose, Romanini, Michela, Macovez, Roberto, Perez-Madrigal, Maria M, Aleman, Carlos, (2024). pH and electrically responsive hydrogels with adhesive property Reactive & Functional Polymers 196, 105841

Applications of sodium alginate (Alg) and polyacrylic acid (PAA) hydrogels in biomedicine are well-known. These are predefined by the strength and weakness of their properties, which in turn depend on the chemical structure and the architecture of their crosslinks. In this work, Alg biopolymer has been grafted to synthetic PAA that has been chemically crosslinked using N,N '-methylene-bisacrylamide (MBA) to produce a pH responsive hydrogel with adhesive property. The double crosslinking network, which combines MBA-mediated covalent crosslinks and ionic crosslinks in Alg domains, results in an elastic modulus that resembles that of highly anisotropic and viscoelastic human skin. After addressing the influence of the dual network onto the Alg-g-PAA hydrogel properties, a prospection of its potential as an adhesive has been made considering different surfaces (rubber, paper steel, porcine skin, etc). The bonding energy onto porcine skin, 32.6 +/- 4.6 J/m2, revealed that the Alg-g-PAA hydrogel can be proposed in the biomedical field as tissue adhesive for wound healing applications. Finally, the hydrogel has been semi-interpenetrated with poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PEDOT-MeOH) chains through a chemical oxidative polymerization process. The resulting hydrogel, Alg-g- PAA/PEDOT-MeOH, which is even more porous than Alg-g-PAA, in addition to being electro-responsive, maintains adhesive properties.

JTD Keywords: Adhesion properties, Adhesion properties,biomedical applications,bonding energy,dual network,conducting hydrogel, Adhesive properties, Adhesives, Biomedical applications, Biopolymers, Bonding energies, Bonding energy, Chemical bonds, Conducting hydrogels, Crosslinking, Dual network, Hydrogels, Medical applications, Methylenebisacrylamide, Poly(acrylic acid), Porcine skin, Property, Rational design,film, Sodium alginate

Ruano, G, Iribarren, JI, Pérez-Madrigal, MM, Torras, J, Alemán, C, (2021). Electrical and capacitive response of hydrogel solid-like electrolytes for supercapacitors Polymers 13, 1337

Flexible hydrogels are attracting significant interest as solid-like electrolytes for energy storage devices, especially for supercapacitors, because of their lightweight and anti-deformation features. Here, we present a comparative study of four ionic conductive hydrogels derived from biopolymers and doped with 0.1 M NaCl. More specifically, such hydrogels are constituted by κcarrageenan (κC), carboxymethyl cellulose (CMC), poly-γ-glutamic acid (PGGA) or a phenylalaninecontaining polyesteramide (PEA). After examining the morphology and the swelling ratio of the four hydrogels, which varies between 483% and 2356%, their electrical and capacitive behaviors were examined using electrochemical impedance spectroscopy. Measurements were conducted on devices where a hydrogel film was sandwiched between two identical poly(3,4-ethylenedioxythiophene) electrodes. The bulk conductivity of the prepared doped hydrogels is 76, 48, 36 and 34 mS/cm for PEA, PGGA, κC and CMC, respectively. Overall, the polyesteramide hydrogel exhibits the most adequate properties (i.e., low electrical resistance and high capacitance) to be used as semi-solid electrolyte for supercapacitors, which has been attributed to its distinctive structure based on the homogeneous and abundant distribution of both micro-and nanopores. Indeed, the morphology of the polyestermide hydrogel reduces the hydrogel resistance, enhances the transport of ions, and results in a better interfacial contact between the electrodes and solid electrolyte. The correlation between the supercapacitor performance and the hydrogel porous morphology is presented as an important design feature for the next generation of light and flexible energy storage devices for wearable electronics.

JTD Keywords: biopolymers, electrochemical impedance spectroscopy, flexible hydrogels, supercapacitor, Biopolymers, Electrochemical impedance spectroscopy, Flexible hydrogels, Supercapacitor

Chen, Tianchi, Callan-Jones, Andrew, Fedorov, Eduard, Ravasio, Andrea, Brugués, Agustí, Ong, Hui Ting, Toyama, Yusuke, Low, Boon Chuan, Trepat, Xavier, Shemesh, Tom, Voituriez, Raphaël, Ladoux, Benoît, (2019). Large-scale curvature sensing by directional actin flow drives cellular migration mode switching Nature Physics 15, (4), 393-402

Cell migration over heterogeneous substrates during wound healing or morphogenetic processes leads to shape changes driven by different organizations of the actin cytoskeleton and by functional changes including lamellipodial protrusions and contractile actin cables. Cells distinguish between cell-sized positive and negative curvatures in their physical environment by forming protrusions at positive curvatures and actin cables at negative curvatures; however, the cellular mechanisms remain unclear. Here, we report that concave edges promote polarized actin structures with actin flow directed towards the cell edge, in contrast to well-documented retrograde flow at convex edges. Anterograde flow and contractility induce a tension anisotropy gradient. A polarized actin network is formed, accompanied by a local polymerization–depolymerization gradient, together with leading-edge contractile actin cables in the front. These cables extend onto non-adherent regions while still maintaining contact with the substrate through focal adhesions. The contraction and dynamic reorganization of this actin structure allows forward movements enabling cell migration over non-adherent regions on the substrate. These versatile functional structures may help cells sense and navigate their environment by adapting to external geometric and mechanical cues.

JTD Keywords: Biopolymers in vivo, Cellular motility