Hydrogel-tissue adhesion by particle bridging: sensitivity to interfacial wetting and tissue composition.

Solid particles placed at the interface between hydrogels and biological tissues can create an adhesive joint through the adsorption of macromolecules onto their surfaces. Here, we investigated how this adhesion by particle bridging depends on the wetting of tissue surfaces and on the heterogeneities in tissue composition. peeling experiments were performed using poly(ethylene glycol) films coated with aggregates of silica nanoparticles deposited on the internal tissues of porcine liver.

PEG-Based Photo-Cross-Linked Networks with Adjustable Topologies and Mechanical Properties.

We report the synthesis of networks having adjustable topologies and mechanical properties. Our approach consists of photopolymerizing poly(ethylene glycol) diacrylates (PEG-DA) in the presence of mixtures of mono- and multifunctional thiols. We show that the introduction of monothiols as non-cross-linking transfer agents provides a simple way to tune the topology of the networks and produce soft extensible networks.

Coatings of hydroxyapatite-bioactive glass microparticles for adhesion to biological tissues.

Adsorption of particles across interfaces has been proposed as a way to create adhesion between hydrogels and biological tissues. Here, we explore how this particle bridging approach can be applied to attach a soft polymer substrate to biological tissues, using bioresorbable and nanostructured hydroxyapatite-bioactive glass microparticles. For this, microparticles of aggregated flower-like hydroxyapatite and bioactive glass (HA-BG) were synthesized a bioinspired route.

A 3D Multi-Tissue Evolution Model Highlights the Relevance of Local Strain Accumulation in Bone Fracture Remodeling.

Since 5-10% of all bone fractures result in non-healing situations, a thorough understanding of the various bone fracture healing phases is necessary to propose adequate therapeutic strategies. models have greatly contributed to the understanding of the influence of mechanics on tissue formation and resorption during the soft and hard callus phases. However, the late-stage remodeling phase has not been investigated from a mechanobiological viewpoint so far.

Rational formulation design of injectable thermosensitive chitosan-based hydrogels for cell encapsulation and delivery.

This work reports a rational design of injectable thermosensitive chitosan systems for cell encapsulation and delivery. Using mixtures of two phosphate salts, beta-glycerophosphate and ammonium hydrogen phosphate, we demonstrate that the pH and the osmolarity can be adjusted separately by varying the molar ratios between the salts and the d-glucosamine monomers. We found the existence of a critical temperature above which gelation time decays following a power-law.

Hydrogel-Tissue Adhesion Using Blood Coagulation Induced by Silica Nanoparticle Coatings.

The fixation of hydrogels to biological tissues is a major challenge conditioning the development of implants and surgical techniques. Here, coatings of procoagulant nanoparticles are devised which use the presence of blood to create adhesion between hydrogels and soft internal organs. Those nanostructured coatings are simply adsorbed at the hydrogel surfaces and can rapidly activate the formation of an interfacial blood clot acting as an adhesive joint.

A clinical-grade acellular matrix for esophageal replacement.

In pathologies of the esophagus such as esophageal atresia, cancers, and caustic injuries, methods for full thickness esophageal replacement require the sacrifice of healthy intra-abdominal organs such as the stomach and the colon and are associated with high morbidity, mortality, and poor functional results. To overcome these problems, tissue engineering methods are developed to create a substitute with scaffolds and cells. The aim of this study was to develop a simple and safe decellularization process in order to obtain a clinical grade esophageal extracellular matrix.

Interfacial fluid transport is a key to hydrogel bioadhesion.

Attaching hydrogels to soft internal tissues is a key to the development of a number of biomedical devices. Nevertheless, the wet nature of hydrogels and tissues renders this adhesion most difficult to achieve and control. Here, we show that the transport of fluids across hydrogel-tissue interfaces plays a central role in adhesion.

In vivo evaluation of the bone integration of coated poly(vinyl-alcohol) hydrogel fiber implants.

Recently, it has been shown that constructs of poly(vinyl alcohol) (PVA) hydrogel fibers reproduce closely the tensile behavior of ligaments. However, the biological response to these systems has not been explored yet. Here, we report the first in vivo evaluation of these implants and focus on the integration in bone, using a rabbit model of bone tunnel healing.

Hydrogel films and coatings by swelling-induced gelation.

Hydrogel films used as membranes or coatings are essential components of devices interfaced with biological systems. Their design is greatly challenged by the need to find mild synthesis and processing conditions that preserve their biocompatibility and the integrity of encapsulated compounds. Here, we report an approach to produce hydrogel films spontaneously in aqueous polymer solutions.

Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite.

Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements.

Erasable and reversible wrinkling of halogenated rubber surfaces.

Few surfaces can exist at rest in either wrinkled or unwrinkled states and switch reversibly between these states. Here, we report a new approach to creating reversibly wrinkling systems using the halogenation of rubber to induce a local increase in the glass-transition temperature within a thin layer at the surface. Such systems are obtained by the bromination of molded rubber films.

Hydrogel fibers for ACL prosthesis: design and mechanical evaluation of PVA and PVA/UHMWPE fiber constructs.

Prosthetic devices for anterior cruciate ligament (ACL) reconstruction have been unsuccessful due to mechanical failure or chronic inflammation. Polymer hydrogels combine biocompatibility and unique low friction properties; however, their prior use for ligament reconstruction has been restricted to coatings due to insufficient tensile mechanics. Here, we investigate new constructs of polyvinyl alcohol (PVA) hydrogel fibers.