Nanocomposite hyaluronic acid-based hydrogel for the treatment of esophageal fistulas.

Fistulas are abnormal connections between two body parts that can impair the quality of life. The use of biological glues represents the least invasive procedure to fill the fistula; however, it is limited by the need of multiple injections, the persistence of infection and the failure in the treatment of high-output fistulas. We describe herein the use of an injectable nanocomposite hydrogel that is able to form in situ a tissue-mimicking matrix as an innovative material for the treatment of esophageal fistulas. Injectable hydrogels that have the dual advantage of being implantable with a minimally invasive approach and of adapting their shape to the target cavity, while the introduction of mesoporous silica nanoparticles opens the possibility of drug/biomolecules delivery. The hydrogel is based on hyaluronic acid (HA), the crosslinking process occurs at physiological conditions leading to a hydrogel made of >96% by water and with a large-pore micro-architecture. The kinetic profile of the hydrogel formation is studied as a function of HA molecular weight and concentration with the aim of designing a material that is easily injectable with an endoscopic needle, is formed in a time compatible with the surgical procedure and has final mechanical properties suitable for cell proliferation. The in vivo experiments (porcine model) on esophageal-cutaneous fistulas, showed improved healing in the animals treated with the hydrogel compared with the control group.

Application of a novel material in the inguinal region using a totally percutaneous approach in an animal model: a new potential technique?

PURPOSE: To evaluate the feasibility and safety of a new percutaneous image-guided surgery technique to simulate a hernia repair using hydrogel. MATERIALS AND METHODS: A comparative prospective study was conducted in animals, with survival. Five pigs without any hernias were used. A hydrogel was injected at a site corresponding to the preperitoneal inguinal region. This procedure was performed bilaterally. An image-guided needle (ultrasound and computed tomography) was used, through which the material was injected. After survival, the local and systemic inflammatory reaction generated by the new material, was studied. RESULTS: All animals survived the procedure. No hemorrhagic or infectious complications were reported. The solidification of the material occurred as expected. In eight out of ten cases, the material was found in the planned site. No systemic inflammatory reaction secondary to the administration of hydrogel was reported. The adhesion of the material to surrounding tissues was satisfactory. CONCLUSION: The introduction of a liquid material which solidifies after injection in a short time (hydrogel) using a needle is feasible. The combined CT-scan and US image guidance allows for the percutaneous placement of the needle in the required location. The introduced hydrogel remains in this space, corresponding to the inguinal region, without moving. The placed hydrogel compresses the posterior wall composed of the transversalis fascia, supporting the potential use of hydrogel for hernia defects.

Electroluminescent device with reversible switching between red and green emission.

Research on new materials for organic electroluminescence has recently focused strongly on phosphorescent emitters, with the aim of increasing the emission efficiency and stability. Here we report the fabrication of a simple electroluminescent device, based on a semiconducting polymer combined with a phosphorescent complex, that shows fully reversible voltage-dependent switching between green and red light emission. The active material is made of a polyphenylenevinylene (PPV) derivative molecularly doped with a homogeneously dispersed dinuclear ruthenium complex, which fulfils the dual roles of triplet emitter and electron transfer mediator. At forward bias (+4 V), the excited state of the ruthenium compound is populated, and the characteristic red emission of the complex is observed. On reversing the bias (-4 V), the lowest excited singlet state of the polymer host is populated, with subsequent emission of green light. The mechanism for the formation of the excited state of the PPV derivative involves the ruthenium dinuclear complex in a stepwise electron transfer process that finally leads to efficient charge recombination reaction on the polymer.