Publications

The present work focuses on the computational study of the structural micro-organization of hydrogels based on collagen-like peptides (CLPs) in complex with Rose Bengal (RB). In previous studies, these hydrogels computationally and experimentally demonstrated that when RB was activated by green light, it could generate forms of stable crosslinked structures capable of regenerating biological tissues such as the skin and cornea. Here, we focus on the structural and atomic interactions of two collagen-like peptides (collagen-like peptide I (CLPI), and collagen-like peptide II, (CLPII)) in the presence and absence of RB, highlighting the acquired three-dimensional organization and going deep into the stabilization effect caused by the dye. Our results suggest that the dye could generate a ternary ground-state complex between collagen-like peptide fibers, specifically with positively charged amino acids (Lys in CLPI and Arg in CLPII), thus stabilizing ordered three-dimensional structures. The discoveries generated in this study provide the structural and atomic bases for the subsequent rational development of new synthetic peptides with improved characteristics for applications in the regeneration of biological tissues during photochemical tissue bonding therapies.

JTD Keywords: collagen-like peptide, crosslinking, molecular dynamics, qm/mm simulations, rose bengal, Anastomosis, Collagen-like peptide, Crosslinking, Green light, Mm simulations, Molecular dynamics, Molecular-dynamics, Photochemical tissue bonding therapies, Qm, Rose bengal

An array with all-solid-state, potentiometric, miniaturized sensors for pH and potassium was developed to be introduced into the stomach or other sectors of the digestive tract by means of flexible endoscopy. These sensors perform continuous and simultaneous measurement of extracellular pH and potassium. This detection seeks to sense ischemia in the gastric mucosa inside the stomach, an event indicative of local microvascular perfusion and tissue oxygenation status. Our array is proposed as a medical tool to identify the occurrence of the ischemia after gastrointestinal or gastroesophageal anastomosis. The stability and feasibility of the miniaturized working and reference electrodes integrated in the array were studied under in vitro conditions, and the behavior of the potassium and pH ion-selective membranes were optimized to work under acidic gastric conditions with high concentrations of HCl. The array was tested in vivo in pigs to measure the ischemia produced by clamping the blood flow into the stomach. Our results indicate that ischemic and reperfusion states can be sensed in vivo and that information on tissue damage can be collected by this sensor array. The device described here provides a miniaturized, inexpensive, and mass producible sensor array for detecting local ischemia caused by unfavorable anastomotic perfusion and will thus contribute to preventing anastomotic leakage and failure caused by tissue necrosis.

JTD Keywords: Endoscopy, Surgery, Tissue, Gastric anastomosis, Gastric conditions, Ion selective sensors, Ischemia, pH detection, Reference electrodes, Simultaneous measurement, Tissue oxygenation, Sensors

It is about 20 years that tubular nerve guides have been introduced into clinical practice as a reliable alternative to autograft, in gaps not-longer-than 20 mm, bringing the advantage of avoiding donor site sacrifice and morbidity. There are limitations in the application of tubular guides. First, tubular structure in itself makes surgical implantation difficult; second, stitch sutures required to secure the guide may represent a site of unfavorable fibroblastic reaction; third, maximum length and diameter of the guide correlate with the occurrence of a poorer central vascularization of regenerated nerve. We report on the in vivo testing of a new concept of nerve-guide (named NeuroBox) which is double-halved, not-degradable, rigid, and does not require any stitch to be held in place, employing acrylate glue instead. Five male Wistar rats had the new guide implanted in a 4-mm sciatic nerve defect; two guides incorporated a surface constituted of microtrenches aligned longitudinally. Further five rats had the 4-mm gap left without repair. Contralateral intact nerves were used as controls. After 2 months, nerve regeneration occurred in all animals treated by the NeuroBox; fine blood vessels were well represented. There was no regeneration in the un-treated animals. Even if the limited number of animals does not allow to draw definitive conclusions, some result can be highlighted: an easy surgical technique was associated with the box-shaped guide and acrylate glue was easily applied; an adequate intraneural vascularization was found concurrently with the regeneration of the nerve and no adverse fibroblastic proliferation was present.

JTD Keywords: Peripheral-nerve, Polyglycolic acid, Guidance cues, Collagen tube, Median nerve, Repair, Growth, Cyanoacrylate, Complications, Anastomosis