1,721,024 research outputs found
Perspectives on: PEO-PPO-PEO triblock copolymers and their biomedical applications
No full textThermo-reversible polymeric gels represent an interesting class of materials that can be tailored for a wide range of applications. The triblock poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) based systems, PEO-PPO-PEO, show thermoreversible gelation around body temperature and, therefore, are particularly suitable for biomedical applications such as drug delivery, gene therapy and tissue engineering. The PEO-PPO-PEO tri-block copolymers have amphiphilic characteristics and self-assemble into micelles to form a variety of close packed structures. By varying the block composition (PEO/PPO ratio) and the molecular weight, it is possible to tailor the final properties of these systems to meet the specific application needs. In this report the thermodynamic basis of micellization of PEO-PPO-PEO systems is described. The factors influencing the micelles formation are discussed along with the methods used to investigate the micellization process and morphology as well as with the main applications of these systems in biomedical fields
Additive effect of a novel Hyaluronic acid derivatives on synovial fluids viscoelasticity
No full textEvaluation of the additive effect of a novel Hyaluronic acid derivatives on synovial fluids viscoelastic properties
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Rheological Characterization of Hyaluronic Acid Derivatives as Injectable Materials Toward Nucleus Pulposus Regeneration
No full textNucleus pulposus (NP) is the soft center of the intervertebral disc (IVD), able to resist compressive loads, while the annulus fibrosus withstands tension and gives mechanical strength. NP function may be altered as consequence of several pathologies or injury and when a damaged IVD does not properly play its role. In the past years, a great effort has been devoted to the design of injectable systems as NP substitutes. The different synthetic- and natural hydrogel-based materials proposed, present many drawbacks and, in particular, they do not seem to mimic the required behavior. In the search for natural-based systems a dodecylamide of hyaluronic acid (HA), HYADD3®, has been proved as bioactive and suitable vehicle to carry cells for NP tissue engineering, while a crosslinked HA ester, HYAFF120® showed interesting results if used as injectable acellular material. Even though these derivatives showed appropriate biological behavior up to now, data on mechanical behavior of these derivatives are still missing. In this frame, the aim of this study was to provide a rheological characterization of these HA derivatives to asses their biomechanical compatibility with the NP tissue. To this, the rheological properties of these derivatives were studied through dynamic shear tests before and after injection through needles used in the current surgical procedure. Both HA derivatives showed a 'gel-like' rheological behavior similar to the native NP tissue and this behavior was not altered by injection
Viscoelasticity and gelling behaviour of thermosensitive hydrogel based on PEO-PPO copolymer and mucoadhesive agents
No full textRheological characterization of vocal fold after injection augmentation in a preliminary animal study
No full textThe investigation of vocal folds viscoelastic properties in an animal model (rabbit) after injection of various augmentation substances, 6 months after injection, is reported. The injected materials were: hyaluronan-based materials (Hylan B gel and Deflux®), cross-linked collagen (Zyplast®) and polytetrafluoroethylene (Teflon®). Rheological properties of the augmentation substances were also evaluated. The results from these animal experiments indicate that the viscoelastic properties of the vocal folds injected with Deflux®, Zyplast® and Hylan B gel are similar to the healthy vocal folds (non-injected samples) used as control, thus demonstrating that these materials are good candidates for further studies aimed at restoring/preserving the vibratory capacity of the vocal folds with injection treatment in glottal insufficiency
Ingegnerizzazione di Gel Mucoadesivi e Termosensibili per applicazioni al rilascio di farmaci per via oculare
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