Biomedical subjects

Mark E Meyerhoff

Publications and source records attributed to Mark E Meyerhoff.

39 records · Page 3Linked to original sources

PubMed2002

Nitric oxide releasing silicone rubbers with improved blood compatibility: preparation, characterization, and in vivo evaluation.

Nitric oxide (NO) releasing silicone rubbers (SR) are prepared via a three-step reaction scheme. A diamino triaminoalkyltrimethoxysilane crosslinker is used to vulcanize hydroxyl terminated polydimethylsiloxane (PDMS) in the presence of ambient moisture and a dibutyltin dilaurate catalyst so that the respective diamine triamine groups are covalently linked to the cured SR structure. These amine sites are then diazeniumdiolated, in situ, when the cured SR is reacted with NO at elevated pressure (80 psi). Although nitrite species are also formed during the NO addition reaction, in most cases the diazeniumdiolated polymer is the major product within the final SR matrix. Temperature appears to be the major driving force for the dissociation of the attached diazeniumdiolate moieties, whereas the presence of bulk water bathing the SR materials has only minimal effect on the observed NO release rate owing to the low water uptake of the SR matrices. The resulting SR films/coatings release NO at ambient or physiological temperature for up to 20 d with average fluxes of at least 4 x 10(10) mol x cm(-2) x min(-1) (coating thickness > or = 600 microm) over first 4 h, comparable to the NO fluxes observed from stimulated human endothelial cells. The NO loading and concomitant NO release flux of the SR material are readily adjustable by altering the diamine triamine loading and film/coating thickness. The new NO releasing SR materials are shown to exhibit improved thromboresistance in vivo, as demonstrated via reduced platelet activation on the surface of these polymers when used to coat the inner walls of SR tubings employed for extracorporeal circulation in a rabbit model.

Animals↗

PubMed2002

Implantable chemical sensors for real-time clinical monitoring: progress and challenges.

Recently, progress has been made in the development of implantable chemical sensors capable of real-time monitoring of clinically important species such as PO(2), PCO(2), pH, glucose and lactate. The need for developing truly biocompatible materials for sensor fabrication remains the most significant challenge for achieving robust and reliable sensors capable of monitoring the real-time physiological status of patients.

Animals↗

PubMedDate not supplied

Polymethacrylate-based nitric oxide donors with pendant N-diazeniumdiolated alkyldiamine moieties: synthesis, characterization, and preparation of nitric oxide releasing polymeric coatings.

A series of new nitric oxide (NO) releasing copolymers have been prepared by covalently anchoring alkyldiamine side chains onto a polymethacrylate-based polymer backbone, followed by NO addition to form the desired pendant diazeniumdiolate structures. The resulting diazeniumdiolated copolymers were characterized via UV spectroscopy, and their proton-driven decomposition to release NO was also examined by UV and FTIR as well as chemiluminescence. Polymers with up to 22.1 mol % of incorporated amine sites that can be converted to corresponding diazeniumdiolates could be prepared, and such polymers release up to 0.94 micromol/mg of NO. Further, novel NO releasing polymeric coatings were formulated by doping one of the new polymethacrylate-based NO donors within inert polymeric matrixes. Biodegradable poly(lactide-co-glycolide) was employed as a film additive to greatly prolong the NO release of such coatings by continuously generating protons within the organic phase of the polymeric films, thereby driving decomposition of the diazeniumdiolates.

Azo Compounds↗