writer：Tuanwei Liu, Dongwei Zhang, Xinlin Yang*, and Chenxi Li
keywords：Nitric oxide; N-diazeniumdiolate polymer microsphere; NO release nanoparticles.
source：期刊
specific source：Polymer Chemistry 6 (9), 1512-1520 (2015). DOI: 10.1039/C4PY01326C
Issue time：2015年

This paper reports the design, preparation and characterization of functional polymer microsphere as a reservoir for nitric oxide (NO)-release. Silica/polymer core-shell microspheres and the corresponding hollow functional polymer microspheres with secondary amino groups were converted to N-diazeniumdiolate as scaffolds for nitrogen oxide (NO) release. The silica/polymer core-shell microspheres were prepared by a multi-step procedure, which involves synthesis of functional 2-(ethyl(boc)amino)ethyl methacrylate (bocAmEMA) monomers with boc-protected secondary amine sites, distillation precipitation polymerization of ethyleneglycol dimethacrylate and boc-protected co-monomers with presence of 3-(methacryloxy)propyltrimethoxysilane (MPS)-modified silica nanoparticles as seeds, de-protection of the amino sites, and subsequent reaction between the secondary amino and NO under high pressure (5.0 atm) in presence of sodium methoxide. The corresponding hollow polymer microspheres are prepared via the selective removal of silica core from silica/polymer core-shell microspheres with hydrofluoride (HF) aqueous solution and the subsequent conversion to N-diazeniumdiolate NO donors via exposure to high pressure of NO (5.0 atm) under basic condition. The hollow microspheres with secondary amino groups exhibited a high storage capacity for NO (up to 5.5 mmol NO/mg), greatly increasing that of NO from the corresponding silica/polymer core-shell donors (3.6 mmol NO/mg). Both the silica/polymer and hollow polymer scaffolds are shown to release NO for extended periods of time with an ‘apparent’ t_1/2 value of 35 min (silica/polymer scaffolds; PBS buffer), 10 min (hollow polymer scaffolds; PBS buffer), 19 min (hollow polymer scaffolds; bovine serum), and release durations of 15 h via the proton initiated diazeniumdiolate decomposition to give off NO spontaneously under physiological conditions.