Water-Soluble Nitric Oxide-Releasing Gold Nanoparticles

• Published in: Langmuir Vol. 23; no. 9; pp. 4938 - 4943
• Main Authors: Polizzi, Mark A, Stasko, Nathan A, Schoenfisch, Mark H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 24-04-2007
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Gold - chemistry; Molecular Structure; Nanoparticles - chemistry; Nitric Oxide - chemistry; Particle Size; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Polyamines - chemical synthesis; Polyamines - chemistry; Solubility; Surface Properties; Time Factors; Tiopronin - chemistry; Water - chemistry; Water; Monolayer; Structure function; Gold; Polyamine; Stability; Nanoparticle; Solubility; Thermogravimetry; Transition metal; Decomposition; Characterization; Amine; Transmission electron microscopy; Storage; Synthesis; Storage capacity; Nitric oxide; Proton; pH; Nuclear magnetic resonance; Release; Ultraviolet visible spectrometry
• DOI: 10.1021/la0633841
• EISSN: 1520-5827
• ISSN: 0743-7463

The synthesis and characterization of water-soluble nitric oxide (NO)-releasing monolayer-protected gold clusters (MPCs) are reported. Tiopronin-protected MPCs (∼3 nm) were functionalized with amine ligands and subsequently exposed to 5 atm of NO to form diazeniumdiolate NO donors covalently bound to the gold MPC. Diazeniumdiolate formation conditions, NO-release, and nanoparticle stability were examined as a function of the structure of the protecting ligand, pH, and storage time. Despite their aqueous solubility, proton-initiated decomposition of the diazeniumdiolate-modified Tio-MPCs resulted in only modest NO-release (<0.023 μmol/mg) for short durations (<1.5 h). To increase the NO storage capacity of gold nanoparticles, polyamine-stabilized MPCs (∼5 nm) were synthesized with significantly enhanced NO-release properties (0.386 μmol/mg) and durations (up to 16 h). Transmission electron microscopy, thermogravimetric analysis, nuclear magnetic resonance spectroscopy, elemental analysis, and UV−vis spectroscopy were used to characterize both nanoparticle systems before and after NO exposure. The MPCs represent the smallest water-soluble NO-release nanoparticles to date (3−5 nm).