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The in vitro analytical performance of fluorescence-based oxygen sensing polymeric films prepared with silicone rubbers that spontaneously release nitric oxide (NO) is examined. The use of NO-release polymers for fabricating functional optical sensors is proposed as a potential solution to lingering biocompatibility and concomitant performance problems encountered with prototype intravascular optical oxygen sensors. Plasticized silicone rubber films formulated with two distinct types of diazeniumdiolate NO donors release NO for more than 24 h. The optical oxygen sensing films prepared by doping these NO release polymeric materials with oxygen indicators (pyrene/ perylene donor/acceptor pair) display different analytical responses, as compared to controls without NO release capability. Nonlinear Stern--Volmer behavior is observed for single-layer NO release oxygen sensors owing to heterogeneous environments for the pyrene/perylene pair and a concomitant quenching of the fluorescence by excess amine sites in such films. In contrast, a dual-layer configuration using an underlying NO-release silicone rubber layer covered with a second polymeric layer containing the fluorescent indicators is shown to yield identical sensitivity and linearity toward oxygen as conventional non-NO-releasing oxygen sensing films, while still providing surface NO fluxes necessary to yield more thromboresistive devices.

The development and in vivo analytical performance of a nitric oxide (NO)-releasing amperometric oxygen sensor with greatly enhanced thromboresistivity are reported. Gas permeable coatings formulated with cross-linked silicone rubber (SR) containing NO-generating compounds (diazeniumdiolates) are shown to release NO for extended periods of time (> 20 h) while reducing platelet adhesion and activation. Oxygen-sensing catheters prepared by dip-coating the NO-releasing films over the outer SR tubes of the implantable devices display similar analytical response properties in vitro (sensitivity, selectivity, response times) when compared to analogous sensors prepared without the NO release coatings. Superior analytical accuracy (relative to blood PO(sub 2) values measured in vitro) and greatly reduced thrombus formation on the outer surface of the sensors are observed in vivo (in canine model) with the NO release PO(sub 2) sensors compared to control sensors (without NO release) implanted simultaneously within the same animals. Based on these preliminary studies, the use of NO release polymers to fabricate catheter-style chemical sensors may be a potential solution to lingering biocompatibility and concomitant performance problems encountered when attempting to employ such devices for continuous intravascular measurements of blood gases and electrolytes.

Research was conducted to examine the air stability of alkanethiol self-assembled monolayers on silver and gold surfaces. Methodologies used were X-ray photoelectron spectroscopy, electrochemistry and surface Raman spectroscopy. Experimental results indicate that ozone is the primary oxidant in ambient laboratory air which generates rapid oxidation of the thiolate moiety.

The prevalence of periodontal disease poses a significant global health burden. Treatments for these diseases, primarily focused on removal and eradication of dental plaque biofilms, are challenging due to limited access to periodontal pockets where these oral pathogens reside. Herein, we report on the development and characterization of nitric oxide (NO)‐releasing carboxymethylcellulose (CMC) derivatives and evaluate their in vitro bactericidal efficacy against planktonic Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, two prominent periodontopathogens. Bactericidal exposure assays revealed that three of the synthesized NO‐releasing polymers were capable of reducing bacterial viability of both species by 99.9% in 2 hr at concentrations of 4 mg ml−1 or lower, reflecting NO's potent and rapid bactericidal action. The NO‐releasing CMCs elicited minimal toxicity to human gingival fibroblasts at their bactericidal concentrations following 24‐hr exposure. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a new nitric oxide (NO)-releasing scaffold prepared from amine-functionalized silica nanoparticles through a one-pot sol-gel process are described. The results show that advantages of silica-derived NO storage/delivery systems have included the ability to store large qualities of NO, modulate NO release kinetics and readily tune particle size based on the composition of the particle.

The synthesis of ~2 nm NO-releasing gold nanoparticles is an important step toward the development of a NO-delivery system that bridges small-molecule diazeniumdiolates and diazeniumdiolate-modified fumed silica particles. Further functionalization of the nanoparticles with receptor molecules to enable specific antibody-antigen or ligand-receptor interactions may allow for the targeting of specific tissues or cells.