S-Nitrosothiol Detection via Amperometric Nitric Oxide Sensor with Surface Modified Hydrogel Layer Containing Immobilized Organoselenium Catalyst

Abstract

A novel electrochemical device for the direct detection of S-nitrosothiol species (RSNO) is proposed by modifying an amperometric nitric oxide (NO) gas sensor with thin hydrogel layer containing an immobilized organoselenium catalyst. The diselenide, 3,3'-dipropionicdiselenide, is covalently coupled to primary amine groups in polyethylenimine (PEI), which is further cross-linked to form a hydrogel layer on a dialysis membrane support. Such a polymer film containing the organoselenium moiety is capable of decomposing S-nitrosothiols to generate NO(g) at the distal tip of the NO sensor. Under optimized conditions, various RSNOs (e.g., nitrosocysteine (CysNO), nitrosoglutathione (GSNO), etc.) are reversibly detected at </=0.1 microM levels, with sensor lifetimes of at least 10 days. The presence of reducing agents (e.g., glutathione) added to the test solution enhances the amperometric dynamic range output to approximately 25 microM levels of RSNO species. Sensitivities observed for different small molecule RSNO species are nearly equivalent, in sharp contrast to the behavior observed previously for a similar RSNO sensing configuration based on an immobilized Cu(I/II) catalytic layer. It is further shown that the new RSNO sensors can be used to assess the "NO-generating" ability of fresh blood samples by effectively detecting the total level of reactive low molecular-weight RSNO species present in such samples.

Photoinstability of S-Nitrosothiols during Sampling of Whole Blood: A Likely Source of Error and Variability in S-Nitrosothiol Measurements

“…We recently developed a novel amperometric RSNO sensor that is based on the use of an immobilized organoselenium catalytic species at the surface of an electrochemical NO detector (9 ). This sensor was shown to respond nearly equally to all low molecular weight (LMW) RSNO species present in blood.…”

Nitric Oxide Sensors for Biological Applications

“…S-nitrosothiol (RSNO) is another upstream compound that is utilized to calculate NO concentration, since it is believed that RSNOs can act as reservoirs or carriers of NO within biological systems without altering NO's activity [52,68,69]. The Meyerhoff lab has shown the use of sensors that can reversibly detect RSNO within blood for a 10-day period, extending the timeframe for NO detection past most of the other sensor options [70]. The downside of this sensor is that it is detecting an upstream component of NO and not actual NO concentrations.…”

Polyurethane with tethered copper(II)–cyclen complex: Preparation, characterization and catalytic generation of nitric oxide from S-nitrosothiols

“…The reduced form of catalyst then reacts with endogenous RSNOs to liberate NO, and reverts the catalytic site to its original oxidized form. NOGPs have been shown to exhibit catalytic NO generation from endogenous RSNOs at physiological pH, in addition to the spontaneous NO production when in contact with fresh animal whole blood in vitro [16,19].…”