Amperometric Nitrosothiol Sensor Using Immobilized Organoditelluride Species as Selective Catalytic Layer

A new amperometric sensor capable of responding to various biological S-nitrosothiol species (RSNOs) is described. The sensor is prepared using an organoditelluride-tethered poly(allyamine hydrochloride) (PAH) polymer crosslinked within a dialysis membrane support mounted at the distal surface of an amperometric NO probe. The surface immobilized organoditelluride layer serves as a selective catalyst to decompose various RSNO species to NO in the presence of a thiol reducing agent added to the sample. The proposed sensor responds directly and reversibly to various low molecular weight (LMW) RSNOs in the range of 0.1 mM to 10 mM with nearly equal sensitivity. The main advantage of this sensor over previously reported Cu(II/I) and organodiselenium-based RSNO sensors is its long operational life-time (at least one month). A discussion regarding solution phase transnitrosation reactions potentially allowing the measurement of higher molecular weight S-nitrosoproteins is provided, along with data showing preliminary results in this direction. Further, the direct detection of endogenous RSNO species in diluted fresh whole sheep blood is also demonstrated using this new sensor.