Detection of trace concentrations of S-nitrosothiols by means of a capacitive sensor

Abstract

Small molecule S-nitrosothiols are a class of endogenous chemicals in the body, which have been implicated in a variety of biological functions. However, the labile nature of NO and the limits of current detection assays have made studying these molecules difficult. Here we present a method for detecting trace concentrations of S-nitrosothiols in biological fluids. Capacitive sensors when coupled to a semiconducting material represent a method for detecting trace quantities of a chemical in complex solutions. We have taken advantage of the semiconducting and chemical properties of polydopamine to construct a capacitive sensor and associated method of use, which specifically senses S-nitrosothiols in complex biological solutions.

Voltage-gated potassium channel proteins and stereoselective S-nitroso-l-cysteine signaling

“…Several previous studies have demonstrated the presence of GSNO and NO-modified proteins, but the GSNO catabolic product L-CSNO is somewhat elusive because of its lability ( 17 , 32 ). We have recently developed a sensor ( 33 ) that can be adapted to be specific for L-CSNO through coupling with an anti–L-CSNO antibody ( 34 , 35 ). Negative controls for this sensor included S -nitrosocysteamine, GSNO, l -cysteine, and S -nitrosoalbumin ( Supplemental Figure 8 ).…”

“…The reference electrode was another insulated carbon fiber coated with polydopamine treated with pH 8.2 Tris buffer, but without antibody. The bath was charged by applying a potential step to the Ag/AgCl pellet, and the response to each electrode was recorded (33). The maximum response current from the sensing electrode is dependent upon the fraction of anti-L-CSNO antibodies binding L-CSNO.…”

“…We use a sensitive L-CSNO sensor as previously published ( 33 ). The tip of insulated carbon fiber electrodes (ALA id CFE-2; NPI Electronics) was coated with a thin layer of polydopamine ( 33 – 35 ). Before passivation, polydopamine is an electrophile, and nucleophiles will covalently bind to it.…”

d-Cystine di(m)ethyl ester reverses the deleterious effects of morphine on ventilation and arterial blood gas chemistry while promoting antinociception

“…In addition, the lack of effect of the powerful reducing agent l -NACme 21 on morphine-induced respiratory depression would tentatively argue that the effects of d -cystine diEE and d -cystine diME are not simply due to the breakdown of the disulfide esters into the monothiol (reduced) forms, which then exert their intracellular actions as reducing agents. We have established methods to determine the pharmacokinetic profile of d -cystine diME in dog plasma 64 and developed an ultra-sensitive method to detect trace concentrations of S-nitrosothiols by means of a capacitive sensor 65 . It will be of considerable interest to see whether the pharmacokinetics of d -cystine diEE and d -cystine diME are altered meaningfully by opioids and whether thiolesters generate and/or are converted to S-nitrosothiols.…”

D-Cystine di(m)ethyl Ester Reverses the Deleterious Effects of Morphine on Ventilation and Arterial Blood Gas Chemistry While Promoting Analgesia

“…We have established methods to determine the pharmacokinetic pro le of D-cystine diME in dog plasma 66 and developed an ultra-sensitive method to detect trace concentrations of S-nitrosothiols by means of a capacitive sensor. 67 It will be of considerable interest to see whether the pharmacokinetics of D-cystine diEE and D-cystine diME are altered meaningfully by opioids and whether the thiolesters indeed generate and/or are converted to S-nitrosothiols.…”