Reaction-Based Turn-on Electrochemiluminescent Sensor with a Ruthenium(II) Complex for Selective Detection of Extracellular Hydrogen Sulfide in Rat Brain

Abstract

Hydrogen sulfide (H2S) has been drawing increasing attention because it plays an important role in the nervous system and has been deemed as a third endogenous gas signal molecule besides nitric oxide (NO) and carbon monoxide (CO). In this study, using a ruthenium complex, [Ru(bpy)2(bpy-DPA)Cu](4+) (where bpy = 2,2'-bipyridine and bpy-DPA = 4-methyl-4'-[N,N-bis(2-picolyl)aminomethylene]-2,2'-bipyridine) as recognition unit, we report a new reaction-based turn-on electrochemiluminescent (ECL) sensor to selectively detect extracellular H2S in rat brain, coupled with in vivo microdialysis for dialysate sampling. To prepare the sensor for sensing endogenous H2S, [Ru(bpy)2(bpy-DPA)](2+) is first designed and synthesized, showing high ECL efficiency with tri-n-propylamine (TPA) as a coreactant and quenching after reaction with Cu(2+) (forming [Ru(bpy)2(bpy-DPA)Cu](4+)). Then a Nafion membrane is coated on the surface of glassy carbon (GC) electrode and [Ru(bpy)2(bpy-DPA)Cu](4+) is confined onto the Nafion membrane through ion exchange. The resulting [Ru(bpy)2(bpy-DPA)Cu](4+)/Nafion/GC sensor exhibits a low ECL signal. The [Ru(bpy)2(bpy-DPA)Cu](4+)/Nafion/GC sensor demonstrates enhanced ECL signal after reacting with volatile H2S due to the high-affinity binding between sulfur and Cu(2+), returning to [Ru(bpy)2(bpy-DPA)](2+)/Nafion/GC. The changes of ECL signal at the sensor depend linearly on the concentration of Na2S in the range from 0.5 to 10 μM, with a detection limit of 0.25 μM. Moreover, the sensor demonstrates high selectivity, free from interference especially by other nonvolatile thiol-containing species, such as cysteine and glutathione. The basal dialysate level of H2S in the microdialysate from the cortex of adult male Sprague-Dawley rats is determined to be 2.3 ± 0.9 μM (n = 4). This method is reliable and is envisaged to help understand the regulation of H2S in physiological and pathological events.

Long Term Amperometric Recordings in the Brain Extracellular Fluid of Freely Moving Immunocompromised NOD SCID Mice

“…The NO sensors demonstrated negligible responses (<1%) from most of the interfering species including ascorbic acid, serotonin, DOPAC, dopamine, l -gluthathione, hydrogen peroxide, 5-HIAA, homovanillic acid, nitrite and uric acid. Further selectivity studies were undertaken against more recent identified interferents including the electroactive gasotransmitters CO and H 2 S. Concentrations representative of their physiological levels were chosen [23,24]. A comparable selectivity over H 2 S (<1%, 1.6 ± 0.1 pA·µM −1 , n = 4) and a slightly higher contribution from CO (ca.…”

Au/AgI Dimeric Nanoparticles for Highly Selective and Sensitive Colorimetric Detection of Hydrogen Sulfide

“…Therefore, it is highly desirable to develop a sensitive and selective method allowing for real‐time and on‐the‐spot detection of sulfide in a simple and fast way. Conventional methods for sulfide detection include fluorescence spectrometry, electrochemistry, chromatography, chemiluminescence, etc. Although these methods are robust and sensitive, most of them are not suited for real‐time and on‐the‐spot analysis because they require sophisticated instrumentation and well‐trained operators.…”

A Benzooxazole‐Based Probe for the Sensitive Detection of Hydrogen Sulfide: Kinetic and Transition‐State Studies and In Vitro Application in HepG2 Cells

“…In recent times, numerous fluorescent probes have been developed for highly specific and sensitive in‐vivo imaging and in‐vitro detection of H 2 S in biological systems . These probes are normally designed on the basis of H 2 S‐persuaded highly specific reactions, like (i) reduction of azide and nitroso groups to amine,, (ii) thiolysis of dinitrophenyl ether or other leaving groups,, (iii) metal sulfide precipitation,, (iv) nucleophilic 1,4‐addition i. e., Michael‐type addition,, (v) a coordinative‐based approach, and (vi) cleavage of an S–O bond,, which are moderately slow and irreversible …”