title: 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.
authors.affiliation: Department of Chemistry, Renmin University of China , Beijing 100872, China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Yue
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Zhu
authors.forename: Meining
authors.initials: M
authors.lastname: Zhang
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Ye
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D000818:Animals; D001923:Brain Chemistry; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D005110:Extracellular Space / Q000737:chemistry*; D006862:Hydrogen Sulfide / Q000032:analysis*; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods*; D008297:Male; D009942:Organometallic Compounds / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D009942:Organometallic Compounds; C103599:bis(bipyridyl)ruthenium(II); D015082:2,2'-Dipyridyl; D006862:Hydrogen Sulfide