Evaluation of the Oxo‐bridged Dinuclear Ruthenium Ammine Complex as Redox Mediator in an Electrochemical Biosensor

Abstract

[a] 1IntroductionTher edox properties of ruthenium polynuclear oxo-complex have been studied with special attention to the stability of the oxidation states of the metallic cation,a nd many studies are based on qualitative molecular orbital interaction schemes dp (metal) Àpp (ligand) [1][2][3][4].T hese polynuclear oxoc omplexes exhibit electront ransfer processes with multiple steps that result in ah igh stability in different oxidation states and the ability to exchange charges between metallic cations.N otably,awide rangeo fd inuclear ruthenium complexes have been chemically and/or electrochemically studied [5,6] [7,8] and Kanekos groups [ 9,10],r espectively.T hese complexes were investigated for their ability to catalyse water oxidation in an artificial photosynthetic system [11] and electrocatalytic processes [12].I na ddition, ruthenium dinuclear oxo-complexes can be used as artificial electron-transfer mediators in biosensors [13].H owever,t he ruthenium dinuclear 4 has not been studied to date as ar edox mediator in the development of glucoseb iosensors.Theu se of artificialr edox mediators allows the flow of electrons from the redox enzyme to the surface of the electrode center, decreasing redox potential and ideally preventing interference by electro-oxidizable species such as ascorbic acid, therefore,i ncreasing the selectivity and sensitivity of the (bio)sensor [14].T he determinationo f the optimal redox mediator for the production of ab iosensor is extremely important for its efficiency.Amediator should be selected that possesses alowerr edox potential than the othere lectrochemically active interfering compounds present in the sample.F urthermore,ahigh electrochemical constant is very desirable,which is important to ensure that the response of the biosensor is not limited by the kinetics of electrodes or by oxygen interference [15].A ni deal mediator is also characterized by reversible kinetics,ahigh chemical stabilityi nb oth reduced and oxidized forms and unreactivity with oxygen [13].T od ate,s everal transition-metalc omplexes such as iron [16][17][18],o smium [19,20] have been investigateda s redox mediators and are the most used, but ruthenium complexes can also be used, due to their higher reactivity with glucose oxidase (GOx) [13,21].This study describes the electrochemical performance of the oxo-bridged dinuclear ruthenium ammine [(bpy) 4 + incorporated into aN afion film coating ag lassy carbone lectrode that acts as an electron-transferm ediator for the development of glucoseb iosensors.T he electrochemical performance of the modified RuÀOÀRu/Nafion /GC electrodew as performed by cyclic voltammetry.T he electrocatalytic activity of the glucosebiosensor GOx/oxo-bridged dinuclear ruthenium ammine/Nafion /GC wasa lso studied.

Size Control of Carbon Spherical Shells for Sensitive Detection of Paracetamol in Sweat, Saliva, and Urine

“…Figure C shows the correlation between the results from the electroanalytical method proposed and the standard method (HPLC) with an intercept value of 3.1 × 10 –8 , a slope of 0.96, and product–moment correlation coefficient of 0.999, thus implying equivalence of the two techniques. The random errors lead to a deviation from the ideal case . In the Student’s t test , the value of 63.4 (higher than the t -critical value of 2.57 for 95% of significance for n = 10 (degrees of freedom = 8; α = 0.05)) showed no significant difference between the two techniques. ,,, Thus, the electroanalytical sensing performance was similar to the standard HPLC for paracetamol in sweat samples.…”

“…The amount of electroactive species (Γ /mol cm –2 ) was estimated using Γ = Q / nFA , , where Q (C) is the background-corrected electric charge, estimated by integrating the anodic peaks of Figure C; n is the number of electrons; F is the Faraday constant (96 485.34 C mol –1 ); and A is the surface geometric area (0.071 cm 2 ). Q was 1.72 × 10 –6 , 1.22 × 10 –6 , and 0.83 × 10 –6 C, and the estimated surface concentration was 1.26 × 10 –10 , 0.89 × 10 –10 , and 0.61 × 10 –10 mol cm –2 at the GC coated with CSS 400 nm , CSS 450 nm , or CSS 500 nm , respectively.…”

“…The random errors lead to a deviation from the ideal case. 35 In the Student's t test, the value of 63.4 (higher than the t-critical value of 2.57 for 95% of significance for n = 10 (degrees of freedom = 8; α = 0.05)) showed no significant difference between the two techniques. 29,35,41,42 Thus, the electroanalytical sensing performance was similar to the standard HPLC for paracetamol in sweat samples.…”