Ascorbic acid-triggered electrochemical–chemical–chemical redox cycling for design of enzyme-amplified electrochemical biosensors on self-assembled monolayer-covered gold electrodes

Photoelectrochemical-Chemical-Chemical Redox Cycling for Advanced Signal Amplification: Proof-of-Concept Toward Ultrasensitive Photoelectrochemical Bioanalysis

“…As shown in Figure b, the feasibility of the proposed PECCC RCA strategy was first investigated by the cyclic voltammogram (CV) behaviors of the ITO electrode in different tris buffer solutions. There was no redox peak of TCEP (curve a), and no obvious oxidation peak of AA was observed (curve b and Figure b inset), which agreed with the previous report . The FcA oxidation occurred at ∼0.540 V (curve c), which clearly indicated that the FcA was more easily oxidized than AA.…”

Electrochemical detection of amyloid-β oligomer with the signal amplification of alkaline phosphatase plus electrochemical–chemical–chemical redox cycling

“…FcM, AAP and TCEP were used as the redox mediator, enzyme substrate and reducing reagent, respectively. The keys to success for the ECC redox cycling are that [44,45] (1) FcM is stable in air and can be regenerated after its electro-oxidation by the ALP enzymatic products during the electrochemical scanning, (2) both AA and TCEP are not oxidized on the SAM-covered gold electrode in the potential scanning range, and (3) TCEP can facilitate the regeneration of AA from its oxidation product dehydroascorbic acid (DAA) at a fast rate, but shows no reaction with ferricinum ion (FcM + , the oxidation format of FcM). Moreover, AAP was chosen as the substrate from kinds of ALP substrates, which is due to its low cost, easy dissolution in aqueous solution, high formal potential and high signal-to-background ratio [44].…”

“…In the present work, cysteine-containing PrP(95-110) was immobilized on a gold electrode to capture AβO; then, alkaline phosphatase (ALP)-conjugated PrP(95-110) (denoted as ALP-PrP(95-110)) was used for the recognition of the captured AβO and the generation of electroactive species. Moreover, to improve the detection sensitivity of ALP-based biosensors, signal amplification based on an enzymatic reaction plus an "outersphere to inner-sphere" electrochemical-chemical-chemical (ECC) redox cycling reactions proposed by Yang and co-workers as well as our group are simple and particularly popular recently [41][42][43][44][45]. Such amplification method only requires the addition of a redox mediator to the electrolyte solution and does not change the detection procedure of conventional enzyme-based assays.…”

Dual-Quenching Electrochemiluminescence Strategy Based on Three-Dimensional Metal–Organic Frameworks for Ultrasensitive Detection of Amyloid-β

“…The Aβ monomers, oligomers (AβO), and fibrils (AβF) were prepared according to previous literatures. − Briefly, lyophilized Aβ peptide was dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol and sonicated for 10 min to form the monomers. Afterward, the resulting products were reconstituted in NaOH solution, diluted by PBS solution (pH 7.4), and incubated for 16 h at room temperature to form AβO.…”