Creatinine Biosensor Based on Reductive H2O2 Detection Using Pentacyanoferrate-bound Polymer

Creatinine is the final product of creatine metabolism in muscle of mammals, and mainly filtered out of blood in kidneys. The creatinine levels are related to the state of renal function, thyroid malfunction and muscular disorders. This indicates the importance of creatinine measurements in blood or urine. The current clinical determination of creatinine is based on Jaffe reaction [1]. However, it is affected by other metabolites found in biological samples. To increase specificity, creatinine amidohydrolase (CNH), creatine amidohydrolase (CRH) and sarcosine oxidase (SAO) have been utilized for creatinine determination based on the detection of produced H2O2 [2]. Mediator has also been utilized in biosensing method to regenerate oxidized SAO for higher signal response and lower operating potential [3]. Nevertheless, O2 needs to be removed to avoid the competition with the mediator, which is difficult and not applicable. On the other hand, mediated biosensors coupled with peroxidase (POD) allow the determination of H2O2 at low operating potential around 0 V vs. Ag|AgCl, with high sensitivity and stability [4]. In this study, pentacyanoferrate-bound poly (1vinylimidazole) polymer (PVI[Fe(CN)5]) [5] is selected as a suitable mediator between POD and an electrode, since PVI[Fe(CN)5] doesn’t react with reactants (e.g. sarcosine) and SAO as an electron acceptor. Three enzymes, POD and PVI[Fe(CN)5] were crosslinked with poly (ethylene glycol) diglycidyl ether (PEGDGE) on a glassy carbon (GC) electrode for a creatinine biosensor fabrication. Reductive current was observed at −0.1 V in the presence of creatinine and O2. Composition of PVI[Fe(CN)5], PEGDGE and enzymes were optimized towards detection of creatinine. Effects of interference were also studied.