A reagentless amperometric biosensor for creatinine assay based on recombinant creatinine deiminase and N-methylhydantoin-sensitive CoCu nanocomposite

Creatinine is a very important biomarker for the diagnostics of kidney disease and the evaluation of the efficiency of the treatment process and hemodialysis. The most utilised enzyme-based biosensors for creatinine assay are based on the detection of ammonia as a product of the creatinine deiminase (CDI)-catalysed reaction, but there are limited data on the monitoring of another CDI reaction product – N-methylhydantoin (NMH). The main drawback of the creatinine-selective biosensors which have been constructed to dateis a high negative working potential that is problematic for the monitoring of creatinine in biological liquids. An amperometric CDI-based biosensor for the direct measurement of creatinine, which works at low potentials due to using electrocatalytic nanocomposites is described in this paper. To choose the best chemosensor on NMH, hybrid CoCu nanoparticles were selected for the development of CDI-based amperometric biosensors. The structure and mechanism of the produced nCoCu–NMH complex on the electrode surface were also elucidated. The novel biosensor exhibited sufficient sensitivity (195 A⋅M−1⋅m−2 for creatinine), a broad linear range (10–800 µM), a low limit of detection (0.5 µM) and excellent selectivity towards the target analyte. The designed bioelectrode was used for estimation of creatinine in biological fluids. •Novel nCoCu as a N-methylhydantoin-sensing element was used for creatinine assay.•Recombinant creatinine deiminase was exploited as a creatinine-selective enzyme.•The structure of the complex nCoCu+–N-methylhydantoin was proposed.•Selective detection of creatinine in biological liquids was demonstrated.