Fabrication of an improved amperometric creatinine biosensor based on enzymes nanoparticles bound to Au electrode

An improved amperometric creatinine biosensor was fabricated that dependent on covalent immobilisation of nanoparticles of creatininase (CANPs), creatinase (CINPs) and sarcosine oxidase (SOxNPs) onto gold electrode (AuE). The CANPs/CINPs/SOxNPs/AuE was characterised by scanning electron microscopy and cyclic voltammetry at various stages. The working electrode exhibited optimal response within 2 s at a potential of 0.6 V, against Ag/AgCl, pH 6.5 and 30 °C. A linear relationship was observed between creatinine concentration range, 0.1-200μM and biosensor response i.e. current in mA, under optimum conditions. Biosensor offered a low detection limit of 0.1 μM with long storage stability. Analytical recoveries of added creatinine in blood sera at 0.5 mM and at 1.0 mM concentrations, were 92.0% and 79.20% respectively. The precision i.e. within and between-batch coefficients of variation were 2.04% and 3.06% respectively. There was a good correlation (R² = 0.99) between level of creatinine in sera, as calculated by the colorimetric method and present electrode. The CANPs/CINPs/SOxNPs/Au electrode was reused 200 times during the period of 180 days, with just 10% loss in its initial activity, while being stored at 4 °C, when not in use.HighlightsPrepared and characterised creatininase (CA), creatinase (CI) sarcosine oxidase (SOx) nanoparticles and immobilised them onto gold electrode (AuE) for fabrication of an improved amperometric creatinine biosensor.The biosensor displayed a limit of detection (LOD) of 0.1 μM with a linear working range of 0.1 μM-200 μM.The biosensor was evaluated and applied to measure elevated creatinine levels in sera from whom suffering from kidney and muscular disorders.The working electrode retained 90% of its initial activity, while being stored dry at 4 ˚C for 180 days.