Nanocubic cobalt-containing Prussian blue analogue-derived carbon-coated CoFe alloy nanoparticles for noninvasive uric acid sensing.

This work describes an electrochemical sensor for the fast noninvasive detection of uric acid (UA) in saliva. The sensing material was based on a cobalt-containing Prussian blue analogue (Na 2- x Co[Fe(CN) 6 ] 1- y , PCF). By optimizing the ratio of Co and Fe as 1.5 : 1 in PCF (PCF 1.5,0 ), particles with a regular nanocubic morphology were formed. The calcination of PCF 1.5,0 produced a carbon-coated CoFe alloy (CCF 1.5 ), which possessed abundant defects and achieved an excellent electrochemical performance. Subsequently, CCF 1.5 was modified on a screen-printed carbon electrode (SPCE) to fabricate the electrochemical sensor, CCF 1.5 /SPCE, which showed a sensitive and selective response toward salivary UA owing to its good conductivity, sufficient surface active sites and efficient catalytic activity. The determination of UA in artificial saliva achieved the wide linear range of 40 nM-30 μM and the low limit of detection (LOD) of 15.3 nM (3 σ / s of 3). The performances of the sensor including its reproducibility, stability and selectivity were estimated to be satisfactory. The content of UA in human saliva was determined and the recovery was in the range of 98-107% and the total RSD was 4.14%. The results confirmed the reliability of CCF 1.5 /SPCE for application in noninvasive detection.