Voltammetric determination of uric acid using a miniaturized platform based on screen-printed electrodes modified with platinum nanoparticles

• Disposable and sensitive SPCE based on PtNPs and MWCNT was designed to detect uric acid in biological fluids. • The approach has potential for POC analysis of urine samples. • Analysis developed with a miniaturized potentiostat coupled to a smartphone. Disposable and sensitive screen-printed carbon electrodes (SPCE) modified with multi-walled carbon nanotubes (MWCNT) and platinum nanoparticles (PtNPs) were constructed to analyse uric acid (UA) in biological samples using a miniaturized smartphone potentiostat system. Combining the nanomaterials with Nafion™ yielded a stable dispersion that could be successfully used as an electroactive layer. Transmission electron microscopy (TEM) and energy dispersive scanning (EDS) were used to characterize the morphology of PtNPs . These revealed approximately spherical shapes with emission lines characteristics of platinum. Furthermore, PtNPs/MWCNT/SPCE film was characterized by scanning electron microscopy (SEM), which demonstrated the tubular characteristic of MWCNT distributed and covered by carbon black (CB) spheres present in the screen-printed ink. An enhanced current response was observed for UA voltammetric analysis, especially due to the synergism effect of PtNPs and MWCNT , which reduced the R ct value. The values of D app (1.6 × 10 −6 cm 2 /s) and k cat (2.76 × 10 3 mol −1 L/s) were determined for UA using the proposed sensor. The sensor displayed linear response for UA in the range from 5.0 × 10 −6 mol/L to 6.9 × 10 −4 mol/L, with a detection limit of 4.9 × 10 −7 mol/L. Along with detectability, excellent performances were verified in terms of repeatability, anti-interference features, and analysis of UA in the biological samples.