Highly specific and sensitive quantification of uric acid in sweat using a dual boron-doped diamond electrode

Boron-doped diamond (BDD) microsensors feature exceptional advantages such as long-term stability, excellent antifouling properties, and ultra-low background currents, considered the ideal biosensors for non-enzymatic quantification of analytes. Herein, we reported, for the first time, the use of dual BDD electrode metallic BDD films on BDD microparticles) for enzyme-free detection of uric acid in complicated sweat environments. The BDDME with a dimension of 450 μm exhibited a fast electron transfer kinetic constant of 1.68 × 10 −2 cm s −1 towards K 3 [Fe (CN) 6 ] and K 4 [Fe (CN) 6 ] and a large electrochemically active surface area of 0.13 mm 2 , larger than the real geometric surface area. The voltammetric response currents of uric acid in sweat environments followed a good linear relation with increasing concentrations in the range of 5 μM - 500 μM, along with a detection sensitivity of 16.02 μA μM −1 cm −2 and a detection limit of 0.77 μM. In addition, the BDDME is capable of achieving highly specific quantification of uric acid in the presence of diverse interference agents such as glucose, urea, and tyrosine. In addition, the BDDME showed long-term stability with 4.6 % fluctuations in the response current during repetitive tests for 360 days and could be fully activated by rinsing with water despite the possible adsorption fouling of urine and bovine serum albumin during tests. This work demonstrated the feasibility of long-term detection of sweat uric acid using a non-enzymatic way and provides a solution for the long-term management of gout and other diseases.