Non-enzymatic electrochemical sensor for uric acid based on surfactant-silica-MWCNT nanohybrids functionalized with APTES

Abstract

The CTAB@SiO 2 @MWCNT-APTES composite was synthesized and applied as a modifier for a glassy carbon electrode (GCE) for the electrochemical the determination of uric acid (UA). APTES was successfully immobilized on multi-walled carbon nanotubes (MWCNTs) through non-covalent hydrophobic interactions and formed a nanoscale network that enhanced electron transfer and access to the detection sites. All experimental parameters were optimized, and the modified sensor exhibited a linear detection range from 5 × 10⁻⁹ to 1 × 10⁻⁸ molL⁻¹ and from 1.25 × 10⁻⁸ to 1.0 × 10 -7 molL⁻¹, a high sensitivity of 2.7 × 10⁷ µA·mol⁻¹L, and a low detection limit (LOD) of approximately 4.5×10⁻ 10 molL⁻¹. Structural characterization by FTIR, EDX and transmission electron microscopy confirmed the integrity and successful functionalization of the composite. The CTAB@SiO 2 @MWCNT-APTES-modified electrode allowed clear separation of the uric acid oxidation peak from common interfering species such as ascorbic acid and dopamine. The sensor was effectively applied to human plasma and urine samples, achieving recovery rates between 92% and 104%, confirming its potential for reliable real-sample analysis and future sensor development.