Biohybrid Nanosystem Fabricated with Marine Diatom Thalassiosira pseudonana for Uric Acid Detection

Due to the intense demand for low-cost, environmentally friendly, and stable uric acid (UA) detection methods, a novel biosensing nanosystem made with marine diatom was studied. Reduced by live diatom (Thalassiosira pseudonana), metallic nanoparticles (Cu_<i>X</i>) were hybridized with the heteronanostructure (Diatom frustule, DF), showing peroxidase activity 2.66-fold over horseradish peroxidase (HRP). To immobilize the enzyme directionally with increasing loading amounts, silaffin peptides (R₅ and T₈) were designed for tagging the urate oxidase (UoX). The enzyme loading on DF of tagged UoX was 1.76-fold (R₅) and 1.54-fold (T₈) that of untagged UoX. The activity of immobilized UoX-R₅ was 5.29–11.76-fold more than that of free UoX-R₅ at various pH levels (5–10) and temperatures (20–60 °C). The nanosystem (UoX-R₅ immobilized on Cu_<i>X</i>-coated diatom frustules, termed as BioHNS) demonstrated a superior linear range of 5 × 10^–6 to 1 × 10^–3 M and a detection limit of 1.6 μM, surpassing the performance of the majority of reported UA sensors. The recoveries of UA in urine were detected by the BioHNS, ranging from 96.93 to 105.35%, with a relative deviation of less than 5.00%. The BioHNS showed excellent anti-interference and storage stability (2 months). In summary, BioHNS demonstrates significant potential as a sustainable and environmentally friendly biosensor for uric acid detection, highlighting its substantial relevance to the biomedical applications of marine diatoms.