Biomimetic nanozymes with tunable peroxidase activity based on peptides co-assembly for colorimetric sensing of uric acid

The construction of simple and efficient artificial enzymes is of great importance in the fields of sensing and catalysis. In this work, peptide nanotubes (CA-PNTs) co-assembled from two short peptides were non-covalently combined with hemin to obtain a series of CA-PNTs/hemin composites as biomimetic peroxidase materials. Due to the introduction of histidine and arginine in the short peptides simulating the microenvironment near the hydrophobic cavity in the activity center of the natural enzyme, CA-PNTs/hemin shows enhanced peroxidase activity compared with free hemin and the single short peptide self-assembled peptide nanotubes-supported hemin complex, and the enzyme activity of the material could be regulated by simply adjusting the proportion of co-assembled short peptides. Further investigation of the catalytic mechanism demonstrates that CA-PNTs/hemin can effectively bind to H₂O₂ to form active intermediates and catalyze the decomposition of H₂O₂ to generate superoxide radicals (O₂^•−), thus promoting the whole enzymatic reaction. Combined with an enzyme cascade reaction and enzyme catalytic chromogenic system, a colorimetric method based on CA-PNTs/hemin for uric acid (UA) sensing was constructed. The strategy shows a linear range of 0.5–80 μM with a low limit of detection (0.2 μM) and good selectivity, and has been successfully applied to the determination of UA in human urine. A portable platform for UA detection was further developed by conjugating the strategy with smartphones.