Accelerating peroxidase-like activity of gold nanozymes using purine derivatives and its application for monitoring of occult blood in urine

Gold nanoparticles (AuNPs) is an important kind of nanozymes and a variety of its artificial enzymatic activities have been reported, such as oxidase, peroxidase, and superoxide dismutase. The DNA with poly purine-modified AuNPs shows an enhancement peroxidase activity compared with poly pyrimidine-modified AuNPs. In this work, purine derivatives are modified on the surface of AuNPs. The peroxidase-like activity of AuNPs is dependent on the chemical structure of the molecules capped on the surface. We find that ferric ions can accelerate the mimic enzymatic ability of 2, 6-diaminopurine (DAP) modified AuNPs. The enhanced catalytic activity comes from the synergistic reaction of AuNPs and ferric ions. The cooperative system can be applied to measure hemoglobin and red blood cells in urine with better sensitivity. Generally, there is no or few red blood cells in human urine. The presence of blood in the urine is closely related with serious diseases, for example chronic nephrotic syndrome and urinary system tumors. Compared the commercial urine test paper, the method based on DAP-AuNPs has a good sensitivity and wider quantitative range and will be helpful to do urine test at home.