When the self-assembled AuNPs were
enlarged by hydroxylamine seeding, the ETR of [Fe(CN)6]3/4 was improved significantly with a peak
separation of 100 mV. Tapping mode AFM showed that the average size of the enlarged-AuNPs (E-AuNPs)
was 50-70 nm. The E-AuNPs modified electrode catalyzes the oxidation of AA and UA, separates their voltammetric
signals by 200 mV, and has excellent sensitivity towards AA and UA with a detection limit of
50 nM. The practical application of the modified electrode was demonstrated by measuring the concentration
of UA in blood serum and urine.