An Innovator Support Material for Tyrosinase Immobilization: Antimony-Doped Tin Oxide Thin Films (ATO-TF)

Tyrosinase (T3824, Sigma) enzymes were immobilized onto SnO₂: Sb thin films (ATO-TF) which were synthesized in laboratory conditions by spray pyrolysis technique. Immobilization of tyrosinase onto SnO₂: Sb thin film (ATO-TF) was confirmed by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The optimum pH of the immobilized tyrosinase (tyrosinase-ATO-TF) was 6.0, and the optimum temperature was found to be 30 °C. In the presence of catechol substrate of immobilized enzymes, Km and Vmax values were determined as 0.34 mM and 312.5 U/cm² min, respectively. The thermal stabilities of the immobilized tyrosinase at 4 °C and 30 °C were investigated for 20, 40, and 60 min. At these temperatures and time intervals, the immobilized tyrosinase was found to be highly stable. The pH stability of the immobilized tyrosinase enzymes was incubated for 24, 48, 72, and 96 h at 4 °C temperature. The enzyme activity was determined under optimum conditions, and the activity of the immobilized tyrosinase enzymes exhibited various values for the range of pH 3.0-8.0. The storage stability of the immobilized tyrosinase enzymes at 4 °C was investigated, and 45.72% of the initial activity was maintained at the end of the seventh day. Furthermore, the reusability of the immobilized tyrosinase enzymes has been examined. The immobilized tyrosinase enzymes can be used 3 times and survived their 50% of initial activity. The ATO-TF can be used as alternative support materials for the immobilization of tyrosinase enzymes.