Analytical Sciences

Yeast-based Biochemical Oxygen Demand Sensors Using Gold-modified Boron-doped Diamond Electrodes

Tribidasari A. IVANDINI,*,** HARMESA,** Endang SAEPUDIN,** and Yasuaki EINAGA*,***

*Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
**Department of Chemistry, Faculty of Mathematics and Sciences, University of Indonesia, Kampus Baru UI, Depok, Jakarta 16-424, Indonesia
***JST CREST/ACCEL, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan

A gold nanoparticle modified boron-doped diamond electrode was developed as a transducer for biochemical oxygen demand (BOD) measurements. Rhodotorula mucilaginosa UICC Y-181 was immobilized in a sodium alginate matrix, and used as a biosensing agent. Cyclic voltammetry was applied to study the oxygen reduction reaction at the electrode, while amperometry was employed to detect oxygen, which was not consumed by the microorganisms. The optimum waiting time of 25 min was observed using 1-mm thickness of yeast film. A comparison against the system with free yeast cells shows less sensitivity of the current responses with a linear dynamic range (R² = 0.99) of from 0.10 mM to 0.90 mM glucose (equivalent to 10 – 90 mg/L BOD) with an estimated limit of detection of 1.90 mg/L BOD. However, a better stability of the current responses could be achieved with an RSD of 3.35%. Moreover, less influence from the presence of copper ions was observed. The results indicate that the yeast-immobilized BOD sensors is more suitable to be applied in a real condition.

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