Session: Advances in Electrochemistry:

Technologies for monitoring the levels of oxygen has been great importance for biomedical application. Such measurements, especially when performed in real-time, could calculate the rates of cellular metabolism and identify undersupplied regions within tissues and cells. In addition, the O₂ is the key metabolite and source of energy cells and is used to produce ATP through the electron transport chain and oxidative phosphorylation process. Therefore, the objective of the present work is to develop an electrochemical oxygen sensor, through the photocatalytic properties of poly(azo-Bismarck) as an alternative strategy for dissolved oxygen sensing. Electrochemical impedance spectroscopy at the polyBBY and polyBBY-AuNP platforms in PBS solution in the absence (0.0 mmol L^-1) and presence of O₂ (1.25 mmol L^-1) revealed that AuNP increases the sensor performance. The ΔZ_real (at 0.10 Hz applied) were 6.13 and 18.4 kW to polyBBY and polyBBY-AuNP, respectively. Posteriorly, the polyBBY-AuNP O₂ photocatalysis was investigated under LED illumination (monoclonal 5W) in the presence and absence of O₂. The EIS analysis based on the circuit equivalent model showed a decrease in the charge transfer resistance (R_tc) to polymer/AuNP interface such as the film/solution interface under illumination at both situations: in the presence and absence of O₂. This behavior might be due to oxygen reduction overpotential decrease. On the other hand, the decrease in the oxygen reduction overpotential leads to an increase in the sensor sensibility, as was observed in Fig. 1. Through the relative Z_real values, calculated by |Z₀-Z_i/Z₀|, where Z_i is the real impedance in presence of O₂ and Z₀ is the real impedance in the absence of O₂, calibration curves were developed, revealing sensitivity of 0.72 kΩ cm² L mmol^-1for polyBBY-AuNP without and 1.07 kΩ cm² L mmol^-1under illumination. The studies revealed the overpotential decrease under illumination, as well as the increase of sensibility. Therefore, the new platform has potential applications for monitoring dissolved oxygen in various environments.

Jessica Crivelaro Pacheco

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