LAUSR

Abstract This work presents the development and application of a biosensor based on cadmium selenide/zinc sulphide core-shell quantum dot modified with the redox protein cytochrome c (CdSe/ZnS-Cytc) for the photoelectrochemical determination of epinephrine (EP). The photoactive biocomposite was immobilized on the surface of a glass substrate modified with indium doped tin oxide (CdSe/ZnS-Cytc/ITO). The photoactive film was characterized by electrochemical impedance spectroscopy and the photocurrent measurements were obtained by chronoamperometry using a LED light lamp as source of irradiation. After the experimental parameters optimization, the biosensor presented a good response for EP oxidation in a wide linear concentration range between 1 μmol L−1 and 1.2 mmol L−1 (with r = 0.999; n = 9). A detection limit of 2 nmol L−1 was obtained. The selectivity of the photosensor was evaluated against species such as uric acid, ascorbic acid, folic acid, barbital, glucose, and urea, and the results showed that the proposed biosensor has a good selectivity for the detection of EP. The CdSe/ZnS-Cytc/ITO photoelectrochemical biosensor was applied in injectable drug samples used in cardiopulmonary resuscitation. The recovery tests in the samples showed recovery values between 101 and 110% suggesting a good accuracy for the proposed method.