Electrochemical determination of glucose in blood serum and sweat samples by the strontium doped Co3O4

Abstract

• The conventional synthesis routes were investigated for the preparation of Sr doped Co 3 O 4 (Sr-Co 3 O 4 ). • The successful incorporation of Sr in Co 3 O 4 lattice was found for hydrothermal method. • The occupation of Sr in octahedral sites increases the non-stoichiometric oxygen in the Co 3 O 4 lattices. • These defected electronic structures were inspected against the electrocatalytic activity of glucose oxidation. • The Sr-Co 3 O 4 is applied in real-time monitoring of glucose in blood serum and sweat samples which received good recoveries. This work reports the noninvasive electrochemical determination of glucose by strontium doped cobaltic cobalt oxide nanostructures (Sr-Co 3 O 4 ). The Sr-Co 3 O 4 is prepared by three conventional methods namely hydrothermal, magnetic stirring, and ultrasound. Among all, the hydrothermal method effectively incorporated the Sr in the Co 3 O 4 lattice. The Sr percentage and Co oxidation states were investigated by x-ray photoelectron spectroscopy. The Sr has a more ionic radius than cobalt, therefore, it is occupied in the octahedral site. As a result, the non-stoichiometric oxygen content was increased in the Co 3 O 4 lattices, which are the main contributor to the electrochemical determination of glucose. The results revealed that hydrothermally synthesized Sr-Co 3 O 4 (HSC) exhibited improved electrocatalytic activity such as low peak potential (0.55 V) and high current (116 µA) towards glucose oxidation than the other electrocatalysts. The HSC/GCE revealed a good sensitivity (9.01 ± 0.15 µA mM −1 cm −2 ) and low LoD (31 ± 3 nM). Also, high selectivity was observed towards glucose detection in the presence of co-interfering species. Moreover, the Sr-Co 3 O 4 is applied in real-time monitoring of glucose in blood serum and sweat samples which received good recoveries.