Facile preparation of porous Co₃O₄ nanocubes for directly screen-printing an ultrasensitive glutamate biosensor microchip

Although L-glutamate is an important biological analyte for the clinic diagnosis and food industry, rare capable glutamate biosensor has been developed in the practical detection. The electrochemical biosensor is an advanced technique due to its on-site and real-time concentration recognition, however, the unsatisfactory performance in the glutamate detection blocks its production transfer. In this work, we proposed a novel screen-printed glutamate biosensor chip fabricated in large-scale through designing a porous nanocubic Co₃O₄. This material is prepared via a facile thermal oxidation strategy by using the cobalt hexacyanoferrate (CoHCF) as a precursor to construct its regular geometric morphology. The obtained Co₃O₄ crystal is of both regular nanocubic outline and abundant interconnected pores to generate high electrocatalysis on the glutamate enzymatic oxidation. It was directly served as the screen-printing ink to fabricate a microchip which integrated all three-electrode components. In detection, with loading a small amount of glutamate oxidation, this biosensor chip can still exhibit a high sensitivity of 20.12 μA mM⁻¹ cm⁻², as well as a wide linear range from 10 to 600 μM and a low LOD = 10 μM. Besides, under a very low working potential of -0.2 V. Moreover, the biosensor chip possesses an excellent anti-interference ability and usage stability to withstand more than 300 tests in 30 days.