Reduced graphene oxide-gadolinium oxide-functionalized paper based immunosensor for electrochemical detection of gentamicin

Excessive consumption of antibiotics like gentamicin (GEN) can lead to hostile effects as antibiotic resistance. Therefore, the detection is important for which, reduced graphene oxide-Gadolinium oxide nanocomposite (rGO@Gd₂O₃ NC) was composed through co-precipitation method for the detection of GEN. The structural, morphological and functional group characterizations were done using XRD, FT-IR, SEM and TEM techniques. The cyclic voltammetry (CV) showed excellent electrocatalytic activity and superior performance towards GEN detection. Through the use of GEN monoclonal antibodies (anti-GEN) on a screen-printed electrode (SPE), a very sensitive electrochemical immunosensor was fabricated. Covalent interactions were employed to construct the electrochemical immunosensor, while bovine serum albumin (BSA) was employed as a blocking agent on the anti-GEN/rGO@Gd₂O₃/SPE electrode surface. The analysis of the CV response of the BSA/anti-GEN/rGO@Gd₂O₃/SPE bioelectrode demonstrated linear detection range from 1 pM – 100 μM, along with limit of detection (LOD) of 0.424 pM and sensitivity of 44.87 μA pM^-1 cm^{− 2}. Additionally, rGO@Gd₂O₃ immunosensor, exhibited a good level of linearity with R² value of 0.978. These findings indicate the excellent potential of the rGO@Gd₂O₃ electrochemical immunosensor for accurately detecting GEN in spiked milk samples at different concentrations.