Biocompatible graphene-zirconia nanocomposite as a cyto-safe immunosensor for the rapid detection of carcinoembryonic antigen

Graphene-based materials have gained remarkable attention in numerous disciplines owing to their unique electrochemical properties. Out of various hybridized nanocomposites, graphene-zirconia nanocomposite (GZ) was distinctive due to its biocompatibility. Zirconia nanoparticles serve as spacers that reduce the stacking of graphene and improve the electrochemical performance of the material. Considering that lungs and skin suffer the greatest exposure to nanoparticles, this study aimed to evaluate the cytotoxicity of the as-synthesized GZ nanocomposites on MRC5 (lung cells) and HaCaT (skin cells) via morphological observation and cell viability assay using 3-(4,5 dimethylthiazol-2-yl)-(2,5-diphenyltetrazolium bromide) tetrazolium (MTT). GZ-treated cells showed a comparable proliferation rate and morphology with untreated cells under microscopic evaluation. Based on MTT results, the IC50 values of GZ were > 500 µg/ml for MRC5 and HaCaT cells. The excellent biocompatibility was the supremacy of GZ over other nanocomposites applied as electrode materials in biosensors. GZ was functionalized with biolinker for the detection of carcinoembryonic antigen (CEA). The proposed immunosensor exhibited good responses towards CEA detection, with a 4.25 pg/ml LOD and correlation coefficient of R2 = 0.99 within a linear working range from 0.01 to 10 ng/ml. The performance of the immunosensor to detect CEA present in human serum was also evaluated. Good recovery of CEA was found, suggesting that the proposed immunosensor possess a high affinity to CEA even in a complex biological matrix, rendering it a promising sensing platform for real sample analysis and open a new way for the detection of cancer-associated proteins.