Gold Nanoparticle Incorporated Graphene Oxide as a SERS Platform for Ultratrace Antibody Free Sensing of the Cancer Biomarker CEA

A simple, fast, low-cost, and efficient method is designed for the synthesis of graphene oxide (GO) (20 nm) from graphite using a strong oxidant Ce(IV). GO is further modified with gold nanoparticles (AuNPs) (5-8 nm) to generate a AuGO nanocomposite (25 nm). Raman spectral analyses confirm that the synthesized AuGO has a potential selective sensing ability for the cancer biomarker carcinoembryonic antigen (CEA) in serum. Sensing assays are also carried out in the presence of high concentrations of glucose, cholesterol, and insulin using this method, which become significantly elevated in conditions of different pathophysiological disorders. Ultratrace antibody free sensing of CEA in serum is achieved using surface-enhanced Raman spectroscopy with an amazing LOD of 12.5 fg/mL. The interaction between CEA and AuGO is further established using Raman, fluorescence, circular dichroism spectroscopy, and theoretical studies. The specificity of sensing is tested by checking the response in the presence of other cancer biomarkers, such as CA 19-9, CA 125, and PSA, which do not show any signal enhancement with AuGO in Raman spectroscopy.