A Bioelectronic Immunosensing Platform Comprising a Gold Dendritic 3D Architecture Sandwiched between Graphene Sheets for Oral Cancer Detection

Epidemiological studies have shown that oral cancer is one of the most lethal forms of cancer, with a high risk of distant metastases and eventual death, largely due to late diagnosis. The noninvasive diagnosis of oral cancer can simplify sample collection, and when paired with single-step detection assays, it can facilitate and popularize early diagnosis, ultimately reducing the mortality rate. In light of this, we have designed a simple and noninvasive immunosensor for the facile and selective identification of the oral cancer biomarker cytokeratin 19 fragment-21-1 (CYFRA-21-1) in saliva samples, specifically in the clinically safe as well as diseased range. Prior to being utilized as a marker for oral carcinomas, CYFRA-21-1 was used as a biomarker for nonsmall cell lung cancer (NSCLC) as well as other cancers. Due to its high salivary secretion, it has become a powerful and reliable marker for the early detection of oral cancer in recent decades; however, there are very few studies pertaining to it. Moreover, the literature has reported the higher sensitivity and specificity of CYFRA-21-1 markers in saliva than in serum samples. Hence, in this study, the sensing surface was developed using a nanocomposite of gold nanodendrites (AuNDs) sandwiched between graphene oxide (GO) sheets for the sensitive detection of CYFRA-21-1 in saliva samples. Metallic dendrites based on nanohybrid systems possess astonishing conductive and catalytic properties. The first layer of GO is used as the substrate for enhanced growth of AuNDs, while the second layer of GO is utilized for covalent binding of the anti-CYFRA-21-1 antibody through bioconjugation reactions. The developed bioelectronic immunosensing platform is able to sense CYFRA-21-1 in a clinically safe as well as diseased range with a low limit of detection (LOD). It is easy to operate and can be integrated with a portable electrochemical analyzer for point-of-care (POC) oral cancer diagnosis in low-resource settings.