Gold/N-trimethyl chitosan/magnetite (Au/TMC/Fe3O4) nanocomposites were employed for the development of ultrasensitive biosensors such as a urine albumin electrochemical biosensor [116], an epidermal growth factor receptor (EGFR) electrochemical biosensor [117] for early cancer diagnosis, a chip-based sandwich electrochemical genosensor for the quantitative assessment of RASSF1A tumor suppressor gene methylation [118], and an electrochemical genosensor for the ultrasensitive detection of microRNA [119]. Here, EGFR is linked to cancer.