Characteristics of a Label-Less Electrochemical Immunosensor Based on a Field-Effect Transistor for the Detection of a Biomarker in Urine

Characteristics of a label-less electrochemical immunosensor based on a field-effect transistor (FET) for the detection of a biomarker in urine have been investigated. The BioFET was fabricated using the conventional CMOS process technology. For the detection of a biomarker, albumin, in urine the gate surface of the BioFET was modified by an engineered self-assembled monolayer, thiazole benzo crown ether ethylamine (TBCEA)-thioctic acid to immobilize anti-albumin. Surface plasmon resonance (SPR) analysis has been utilized to verify formation of SAM, immobilization of anti-albumin, prevention of non-specific binding and selective interaction between anti-albumin and albumin. A mixture of albumin and C-reactive protein (CRP) and an albumin-only solution were used to prove high specificity of biorecognition element on the BioFET to target molecule, albumin. The output drain current characteristics of the BioFET with respect to various albumin concentrations were obtained. The results went a step further to realize the albumin BioFET sensor for diagnosing nephritis and to develop a BioFET sensor array for the detection of multi biomarkers simultaneously.