Highly Sensitive Enzyme-Modified Field Effect Transistor Based Biosensor for Sarcosine Detection

In this work, a carbon nanotube (CNT)-based enzyme modified field effect transistor (ENFET) based biosensor has been fabricated for the detection of the analyte Sarcosine, a potential biomarker for Prostate Cancer (PCa). The biosensor consists of indium tin oxide glass slide as substrate, on top of which polyethyleneimine (PEI)-doped multiwalled CNT as the channel has been synthesized using chemical solution process, followed by niobium pentoxide (Nb2O5) as high- $\kappa $ dielectric, and dimethyl sulfoxide (DMSO) treated poly 3,4-ethylenedioxythiophene (PEDOT): Poly styrene sulfonate (PSS)-multiwalled carbon nanotubes (MWCNT)-CHIT nanocomposite as biosensing membrane. Enzyme sarcosine oxidase (SOx) has been immobilized on top of it using physical adsorption technique. Experiments performed on the developed biosensor with commercially available sarcosine samples have shown good linearity in the range 0.89– $123.846~\mu $ M, with limit of detection (LOD) 0.962 nM, voltage sensitivity 64 mV/log(molar) and current sensitivity $3.43 \times 10^{{3}}~\mu $ A/ $\mu $ M. The biosensor also exhibits good repeatability and reproducibility, along with acceptable stability.