Significance of blocking layer in GaN HEMT biosensor for S100B detection using serum and saliva

Abstract

The work reports a meander-gated GaN HEMT-based biosensor for the noninvasive detection of the Scandinavian Neurotrauma Committee (SNC) recommended biomarker S100B in clinically relevant concentration ranges. The proposed bio-assay for S100B detection has been validated using different surface characterization techniques. The impact of BSA blocking for suppressed nonspecific adsorption and possible sensitivity enhancement has been discussed in depth based on electrical and contact angle measurement-based studies. The biosensor sensitivity was enhanced by ∼58.04 μA/ng/ml for the BSA-coated sensor with a better linearity trend. The measured contact angle for the sensor dynamic range of 100 fg/ml to 10.0 ng/ml has been correlated with the sensor response for a better understanding of the antibody-antigen conjugation over the sensing areas. The inclusion of the BSA layer resulted in a 59.08 % increase in sensor response for the various S100B concentrations ranging from 1.0 ng/ml to 4.0 ng/ml. The platform has been utilized for the noninvasive saliva-based detection and invasive serum-based detection of the S100B biomarker. The platform offers a sensitivity of 250.12 μA/ng/ml and 0.84 mA/ng/ml for saliva and serum-based detection with excellent linearity. The platform is suitable for early diagnosis and prognosis of TBI in real-time application areas with a limit of detection of 1.47 fg/ml and ultrasensitive with a response time of 5–10s with a low sample volume requirement of 1–2 μl.