Label-free detection of lactoferrin and beta-2-microglobuin in contrived tear film using a low-cost electrical biosensor chip

In this paper, we present a biosensor chip to study two important biomarkers, lactoferrin (LCF) and beta-2-microglubin (B2M) present in our tear fluid. LCF and B2M have direct relevance with dry eye syndrome and diabetic retinopathy in patients respectively. We have developed a multi-layer paper-based biosensor chip connected with handheld printed circuit board (PCB) to monitor the effectiveness of B2M and LCF in contrived tear film (TF) with a wide range of detection (RoD) from 0.001 to 1ng/mL (R2=0.9886) and 1 to 10mg/mL (R2=0.9554) respectively. Multilayer biosensor is composed of graphene nanoplatelet and diblock-co-polymer coated on a filter paper followed by deposition of micro-Au electrodes. Anti-LCF and anti-B2M antibodies were immobilized via 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester (DTSP) as a self-assembled monolayer (SAM) on Au. In addition to electrical measurements in real-time setup, Raman spectral analysis and SEM were utilized to characterize the sensor surface before and after testing the relevant proteins. We anticipate that the fabricated sensor chip has promising application to study dry-eye-disease (DED) and diabetes in Point-of-care (POC) setting.