Antibody Micropatterned Lubricant‐Infused Biosensors Enable Sub‐Picogram Immunofluorescence Detection of Interleukin 6 in Human Whole Plasma

Abstract

Abstract Recent studies have shown a correlation between elevated interleukin 6 (IL‐6) concentrations and the risk of respiratory failure in COVID‐19 patients. Therefore, detection of IL‐6 at low concentrations permits early diagnosis of worst‐case outcome in viral respiratory infections. Here, a versatile biointerface is presented that eliminates nonspecific adhesion and thus enables immunofluorescence detection of IL‐6 in whole human plasma or whole human blood during coagulation, down to a limit of detection of 0.5 pg mL −1 . The sensitivity of the developed lubricant‐infused biosensor for immunofluorescence assays in detecting low molecular weight proteins such as IL‐6 is facilitated by i) producing a bioink in which the capture antibody is functionalized by an epoxy‐based silane for covalent linkage to the fluorosilanized surface and ii) suppressing nonspecific adhesion by patterning the developed bioink into a lubricant‐infused coating. The developed biosensor addresses one of the major challenges for biosensing in complex fluids, namely nonspecific adhesion, therefore paving the way for highly sensitive biosensing in complex fluids.