Microcontact-Printed Optical Biosensor for Non-Invasive Detection of TNF-α: Point-of-Care Monitoring of Heart Failure

Tumor Necrosis Factor-alpha (TNF-α) is a pro-inflammatory cytokine strongly associated with the early onset and progression of heart failure (HF). In this study, we present the design and fabrication of a label-free, fluorescence-based biosensor for the detection of TNF-α cytokines. The biosensor is constructed using microcontact printing (μCP) to pattern Triethoxysilylundecanal (TESUD) on oxygen plasma-activated polydimethylsiloxane (PDMS) substrates, forming self-assembled monolayers (SAMs) of microstructures. TNF-α antibodies are then covalently immobilized via imine coupling. Detection of TNF-α cytokines at 50 µg/mL was achieved via an optical “sandwich” immunoassay with rhodamine-labeled secondary antibodies, enabling visualization by fluorescence microscopy. Surface wettability analysis confirmed successful stepwise functionalization, while imaging revealed well-defined microstructures and specific immune binding of TNF-α. This platform demonstrates a proof-of-concept and offers a non-invasive, sensitive, and cost-effective alternative for the early detection of TNF-α in biological fluids, with potential applications in HF monitoring.