PLUS: Primary Layer for Universal Sensing Enabling Improved Immunocapture of Biomarkers in Clinical Scenarios.

The biofunctionalization of sensor surfaces to enable biorecognition capabilities remains a major challenge in developing diagnostic devices. However, efficient surface chemistries applicable to various sensor types remain elusive. In this study, Primary Layer for Universal Sensing (PLUS), a universal coating for bioprobe immobilization designed to enhance sensor functionality across diverse substrates, is introduced. Derived from the mussel-inspired, catechol-based adhesive polydopamine (pDA), PLUS ensures material-independent coating ability. Unlike conventional methods that involve secondary bioprobe immobilization onto a pre-formed pDA layer, PLUS is directly grown from dopamine (DA) and avidin proteins as co-polymerization precursors, resulting in a highly roughened surface with abundant biotin-binding sites. This strategy, combined with end-functionalization using biotinylated antibodies, significantly enhances immunocapture efficiency compared to traditional immunoassays. Furthermore, the PLUS layer interacts effectively with blocking proteins, preventing non-specific binding of unwanted molecules. This ensures reliable biomarker capture even in complex biological samples, such as 50% human serum and plasma. It is envisioned that this bioprobe immobilization technique will play a pivotal role in advancing high-performance sensor adaptability for molecular diagnostics.