Black phosphorus platforms for electrochemical biosensing: stability, functionalization, and wearable applications

Black phosphorus (BP), a two-dimensional (2D) layered material, has emerged as a highly promising candidate for next-generation electrochemical biosensing platforms. Its unique combination of a layer-tunable direct bandgap, high charge carrier mobility, and pronounced in-plane anisotropy distinguishes it from other 2D materials such as graphene and transition metal dichalcogenides. These intrinsic properties render BP highly responsive to local electronic perturbations, enabling sensitive transduction for low-abundance biological targets. However, practical deployment is severely hampered by rapid degradation under oxygen, water, and light. This review is primarily focused on BP-enabled electrochemical biosensing, emphasizing stability engineering, surface functionalization for biointerfaces, and device integration toward flexible and wearable sensing; imaging or drug-delivery studies are discussed only when they provide transferable stabilization or biocompatibility insights. We analyze BP degradation mechanisms, then compare stabilization strategies with explicit attention to the tradeoffs between physical encapsulation and chemical functionalization (covalent versus non-covalent). We next summarize electrochemical detection across representative analyte classes, spanning small molecules (e.g. neurotransmitters) to macromolecular biomarkers (e.g., nucleic acids and proteins), and we close by outlining wearable integration routes and the remaining barriers for real-world operation in complex biofluids and scalable manufacturing.