A Programmable Carbon Nanotube-Based Diagnostic Toolkit: Modular Architecture for Universal Multitarget Biosensing through Synergistic Surface Engineering

oxidation with Tween-20 surfactant modification, we achieved 10-fold signal amplification and superior colloidal stability compared to conventional approaches. This universal system was successfully applied to two disparate detection modalities: as a sandwich immunoassay for tumor markers (e.g., CEA, LOD 0.25 ng/mL) and as a competitive immunoassay for mycotoxins (e.g., Ochratoxin A, LOD 4.31 pg/mL). Performance in complex matrices included >95% specificity, <8% relative standard deviation, and 96-105% recoveries. Crucially, transitioning between analytes requires only antibody substitution and limited assay-level operating parameters adjustment, while the core CNT functionalization, conjugation protocol, and strip design remain constant. This plug-and-play capability minimizes development cycles, shifting biosensor engineering from target-specific optimization to modular assembly. The platform provides a versatile framework for rapidly addressing diverse diagnostic challenges.