Synergistic immune-network-oriented probe based on pCuGA-AFcI for enhanced on-site detection of pentachlorophenol

Orientation-specific immobilization of antibodies (Abs) onto nanoparticles to maintain Abs-antigen recognition is one of the main strategies to improve immunochromatographic assay (ICA) performance. Inspired by an immune-network-based probe synthesis strategy, we proposed a novel immune-bridging mechanism utilizing the specific interaction between anti-Fc immunoglobulins (AFcI) and Abs. This enhanced affinity facilitates the construction of immune-network, thereby improving the stability of Abs binding. Herein, a bio-derived tracer, pupal-like CuGA (pCuGA), self-assembled from Cu²⁺ and gallic acid (GA) was developed and further modified with AFcI. This modification addresses potential Abs shedding caused by unstable carrier-Abs binding and enables synergistic Abs orientation for immune-network stabilization and signal amplification. The resulting tracer exhibits excellent biocompatibility and preserves Abs bioactivity through a simple stirring-based labeling process, eliminating the need for cumbersome chemical modification. Compared with the conventional pCuGA-Ab probe-based ICA, the pCuGA-AFcIAb probe-based ICA not only improved sensitivity by halving Ab consumption but also achieved significantly lower detection limits, with an IC₁₀ of 0.019 ng/mL and a cut-off value of 3.00 ng/mL, representing at least 3.2- and 4.0-fold enhancements, respectively. Furthermore, the feasibility of the method was verified in chopsticks, fish, environmental water, fetal bovine serum, and shrimp paste samples, yielding satisfactory recoveries. The results of blind samples detection were consistent with those of liquid chromatography tandem mass spectrometry. This study provides new possibilities for the functional modification of ICA tracers and paves the green road for ICA detection.