A pre-symptomatic warning platform: Ultrasensitive HHV-8 detection enabled by a TAPB-PDA COF-based electrochemical...

The detection of Human herpesvirus 8 (HHV-8), a key oncogenic virus associated with Kaposi's sarcoma, requires highly sensitive analytical methods for early diagnosis. To address this need, we fabricated a noble metal-free electrochemical immunosensor based on two synthesized imine-bonded covalent organic frameworks (COF), TAPB-PDA and TAPB-ClPDA. When evaluated as a sensing interface on carbon paper substrates, the TAPB-PDA-based interface demonstrated superior capability for immobilising antibodies. This property enabled directional anchoring of the capture antibodies, thereby enhancing the sensor's sensitivity by improving its specific antigen-binding capacity. This performance is well-suited for practical early-stage viral detection. Leveraging TAPB-PDA as the core interface allowed for efficient covalent antibody conjugation. Moreover, its inherent high surface area and porosity, combined with the excellent conductivity of the carbon paper substrate, synergistically amplified the electrochemical signal. The optimised immunosensor exhibited a wide linear detection range from 0.497 fg/mL to 368 fg/mL for HHV-8 antigen, with an ultra-low detection limit of 0.014 fg/mL (S/N = 3). This work establishes a novel and highly sensitive COF-based platform for the reliable, early detection of HHV-8 infection.