A PDMS/chitosan/MPMs composite film based on multi-field coupling enhancement for African swine fever virus P72 protein detection

African swine fever (ASF) is an acute hemorrhagic disease in pigs caused by the African swine fever virus (ASFV), which has a high mortality rate and brought great damage to global pig farming industry. At present, there is no effective treatment or vaccine to combat ASFV infection, so early detection of ASFV has become particularly important. Therefore, the PDMS/chitosan/MPMs composite film was proposed to detect ASFV P72. PDMS mixed with chitosan particles were used to provide biological modification sites for the ASFV P72 antibody, which simplified the functional modification process. The specific binding of antigen and antibody leads to the mechanical deformation of the composite film, which was observed through optical method to change the microsphere spacing. The polystyrene microsphere (PMs) spacing changes were acquired by simply measuring the diameters of the Debye ring diffracted by the PDMS/chitosan/PMs with a simple laser pointer. The conductive layer formed by AgNWs realize the transformation of biological signals to electrical signals. By conjugating PMs with Fe₃O₄ nanoparticles (MPMs) and applying a magnetic field, a magnetic-stress-electric coupling system has been constructed, which amplifies the deformation of the composite film and enhances the sensitivity of the flexible film. The experimental results showed that the flexible film has wide linear range of 10 ng/mL-100 μg/mL, and the optimal detection limit (LOD) is 0.059 ng/mL, which was about one order of magnitude lower than that without magnetic field. In addition, the flexible film showed a good stability, specificity, and selectivity.