Peptide-Conjugated Silver Nanoparticle for Autoantibody Recognition

In this work, we considered the autoantibodies proposed as putative biomarkers of demyelination taking into account their reactivity towards myelin oligodendrocyte glycoprotein (MOG) and myelin basic protein (MBP). These myelin proteins are among the most commonly researched targets in the immunopathology of demyelinating diseases. In this context, the development of assays for autoantibody detection can contribute as a predictive value for the early diagnosis of demyelinating diseases. Hence, we aimed to address the application of silver nanoparticles (AgNPs) as a sensing device of autoantibodies. AgNPs were synthesized via a chemical reduction method and characterized using atomic force microscopy (AFM), X-ray diffractometry, dynamic light scattering, and UV-visible spectrophotometry. The process of peptide conjugation on the nanoparticles was also analyzed. The autoantibody recognition by the peptide-conjugated AgNPs was evaluated with UV-visible spectrophotometry, atomic force spectroscopy (AFS), and color changing. AgNPs exhibited spherical morphology, low polydispersity, face-centered cubic crystal structure, and an average size of 29.3 +/- 3.0 nm. The hydrodynamic diameter variation and AFM showed that the MBP peptide induced greater agglomeration, compared to MOG peptide. The AFS measurements indicated the efficient binding of peptides to the AgNPs maintaining their activity, revealed by typical adhesion force and shapes of curves. The absorption spectrum features were more affected by the interaction with the specific autoantibodies, which also caused a visible color change in suspension providing a qualitative response. We described a preliminary study of MOG- and MBP-conjugated AgNPs which showed to be applicable in the autoantibody recognition. These have promising implication in the searching for biological markers for diagnostic purposes in the demyelination context, in which the nanoscale sensing exploitation is recent.