Exploring the versatility of dendrimer-stabilized silver nanoparticle platforms: synthesis, characterization, and protein immobilization for enhanced biosensing applications

Abstract

Surface plasmon resonance (SPR)-based biosensors have gained increasing prominence due to their ability to provide fast, accurate and real-time results. The functionalization of the SPR sensor chip is essential to ensure the effective binding of recognition biomolecules, making it a crucial step in the efficient construction of biosensors. We demonstrate here the functionalization of the SPR sensor chip with inorganic–organic nanocomposites formed by poly(amidoamine) dendrimers and silver nanoparticles (AgDENs). Several techniques were employed to characterize the structure and morphology of the nanocomposites. Silver nanoparticle/dendrimer structures with a size distribution between 3.7 and 16.2 nm were obtained, and chemical interactions were found between the amide groups of the dendrimers and the silver nanoparticles. Afterward, the synthesized AgDENs were combined with cysteamine using the layer-by-layer (LbL) technique to create multivalent films on the SPR sensor chip. To assess the versatility of these molecular assemblies in the biomaterial anchoring process, studies involving the immobilization of different types of proteins, including the Chaperone CHIP protein (carboxyl terminus of the Hsc70-interacting protein), heat shock cognate protein 70 (Hsc70), Free Candida antarctica lipase B (CALB L), and a recombinant protein (C1 protein) from the protozoan Leishmania infantum to the AgDENs were conducted. To evaluate a specific application, an immunosensor was constructed by anchoring the C1 protein on the proposed platform (AgDENs) to selectively detect Leishmania infantum antibodies in canine serum samples from positive and negative groups for visceral leishmaniasis. In brief, the nanostructured materials composed of poly(amidoamine) dendrimers and silver nanoparticles proved to be effective in anchoring different biological recognition elements, demonstrating their versatility for biosensor applications. An increase in sensor interface sensitivity was observed, likely due to the coupling of localized surface plasmons of silver nanoparticles with the plasmon of the flat Au. The large surface area of the film, combined with its excellent chemical stability, shows that the proposed platform is a very interesting strategy in biosensing.