Spectroscopic, Tensiometric, and Molecular Docking Analysis of Myoglobin Interaction with Gemini Surfactant-Functionalized Silver Nanoparticles

Nanoparticle-biological fluid interaction is governed by the formation of a protein corona, which is a critical determinant of the fate and efficiency of a nanocarrier within the body. The current article reports an extensive synthesis and the complex interactions between silver nanoparticles capped with biodegradable and biocompatible diester-bonded cationic gemini surfactants (C₁₂-E2O2-C₁₂) and Myoglobin (Mb) employing multi-spectroscopic and tensiometric techniques. The Gemini surfactant architecture provides unique surface properties (high charge density, tunable hydrophobicity, and diester spacer) that modulate protein binding and corona stability differently from conventional single-chain surfactants. UV-Vis spectroscopy identified slight variations in the heme microenvironment of myoglobin upon interaction with the surface-modified nanoparticles. UV-Vis analysis revealed that the complexation of Mb with C₁₂-E2O2-C₁₂-AgNPs was primarily driven by a combination of electrostatic and hydrophobic interactions. UV-Vis absorption and fluorescence studies further confirm the formation of Mb and C₁₂-E2O2-C₁₂-AgNPs complex. Synchronous fluorescence measurements revealed perturbations in Mb's tertiary structure, including increased solvent exposure of tyrosine residues and the relocation of tryptophan residues into more hydrophobic environments within the nanoparticle coating. Fourier transform infrared (FT-IR) spectroscopy reveals conformational changes in the secondary structure of Mb upon interaction of C₁₂-E2O2-C₁₂-AgNPs. Far-UV circular dichroism spectroscopy showed conformational change in the secondary structure of Mb. By circular dichroism (CD) spectroscopy, we observed that Mb's α-helical content decreased following its complexation with the C₁₂-E2O2-C₁₂-AgNPs. The surface activity of the C₁₂-E2O2-C₁₂-AgNPs and Mb-C₁₂-E2O2-C₁₂-AgNPs was also studied by surface tension measurement. Tensiometry proved that the complex of C₁₂-E2O2-C₁₂-AgNPs adsorbs on Mb via a multi-stage mechanism, and as a result, significantly alters the surface activity of the system. These findings demonstrate their potential as an appropriate platform for diagnostics, drug delivery, and nanobiotechnology applications and thus merit further extensive exploration. They also provide a comprehensive description of the surface forces between Mb and specifically designed C₁₂-E2O2-C₁₂-AgNPs.