Aptamer functionalization effect on the interaction of sphingomyelin nanoemulsions with plasma proteins. A thermodynamic approach

Thermodynamic parameters at bio/nano interface emerge as key descriptors for the dominant contributions determining the adsorption processes during the interaction of Aptamer-Sphingomyelin Nanoemulsions with Serum Proteins. [Display omitted] •Aptamer-sphingomyelin nanoemulsions interaction with proteins is investigated by a thermodynamic approach.•An entropy-controlled process and water mediated is highlighted.•The native conformation of the protein is stabilized following the adsorption process.•Thermodynamic parameters are key descriptors of the interaction at bio/nano interface. The study of the interactions between nanoparticles and biomolecules is a fundamental challenge of nanomedicine research offering insights into the adsorption processes that may impact the biological responses. In the present work thermodynamic signature associated to the interaction of VitaminE-sphingomyelin nanoemulsions (SNs) conjugated to aptamers with three model proteins (bovine serum albumin, immunoglobulin G and bovine plasma fibrinogen) were investigated. SNs have good properties in terms of biodegradability, stability in biological media, biocompatibility, and significant versatility, being able to associate with a wide variety of molecules in cancer diagnosis and therapy. Aptamers are single-stranded oligonucleotides that can bind to target molecules with excellent specificity and affinity due to their 3D conformational structure. The binding parameters of the SNs and SNs-APT interaction with proteins (binding constant, binding stoichiometry, binding enthalpy, entropy and Gibbs free energy) were evaluated by isothermal titration calorimetry. The proteins were also analyzed as free solvated species and adsorbed onto the nanosystems to examine the changes in their thermal stability. The thermodynamic fingerprint shows that the binding has an entropic character dominated by the entropy gain associated with solvent release and reorganization. The thermodynamic approach of such binding events may aid future development of efficient formulations with potential for applications in nanomedicine.