Silver Nanoparticle Coated with Deep Eutectic Solvent as an Effective Medium for Improving the Structural and Thermal Stability of Immunoglobulin G Antibodies.

Immunoglobulin G (IgG), widely used in therapeutic and diagnostic applications, is prone to denaturation and aggregation, reducing bioactivity and shelf life and increasing immunogenic risks. Current methods fall short of preserving IgG's stability, highlighting the need for innovative strategies to enhance its resilience and therapeutic reliability. In this work, we investigated choline chloride:glycerol (ChCl:Gly)-based deep eutectic solvent (DES) and silver nanoparticle coated with DES (AgNP:ChCl:Gly) as effective stabilizers for IgG. Various spectroscopic, imaging, and size-determining techniques were utilized to assess formulation-dependent changes in IgG structure and thermal response. Thermal fluorescence spectroscopy studies were performed to obtain the apparent transition temperature (Tapp) in the presence of DES and AgNP coated with DES aqueous solutions. The measurements revealed a concentration-dependent increase in Tapp of IgG from 76.1 °C in buffer to 78.4 °C in the presence of DES and up to 82.9 °C with AgNP coated with DES at 0.4 mM, indicating enhanced resistance to thermal perturbation. Furthermore, dynamic light scattering showed formulation-dependent changes in the apparent hydrodynamic size (dH) and surface charge of IgG under the studied conditions. This work highlights the potential validity of using AgNP coated with ChCl:Gly in IgG formulations, highlighting their potential utility as formulation additives for improving the thermal and structural robustness of IgG.