Charge Effects: Influence of Surface Charge on Protein Corona Adsorption Behavior on Liposomal Formulations

Background: Liposomes have been successfully used in clinics as an excellent drug delivery system. However, once they enter the body, they adsorb surrounding proteins and form a protein corona, which affects how liposomes behave in vivo. Therefore, controlling the formation of the protein corona is crucial for achieving effective treatment outcomes. Among the many variables affecting liposome protein corona formation, the composition of the liposomes themselves and the surrounding ionic environment are two particularly critical factors. Methods: In this context, this study selected bovine serum albumin as a model protein to investigate the influence and mechanism of physiologically relevant inorganic ions (magnesium chloride) and varying proportions of cationic lipid components (1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)) on protein adsorption behavior of liposomes. We evaluated characterization parameters, including particle size and zeta potential, and employed various spectroscopic techniques to elucidate the changes during the interaction between bovine serum albumin and liposomes. Results: The zeta potential results showed that liposomes without DOTAP exhibited a significantly negative potential (-45.20 ± 0.24 mV), while the zeta potential became increasingly positive with higher DOTAP proportions (+19.64 ± 0.39 mV and +51.03 ± 1.74 mV). Correspondingly, the amount of protein adsorption also increased with the rising DOTAP content. Furthermore, fluorescence spectroscopy indicated that the addition of either DOTAP or magnesium ions led to a decrease in both the K_sv and K_a parameters. Conclusions: Specific hypothetical models were advanced subsequently; per the varying proportion of DOTAP, we proposed an insertion or surface adsorption model, and further examined the influence of magnesium chloride on the interactions between the liposomes and proteins. We believe this study will provide a new research paradigm for the design and application of liposomes, laying a foundation for further in vivo investigations.