Preparation and Thermodynamic Characterization of Nanoliposomes for Cosmeceutical Applications

Nanoliposomes are systems composed of phospholipids or cholesterol that are used as carriers for topical delivery. Their formation, interaction, and stability depend on molecular organization and thermodynamics of self-assembly, describing how molecules spontaneously arrange into ordered structures by attractive or repulsive forces. These vesicles can encapsulate and transport substances, improving their stability, bioavailability, and skin penetration.

In this research, phosphatidylcholine (PC)-based nanoliposomes were prepared by ultrasonication at 25–40 °C. Lipid concentration ranged from 0.3 to 2.5 mM. Characterization included dynamic light scattering (DLS), zeta potential (ζ), scanning electron microscopy (SEM), and isothermal titration calorimetry (ITC). Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were determined using the following:

ΔG=−RTlnK

where R is the universal gas constant, T the absolute temperature, and K the equilibrium constant for lipid–lipid or lipid–additive interactions.

To describe micellization-related behavior, critical micelle concentration (CMC) and standard Gibbs energy of micellization were also considered using the following:

ΔGmic​=RTln(CMC)

According to the results, the most stable systems were found in a concentration range of 1.0 to1.2 mM, showing z values of -42.7 0.5 mV. This indicates a high stability. DLS measurements reported particle sizes between 115 and 135 nm with 1.1PDI. SEM images show spherical and homogeneous morphologies of liposomes, suggesting an efficient lipid packing and self-assembly. On the other hand, ITC experiments revealed exothermic binding profiles during formation. Thermodynamic analysis yielded negative values for enthalpy change (∆H° = -15 KJ/mol) at 25 ºC and 30 °C due to strong van der Waals and hydrophobic interactions. Nevertheless, positive values of ∆H° = 15 KJ/mol were obtained at 35 ºC and 40 °C attributed to a highly disordered structure. This indicates a reduced enthalpic contribution due to increased membrane fluidity. In summary, nanoliposomes could have a high potential to be used as nanocarriers in the cosmetic area.