Atomic force microscopy and photon correlation spectroscopy: two techniques for rapid characterization of liposomes

Area of Science:

• Nanotechnology
• Materials Science
• Pharmaceutical Sciences

Background:

• Evaluating nanoparticle heterogeneity in drug delivery systems like liposomes is challenging due to their small size and complex characteristics.
• Liposomes are crucial nanometric drug delivery systems, but their physical stability during storage is a key concern for efficacy.

Purpose of the Study:

• To investigate how lipid ratio and composition affect the physical stability of liposomes during storage.
• To compare the effectiveness of Atomic Force Microscopy (AFM) and Photon Correlation Spectroscopy (PCS) in assessing liposome characteristics.

Main Methods:

• Liposomes were prepared using various lipid mixtures and preparation techniques.
• Atomic Force Microscopy (AFM) was used to visualize liposome morphology.
• Photon Correlation Spectroscopy (PCS) was employed to measure liposome size distribution and monitor changes over a 7-month period.

Main Results:

• AFM confirmed the spherical shape of liposomes immediately after preparation.
• Both AFM and PCS showed comparable average liposome sizes throughout the 7-month storage experiment.
• PCS analysis and AFM imaging indicated significant liposome aggregation during storage, correlating with increased polydispersity index.
• Lipid composition was identified as the primary factor influencing liposome stability, more so than the preparation method.

Conclusions:

• Liposome aggregation and reduced physical stability during storage are influenced by lipid composition.
• Atomic Force Microscopy (AFM) offers a relatively simple and effective method for technological control of liposome size distribution and batch-to-batch reproducibility.
• AFM can aid in optimizing liposome formulation for enhanced stability in drug delivery applications.