Microfluidic Digital Quantitative PCR to Measure Internal Cargo of Individual Liposomes

Area of Science:

• Biotechnology
• Nanotechnology
• Drug Delivery

Background:

• Lipid nanoparticles are crucial drug delivery vehicles for nucleic acids.
• Current bulk measurement methods obscure critical heterogeneity in liposomal formulations.
• Assessing individual liposome drug loading is essential for optimizing biopharmaceutical products.

Purpose of the Study:

• To develop a single-liposome analysis method for quantifying DNA copy numbers within individual liposomes.
• To assess and characterize population heterogeneity in liposomal drug formulations.
• To provide a tool for improving liposome synthesis and biopharmaceutical formulation uniformity.

Main Methods:

• Integration of digital PCR (dPCR) and quantitative PCR (qPCR) into a single microfluidic assay, termed digital quantitative PCR (dqPCR).
• dPCR was used to quantify captured liposomes, validating the single-liposome analysis regime.
• qPCR was employed to measure the DNA copy number within each individual liposome.

Main Results:

• The developed dqPCR method enabled parallel analysis of a large number of single liposomes.
• Significant population heterogeneity in DNA loading was revealed, which is undetectable by standard bulk analysis.
• The method successfully quantified DNA copy numbers within individual liposomes, demonstrating its efficacy.

Conclusions:

• The novel single-liposome analysis method provides unprecedented insight into liposomal formulation heterogeneity.
• This technique can inform and optimize liposome synthesis procedures for more uniform drug delivery systems.
• Enhanced uniformity in liposomal biopharmaceutical formulations has the potential to improve drug safety and therapeutic efficacy.