LNP Applications Highlight: Microfluidics Preparation Method for a Cationic Liposome-Based Vaccine Adjuvant

Posted on August 11, 2021

Microfluidics Setup

Microfluidics is a promising new method for preparing large-scale particle-based pharmaceuticals. This method is robust and can be scaled from the research laboratory to good manufacturing practice (GMP) production for use in clinical trials and commercial pharmaceuticals. Another useful characteristic of the microfluidics method is the ability to control various parameters. Dr. Yvonne Perrie and her research group conducted a study monitoring several parameters of microfluidics preparation of a cationic liposome-based vaccine adjuvant.

The adjuvant (CAF09b) is composed of dioctadcyldimethylammonium bromide (DDA), monomycoloyl glycerol analogue 1 (MMG), and polyinosinic:polycytidilic [poly(I:C)]. This cationic liposomal-based adjuvant is being assessed in therapeutic cancer vaccines. The current manufacturing method for this adjuvant is a top-down approach using bulk lipid hydration and high shear mixing. The larger lipid bilayers are broken down into smaller liposomes. This method regulates liposomal particle sizes via the input of energy from the applied force from high shear mixing. Microfluidics takes a much different approach in preparing liposomes. This is a bottom-up approach that builds liposomes by mixing lipid components and using lamellar mixing. Some of the variables that can be precisely controlled in this approach include total flow rate (TFR), flow rate ratio (FRR), aqueous buffer, organic solvent, and lipid concentration. This method can be used to prepare other nanoparticles with different morphologies. For example, complexing nucleic acids during liposome formation results in lipid nanoparticles rather than liposomes.

The primary difference between these manufacturing methods is the homogeneity of the conditions each lipid molecule experiences during the process. Conditions experienced during the microfluidics method are more reproducible and each lipid molecule will experience very similar conditions during the formulations process. In the rehydration/high shear mixing method, individual lipid molecules may experience vastly different conditions depending on their location in the sample. Also, the microfluidics method is easier to scale up and can be set up to run as a continuous process. This particular study evaluated different process parameters and their effect on the particles that were produced.

The study successfully transferred the manufacturing of CAF09b from a slow, complex, multi-stage process to a microfluidics-based, single-step liposome synthesis process. Satisfactory particle size and colloidal stability physicochemical characteristics were achieved. The study found that particle size was heavily dependent on FRR and colloidal stability was dependent on the concentration of lipid and organic solvent. Importantly, the zeta potential and adsorption rates for poly(I:C) were not altered by changing the manufacturing method. And ultimately, the cellular response to the microfluidics manufactured CAF09b adjuvant was no different than the response produced by the HPV-16 E7 antigen itself. This study shows some of the characteristics of microfluidics-based manufacturing of liposomes and other lipid-based nanoparticles that make it so appealing in large-scale manufacturing.

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Click HERE to read the full research article published by Dr. Perrie!