Microfluidic Formulation Techniques for Liposomal Drug Delivery

Liposomes are nanoscale vesicles composed of one or more phospholipid bilayers capable of encapsulating a wide range of therapeutic agents. Traditional bulk formulation methods often suffer from limited reproducibility, broad size distributions and scale-up challenges. Microfluidic formulation techniques address these issues by controlling the mixing of lipid-dissolved organic solvent and aqueous buffer streams within microscale channels under laminar flow. Key process parameters include the total flow rate, the flow-rate ratio between solvent and aqueous phases, and the geometry of the mixing region—ranging from hydrodynamic focusing junctions to chaotic micromixer structures. These devices enable the bottom-up assembly of liposomes with precise control over size, lamellarity and polydispersity, while minimising shear stress and thermal exposure of sensitive payloads. Continuous-flow microfluidic platforms further allow inline purification and high-throughput production, supporting the translation of liposomal formulations from laboratory research to clinical and industrial manufacturing.

Research from Nature Portfolio

Recent studies have advanced the understanding of microfluidic liposome production across both mechanism and scale. A module-based continuous-flow microfluidic system demonstrated the integrated formation, modification and purification of liposomes below 300 nm in under four minutes, achieving over 98 % lipid recovery and rapid removal of non-entrapped drug, protein and solvent. Investigations into herringbone-channel mixers revealed that intermediate phospholipid bilayer fragments and their fluidity critically determine final vesicle size; increased membrane fluidity consistently yielded smaller, more uniform liposomes. More recently, axisymmetric microfluidic vortex focusing has enabled the generation of liposomes as small as 27 nm with low size variance while operating at throughput rates exceeding 20 g/h. By tuning individual buffer and lipid flow rates, this approach offers a direct route to mass-production of size-tunable liposomes without compromising monodispersity.

Microfluidic Formulation Techniques for Liposomal Drug Delivery publication trend

The graph below shows the total number of articles in microfluidic formulation techniques for liposomal drug delivery across all publications each year (not limited to Nature Index journals).

Technical terms

Microfluidics: The manipulation of fluids within channels of micrometre dimensions to achieve precise control over mixing, reaction times and flow patterns.

Hydrodynamic focusing: A microfluidic technique where a central fluid stream is narrowed by flanking streams, enhancing mixing and interface control.

Flow-rate ratio (FRR): The volumetric ratio of the solvent stream to the aqueous stream, a determinant of mixing dynamics and vesicle size.

Total flow rate (TFR): The combined flow velocity of all inlet streams in a microfluidic device, influencing residence time and shear conditions.

Laminar flow: A regime characterised by parallel fluid layers with minimal turbulence, typical in microchannels and essential for predictable mixing.

Polydispersity index (PDI): A dimensionless measure of particle size distribution; values below 0.2 indicate narrow size distributions.

Phospholipid bilayer fragment: A transient, discoidal lipid assembly formed during rapid solvent exchange that evolves into closed vesicles.

Vortex focusing: A microfluidic mixing approach using a rotating flow field to confine and rapidly mix a lipid solution for controlled vesicle formation.

References

1. Liposome production by microfluidics: potential and limiting factors. Scientific Reports (2016).
2. High-throughput manufacturing of size-tuned liposomes by a new microfluidics method using enhanced statistical tools for characterization. International Journal of Pharmaceutics (2014).
3. Understanding the formation mechanism of lipid nanoparticles in microfluidic devices with chaotic micromixers. PLOS ONE (2017).
4. The Impact of Solvent Selection: Strategies to Guide the Manufacturing of Liposomes Using Microfluidics. Pharmaceutics (2019).
5. Formation and purification of tailored liposomes for drug delivery using a module-based micro continuous-flow system. Scientific Reports (2017).
6. Preparation of nanoliposomes by microfluidic mixing in herring-bone channel and the role of membrane fluidity in liposomes formation. Scientific Reports (2020).
7. Microfluidic vortex focusing for high throughput synthesis of size-tunable liposomes. Nature Communications (2022).