3D Filters for Liposome Extrusion

Dr. Baldacchini is a scientist at Newport Corporation, creating micron-scale filtration devices to extrude liposomes with a uniform size distribution. Few research projects cover as many disciplines as this study,* encompassing micro-3D printing of filters, microfluidics, two-photon polymerization (TPP), femtosecond laser irradiation with chemical etching (FLICE), scanning electron microscopy (SEM), micromechanical compression and adhesion testing – all for liposome extrusion for drug delivery applications.

Complex polymeric microstructures with fine features can be fabricated by TPP. Large networks of micro-channels in fused silica can be created with FLICE. As a result of this work, a hybrid microfabrication approach is proposed to create microfluidic devices for liposome extrusion.

The structures created for this project required frequent imaging with a scanning electron microscope. This is one reason that Dr. Baldacchini decided to bring imaging in-house with a desktop SEM. He chose the Phenom because it was intentionally designed and engineered for R&D work, having a brighter source and quick sample loading. He also appreciated the expertise that Nanoscience Instruments could offer in support. At Newport, the Phenom SEM is used to confirm structural dimensions of microfabricated features like this filter shown here.

Phenom SEM image of microfabricated TPP structures for liposome extrusion

Phenom SEM image of microfabricated filter

Because of the strong liquid flows in microfluidic devices, the strength of the microstructures and their adhesion to glass also were investigated. The strength is quantified by the Young’s modulus retrieved by performing compression mechanical tests; adhesion is quantified by measuring the maximum force required to dislodge a polymeric microstructure from its substrate. These data were acquired using an FT-MTA02 Micromechanical Testing and Assembly Station from Nanoscience Instruments. A stress-strain plot is shown below for TPP microfabricated polymeric cubes.

Baldacchini_Femto_ForcevsZ.png

Stress-strain plot for a microfabricated cube

Read more: Tommaso Baldacchini, et al. “Microfabrication of three-dimensional filters for liposome extrusion” Proc. SPIE, vol. 9353, 93530W-1 (2015).