Mini Extruder Pro FAQs
About the Mini Extruder Pro
What is new about the Mini Extruder Pro?The Mini Extruder Pro is an updated version of Avanti’s original Mini Extruder designed to improve the user experience while maintaining the same general extrusion workflow customers are familiar with. The updated design uses new luer-lock syringes instead of the original screw-cap syringe/needle configuration. The base and internal PTFE membrane support have also been redesigned to accommodate the updated syringe connection.
How is the Mini Extruder Pro different from the original Mini Extruder?
The main differences are the syringe connection, internal support geometry, and holder/base design. The Mini Extruder Pro uses gas-tight luer-lock syringes, while the original Mini Extruder used screw-cap syringes with needles. Because the syringe interface and internal PTFE membrane support have changed, many original Mini Extruder parts are not interchangeable with the Mini Extruder Pro. Also the PTFE Seal (610035) and the PTFE Extruder Washer (610019) being eliminated from the system, simplifying the design.
Are the new luer-lock syringes gas-tight?
Yes. The luer-lock syringes used with the Mini Extruder Pro are gas-tight. The updated connection is intended to improve handling and help reduce common leaking issues associated with syringe connection points.
What temperature can the Mini Extruder Pro syringes tolerate?
The new syringes have been tested for use up to 80 °C, which is the same maximum use temperature as the original Mini Extruder syringes.
Compatibility with Original Mini Extruder Parts
Can I use Mini Extruder Pro syringes with the original Mini Extruder?
No. The luer-lock syringe hub used with the Mini Extruder Pro is too large to fit into the internal PTFE membrane support of the original Mini Extruder.
Can I use the original screw-cap syringe needle with the new luer-lock syringe?
No. The needle from the original screw-cap syringe design is not compatible with the Mini Extruder Pro luer-lock syringe.
Can I use my original holder/base with the Mini Extruder Pro?
No. The Mini Extruder Pro must be used with the base designed for the updated system.
Will replacement parts for the original Mini Extruder still be available?
Replacement parts for the original Mini Extruder are expected to remain available until December 2026.
Will the original Mini Extruder still be available for purchase?
The original Mini Extruder will be removed from the Avanti Research website when the Mini Extruder Pro becomes available.
Membranes, Supports, and Expected Particle Size
Can I reuse membranes or polyester membrane supports?No. Membranes and polyester membrane supports are single-use consumables. Use them for one preparation, then discard them before starting a new batch.
What membranes are compatible with the Mini Extruder Pro?
Use circular membranes that are 19 mm in diameter. Avanti recommends using membranes from a reputable supplier and selecting the membrane material and pore size based on the formulation and application – though we only guarantee function with membranes that we supply.
What particle size should I expect from a given membrane pore size?
Extruded particle size is typically close to, but not identical to, the membrane pore size. As a general guideline, the resulting particle size may be approximately 10% higher than the stated membrane pore size. For example, extrusion through a 0.1 µm membrane will produce particles around 110–120 nm under suitable conditions.
Actual particle size depends on formulation composition, starting particle size, extrusion temperature, number of passes, membrane pore size, and sample preparation. Dynamic light scattering (DLS) or another suitable particle-sizing method is recommended to confirm the final size distribution.
How many passes are usually needed for size reduction?
Approximately 11 passes are commonly used during extrusion, although the optimal number of passes may vary depending on the formulation and desired size distribution. Always complete extrusion with an odd number of passes.
Preparing Samples for Extrusion
How should I choose a membrane pore size?Avoid using a membrane pore size that is too small in comparison to the starting particle size of the formulation. If the starting particles are too large, excessive back pressure can occur and material may be difficult or impossible to extrude.
A step-down approach is recommended. Start with a larger pore size membrane, then move to smaller pore sizes until the desired final particle size is reached. For example, a formulation may be passed through a 0.7 µm membrane, then 0.4 µm, then 0.2 µm or 0.1 µm, depending on the target size.
Should I sonicate my sample before extrusion?
Sonication before extrusion can help reduce the starting particle size and make extrusion easier. This helps for formulations that produce large or heterogeneous particles after hydration. A common troubleshooting approach is to sonicate the material before extrusion, then begin with a larger pore size membrane and step down gradually.
Does my lipid formulation need to be heated during extrusion?
Some formulations must be heated to extrude properly. During extrusion, lipid suspensions should be maintained above the transition temperature of the lipid formulation. If the formulation is below its transition temperature, the liposomes will not pass efficiently through the membrane, which will increase back pressure and contribute to leaking or poor material transfer and may result in a ruptured membrane.
For example, DPPC has a transition temperature of approximately 41 °C, so DPPC-containing formulations typically require heating above this temperature during extrusion.
Can the Mini Extruder Pro be used to prepare LNPs containing nucleic acids?
The Mini Extruder Pro is not designed for encapsulating nucleic acids into lipid nanoparticles. For nucleic acid-containing LNPs, solvent injection methods, particularly microfluidic mixing, are commonly used. In this approach, the nucleic acid is dissolved in an aqueous buffer and the lipids are dissolved in an organic solvent such as ethanol, then the two phases are combined under controlled mixing conditions.
Does Avanti provide protocols for preparing liposomes, LNPs, or other vesicles?
Avanti does not provide proprietary preparation protocols for specific customer formulations. For general method development, customers may consult the scientific literature for established approaches such as thin-film hydration for liposomes or solvent injection/microfluidic methods for LNPs.
Cleaning, Care, and Sanitization
How should I clean the Mini Extruder Pro?Clean the Mini Extruder Pro before first use, after every batch, and again before use if it has been stored for an extended period. A mild laboratory-appropriate detergent or detergent followed by thorough rinsing with copious amounts of deionized water is generally suitable for cleaning extruder components.
Always ensure that all detergent residue is removed before reassembly and use; rinsing with a solvent like methanol is a good step prior to storage.
How often should I clean the syringes and extruder?
Clean upon receipt of the equipment and subsequently before and after each use. Regular cleaning helps reduce residue buildup and supports consistent extrusion performance.
Can the Mini Extruder Pro be autoclaved?
The Mini Extruder Pro body components, including PTFE, stainless steel, glass, and aluminum parts, can tolerate autoclaving. However, PTFE can become more malleable under extreme temperatures, and Avanti’s warranty does not extend to damage caused by autoclaving.
Do not autoclave the syringes. The syringe components are not recommended for typical steam sterilization conditions such as 121 °C for 20–30 minutes.
Troubleshooting
My extruder is leaking. What should I check first?First, identify where the leak is coming from. Leaking may be caused by syringe wear, improper assembly, excessive back pressure, membrane clogging, or trying to extrude below the formulation’s transition temperature.
Make sure the system is assembled correctly. Ensure the membrane, filter supports, and syringes are properly seated. Confirm the formulation is being extruded above its transition temperature. Verify the membrane pore size is appropriate for the starting particle size.
Why is there back pressure during extrusion?
Back pressure is expected during extrusion. Extrusion forces particles through a membrane with a defined pore size to reduce the size. However, excessive back pressure can indicate the particles are too large to extrude through the pore size of the membrane being used. It is also an indication of the formulation is not being heated appropriately.
To reduce excessive back pressure, sonicate the suspension before extrusion, use a membrane with a larger pore size, and confirm the formulation is above its transition temperature.
The syringes are very hard to push and material is not transferring. What should I do?
This usually means the particles are too large for the membrane pore size being used or that the formulation is not extruding through the membrane efficiently. Measure the particle size, then choose an appropriate membrane pore size. Gradually step down to smaller pore sizes until the desired particle size is achieved.
Confirm the extrusion temperature is appropriate for the formulation. If you cannot confirm particle size, sonicate for at least 30 minutes. Start with a 0.7 µm membrane and step down to a smaller pore size until the desired particle size is achieved.
My syringe is not drawing up fluid. What should I check?
The syringe, plunger, or connection point may be worn or blocked. Inspect the syringe barrel, plunger, and luer-lock connection for signs of wear, damage, residue, or blockage. If the syringe does not draw or dispense fluid properly after cleaning and inspection, replacement parts or a replacement syringe may be needed.
Liquid is leaking from the back of my syringe. Why?
Liquid leaking from the back of the syringe usually indicates that the plunger tip is worn. Replacing the plunger may resolve the issue.
What should I do if a syringe needle or connector becomes stuck?
If any syringe component becomes stuck in the extruder assembly, stop using the device and carefully remove the part using appropriate tools and laboratory safety precautions. Damaged or deformed parts should not be reused.
Liposome Storage and Handling
At what temperature should I store my liposomal suspension?Once prepared, liposomal suspensions are most stable when stored refrigerated at 2–8 °C. Do not freeze liposomal suspensions unless the formulation has been specifically validated for freeze/thaw storage, as freezing can significantly change particle size.
What buffer conditions are recommended for liposome storage?
Neutral pH buffers are recommended for liposome storage. Storage outside the neutral pH range can reduce stability. Optimal buffer conditions depend on the lipid composition and intended application.
Warranty and Availability
Does the Mini Extruder Pro come with a warranty?
Yes. Avanti guarantees the product is free of workmanship defects for 30 days. If a workmanship-related issue occurs during this period, contact Avanti Research for assistance with replacement or exchange.
Can I test the Mini Extruder Pro before purchasing?
Avanti does not offer demos for this product.