Скачать или смотреть Can Ultrafiltration Centrifugal Tubes Be Reused? A Guide to Cleaning and Sterilization

A common question in cost-conscious laboratories is whether ultrafiltration (UF) tubes can be reused. The short answer is yes, but with significant caveats. Reuse is feasible primarily for non-critical research applications, provided strict cleaning and validation protocols are followed to prevent cross-contamination, loss of performance, and membrane damage.

Part 1: Guidelines for Safe Reuse
Reuse is NOT RECOMMENDED for:

Applications requiring absolute sterility or being endotoxin-free (e.g., cell therapy, clinical samples).

Samples containing infectious agents, radiolabels, or difficult-to-remove substances (e.g., lipids, viscous lysates).

When membrane integrity is compromised (visible cracks, scratches, or altered flow rates).

If reuse is considered acceptable, adhere to these rules:

Limit Reuse: A single device should ideally be reused only 3-5 times for processing the same or very similar type of sample.

Label Clearly: Mark the tube with the sample type and usage count (e.g., "BSA-1/3").

Never Let the Membrane Dry Out: A dried membrane, especially one that has retained proteins, often suffers irreversible pore blockage and performance loss.

Part 2: Standard Cleaning Protocol
The goal is to remove all residual biomolecules and, crucially, the cleaning agents themselves.

1. Immediate Post-Use Rinse:
Immediately after centrifugation, disassemble the device. Rinse both the inner filter device (with membrane) and the outer collection tube thoroughly with deionized (DI) water or an appropriate cleaning solution to prevent sample drying.

2. Reverse Flushing (Key Step for the Membrane):

Place the inner device upside down in a clean outer tube.

Add DI water or mild cleaning solution until it just covers the membrane.

Centrifuge at a low speed (500-1,000 x g) for 1-2 minutes. This reverse flow helps dislodge particles trapped within the membrane pores.

Repeat 1-2 times.

3. Chemical Soaking (Choose based on contaminant):

General Proteins/Salts: DI water soak with agitation.

Robust Removal & Sanitization: 0.1 M Sodium Hydroxide (NaOH). Soak for 30-60 minutes at room temperature. This is highly effective for denaturing and removing proteins, lipids, and providing a level of microbial inactivation. First, verify chemical compatibility with your device's membrane and housing.

Stubborn Precipitates/Denatured Proteins: 1% SDS or 4M Urea soak for several hours.

Nucleic Acids: Commercially available DNase/RNase removal solutions or a dilute HCl soak.

4. Thorough Rinsing to Remove Cleaning Agents:
This is critical. Rinse both components exhaustively with DI water (at least 5-7 cycles) to ensure all traces of NaOH, SDS, etc., are removed. Perform a final reverse flush with DI water.

5. Drying and Storage:

Air-dry components upside down in a clean, dust-free environment (e.g., laminar flow hood).

Alternatively, dry in a low-temperature oven (do not exceed 50°C for most plastic devices).

Once completely dry, reassemble and store in a sealed bag.

6. Pre-Use Validation Test:
Before the next experiment, perform a blank run:

Load the buffer you plan to use.

Centrifuge and collect the filtrate.

Measure the UV absorbance at 280 nm and the pH/conductivity. Results should match those of the fresh buffer, confirming the absence of contaminant carryover.

Part 3: Sterilization Methods
If reuse for sterile applications is unavoidable, consider these methods after cleaning:

Chemical Sterilization/Sanitization: Soaking in 0.1 M NaOH for 30+ minutes is a common and effective bioburden reduction step for many research applications. This must be followed by exhaustive rinsing with sterile, pyrogen-free water.

Ethanol Treatment: For membranes compatible with alcohols (e.g., PES), a 70% ethanol soak for 20 minutes can be used. Rinse thoroughly with sterile water afterward.

UV Irradiation: Expose the clean, dry, and disassembled device to UV light in a biosafety cabinet for 30 minutes per side.

Important: Autoclaving (steam sterilization) is generally NOT recommended, as the high heat and pressure can warp the plastic housing and permanently degrade the microstructure of most UF membranes (particularly regenerated cellulose).

Conclusion
Reusing UF tubes is a balance between cost-saving and risk management. It can be done successfully for routine, non-GxR research by implementing a rigorous, multi-step cleaning protocol focused on reverse flushing, chemical soaking, and exhaustive rinsing, followed by a validation test. For critical applications where data integrity is paramount, single-use remains the safest and most reliable choice.