For daily and between-transfer cleaning, V&P Scientific recommends the VP 110 Pin Cleaning Solution. This proprietary liquid uses a combination of acid and detergent to remove soiling caused by cell debris, salts, proteins and nucleic acids. However, it may become necessary to use a more aggressive cleaning agent; caked on protein, organic soils, or burnt-on carbon deposits caused by flaming handheld replicators can affect transfer volume and consistency, and can be difficult to remove.
For these cases, a solution of Sodium Hydroxide, or caustic soda, is recommended for deep cleaning. V&P Scientific pins are made from stainless steel and are not damaged by high pH, though, we recommend against exceeding solutions of more than 3% sodium hydroxide to avoid pitting of the stainless steel. Start with a 1% solution and increase for subsequent cleanings if needed. For best results, use the NaOH solution hot- between 60 and 80 degrees C. You can adjust the concentration, temperature, and residence time of the pins in the solution to accommodate the level of soiling.
A sonicator may also be used to aid in cleaning, and can help maintain the temperature of the cleaning solution. Be sure to cover the pin tool during sonication to avoid splashing and wear all appropriate PPE as hot caustic solutions are extremely dangerous. An example cleaning procedure is described below:
1. Prepare a solution of 2% NaOH in distilled or deionized water.
2. Heat the solution to 60C.
3. Immerse the Pin Tool in the hot solution, making sure that the float plate and frames do not come into contact with the solution. Only the pins should be submerged.
4. Sonicate with heat on 60C for 30 minutes.
5. Remove pins from cleaning solution and blot using V&P Scientific's VP 540DB blotting station.
6. Rinse pins well with distilled water. If any cleaning solution has splashed onto float plates, rinse the float plates. Blot.
7. Rinse pins well with 70% ethanol. If the float plates are wet, rinse the float plates with ethanol. Blot.
8. Air Dry Pin Tool
9. If pins are fully clean, perform the standard cleaning procedure with VP 110 Pin Cleaning solution and return pin tool to service.