Frequently Asked Questions: Sil-Select Stock

FAQ1: Can we make our own gradients using Sil-Select Stock ?
Yes you can. Sil-Select Stock is an isotonic stock solution of our silica based density gradient. To make your own gradients simply add adequate amounts of cell culture medium to make up the correct dilutions.
Note that the use of HEPES buffered dilution media is strongly encouraged since using HCO3-buffered media under air, will result in solutions with a very unstable pH.

FAQ2: How long can I use Sil-Select Stock after opening the bottle?
Two factors limit the shelf life of a product after opening the bottle:

  • Gas exchange: influences the pH
  • Contamination with viable organisms

We have performed open bottle tests on our media for up to 7 days and found that the product parameters remained within the specifications in this time period, taking into consideration that the bottle was opened under sterile conditions and the product was stored at 2-8°C after opening.

FAQ3: How long after liquefaction can density gradient centrifugation be performed?
Density gradient centrifucgation should be performed as soon as possible.

FAQ4: Which medium should be used for washing after performing density gradient centrifugation?
FertiCult Flushing medium or Sil-Select Plus Sperm Washing/Insemination medium.

FAQ5: How to handle a bad semen sample with a volume larger than 2.5ml?
Use more than one tube, with a maximum of 100×106 sperm cells, where the ideal volume ratio of upper layer/lower layer/semen isn’t altered (2.5ml each). The gradient/semen can be centrifuged for an additional 5-10 minutes (total of 23-28 min @ 400g).

FAQ6: How to resuspend the pellet after centrifugation?
A syringe or micropipet can be used. Vortexing should be avoided because this can harm the spermatozoa.