Bead Beating: A Primer (continued)
Hard Animal Tissues: Bone/Hair/Nail
Hard animal tissues such as bone, hair, fish scale,
and nail are best homogenized using a disproportionally large grinding ball
to crack the sample. Most hard tissues are ground cryogenically, using
liquid nitrogen to make substances extra brittle. Hair is very fine, making
it difficult to grind into a fine powder, while nail is more resilient and
requires cryogenic temperatures for homogenization. Bone,
however, can be homogenized with buffer because it is naturally brittle when
compared to hair and nail.
The size and mass of samples will influence which
ball size, bead beater and configuration one should use.
As homogenization is the result of crushing the sample between a grinding
balls and vessel wall, a hard plastic (such as polycarbonate) is needed.
Therefore, samples less than 100 mg are best homogenized in a 4 ml
polycarbonate vial with one 3/8” stainless steel or tungsten carbide ball.
Larger samples should be processed in a 15 ml polycarbonate
vial with two 7/16” stainless steel grinding balls. In the event that
stainless steel balls do not have enough energy to pulverize the sample,
tungsten carbide grinding balls can be substituted.
animal tissue requires grinding vials made of polycarbonate. If bead beating at ambient temperatures, do not overfill tubes with
buffer. For cryogenic grinding, omit buffer during the
processing. Buffers can be added after grinding, or the
sample can be left frozen (and archived) until needed.
||Prepare samples according to the following table:
||4 ml Vials
||15 ml Vials
||Up to 1 gm
||1 x 3/8"
||2 x 7/16”
|Bead Beater Speed
||Process the samples as stated in the table. During longer processing runs, sample may warm and melt.
||Sample homogenization can be monitored visually. For cryogenic grinding, homogenized sample should appear as a fine
powder. With bone, a homogeneous solution is an indication of an effective process. Small flakes of bone
may often be present in the bottom of the tube.
||Frozen samples can be stored. Alternatively, samples can be processed immediately after grinding.
||3/8’’ Stainless Steel (GBSS
375-1000-02), 7/16’’ Stainless Steel (GBSS
||24 Well PC Vial Set (PCVS
04-240-03), 15 ml Polycarbonate Vial Sets (PCVS
||See Appendix A
||Cryogenic grinding requires a GenoGrinder® or Mini G™. See Appendix A.
||Cryoblocks (4 ml and