Bio-Rad PDS-1000 / He™ and Hepta™ Systems - Manual (Page 36)

Fig. 5.1. Target shelf placement and corresponding target distances.
5.9 Microcarrier Selection
Types of Microcarrier
Two types of microcarriers are available, gold and tungsten. The density of these micro-
carriers is sufficient to penetrate a wide variety of cell and tissue types using the Biolistic
PDS-1000/He acceleration system.
Five tungsten particle sizes are available. The tungsten particles are less expensive, but
more irregular in shape and the size variation within a given particle size is much wider than
gold. This size variation makes optimization using a certain particle size more difficult. Also,
tungsten may be toxic to certain cell types and may oxidize to alter DNA binding.
Gold microcarriers are available in three sizes. Gold particles are more spherical and are
more uniform in size within a given sample than tungsten microcarriers. Gold is biological-
ly inert, but the DNA coating of this type of microcarrier is subject to more variation during
precipitation than tungsten.
Microcarrier Size
The velocity of the chosen microcarrier increases with larger particle size. Increased
microcarrier velocity has a major effect on particle penetration into target cells/tissue and
thus transformation efficiency.
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L1= 3 cm
L2= 6 cm
L3= 9 cm
L4= 12 cm