Bio-Rad Helios® Gene Gun System - Manual (Page 40)

1. Rewash remaining microcarrier prep 2–3 times using a
fresh bottle of 100% ethanol.
2. Flush Gold-Coat tubing with nitrogen gas for 15 min prior to
loading with DNA/gold microcarrier solution.
3. If using PVP, make a new stock of PVP in ethanol using a
fresh bottle of alcohol.
4. Resuspend gold/DNA pellet prior to first ethanol wash.
5. After drawing off the ethanol, quickly turn the Gold-Coat
tubing with your fingers prior to rotating.
8.3 Helios Gene Gun Operation
Problem LED display not lit.
Possible solutions Battery missing or discharged; replace battery.
Problem Device does not fire (helium burst does not occur).
Possible solutions 1. Check that the helium tank and regulator knobs are opened
and that there is sufficient helium in the tank.
2. Check that the helium hose is properly connected.
3. Check that the battery is good and that the LED display
indicates that a cartridge is in firing position.
Problem The first cartridge fires well but gold is not delivered in
subsequent cartridges.
Possible solutions Check that the O-rings are in place and are not worn (see Section 10.2).
Check that the cartridge holder is properly positioned in the Gene
Gun (see Section 5.2).
Problem The device fires but gold is not delivered.
Possible solutions 1. Check that the O-rings are in place and are not worn.
2. Check that the barrel liner is tight (see Section 10.2).
3. Check that the cartridge holder is properly positioned in the
Gene Gun (see Section 5.2).
4. Helium pressure is too low; increase the discharge pressure.
5. Cartridge preparation is bad; make new cartridges.
6. Too much PVP in tubes; increase helium pressure or reduce
PVP concentration.
Problem A discharge of helium occurs from the gun after first turning on
the helium regulator and pressurizing the system.
Possible solutions Open the helium regulator quickly one or two turns and pressurize the
system to > 100 psi. The pressure can then be re-adjusted to another setting.
If continuous helium discharge is observed after this, contact Bio-Rad.
8.4 In Vitro and in Vivo Targeting
Problem Gold does not penetrate skin or organ.
Possible solutions 1. Check that the helium pressure has not dropped below the
desired delivery pressure.
2. Increase the PVP concentration in the cartridge preparations.
3. Increase the delivery pressure.
4. Check that the gold has been discharged from the cartridge
after firing.
5. Use larger gold particles.
Problem Poor or no expression.
36