For 1cm distance it is 200psi
and for 3cm distance it is 50 psi

In Biolistics method of rdna technology, cells are bombarded with high velocity micro-particles of Gold or Tungsten. This method, also known as particle bombardment or gene gun, is widely used for delivering foreign DNA into plant or animal cells.

The pressure required for the Biolistics method depends on several factors such as the size and density of the particles, the distance between the particle accelerator and the target cells, and the desired penetration depth.

The process involves the following steps:

1. Particle Preparation:
- Gold or Tungsten particles are coated with the desired DNA.
- The DNA can be coated directly onto the particles or attached to small carrier molecules, such as spermidine.

2. Acceleration:
- The particles are loaded into a small cartridge or chamber.
- This chamber is placed within a particle accelerator or gene gun device.
- The accelerator produces a high-pressure pulse of gas, such as helium, which propels the particles towards the target cells.

3. Bombardment:
- The high-velocity particles are directed towards the target cells.
- The particles penetrate the cell walls and nuclear membranes, delivering the foreign DNA into the cell.

4. Selection and Regeneration:
- After bombardment, the cells are typically cultured under selective conditions.
- This allows only the cells that have successfully incorporated the foreign DNA to survive and proliferate.
- The cells can then be regenerated into whole plants or used for further analysis.

The pressure required for the Biolistics method varies depending on the specific setup and target cells. Typically, pressures in the range of 1000 to 5000 psi (pounds per square inch) are used. However, it is important to note that the pressure alone is not the only factor influencing the success of gene delivery. Factors such as particle size, shape, and density also play a crucial role in determining the efficiency of DNA delivery.

The Biolistics method offers several advantages for gene delivery, including the ability to deliver DNA into a wide range of cell types and the potential for delivering intact DNA without the need for complex vector systems. However, it also has limitations, such as potential damage to the target cells due to the high-velocity particle bombardment.

In conclusion, the pressure required for the Biolistics method of rdna technology can range from 1000 to 5000 psi. This method allows for the efficient delivery of foreign DNA into plant or animal cells and has become a valuable tool in genetic engineering and biotechnology research.