One of the Metal circle gasket cheapest methods is transfection by calcium phosphate. A HEPES-buffered saline solution containing phosphate ion is combined with a calcium chloride solution containing the DNA to be transfected. When the two are combined, a fine precipitate of the positively charged calcium and the negatively charged phosphate is formed, fusing the DNA to be transfected on its surface. The suspension of the precipitate is then added to the cells to be transfected. The cells then take up some of the precipitate, and with it, the DNA.

A stable transfection must happen if the transfected gene has to remain in the genome of the cell and the daughter cells that follow. To achieve this, a marker gene is co-transfected, which offers the cell resistance towards a certain toxin. Few of the transfected cells will absorb the foreign genetic material into their genome. If the toxin is then added to the cell culture, only those few cells with the marker gene introduced into their genomes will be able to multiply, while other cells will die. This selective process will allow only the cells with a stable transfection to survive and they can be cultivated further. A common agent for stable transfection is Geneticin.

The term gene silencing is generally used to describe the "switching off" of a gene by a mechanism other than genetic modification. Gene expression (turned on) under normal circumstances is switched off by machinery in the cell. Mechanisms of gene silencing protect the organism's genome from part of the DNA capable of replicating itself and viruses. Gene silencing thus is part of an immune system protecting from infectious DNA elements.

RNA interference (RNAi) is a powerful method for inhibiting gene expression. Small/short interfering RNA or siRNA transfection is a recent method for introducing foreign genetic information by encouraging RNA interference. siRNA works by silencing key sequences on messenger RNA, which stops gene expression by severing them on the RNA strand. 

When RNA transfection was first used, double-strand RNA (dsRNA) was the way of delivery; but dsRNA elicited a viral response, and grew less effective over a period. Then chemically severed dsRNA or siRNA was used to cleave the mRNA which did not cause a viral response. 

siRNA transfection is thus the introduction of the siRNA into the cell through chemical and biological reagents. siRNA transfection is currently being researched as a means to deliver designer transfection genes into cancer cells targeting the faulty DNA directly, and there is great potential in using this method for treating a number of other human ailments.