The introduction of genetically modified material into a target cell using non-viral (also: physicochemical) vectors is called transfection. Drawbacks compared to the use of viral vectors include the problem of overcoming the membrane of the target cell and, above all, difficulties in successfully integrating the transgene. Since these methods often require large numbers of transgene copies to be introduced into the cell in order to prevent the DNA sequence from being damaged or destroyed, for example by the cell's own ribonucleases (enzymes whose functions include the degradation of RNA), the risk of incorrect integration of these genes increases. In contrast, the advantages of non-viral vectors are the increased biological safety for the patient due to the absence of viral elements and the resulting reduced risk of an immunological reaction. In addition, there is less limitation with regard to the size of the transgene.

Generally, two variants of non-viral vectors can be distinguished: 

One option for transfection is to penetrate the membrane of the target cell using physical methods and then introduce the transgene. This can be done by means of electrical impulses (electroporation), magnetic fields (magnetofection), ultrasound (sonoporation), the mechanical injection of DNA (microinjection) or by using a so-called gene gun. 

The second option is to employ chemical processes, such as the use of cationic lipids or cationic polymers, which form condensed complexes with the negatively charged DNA via electrostatic interaction. This compound protects the transgene and simultaneously ensures successful introduction into the target cell as well as intracellular integration of the transgene. The use of inorganic particles of calcium sulfate, silicon, gold or similar also belongs to the chemical processes. As some chemical vectors can also be produced synthetically, the term synthetic vectors is also used in this context.