One way of physically introducing DNA into cells is as carried by liposomes.
Liposomes are lipid-bilayer bounded vesicles.
They can be formed by hydrating lipids in aqueous solutions. If DNA is present in the solution, DNA becomes incorporated into the liposomes. Liposomes interact with wall-less cells. The liposomal contents are transferred to the inside of the cell. Both membrane fusion and endocytosis have been implicated as mechanisms.