Opti-MEM allows one to keep cells in reduced serum conditions during transfection as it contains insulin, transferrin, hypoxanthine, thymidine, and trace elements which make up for lesser serum. Also Opti MEM is better buffered than DMEM with higher amount of HEPES and sodium bicarbonate and this will keep cells happy during transfection procedures
Serum negatively affects transfection efficiency in a wide variety of cells. So it is recommended to use opti MEM when one complexes DNA and transfection reagents such as lipofectamine. Since siRNAs typically take 48 hrs to show their effects, it would be preferred to keep the siRNA complexes in low serum free media for longer time points as this enhances their transfection. However many secondary cell lines are well transfected with siRNAs even in serum containing media such as DMEM.
Opti-MEM allows one to keep cells in reduced serum conditions during transfection as it contains insulin, transferrin, hypoxanthine, thymidine, and trace elements which make up for lesser serum. Also Opti MEM is better buffered than DMEM with higher amount of HEPES and sodium bicarbonate and this will keep cells happy during transfection procedures
Serum negatively affects transfection efficiency in a wide variety of cells. So it is recommended to use opti MEM when one complexes DNA and transfection reagents such as lipofectamine. Since siRNAs typically take 48 hrs to show their effects, it would be preferred to keep the siRNA complexes in low serum free media for longer time points as this enhances their transfection. However many secondary cell lines are well transfected with siRNAs even in serum containing media such as DMEM.
I've used DMEM for transfections before - Karthik is right that Opti-MEM is better for transfection purposes (it was kind of developed for it), but that doesn't mean there aren't cheaper alternatives. If your cells don't require serum, DMEM should be perfectly fine, and siRNA transfection results will be ok as well (see https://altogen.com/product/cho-transfection-reagent-chinese-hamster-ovary-cells/).
Opti-MEM is very good for transfection, but DMEM with no addition of serum is also OK for siRNA transfection, which is much cheaper and very convenient.
Genemedi launched a product of Lipogene, comparable to lipofectamine 3000. You could find more information on this website: www.genemedi.net/i/lipogene-transfection-reagent