How to avoid nonspecific amplification (band) in PCR - (Jul/26/2013 )

Hi,
How to avoid nonspecific amplification in PCR from PCR?

thanks.

check the magnesium concentration you used as well as annealing temperature. Usually high mg+ results in non specific amplification

Gradient PCR to set specific Tm for the target gene.

very specific (and long?) primers

higher annealing temperatures help too

Several additives such as:

dimethylsulfoxide (DMSO)

glycerol

formamide

betaine

tetramethylammonium chloride (TMAC)

polyethylene glycol (PEG)

can help but not necessarily.

Some are also seen as additives that facilitate the reaction, increasing yield or work against inhibitors, the functions seem to differ between authors and are somewhat difficult to define precisely. So it's trial and error, as with the recommended concentrations.