Hello Deepshikha Keot

Primer dimer is formed in the PCR reaction when primers are at extra levels over the template concentration and liable to self-anneal or anneal the further primers to appear as small product in agarose gel (60% you could use 5.5 to 7% of DMSO.

If required, the exact concentration to match your requirement would need optimization. Use a gradient of 4, 5 and 6% DMSO in a reaction and choose the concentration best suited for your experiment.

Best.

Hi,

If possible, you could try to reduce the GC% in your primer sequence and make sure you don't have strong hairpin loops in the sequence. I like to use Generunner tool to analyse my primer sequences and it works very well. If the Tm for the hairpin loops is higher than the primer Tm then adding DMSO might help. DMSO from 1% to 5% final concentration can be used. Most times 1% DMSO worked for me when I was working with longer, GC rich primers.

Don't use too much DMSO as it can inactivate the polymerase. You will need to run gradient PCR to identify suitable Tm in presence of DMSO.

Some other factors you could change are,

1. Template: For gDNA 100-500ng, no more and for purified plasmids