Nonspecific Bands in PCR (End-point PCR Primers)

Question

Accepted Answer

Multiple unwanted bands appear on gel electrophoresis alongside or instead of the desired PCR product Common causes: 1) Primers have complementary sequences at 3′ ends causing primer-dimer formation 2) Annealing temperature too low allowing nonspecific binding 3) Suboptimal magnesium concentration 4) Excessive annealing time Solutions: 1) Verify primers lack complementary sequences at 3′ ends 2) Use hot-start polymerase to reduce nonspecific amplification 3) Increase annealing temperature in 2–5°C increments and minimize annealing time 4) Optimize magnesium concentration for each template and primer combination 5) Try nested PCR approach