text: Another approach to prevent or reduce PD formation is by modifying the primers so that annealing with themselves or each other does not cause extension.
  HANDS (Homo-Tag Assisted Non-Dimer System): a nucleotide tail, complementary to the 3 end of the primer is added to the 5 end of the primer. Because of the close proximity of the 5 tail it anneals to the 3 end of the primer. The result is a stem-loop primer that excludes annealing involving shorter overlaps, but permits annealing of the primer to its fully complementary sequence in the target.
  Chimeric primers: some DNA bases in the primer are replaced with RNA bases, creating a chimeric sequence. The melting temperature of a chimeric sequence with another chimeric sequence is lower than that of chimeric sequence with DNA. This difference enables setting the annealing temperature such that the primer will anneal to its target sequence, but not to other chimeric primers.
  Blocked-cleavable primers: a method known as RNase H-dependent PCR (rhPCR), utilizes a thermostable RNase HII to remove a blocking group from the PCR primers at high temperature.  This RNase HII enzyme displays almost no activity at low temperature, making the removal of the block only occur at high temperature.  The enzyme also possess inherent primer:template mismatch discrimination, resulting in additional selection against primer-dimers.
  Self-Avoiding molecular recognition systems :also known as SAMRS, eliminating primer dimers by introducing nucleotide analogues T*, A*, G* and C* into the primer. The SAMRS DNA could bind to natural DNA, but not to other members of the same SAMRS species. For example, T* could bind to A but not A*, and A* could bind to T but not T*. Thus, through careful design, primers build from SAMRS could avoid primer-primer interactions and allowing sensitive SNP detection as well as multiplex PCR.