Crude PNAs are purified by reverse phase HPLC using acetonitrile and water containing 0.1% TFA, followed by freeze-dry. and as a result the purified PNA will be protonated at all the basic amino groups (at A, C and the amino terminus). This helps keep the PNA in solution at the high concentration typical of PNA stock solutions.

The purified PNA (~100nmol) should be dissolved in 100-500 ¥ìl water and divided into aliquots. The aliquots are diluted with appropriate buffer solution before use. Aliquots that are not going to be used the same day should preferably be dried down, for example using a speed-vac concentrator or freeze-dryer.

Alternatively, the PNA can be dissolved in the appropriate buffer and the aliquots kept frozen until they are going to be used. This is not recommended and will only work for certain PNA sequences, i.e. short PNAs with few purines.

Occasionally, it may be difficult to dissolve a particular oligomer. Addition of 0.1% TFA or 10-20% acetonitrile to the aqueous solution and eventually heating the sample to 50¡ÆC for about 10 minutes most often help.

PNA oligomers have high affinity for glass surfaces and polystyrene. We recommend to use polypropylene or polyethylene materials during handling and storage of PNA.