Un example:
http://ist.inserm.fr/BASIS/elgis/fqmr/rapp/DDD/550.pdf
Page 12:
Il est possible de recourir à des anti-sens ADN, natifs ou modifiés, d'anomérie β ou α. Ces ADN, généralement courts (20 à 30-mer), forment avec la séquence ARN-cible un hétéroduplex, suivi probablement par une dégradation subséquente du brin ARN par la RNase H. sauf dans le cas des ADN α qui donnent deshétéroduplex insensibles à cette enzyme.

In English too:
http://www.neb.com/nebecomm/products/productS1267.asp
PrimerN (30-mer)

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&d...
Liposomal delivery of a 30-mer antisense oligodeoxynucleotide to inhibit proopiomelanocortin expression
An oligodeoxynucleic sequence of 30 bases (30-mer ODN), complementary to a region of beta-endorphin mRNA, was synthesized to have an antisense effect with regard to the expression of this oligopeptide. Following the solid-phase synthesis of the oligodeoxynucleotide, the 30-mer ODN was encapsulated within liposomes to provide a higher resistance against DNases and an improved entrance into cells. The most suitable liposome formulation as a 30-mer ODN carrier consisted of small unilamellar vesicles (50 nm) with an encapsulation capacity of 4.76 microL/micromol. The liposomal formulations containing dipalmitoyl-DL-alpha-phosphatidyl-L-serine presented fusogenic properties, which are of great importance for the delivery of antisense compounds. The antisense activity of 30-mer ODN-loaded liposomes was evaluated by the determination of beta-endorphin levels in AtT-20 cells. The free 30-mer ODN did not provide any lowering of the beta-endorphin production, whereas the liposomally entrapped compound elicited a concentration-dependent inhibition. The inhibition was determined by a sequence-specific binding of the 30-mer ODN with the target mRNA.

Voilà en Nederlands:
http://home.hetnet.nl/~tomhuls/folding/results.html
HET VOUWEN VAN EEN ALFA-HELIX GEBRUIKMAKEND VAN DISTRIBUTED DYNAMICS
(...)
20-mer van polyalanine: MPEG-filmpje -- 30-mer van polyalanine: MPEG-filmpje

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Note added at 5 hrs (2006-06-13 04:10:52 GMT)
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http://mailman.few.vu.nl/pipermail/fcsgroup-l/2005-April/000...
Bestelling: 0000146240

Uw ref Aantal Eh Kostenobject Omschrijving
---------- --------- --- ------------ ------------
1094654 1 EH 6405360 32-mer Oligonucleotide 50 nmol PCR
1094654 1 EH 6405360 30-mer Oligonucleotide 50 nmol PCR