HYBRIDIZATION BASED DNA SCREENING ON PEPTIDE NUCLEIC-ACID (PNA) OLIGOMER ARRAYS

Arrays of up to some 1000 PNA oligomers of individual sequence were sy nthesised on polymer membranes using a robotic device originally desig ned for peptide synthesis, At similar to 96%, the stepwise synthesis e fficiency was comparable to standard PNA synthesis procedures. Optiona lly the individual, fully deprotected PNA oligomers could be removed f rom the support for further use, because an enzymatically cleavable bu t otherwise stable linker was used. Since PNA arrays could form powerf ul tools for hybridisation based DNA screening assays due to some favo urable features of the RNA molecules, the hybridisation behaviour of D NA probes to PNA arrays was investigated for a precise understanding o f PNA-DNA interactions on solid support. Hybridisation followed the Wa tson-Crick base pairing rules with higher duplex stabilities than on c orresponding DNA oligonucleotide sensors. Both the affinity and specif icity of DNA hybridisation to the PNA oligomers depended on the hybrid isation conditions more than expected, Successful discrimination betwe en hybridisation to full complementary PNA sequences and truncated or mismatched versions was possible at salt concentrations down to 10 mM Na+ and below, although an increasing tendency to unspecific DNA bindi ng and few strong mismatch hybridisation events were observed.