PNA binding and combined DNA-orientation test. The oligonucleotide LCF5-Btn attaches side A of the double DNA-construct to the surface and immobilizes the strand. On the side B a probe oligonucleotide (Cy5-cF6) which is Cy5 labelled is bound. The PNA-3927 can bind to the double stranded DNA at position 2668. Because two strands were combined, the PNA can bind to two identical positions. With help of an adapter oligonucleotide the PNA is detected by hybridizing a fluorescence labelled marker.