(a) Immobilization of oligonucleotides via route A. H2N-(CH2)5-OPO3-d(CAG AGG TTC TTT GAG TCC TT) (entry 1, Table 1) and HS-(CH2)6-OPO3-d(CAG AGG TTC TTT GAG TCC TT) (entry 2, Table 1) visualized after hybridization with FAM-d(AAG GAC TCA AAG AAC CTC TG) (entry 7, Table 1). (b) Immobilization of oligomers via route B. H2N-(CH2)5-OPO3-d(CTC CTG AGG AGA AGG TCT GC) (entry 5, Table 1) and HS-(CH2)6-OPO3-d(CTC CTG AGG AGA AGG TCT GC) (entry 3, Table 1) visualized after hybridization with FAM-d(GCA GAC CTT CTC CTC AGG AG) (entry 8, Table 1).