The 5
-amino-modified DNA oligonucleotides (5
-
AGAGAACCTGGGGGAGTATTGCGGAGGAAGGT-3 for the aptamer
and 5
-TGAAGCAGACTGAGGTACGTGTGAGGAGGGAG-3 for the
scrambled oligonucleotide) with a C6 spacer arm were synthesized
in Oligo Macrogen (Seoul, South Korea). The sequence of the
aptamer of adenosine used in this work has been reported by Yan
et al.[18]. Standard stock solution of adenosine (1000 g mL−1) was
prepared in MeOH–H2O (50:50, v/v). Working solutions of adenosine
were prepared daily by diluting stock solution with methanol
and 0.1 M acetic acid (99:1, v/v). Deionized water was prepared
by OES (Overseas Equipment & Services) water purification system
(OK, USA).
2.2.