Figure 2: ATP-triggered Dox release from duplex.
(a) The fluorescence spectra of the Dox solution (1.33 μM) with increasing molar ratios of hybridized DNA duplex of ATP aptamer and its complementary single-stranded DNA (from top to bottom: 0, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1 equiv.) after 15 min of incubation in the HEPES buffer (5 mM). (b) The fluorescence spectra of Dox/Duplex (1.33 μM) at the molar ratio of duplex to Dox as 0.5 in the presence of different concentrations of ATP (0.2, 0.4, 1, 2, 4, 8 mM) after 15 min of incubation. (c) Fluorescence recovery ratios of Dox/Duplex in the presence of different concentrations of ATP, GTP, CTP and UTP (0.2, 0.4, 1, 2, 4, 8 mM). Error bars indicate s.d. (n=3). (d) Fluorescence recovery ratios of Dox/Duplex and Dox/cDuplex in the presence of 4 mM ATP. Error bars indicate s.d. (n=3). The fluorescence recovery ratio is indicated as (FNTP−F)/(F0−F), where F0 is the fluorescence intensity of Dox in the Dox solution without the duplex, and FNTP and F are the fluorescence intensities of Dox in Dox/Duplex at the same Dox concentration with the Dox solution in the presence and absence of NTP, including ATP, CTP, GTP and UTP, respectively. In (b–d), the buffer and salt condition is the HEPES buffer (5 mM) containing 10 mM MgCl2 and 137 mM NaCl. CTP, cytidine triphosphate; GTP, guanosine triphosphate; UTP, uridine triphosphate.
