. Author manuscript; available in PMC: 2012 Oct 25.

Published in final edited form as: ACS Nano. 2011 Sep 7;5(10):7722–7729. doi: 10.1021/nn2006927

Table 2.

Surface adsorption and dissociation constants for HAP aptamers and the theophylline aptamer. Mutant 21-R gave no signal and was used as the reference sample in BSI experiments in free or packaged form as appropriate, so no K_d is given.

Aptamer	Small molecule	1/K_ads (SPR)	K_d (BSI)	Notes
21	1b	49.9 ± 9.5 nM	36.1 ± 23.6 pM
21-E	1b	223 ± 92 nM	350 ± 240 pM
21-R	1b	no binding ^b	no binding ^b
Qβ@21(s) ^a	1b	n.a.	30.0 ± 3.5 pM
Qβ@21(d) ^a	1b	n.a.	24.0 ± 2.4 pM
Qβ@21-E(s) ^a	1b	n.a.	3.4 ± 1.3 nM
Qβ@21-E(d) ^a	1b	n.a.	2.6 ± 1.1 nM
Qβ@21-R(s) ^a	1b	n.a.	no binding ^b
Qβ@21-R(d) ^a	1b	n.a.	no binding ^b
ThA	Theophylline	n.d.	1.32 ± 0.53 nM	literature: 0.21 – 0.86 µM ^c–^g
ThA	Caffeine	n.d.	no binding ^b	literature: ~3.5 mM ^h

^[a]

The @ symbol denotes an aptamer packaged inside the Qβ virus-like particle shell; values of K_d are calculated per particle. (s) indicates the use of the single-pasmid method, and (d) notes the use of a dual-plasmid system.

^[b]

No signal was observed at the highest ligand concentration tested.

^[c]

0.4 µM (eq. filtration).⁴⁴

^[d]

0.21 µM (eq. filtration).⁴⁵

^[e]

0.30 µM (UV-vis).⁴⁶

^[f]

0.86 ± 0.12 µM (ITC).⁴⁷

^[g]

0.3 ± 0.1 µM (fluorescence).⁴⁰

^[h]

Affinity determination was not performed for this aptamer sequence and caffeine, so the value listed is for a similar theophylline aptamer with the same binding site sequence (TCT8-4).⁶

(n.a. = not applicable; n.d. = not determined.)