for details of the synthesis and characterization of dyes 1 and 2 , as well as the preparation and purification of dna122 , see the supporting information available on the www under http://dx.doi.org/10.1002/open.201402137 . as a service to our authors and readers , this journal provides supporting information supplied by the authors . such materials are peer reviewed and may be re - organized for online delivery , but are not copy - edited or typeset . technical support issues arising from supporting information ( other than missing files ) should be addressed to the authors .
dna - based aptamers are commonly used recognition elements in biosensors for a range of target molecules . here , the development of a wavelength - shifting optical module for a dna - based adenosine - binding aptamer is described . 
 it applies the combination of two photostable cyanine - styryl dyes as covalent modifications . 
 this energy - transfer pair is postsynthetically attached to oligonucleotides via a copper(i)-catalyzed azide 
 alkyne cycloaddition by two structurally different approaches : 1 )  as nucleotide modifications at the 2-position of uridines and 2 )  as nucleotide substitutions using ( s)-amino-1,2-propanediol as acyclic linker between the phosphodiester bridges . 
 both dyes exhibit a remarkable photostability . 
 a library of dna aptamers consisting of different combinations of the two dyes in diagonal orientations were evaluated by their emission color contrast as readout . 
 further optimization led to aptasensors with improved fluorescent readout as compared with previously reported aptasensors . 
 this approach described is synthetically facile using simple propargylated phosphoramidites as dna building blocks . 
 as such , this approach could be applied for other dyes and other chemical / biological applications .