Dye-aptamer

Dye-aptamer complexes can be used also to develop high specific and selective colorimetric chemosensors. For example, the displacement of the heptamethine dye 26b... 

Figure 12.18 (A) Colorimetric method. (B) Mimic color of a dye-aptamer complex in...

Aptamers are oligonucleic acids or peptide molecules that bind to a specific target biomolecule (Fig. 2). A dye molecule can be noncovalently or covalently bound to an aptamer. 

This chapter describes the synthesis, properties, and biomedical applications of cyanine and squaraine dyes encapsulated in CDs, CBs, Leigh-type tetralactam macrocycles, aptamers, and micro- or nano-particles. The optical and photochemical properties of supramolecular guest-host nanostructures that are based on intra-and intermolecular complexes of crown-containing styryl dyes with metal cations, and aggregates of carbocyanine dyes are discussed in a separate review [18]. 

Embedding of cyanine and squaraine dyes in macromolecules such as proteins, dendrimers, or aptamers also allows fine-tuning of the photophysical properties and the selectivity of these fluorescent probes and labels. 

The cyanine dye dimethylindole red (DIR), with significantly reduced affinity for double-stranded DNA and nonspecific RNA, was used to generate a fluorescent complex (fluoromodule) with high affinity RNA aptamers (Fig. 12) [8]. DIR has... 

Scheme 13 Illustration of the specific detection of target proteins by using the complex of a cationic polythiophene(2I)/dye-labeled ssDNA aptamer on glass slides. Reproduced with permission from [102]...

In addition to protein detection using specific antibody/antigen and aptamer/protein interactions, array detection was demonstrated based on nonspecific interactions between the CPE/dye-labeled ssDNA complexes and proteins [103]. The design concept is motivated by the fact that external agents can effectively perturb the electron coupling of optical units within the complex of CPE/ssDNA-C and in turn vary the FRET-induced fluorescence of both CPE (donor) and C (acceptor). Owing to discrepancies in local hydrophobic and charged domains of different... 

Wang J, Liu B (2009) Fluorescence resonance energy transfer between an anionic conjugated polymer and a dye-labeled lysozyme aptamer for specific lysozyme detection. Chem Commun 17 2284—2286... 

As with DNA aptamers, there is a trend towards applying RNA aptamers to a particular application. Allosteric ribozyme sensors have been developed which are specific for caffeine and aspartame. " Using a fluorescence-based assay, caffeine or aspartame may be detected in solution over a 0.5 5mM concentration range. Aptamers designed to malachite green (151) or other triphenylmethane dyes have been developed that enhance the fluorescence of the dye up to 2300-fold. " A further fluorescence-based assay has been... 

The additional attractive aspect of aptamers for researchers in the analytical field is the wide range of molecules for which they can be selected, including organic dyes (6), amino acids (7 ), antibiotics (8), peptides (9), proteins (10), vitamins (11), and also whole cells (12) or micro-organisms such as bacteria (13). 

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