Abstract
The ultimate goal in any biosensor development project is its use for actual sample detection. Recently, there has been an interest in biosensors with aptamers as bio-recognition elements, but reported examples all deal with standards, not human serum. In order to verify the differences of aptamer-based biosensor and antibody-based biosensor in clinical detection, a comparison of the performance of aptamer-based and antibody-based quartz crystal microbalance (QCM) biosensors for the detection of immunoglobulin E (IgE) in human serum was carried out. Aptamers (or antibodies) specific to IgE were immobilized on the gold surface of a quartz crystal. The frequency shifts of the QCM were measured. The linear range with the antibody (10–240 μg/L) compared to that of the aptamer (2.5–200 μg/L), but a lower detection limit could be observed in the aptamer-based biosensor. The reproducibility of the two biosensors was comparable. The aptamers were equivalent or superior to antibodies in terms of specificity and sensitivity. In addition, the aptamer receptors could tolerate repeated affine layer regeneration after ligand binding and recycling of the biosensor with little loss of sensitivity. When stored for three weeks, the frequency shifts of the aptamer-coated crystals were all greater than 90% of those on the response at the first day.
Highlights
Systematic evolution of ligands by exponential enrichment (SELEX) is an iterative selection procedure used to identify oligonucleotides with desired properties
The SELEX-derived aptamers generally have a high degree of similarity to antigen–antibody binding in both their specificity and affinity
Aptamers were likely to be immobilized in a denser arrangement than antibodies due to their smaller size, signal saturation did not shift to higher concentrations
Summary
Systematic evolution of ligands by exponential enrichment (SELEX) is an iterative selection procedure used to identify oligonucleotides with desired properties. Single-stranded DNA or RNA molecules that fold up into unique 3-D structures, which allows them to bind to other target molecules. Since their discovery about 20 years ago [1,2], aptamers have exhibited high affinity to their targets with. Even different conformational states of the same target molecule can be discriminated by using the aptamers with high specificity [3,4] Due to these characteristics, aptamers have been successfully used in different areas of biotechnology such as purification processes [5], target validation [6], drug discovery [7], diagnostics [8], and therapy [9,10]
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