Aptamers can be used in detection, useful in fields such as environmental science, where aptamers can detect pesticides or pollutants to gauge water quality. For example, an aptasensor has been developed to detect heavy metal ion pollutants in water. (1) One of our lab's prior projects focused on designing an aptasensor targeting E.coli to detect contamination in water.
Aptamers can be used in diagnosis, useful in early diagnosis of health-related diseases. One of our lab's prior projects focused on developing an aptamer targeting the protein HE4, used as a biomarker for diagnosis of ovarian cancer.
Aptamers can be used in therapeutics in applications such as aptamer-mediated target delivery to delivery drugs noninvasively through the usage of aptamer-nanoparticle complexes. There has been research for the development of using this technology in cancer therapeutics. (2)
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Systematic Evolution of Ligands by EXponential enrichment (SELEX), or in vitro selection, is a technique used to produce DNA or RNA oligonucleotides that bind to target ligands. SELEX starts with an initial library that contains a randomized region of nucleotides. The library is then thrown against the target ligand, and certain aptamer candidates bind to the target. Any unbound aptamers are washed away, leaving the bound aptamers to the ligand. The bound aptamers are then eluted and amplified through PCR. SELEX can be repeated to increase specificity of ligand binding and strength of aptamer, and the resulting aptamer candidates can be sent off for sequencing or binding affinity assays.
Aptamers are chemically synthesized, making them inexpensive and easy to mass-produce. Antibodies require cell culturing, which are expensive and labor-intensive (3).
Aptamers are single stranded DNA or RNA whereas antibodies are proteins. Antibodies are more susceptible to higher temperatures and pH changes than aptamers (3).
Aptamers are very small, around 30 kilodaltons, while antibodies are larger at around 150 kilodaltons. This allows aptamers to more easily enter tissues and even cells (3)
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(1) Tan, L., Chen, Z., Zhao, Y., Wei, X., Li, Y., Zhang, C., Wei, X., and Hu, X. (2016). Dual channel sensor for detection and discrimination of heavy metal ions based on colorimetric and fluorescence response of the AuNPs-DNA conjugates. Biosens. Bioelectron. 85, 414–421.
(2) Tan, L., Chen, Z., Zhao, Y., Wei, X., Li, Y., Zhang, C., Wei, X., and Hu, X. (2016). Dual channel sensor for detection and discrimination of heavy metal ions based on colorimetric and fluorescence response of the AuNPs-DNA conjugates. Biosens. Bioelectron. 85, 414–421.