http://technologyinscience.blogspot.com/2014/01/aptamers-new-class-of-oligonucleotide.html Aptamers are single-stranded RNA or DNA oligonucleotides 15 to 60 base in length that bind with high affinity to specific molecular targets; most aptamers to proteins bind with Kds (equilibrium constant) in the range of 1 pM to 1 nM similar to monoclonal antibodies. These nucleic acid ligands bind to nucleic acid, proteins, small organic compounds, and even entire organisms. Aptamers have many potential uses in intracellular processes studies, medicine and technology. Aptamers are often identified using a technique called SELEX (Systematic Evolution of Ligands by EXponential enrichment). By this techniques aptamers(oligos) having high affinity and specificity to the target is isolated from the sequence pool after several rounds of selection.

1. Aptamers
A new class of Oligonucleotides for
Therapeutic & Diagnostic Use
Bio-Resource
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2. Aptamers - Definition
• Aptamers are oligonucleotides (DNA or RNA) having high
affinity and specificity in identifying the target molecules.
• The word aptamer is derived from the latin “aptus – fit” and
greek “meros – part”.
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3. Aptamer – Binding & Affinity
• Equilibrium Constant (Kd) of Aptamer – Protein Binding :
1 pico Molar to 1 nano Molar,.
• Aptamers can bind to nucleic acid, proteins, small organic
compounds.
• Aptamers are often identified using a technique called SELEX
Systematic Evolution of Ligands by EXponential enrichment.
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4. Aptamers – Special Features
• Aptamers have similar affinities as antibodies to the target
molecules.
• Greater Stability.
• Low Immunogenicity.
• Easier Large Scale Production.
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5. Structure of an Aptamer
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6. Aptamer – Target
Binding Mechanism
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7. Aptamer Selection Process:
Invitro Selection
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8. Aptamer Selection
• The aptamers are selected by incubating the target molecule
in a large pool of oligonucleotide.
• Aptamers can distinguish between closely related but non-
identical members of a protein family, or between different
functional or conformational states of the same protein.
• Specificity: Aptamers have high specificity.
Example:
small molecule theophylline binds with 10,000 fold lower
affinity to caffeine, that differs from theophylline by a single
methyl group.
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9. Aptamer Selection Methods
• Nitrocellulose Membrane Filtration-Based SELEX
• Affinity Chromatography and Magnetic Bead-Based SELEX
• Capillary Electrophoresis-Based SELEX
• Microfluidic-Based SELEX
• Cell-SELEX
• Other Method-Based SELEX : AFM, EMSA, and SPR, have been
performed in connection with SELEX.
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10. Advantages of Aptamers
• Easier and more economical to produce.
• Compared to antibodies, toxicity and low immunogenicity of particular antigens do not
interfere with the aptamer selection.
• Aptamers are capable of greater specificity and affinity than antibodies.
• Aptamers can easily be modified chemically to yield improved, custom tailored properties.
• Aptamers can specifically bound to either small molecules and complex multimeric
structures.
• Improved transport properties allowing cell specific targeting and improved tissue
penetration.
• Aptamers are much more stable at ambient temperature than antibodies.
• Ability to inactivate proteins, without altering genetic material.
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11. Disadvantages of Aptamers
• Lower levels of affinities than antibodies.
• Aptamers will not bind to some target molecules.
• Aptamers identification is expensive and labour intensive.
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12. Applications of Aptamers:
• New Drug Development
• Bio Imaging
• As Therapeutic Tool
• Drug Discovery
• Disease Diagnosis
• Hazard Detection
• Food Inspection
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13. References
Review Articles:
• Aptamer-modified nanoparticles and their use in cancer diagnostics and treatment, Christine
Reinemann, Beate Strehlitz- UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany.
•
• Aptamers and Their Biological Applications, Kyung-Mi Song, Seonghwan Lee and Changill Ban -
Department of Chemistry, Pohang University of Science and Technology, San31, Hyoja-dong,
Pohang, Gyeongbuk 790-784, Korea
Technical Resources
• Base Pair Biotechnologies
• Gene Link
• Integrated DNA Technologies
• Aptagen
• NeoVentures Biotechnology Inc
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14. Thank You
Bio-Resource
http://technologyinscience.blogspot.com/2014/01/aptamers-
new-class-of-oligonucleotide.html
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