What is AS1411?

AS1411 is a G-rich DNA oligonucleotide that functions as an aptamer of the protein nucleolin, found at high levels on the surface of cancer cells but not on the surface of normal cells.

What are aptamers used for?

Aptamers are short, single-stranded DNA, RNA, or synthetic XNA molecules that can be developed with high affinity and specificity to interact with any desired targets. They have been widely used in facilitating discoveries in basic research, ensuring food safety and monitoring the environment.

Are aptamers antibodies?

Key advantages of Aptamers over Antibodies Aptamers are synthetic molecules that can be raised against any kind of target, including toxic or non immunogenic ones. They are 10 fold smaller than antibodies and can be chemically-modified at will in a defined and precise way.

Are aptamers DNA or RNA?

Aptamer Diversity Early aptamer studies focused primarily on RNA. It is generally accepted that RNA aptamers form more diverse and intricate three-dimensional structures, enabling a greater number of conformations compared with DNA Aptamers (1,2).

How are aptamers synthesized?

Ease of synthesis: Aptamers can be synthesized using solid phase oligonucleotide synthesis, whereas antibodies have to be obtained using less efficient biochemical or biological methods.

What is the difference between aptamer and antibody?

They are in general more stable than antibodies, and have a longer shelf life. Aptamers are produced through a simple and inexpensive process and the time required to generate aptamers is comparatively short. Unlike antibodies, aptamers do not need animals or an immune response for their production.

How are aptamers produced?

Aptamers are generated via an in vitro process known as the Systematic Evolution of Ligands by EXponential enrichment, also known as SELEX. Tuerk and Gold (1990), aiming to find an RNA aptamer sequence that would bind T4 DNA polymerase, first termed the process.

How aptamers bind to their targets?

Aptamers are nucleic acid macromolecules that bind to molecular targets, including proteins, with high affinity and specificity. Stable tertiary structure, resulting from combinations of these secondary structures, allows aptamers to bind to targets via van der Waals, hydrogen bonding, and electrostatic interactions.

How does an aptamer work?

Aptamers are single-stranded oligonucleotides that fold into defined architectures and bind to targets such as proteins. In binding proteins they often inhibit protein–protein interactions and thereby may elicit therapeutic effects such as antagonism.

What is RNA aptamers?

RNA Aptamers are defined as RNA oligonucleotides that bind to a specific target with high affinity and specificity, similarly to how an antibody binds to an antigen. Furthermore, nucleic acids such as RNAs are generally considered to be more thermodynamically stable than peptides or antibodies.

Why are aptamers more stable than antibodies?

They bind their target with affinity similar or higher than antibodies. They are 10 fold smaller than antibodies and can be chemically-modified at will in a defined and precise way. They can be easily stored and delivered ; they can be reversibly heat-denatured.

What is the SELEX process?

Specifically, SELEX process includes (1) the incubation of target molecules with the random sequence pools, (2) and the subsequent separation of unbound oligonucleotides and the elution of bound oligonucleotides, (3) then PCR amplification of bound aptamers.

What is as1411 used for?

AS1411 is a 26mer unmodified phosphodiester-based guanosine rich oligonucleotide which, as a dimer, forms a serum-resistant quartet structure. It is postulated to exert anti-cancer activity by binding to cell surface nucleolin resulting in S-phase cell cycle arrest.

Is as1411 a non SELEX aptamer?

AS1411, a 26-mer DNA aptamer with G-quadruplex structure known as a non-SELEX aptamer that binds to nucleolin, was discovered serendipitously by Bates et al. [ 16 ]. This aptamer is heat stable and non-immunogenic.

How can as1411 aptamer be used to target cancer cells?

In this work, AS1411 aptamer was used not only for targeting nucleolin positive cancer cells, but also to control the mechanical transformation of the DNA nanorobot to expose the thrombin at the tumor site. 2.3.2.6. AS1411 aptamer conjugation to silica nanoparticles

How many as1411 aptamers are in nanorobot?

Next, the DNA nonostructure was rolled up using six pairs of AS1411 aptamer to form a hollow tubular nanorobot shielding thrombin from the innate coagulation system during delivery. Moreover, nanorobot was decorated with eight AS1411 aptamers for efficient cell targeting.