How do I select aptamer?

Aptamers can be obtained through an iterative selection process known as SELEX (systematic evolution of ligands by exponential enrichment) by using single-stranded DNA or RNA. An initial pool of 1014-1015 random oligonucleotide (ONT) strands are subjected to binding with the target.

What is the aptamer sequence?

Aptamers are short nucleic acid sequences capable of specific, high-affinity molecular binding. They are isolated via SELEX (Systematic Evolution of Ligands by Exponential Enrichment), an evolutionary process that involves iterative rounds of selection and amplification before sequencing and aptamer characterization.

What is DNA aptamer?

Aptamers are a special class of nucleic acid molecules that are beginning to be investigated for clinical use. These small RNA/DNA molecules can form secondary and tertiary structures capable of specifically binding proteins or other cellular targets; they are essentially a chemical equivalent of antibodies.

Are DNA aptamers single stranded?

Aptamers are single stranded (ss)DNA or RNA molecules, typically 25–100 nucleotides, which fold into a well-defined secondary structure. Aptamers can be selected without knowing the cellular target.

What is cell SELEX?

Cell-SELEX is a term that describes the process whereby live cells are used to select aptamers for target recognition. Thus, cell-SELEX is a particularly promising selection strategy for various applications, including cancer research and therapy.

How do oligonucleotides work?

Oligonucleotides readily bind, in a sequence-specific manner, to their respective complementary oligonucleotides, DNA, or RNA to form duplexes or, less often, hybrids of a higher order. This basic property serves as a foundation for the use of oligonucleotides as probes for detecting specific sequences of DNA or RNA.

Is an aptamer sequence necessary?

7.6. It is not essential for the aptamers to be complementary to the target mRNA; instead its three-dimensional tertiary and quaternary structures determine the specificity and binding capabilities. Aptamers can be well utilized as nonimmunogenic alternatives of antibodies even at 1000 times higher doses.

Who invented aptamers?

While the process of artificial engineering of nucleic acid ligands is highly interesting to biology and biotechnology, the notion of aptamers in the natural world had yet to be uncovered until 2002 when two groups led by Ronald Breaker and Evgeny Nudler discovered a nucleic acid-based genetic regulatory element (which …

Can DNA act as an enzyme?

Deoxyribozymes, also called DNA enzymes, DNAzymes, or catalytic DNA, are DNA oligonucleotides that are capable of performing a specific chemical reaction, often but not always catalytic. This is similar to the action of other biological enzymes, such as proteins or ribozymes (enzymes composed of RNA).

What does SELEX stand for?

systematic evolution of ligands by exponential enrichment
SELEX stands for systematic evolution of ligands by exponential enrichment.

What is the purpose of SELEX assay?

Systematic evolution of ligands by exponential enrichment (SELEX) is an in vitro approach for determining binding affinities of proteins, peptides, drugs, and small molecules to either DNA or RNA (Ellington & Szostak, 1990; Tuerk & Gold, 1990; Yang, Yang, Schluesener, & Zhang, 2007).

What is SELEX used for?

Systematic Evolution of Ligands by EXponential Enrichment (SELEX) is a common method currently used for isolating high-affinity single-stranded (ss) DNAs or RNAs from a large library with random sequences [1,2,3].

How to select a DNA aptamer for cadmium detection?

Herein we chose Cd ( II) as a model of a small molecule with less sites, and proposed a novel SELEX strategy of immobilizing ssDNA libraries rather than target molecules on a matrix, for selection of aptamers with high affinity to Cd ( II ).

How are aptamers separate in the Selex system?

To incubate and separate target-specific aptamers, the conventional SELEX procedures generally need to immobilize target molecules on a matrix, which may be impotent to screen aptamers toward small molecules without enough sites for immobilization.

Can a CD-4 aptamer be used for colorimetric detection?

Moreover, the Cd-4 aptamer was considered a recognition element for the colorimetric detection of Cd ( II) based on the aggregation of AuNPs by cationic polymer. Through spectroscopic quantitative analysis, Cd ( II) in aqueous solution can be detected as low as 4.6 nM.

How is the dissociation constant of CD-4 aptamer determined?

The dissociation constant ( Kd) of Cd-4 aptamer was determined as 34.5 nM for Cd ( II ). Moreover, the Cd-4 aptamer was considered a recognition element for the colorimetric detection of Cd ( II) based on the aggregation of AuNPs by cationic polymer.