Aptamer Synthesis Platform
Depending on the target, nucleic acid aptamers include DNA aptamers, RNA aptamers, protein aptamers, and cell membrane aptamers.
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Aptamer Synthesis Platform
Introduction to Nucleic acid aptamers
Nucleic acid aptamers, also known as aptamers, complexes, and chemical antibodies, are obtained by in vitro selex screening by the ligand exponential enrichment system evolution (SELEX) technique. It is a single-stranded deoxyribonucleic acid (ssDNA) or ribonucleic acid (RNA) that binds specifically and efficiently to a target molecule, and typically consists of 20-80 bases.
Nucleic acid aptamers obtained by in vitro screening are structurally stable, simple to synthesise and easy to modify, and are superior to commonly used biologically derived antibodies in terms of synthesis and application; in addition, nucleic acid aptamers can specifically bind to their targets through a variety of different forces, in general, they interact with small molecules based on a wide range of conformations (e.g., hairpins, concave-convex, pseudo-twisted, etc.) through hydrogen bonding, electrostatic forces, hydrophobic interactions, etc. molecules. Depending on the target, nucleic acid aptamers include DNA aptamers, RNA aptamers, protein aptamers, and cell membrane aptamers.
Alpha Lifetech's aptamer synthesis platform, which mainly involves SELEX aptamer library synthesis service and aptamer (DNA, RNA or XNA) development service, as well as downstream aptamer screening, aptamer optimization, and aptamer identification analysis services.
Technical process of Aptamer synthesis
Fundamental Principle and Technological Process
The process of nucleic acid aptamer synthesis technology is that a library of single-stranded oligonucleotides is chemically synthesised in vitro, mixed with the target substance, and a complex of the target substance and nucleic acid is present in the mixture, the nucleic acid that does not bind to the target substance is washed away, and the nucleic acid molecules that do bind to the target substance are isolated, and the nucleic acid molecules are used as templates to perform PCR amplification for the next round of screening. Through repeated selex screening and amplification, some DNA or RNA molecules that do not bind to the target substance or have low or moderate affinity for the target substance will be washed away, and aptamers, i.e., DNA or RNA with high affinity for the target substance, will be separated from the very large random library, and their purity will increase with the SELEX process, and eventually they will occupy a large portion of the library.
Technical Process Key Points
The process of selex screening of nucleic acid aptamers begins with the assembly of chemically synthesised random oligonucleotide libraries. Random oligonucleotide libraries have a large library capacity. High diversity is its significant advantage. Theoretically, if the random sequence in an oligonucleotide consists of n bases, the library capacity is 4n. If we consider the artificial modification library, it will increase the diversity of random sequences. Currently, the length of random sequences of oligonucleotides commonly used in SELEX experiments is generally 30 bases, and the library capacity can be as high as 10^18. The library capacity is crucial for selex screening of high-affinity ligands. However, since the concentration of the synthetic libraries is certain, too long random sequences will reduce the abundance of each oligonucleotide in the libraries, which will reduce the probability of selex screening for a specific aptamer. Generally, the library capacity of 10^13~10^15 in the first round of selex screening can meet the practical needs.
Fig.1 SELEX Technical Process
advantages of Nucleic acid aptamer
| Advantages | Details |
|---|---|
| Direct | Avoiding the traditional process of animal experiments and selecting directly from in vitro libraries; selex screening for aptamers of target molecules that are non-immunogenic, low-immunogenic or even toxic. |
| Wide Range of Applications | The target molecules can be organic dyes, amino acids, proteins, antibiotics, peptides, vitamins, drugs, even cells, pathogens, viruses, tissues, etc. |
| Strong Affinity | Aptamers show high specificity and affinity for in vitro screening of target molecules. |
| Stability | Aptamers are small in size, easy to obtain, reproducible in synthesis, and their stability can be enhanced by chemical synthesis and modification. The aptamers are chemically stable, have a long shelf life and can be transported at room temperature. |
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Analytical testing field: organic pollutants detection, small molecule drug detection, foodborne pathogens detection
In this field, the nucleic acid aptamer synthesis technology will be used in conjunction with colloidal gold immunochromatography, in which colloidal gold will first be prepared and quality identified, and then connected to the nucleic acid aptamer, characterised and sprayed on a binding pad, and test strips will be prepared using the polyclonal antibody to be detected as the detection line, and the complementary sequence of the nucleic acid aptamer as the quality control line, so as to analyse the presence of the target substance on the basis of the results of the negative and positive experiments.
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Biological field: development of biosensors
Nucleic acid aptamer sensors use the aptamer as a recognition element for recognising a target substance and converting the recognition result into a signal that can be measured. The signal conversion can be electrochemical, optical, temperature, piezoelectric, magnetic and micromechanical or a combination of these techniques. Compared with the existing detection methods, the nucleic acid aptamer-based sensors are generally easy to operate, specific, responsive and sensitive, and these advantages make them easier to be applied in real samples and have good prospects for development.
SELEX Aptamer Synthesis Service
Alpha Lifetech's SELEX aptamer synthesis service includes SELEX aptamer library construction, SELEX optimization, etc. Alpha Lifetech aims to obtain high affinity and high specificity SELEX aptamers for customers through an in vitro screening process.
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Nucleic Acid Aptamer Development Service
The nucleic acid aptamer development service of Alpha Lifetech is mainly on the ground of SELEX technology for SELEX aptamer screening, including the development of DNA aptamers, RNA aptamers and XNA aptamers, involving library design, oligonucleotide synthesis, library construction and verification.
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2018-07-16
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