Aptamer Optimization Service

Aptamers are single-chain oligonucleotides that can bind specifically to target molecules. They form a specific three-dimensional structure after adaptive folding through various interaction forces such as nucleotide base complementary pairing, hydrogen bonding, π-π stacking, electrostatic force, etc. This structure binds specifically to target molecules through intermolecular force. Aptamers are usually produced by SELEX screening. Aptamer optimization methods mainly focus on improving the affinity, selectivity and stability of aptamers.

Alpha Lifetech is committed to providing customers with accurate and efficient nucleic acid aptamer screening and optimization services. The screening and optimization process is not only a key step in obtaining high-quality aptamers, but also an important foundation for advancing these applications. Alpha Lifetech continues to introduce cutting-edge technologies and optimize service processes to ensure that our services are always at the forefront of the industry and bring customers a more efficient nucleic acid aptamer screening and optimization service experience.

SELEX Aptamer Selection

Alpha Lifetech has been focusing on the nucleic acid aptamer development for many years, mainly divided into nucleic acid aptamer design, nucleic acid aptamer library construction, nucleic acid aptamer screening and nucleic acid aptamer synthesis.

SELEX screening technique is the main method for screening aptamers. Alpha Lifetech can not only provide SELEX aptamer selection, but also other methord based on SELEX technology, such as Cell-SELEX, CE-SELEX, Capture-SELEX,etc. Through in vitro screening of aptamers, aptamers that can specifically identify the target molecule and have high affinity to the target molecule are obtained, and then high-throughput sequencing is performed on the screened aptamers, and finally the aptamers are synthesized through in vitro chemical synthesis. In addition, Alpha Lifetech can optimize the selected aptamers and verify the functions of the optimized aptamers.

Introduction to Aptamer Optimization

Although the nucleic acid aptamers screened by SELEX technology have strong affinity for target molecules, in practical applications, the aptamers still need to be optimized to further improve the aptamer specificity, aptamer affinity and aptamer stability to meet the needs of specific application scenarios.

The main aptamer optimization methods include the following aspects:

Structure cutting

Truncation: By removing parts of the aptamer sequence that do not affect or less affect the binding ability of the target molecule, preserving the core recognition area, the length of the aptamer can be shortened, and its synthesis efficiency and aptamer stability can be improved.

Based on secondary structure simulation and empirical trial and error, the local higher structure of the aptamer (such as stem ring, pseudojunction, G-quadruplet, etc.) was artificially defined, unformed or paired single chains were removed, the stem was shortened, small convex rings were removed, rings were reduced, etc. Molecular docking technology is used to predict the three-dimensional structure of the aptamer and the target molecule for more accurate tailoring.

Introducing mutation

Random mutation: Using mutagenesis techniques (such as PCR mutagenesis) to introduce random mutations into the aptamer sequence, and re-screening by SELEX technology can obtain mutants with higher affinity and selectivity. This method can explore the diversity of aptamer sequences and discover new binding patterns and optimization directions.

Site-specific mutation: Based on structural analysis and binding site prediction, possible mutation sites are selected for single base or multi-base substitution to explore the effects of different sequences on aptamer performance. Site-specific mutation can precisely control the structural changes of the aptamer to optimize its performance.

Chemical modification

The aptamer is chemically modified, and modification groups are introduced in different positions of the aptamer (such as base, sugar ring, phosphate group, etc.) to improve the stability, anti-nuclease ability and affinity of the aptamer.

Fig.1 Common modifications of aptamers. (Reference source: Nucleic-acid” Book, “Nucleic acid aptamers ” Chapter

Common modifications include 2 '-fluororibose, 2' -amino ribose, 2 '-o-methylribose, LNA (locked nucleic acid), and unmethylated purine nucleic acid (UNA). These modifications can reduce the recognition of nucleases, increase the ability of aptamers to resist degradation, or alter their binding properties to target molecules.

Introducting Function Area

The aptamer is endowed with new functions, such as enzyme activity and fluorescence reporting ability. The ligand-binding region is combined with the catalytic region to produce an aptamer with enzyme activity. For example, adding regions that bind to fluorescence-emitting molecules creates a self-reporting aptamer that emits a fluorescent signal after successful target binding.