Due to the low affinity of MAb therapy for biological macromolecules lipids and carbohydrates, the application of MAb has certain clinical limitations. To improve the affinity with the above biomacromolecules and lipids, carbohydrates, and other substances, the artificial ligand-aptamers are gradually produced and expanded. The aptamer is a kind of single-chain nucleic acid chain, that can be combined with a variety of different targets, with small size, low cost, uniform synthesis, custom modification, nucleic acid template properties, and other unique advantages, can expand the scope of the potential target, such as small molecule nucleic acid aptamer and ion aptamer can be used as a supplementary antibody, nucleic acid aptamer technology is now is developing rapidly. The nucleic acid aptamer is a kind of specific molecular recognition ability of single-stranded DNA or RNA molecules, by SELEX through in vitro screening, consists of 20~110 nucleotides, sequence contains random sequence and fixed sequence, by folding can form a tertiary structure, high affinity, can specifically binding target molecules of small molecule group.TEK Biotech has completed several aptamer projects, with rich experience and mature technology. In addition, TEK Biotech also provides customized ligand library design, antibody expression and purification, affinity determination, antibody sequencing, etc., to meet the needs of customers.

The basis for screening services for aptamers is the SELEX technology, The SELEX technology follows from researchers using the technology to synthesize a single-stranded oligonucleotide library in vitro, Our target molecules or target sites were then incubated in a library containing different nucleic acid sequences, Finally, the oligonucleotide without binding was washed out by the washing solution, Enabling unbound nucleotides and library separation, We then eluted the bound library before using a high concentration of the salt solution, The eluted oligonucleotides are the oligonucleotides we need that can bind to the target molecule, We then used PCR to deamplify oligonucleotides that can bind to the target molecule, Start with the next round of screening. Repeat the above steps for repeated rounds of screening, and each round involves the binding of the target molecule, isolation of the unbound sequence, and amplification of the bound sequence. As we repeated multiple screens, the higher the round of screening, the higher the specificity and affinity of our library, and eventually we can screen oligonucleotide sequences that are highly bound and highly affinity to our target molecules. However, we need to note that when screening RNA aptamers by RNA aptamer library synthesis service, we need to reverse transcription of RNA into DNA, and then conduct subsequent SELEX aptamer library screening.

In the nucleic acid aptamer library service, we may find that the nucleic acid aptamer library sequence is not enough, and diversity cannot meet our requirements, this situation may cause our build library no way to be all possible and molecular binding sites to be identified, may appear missing phenomenon, lead to our screening to high-affinity nucleic acid aptamer probability also reduced together. At the same time, sequence errors, deletions, or contamination may occur during the construction of the aptamer library, which will also reduce the quality of our library and reduce the possibility of getting high-affinity nucleic acid aptamers. Given the above series of problems, in the library design, the library design parameters are optimized, such as the sequence length of nucleic acid, nucleic acid GC content, secondary structure, and other factors, to improve the diversity of our library construction. TEK Biotech also uses advanced aptamer synthesis technology to ensure the randomness and diversity of our synthetic sequences and improve the efficiency of our synthetic sequences. At the same time, TEK Biotech also strengthened the quality control in each step of building the library and improved the quality of primers, templates, and enzymes by using high-quality reagents and strictly following the standard steps. At the same time, our company also tests the sequencing quality of the aptamer libraries to ensure that the libraries delivered to customers are of high quality and stable.

In the aptamer library service, we found that the process of building the aptamer library takes a long time, the instruments and materials are expensive, and the whole process is not efficient. At the same time, we may find that the constructed aptamer library does not bind well to the target molecule, and then the experimental screening effect is not good. The above situation may be our stumbling block in the process of building nucleic acid aptamer library, TEK Biotech can through the process of library construction optimization and the reasonable arrangement of experimental time, then use advanced efficient aptamer synthesis technology and amplification technology, improve the efficiency of our library construction, save our experimental time and cost. At the same time, at the beginning of the aptamer library design, TEK Biotech fully considered the characteristics of the target molecule and the need to combine with the aptamer, and the researchers designed the nucleic acid sequences with high affinity and specificity according to the above requirements. At the same time, in the process of library screening, TEK Biotech uses various screening strategies and optimization of various screening conditions to help us improve the binding ability of the library and target.

When screening nucleic acid aptamers, if the number of repeats is not enough, the specificity and affinity of our selected aptamers may be low. Therefore, with the continuous development of modern technology, the traditional SELEX aptamer library screening technology has been continuously improved and a series of related technologies have been derived. IP-SELEX is SELEX, which can be combined with immunoprecipitation; Cell-SELEX is operated at the cellular level and is generally used to screen aptamers that can identify cell surface molecules; Apta-Seq and high-throughput sequencing technology are combined to screen large-scale libraries, which greatly improves the efficiency of library screening. In addition, there are AFM-SELEX for atomic force microscope and CE-SELEX for capillary electrophoresis, which greatly improve the success rate of SELEX technology. The screening of nucleic acid aptamers enables the discovery of specific nucleic acid sequences of aptamers that bind to their target molecules with high affinity. The screening of nucleic aptamers provides new research directions for the treatment of diseases and the development of new drugs. Over the years, TEK Biotech has been committed to providing customers with high affinity, high specificity aptamer screening technology services, for customers' subsequent aptamer function verification, drug molecule screening, and other downstream research and development support.