aptamer screening service-Nucleic Acid Aptamer Synthesis Service

Nucleic acid aptamers exhibit exceptional specificity in recognizing and binding to their target molecules, allowing them to pinpoint targets amidst a myriad of molecules, effectively sidestepping the disruptions posed by nonspecific binding. Their binding capacity with target molecules is robust, sometimes even surpassing that of antibodies. This superior affinity renders nucleic acid aptamers exceptionally sensitive and precise in applications like detection and diagnosis. SELEX technology offers a highly efficient and targeted approach for the screening of nucleic acid aptamers, thereby advancing their utilization and progress across diverse domains. KMD Bioscience employs this SELEX technology to identify aptamers with strong affinity for specific, targeted substances from a randomly generated library of single-stranded nucleic acid aptamers.

KMD Bioscience uses advanced SELEX screening technology to accurately extract oligonucleotides with high affinity for targets from a large random library. After multiple rounds of screening cycles, SELEX fragments were sequenced based on their enrichment levels to obtain adapter sequences (RNA aptamers, DNA aptamers). Among them, the oligonucleotide library has been uniquely designed with fixed sequences at both ends and cleverly inserted with random sequences (RNA aptamers, DNA aptamers) in the middle. In the fixed sequence section, primer binding sites that are conducive to PCR amplification are specifically embedded. Random sequences, typically composed of 30 to 60 nucleotides, ensure high diversity in the library and enable effective binding of these sequences to target substances. The initial stage of library design plays a decisive role in screening effectiveness. The design of the fixed region must prevent self dimerization during amplification, therefore, the length of the primer region is precisely controlled between 18 and 21 nucleotides. Random regions are generally located within a length range of 30 to 60 nucleotides (nt), with 40 nt being a commonly used length. A shorter random region design facilitates subsequent truncation and application, while longer regions are more likely to screen for structurally complex and highly specific adapter sequences in adapter screening techniques. Single nucleotide molecules can dock and recognize high affinity binding sites on target molecules, and the resulting nucleotides can be assembled into short fragments as binding units for nucleic acid aptamers. A stable unit based on a thermally stable secondary structure (such as a mini DNA hairpin structure) is assembled together with a binding unit to form a full-length adapter. The selection of fixation medium is crucial in the process of ligand screening. Common fixed media include nitrocellulose membrane, gel column, microporous plate, etc. The properties of the target will affect the screening and design of aptamers. For example, for targets such as cells, bacteria, or viruses, the Cell SELEX method is often used for screening. For soluble small molecule targets, solid-phase adsorption and elution techniques or FluMag SELEX methods may be used. The selected and designed aptamers need to be validated and optimized to ensure their high affinity and specificity. Common validation methods include BLI, SPR measurement, etc. The detailed process of constructing libraries and screening aptamers at KMD Bioscience is shown in Figure 1.

Figure 1 Screening process diagram for nucleic acid aptamers

Nucleic Acid Aptamer Synthesis Service Workflow