Aptamer Synthesis Platform

KMD Bioscience offers a wide range of aptamer synthesis services, based on the SELEX screening technique, to choose from for our clients, including nucleic acid aptamer synthesis, protein aptamer synthesis, cell-SELEX aptamer synthesis, etc.

Nucleic Acid Aptamer

Nucleic Acid Aptamer is a class of single-stranded DNA or RNA molecules that can recognize specific molecules. It encompasses DNA aptamer and RNA aptamer and is produced by SELEX screening.

 Because of its unique advantages, aptamers have shown wide application prospects in many fields such as biosensors, disease identification, pharmaceutical research and development, and cell imaging. For example, in the field of biosensors, nucleic acid aptamers can be used to build detection platforms with high sensitivity and specificity; In terms of disease identification, aptamers can be used to detect biological molecules such as tumor markers and pathogens. In pharmaceutical development, aptamers can be used as carriers of targeted pharmaceuticals or therapeutic agents themselves.

DNA Aptamer

DNA aptamers are aptamers composed of deoxyribonucleic acid (DNA). They usually have a double helix structure and are composed of four bases (adenine A, thymine T, guanine G, cytosine C) connected by phosphodiester bonds. They are single-stranded oligonucleotide sequences, typically with 56-120 bases, that bind the target sequence efficiently by recognizing specific spatial structures.

DNA aptamers are widely used in biological analysis, biomedicine, and other fields because of their stability and easy chemical modification.

RNA Aptamers

RNA aptamers are aptamers composed of ribonucleic acid (RNA). RNA aptamers occur naturally within cells and are involved in a variety of biological processes, such as protein synthesis and gene expression regulation. They have more complex structures, such as hairpin rings, pseudoknots, etc., which contribute to their high affinity binding to target molecules.

Synthesis of Nucleic Acid Aptamer

The synthesis of nucleic acid aptamers provided by KMD Bioscience is mainly achieved through in vitro aptamer screening techniques, among which SELEX (Systematic Evolution of Ligands by Exponential Enrichment) is the most commonly used. Through multiple rounds of screening and amplification, SELEX technology can screen out DNA aptamers or RNA aptamers with high specificity binding to target molecules from a large number of random sequences of DNA or RNA oligonucleotide libraries.

Protein Aptamers

Protein aptamers target proteins, also called protein-targeted aptamers, which are short oligonucleotide sequences or short polypeptides obtained by in vitro screening that bind to corresponding proteins. These aptamers, through their specific sequences and structures, form stable complexes with target proteins and thus perform various functions in living organisms.   

Cell-SELEX Aptamer

Cell-SELEX Technology

The Cell-SELEX technology is a SELEX technique for screening directly at the cellular level, which is specifically designed to find aptamers that can specifically recognize molecules on the Cell surface. Cell-SELEX technology is based on the fundamental principle of SELEX technology. Through multiple rounds of affinity and elution process, aptamers with high affinity binding to specific molecules on the Cell surface are gradually screened.

Process of Cell-SELEX Aptamer Screening

Fig.1 Process of Cell-SELEX Aptamer Screening 

Initial Library Construction

Design and synthesize DNA or RNA libraries containing large numbers of random sequences. Sequences in these libraries are diverse and can cover a wide range of potential binding sites.

Target Cell Preparation

Select and culture target cells that express specific molecules on their surfaces as screening targets.

Screening Process

Binding: Nucleic acid molecules in the library are mixed with target cells, allowing them to bind to target molecules on the cell surface.

Separation: Separation of unbound nucleic acid molecules from the target cell-nucleic acid complex by physical or chemical methods (e.g., differential centrifugation, washing, etc.).

Amplification: PCR (polymerase chain reaction) amplification of nucleic acid molecules bound to target cells to obtain a sufficient number of specific binding sequences.

Iteration: Repeat the above binding, separation, and amplification steps several times (usually several to dozens of rounds) to gradually enrich the nucleic acid sequence with the strongest binding force to the target molecule.

Sequencing

The final enriched nucleic acid sequence was cloned and sequenced to determine its sequence information.

Aptamer identification and optimization

The binding affinity between the aptamer and the target molecule was determined by biological experiments, and the aptamer with high affinity and specificity was selected for follow-up study. The aptamer sequence was optimized to improve its binding performance and stability.

Application of Cell-SELEX

Aptamers targeting specific molecules on the surface of tumor cells are screened by Cell-SELEX technology, which can be used for early estimate and therapeutic monitoring of tumors. For example, studies have shown that aptamers screened by Cell-SELEX technology can specifically bind Frizzled-8 protein on tumor Cell surface and can be used for fluorescence imaging differential diagnosis of tumor tissues.

Fig.2 Application of Cell-SELEX In Cancer. (Reference Source: Progress on Aptamer for Cancer Theranostics[J].)

Reference

[1]. DONG Qian, LI Zhaoqian, PENG Tianhuan, CHEN Zhuo, TAN Weihong. Progress on Aptamer for Cancer Theranostics[J]. Chem. J. Chinese Universities, 2020, 41(12): 2648.

[2]. Shraim AS, Abdel Majeed BA, Al-Binni MA, Hunaiti A. Therapeutic Potential of Aptamer-Protein Interactions. ACS Pharmacol Transl Sci. 2022 Nov 4;5(12):1211-1227.

How to Order?

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