Aptamer Development Platform

Aptamers are single-stranded oligonucleotide (DNA, RNA or XNA) with the property of high affinity and high specificity that specifically bind to target molecules like antibodies, and they are extensively used for the development of biosensors, diagnosis and therapeutics.

The aptamer platform provided by Alpha Lifetech includes two categories: aptamer synthesis platform, which mainly involves SELEX aptamer library synthesis service and aptamer (DNA, RNA or XNA) development service, and aptamer screening platform including screening services based on SELEX technology for proteins, peptides, cells, small molecules, metal ions and other target molecules, as well as downstream aptamer optimization and identification analysis services.

Aptamer Synthesis Platform

SELEX aptamer library synthesis service

SELEX aptamer library synthesis service mainly involves in constructing a library containing a large number of random single-stranded oligonucleotide sequences by in vitro chemical synthesis according the target moleculars. Library construction is the starting point of SELEX technology, which provides abundant candidate sequences for the subsequent screening process by constructing huge random libraries and increases the possibility of screening high-affinity aptamers.

Library synthesis is mainly divided into the following steps:

Steps	Technology Details
Identify Target Molecules	Identify the target molecules that need to be screened for aptamers, which can be proteins, nucleic acids, small molecular, metal ions, etc.
Random Sequence Design	Random sequence length, base composition and other parameters were designed according to the characteristics of target molecules and screening requirements. Typically, random sequences are between tens and hundreds of bases in length.
Synthesis of Fixed Sequences	Oligonucleotide fragments with fixed sequences (such as PCR primer sequences) at both ends are designed and synthesized, which will be used in the subsequent amplification and screening process.

The synthesized library still needs to be further processed for quality control. The concentration of the library was determined to ensure its applicability in the subsequent screening process. The diversity and accuracy of random sequences in the library were verified by sequencing and other methods to ensure that the quality of the library met the screening requirements.

Through the above steps, a high-quality and highly diverse SELEX aptamer library can be synthesized, which can provide abundant candidate sequences for the subsequent screening process.

Aptamer development services (DNA, RNA or XNA)

Aptamers usually refer to nucleic acid aptamers. Nucleic acid aptamers incudes DNA aptamers, RNA aptamers, and XNA aptamers which is chemically modified nucleic acid aptamers. The SELEX technique is widely employed for the development of aptamers. The basic workflow of aptamer development services includes library construction, target binding, isolation and purification, amplification, multiple rounds of screening, and sequence identification. For many years, we have focused on library construction and rich experience in aptamer development. We are committed to providing customer with better services.

SELEX Technology Process

The SELEX process consists of multiple rounds, each of which consists of the following key steps:

Library and Target Binding

The constructed nucleic acid library is mixed with specific target molecules (such as proteins, small molecule compounds, etc.), so that the nucleic acid sequences in the library have the opportunity to bind to the target molecules.

Isolation of Unbound Molecules

Nucleic acid sequences that are not bound to the target molecule are separated from the mixture by specific methods such as affinity chromatography, magnetic bead separation, etc.

Amplification of Binding Molecules

The nucleic acid sequence bound to a target molecule is amplified, usually using polymerase chain reaction (PCR) technology. For the subsequent screening phase, the amplified sequences will be used as the starting library.

Fig 1: SELEX screening process

Aptamer Screening Platform

Aptamer screening service

Alpha Lifetech offers a diverse range of specialized aptamer screening services applying various SELEX methodologies for different types of your molecules:

Target Types	Technical Details
Protein Aptamer Screening by SELEX	The main purpose of protein aptamer screening is to screen aptamers that can specifically bind to target protein molecules. These aptamers are simpler to synthesize, more stable and less susceptible to environmental factors.
Peptide Aptamer Screening by SELEX	Peptide aptamers are a class of short peptide sequences with high specificity and affinity, which can specifically bind to target substances and show a wide range of application potential in the biomedical field. Through a specific screening process, peptide aptamers that can specifically bind to target molecules are screened from a large number of random peptide sequence libraries.
Cell-specific Aptamer Screening (Cell-SELEX)	Target cells or specific molecules on the cell surface are prepared as targets. Targets can be whole cells, receptors on the cell membrane, proteins, or other small molecules.
Small Molecule Aptamer Screening by Capture SELEX	Capture SELEX is an in vitro screening technique for the screening of small molecule aptamers, which is a variant of SELEX. Capture SELEX is particularly well suited for aptamer screening of small molecule targets, which typically have fewer functional groups and are difficult to immobilization directly on solid phase supports.
Live Animal-based SELEX services	Live animal-based screening service is an experimental technique widely used in the fields of bioscience, medicine and biotechnology, which uses live animals as experimental models to screen and evaluate specific molecules, medician, therapeutics or biological processes. The services are designed to simulate the physiological environment in the human body to more accurately predict and evaluate the efficacy and safety of experimental results in the human body.

Aptamer optimization service

The hydrophilicity, high affinity loss during production, and rapid excretion of aptamers limit their application. At present, a variety of optimization methods have been explored to enhance the performance of aptamers.

We also have a variety of ways to optimize aptamer consisting of truncation, modifications, conjugation to the appropriate group (thiol, carboxy, amine, fluorophore, etc.).

Aptamer characterization analysis service

Aptamer characterization analysis service refers to the professional service of performance evaluation structure resolution and functional verification of the obtained aptamer to ensure that the aptamer meets the specific binding ability, stability and specificity requirements. It mainly includes affinity and specificity analysis, stability evaluation and biological function verification.