Aptamer Development Platform

Aptamers are single-stranded oligonucleotides (DNA, RNA, or XNA) that bind target molecules with high affinity and specificity, making them valuable alternatives to antibodies in biosensor development, diagnostics, and therapeutics.

Alpha Lifetech's aptamer platform encompasses two integrated services: an aptamer synthesis platform offering SELEX-based library construction and custom aptamer development (DNA, RNA, and XNA); and an aptamer screening platform delivering target-specific screening against proteins, peptides, cells, small molecules, and metal ions, complemented by downstream optimization and characterization.

Aptamer Synthesis Platform

SELEX aptamer library synthesis service

Library construction is the foundation of SELEX technology. Our service builds high-diversity, single-stranded oligonucleotide libraries through in vitro chemical synthesis, providing the candidate sequence pool essential for downstream aptamer screening.

Library synthesis follows three core steps:

Steps	Technology Details
Identify Target Molecules	Define the screening target — proteins, nucleic acids, small molecules, metal ions, or other molecule types.
Random Sequence Design	Design random sequence length and base composition based on target characteristics and screening requirements. Random regions typically range from tens to hundreds of nucleotides.
Synthesis of Fixed Sequences	Synthesize oligonucleotide fragments with fixed flanking sequences (e.g., PCR primer sites) to enable amplification and iterative screening.

Each library undergoes quality control including concentration determination, sequence diversity verification, and accuracy validation by sequencing, ensuring it meets the requirements for subsequent SELEX screening.

Aptamer development services (DNA, RNA or XNA)

Nucleic acid aptamers - including DNA, RNA, and chemically modified XNA aptamers - are selected via SELEX through iterative cycles of library construction, target binding, isolation, amplification, and sequence identification. Alpha Lifetech offers end-to-end aptamer development with deep expertise across all three nucleic acid formats, delivering validated aptamers tailored to your specific target and application.

SELEX Technology Process

The SELEX process is performed over multiple iterative rounds, each comprising three key steps:

Library and Target Binding

The nucleic acid library is incubated with the target molecule — such as a protein or small molecule compound — allowing sequences with binding affinity to associate with the target.

Isolation of Unbound Molecules

Non-binding sequences are removed from the mixture using separation techniques such as affinity chromatography or magnetic bead separation, enriching the pool for target-binding candidates.

Amplification of Binding Molecules

Target-bound sequences are amplified by PCR, generating an enriched library that serves as the input for the next selection round.

Fig 1: SELEX screening process

Aptamer Screening Platform

Aptamer screening service

Alpha Lifetech provides specialized aptamer screening services across multiple SELEX platforms, supporting a broad range of target types:

Target Types	Technical Details
Protein Aptamer Screening	Screens for aptamers with high binding specificity to target proteins. Compared to antibodies, protein aptamers offer easier synthesis, greater stability, and lower sensitivity to environmental conditions.
Peptide Aptamer Screening	Selects high-affinity, high-specificity aptamers against target peptides from large random libraries, with broad applicability in biomedical research and diagnostics.
Cell-SELEX	Uses whole cells, membrane receptors, or cell-surface proteins as targets, enabling aptamer selection without prior knowledge of specific molecular targets.
Small Molecule Aptamer Screening (Capture SELEX)	A SELEX variant optimized for small molecule targets that have limited functional groups and are difficult to immobilize on solid supports.
Live Animal-based SELEX	Conducts in vivo screening using live animal models, more accurately reflecting physiological binding conditions to assess aptamer efficacy and safety.

Aptamer optimization service

Aptamer performance can be limited by factors such as nuclease susceptibility, affinity loss during production, and rapid in vivo clearance. Alpha Lifetech offers tailored optimization strategies including sequence truncation, chemical modifications, and conjugation with functional groups - such as thiol, carboxy, amine, or fluorophore - to enhance stability, binding affinity, and applicability.

Aptamer characterization analysis service

Following selection, aptamers undergo comprehensive characterization to confirm binding performance and functional suitability. Our analysis covers affinity and specificity assessment, stability evaluation, and biological function verification, ensuring each aptamer meets the requirements of its intended application.