Our Custom Aptamer Synthesis service provides sequence-defined DNA, RNA, modified nucleic acid, labeled, and conjugated aptamers for research teams developing binding assays, biosensors, affinity capture tools, imaging reagents, and targeted delivery models. Aptamers function through sequence-dependent folding, so successful production requires more than routine oligonucleotide synthesis. Length, base composition, secondary structure, modification placement, purification method, counterion, and final formulation can all influence whether the delivered material is suitable for the intended experiment.
We support projects from synthesis feasibility review through solid-phase or fit-for-purpose hybrid production, purification, analytical verification, formulation, and technical handoff. When a validated aptamer sequence is already available, our team helps translate it into a practical synthesis specification without assuming that sequence identity alone guarantees target binding. For early programs, we can also prepare randomized libraries and candidate panels while clearly separating aptamer synthesis from upstream target-specific selection.
Fig 1. Different types of modifications in aptamers. (Srivastava et al., 2021)
Preserving Functional Folding: A chemically correct sequence may still perform poorly if a label, linker, terminal group, or stabilizing modification disrupts the structure responsible for target recognition. We review modification position, spacer length, folding requirements, and assay conditions before finalizing the synthesis plan.
Managing Difficult Sequences: Long, GC-rich, repetitive, highly structured, or modification-dense aptamers can show reduced coupling efficiency, incomplete deprotection, aggregation, or low recovery during purification. Sequence-specific route selection helps identify these risks before material is committed to production.
Balancing Stability and Binding: Modifications such as 2'-fluoro, 2'-O-methyl, LNA, phosphorothioate linkages, or terminal caps can improve resistance to degradation or handling robustness, but they may also change conformation, duplex behavior, or target affinity. We help customers choose a rational modification pattern and recommend functional re-evaluation after structural changes.
Removing Failure Sequences: Truncated products and closely related impurities become more consequential as aptamer length and modification density increase. Purification is selected according to sequence, chemistry, scale, and downstream sensitivity rather than treated as a generic add-on. Related oligo analysis and purification support can be incorporated when a more detailed separation strategy is needed.
Delivering Assay-Ready Material: Customers often need more than a dry oligonucleotide. Counterion preference, concentration, buffer compatibility, nuclease-aware handling, label protection, and refolding instructions can affect first-use success. We define the requested format and documentation before synthesis so the final material fits the receiving workflow.
Our service platform is designed for customers who already have an aptamer sequence, need a randomized library, or want to compare several chemically defined candidates. Each project is scoped around the intended target environment, readout method, required purity, modification pattern, quantity, and formulation.
Sequence review, synthesis, labeling, conjugation, purification, and analytical verification can be combined in one project plan. This coordinated approach reduces the risk that a technically feasible oligonucleotide is delivered in a format that is unsuitable for binding, immobilization, sensing, or downstream assay development.
The appropriate synthesis strategy depends on whether the customer needs a fixed aptamer, a modified stability variant, a reporter-ready construct, a conjugate, or a selection library. The matrix below summarizes the main decision points that should be resolved before quotation and production.
| Aptamer Format | Best-Fit Research Need | Key Design Decisions | Primary Synthesis Considerations | Typical Deliverables |
| DNA Aptamer | Binding assays, biosensors, affinity capture, surface immobilization, and candidate comparison | Sequence length, folding buffer, terminal groups, spacer placement, purity level | GC-rich regions, self-complementarity, long sequences, purification recovery | Purified ssDNA aptamer, quantity data, identity and purity results as agreed |
| RNA Aptamer | Structure-sensitive binding studies, RNA interaction research, and functional RNA constructs | Native versus modified RNA, RNase handling, refolding conditions, label placement | Deprotection, hydrolysis risk, purification difficulty, sequence-dependent yield | Purified RNA aptamer, handling guidance, analytical results, selected formulation |
| Modified Aptamer | Programs requiring improved nuclease resistance, altered thermodynamic behavior, or greater handling robustness | Modification type, position, density, backbone pattern, terminal protection | Monomer compatibility, coupling efficiency, folding changes, need for binding re-evaluation | Defined modified sequence, structural map, analytical verification, comparison panel if requested |
| Labeled Aptamer | Fluorescence, imaging, plate assays, pull-down workflows, electrochemical sensing, and surface analysis | Reporter type, attachment site, spacer length, excitation or readout requirements | Dye stability, steric effects, hydrophobicity, conjugation recovery, light sensitivity | Labeled aptamer, label configuration, purity and identity data, handling notes |
| Aptamer Conjugate | Targeted delivery research, multicomponent sensors, affinity reagents, and cargo-binding studies | Cargo, linker, stoichiometry, attachment chemistry, target-facing orientation | Conjugate heterogeneity, aggregation, purification route, retained aptamer folding | Purified conjugate, composition data, analytical package, project-specific formulation |
| Long or Multivalent Aptamer | Extended structural domains, bivalent binding, scaffolded sensors, and fused oligonucleotide constructs | Domain order, linkers, total length, assembly strategy, folding sequence | Cumulative synthesis loss, truncations, assembly junctions, purification recovery | Full-length construct, route summary, analytical verification, refolding guidance where applicable |
| Randomized Library | SELEX input pools, reselection libraries, motif-focused pools, and candidate diversification | Random-region length, flanking primers, base distribution, fixed motifs, pool format | Representation bias, scale, amplification compatibility, purification choice | Defined library pool, architecture record, quantity data, agreed QC summary |
Aptamer quality cannot be judged from one analytical result alone. The most useful package combines a purification method suited to the construct with orthogonal checks for identity, purity, and quantity. The final plan should reflect sequence length, modification density, label chemistry, intended assay, and acceptable material loss.
| Option | Primary Purpose | When It Is Considered | Important Decision Point | Typical Output |
| Desalting | Remove small-molecule synthesis residues and exchange material into a usable form | Randomized libraries, screening pools, or low-sensitivity applications where sequence isolation is not the objective | Desalting does not separate full-length aptamer from closely related truncation products | Desalted pool or oligonucleotide with quantity information |
| RP-HPLC | Separate products by hydrophobic interaction and remove many synthesis-related impurities | Fixed-sequence DNA or RNA aptamers, labeled constructs, and many modified oligonucleotides | Retention can change substantially with dyes, hydrophobic labels, or extensive modification | Preparatively purified aptamer with analytical purity assessment |
| Ion-Exchange HPLC | Resolve oligonucleotides according to charge-related behavior | Longer or highly charged constructs and sequences requiring an alternative to reverse-phase separation | Resolution depends on length, chemistry, counterion, and method conditions | Purified material and chromatographic purity data |
| PAGE | Separate oligonucleotides primarily by size with strong resolution of length variants | Fixed aptamers where truncated products are a major concern or where high length discrimination is needed | Recovery, scale, modification compatibility, and extraction handling must be balanced against resolution | Full-length enriched aptamer with electrophoretic or complementary purity assessment |
| Mass Analysis | Confirm that observed molecular mass is consistent with the intended sequence and modifications | Sequence-defined aptamers, labeled constructs, and conjugates when the molecular format is technically suitable | Very long, heterogeneous, or high-mass conjugates may require alternative or complementary characterization | Molecular-mass result with interpretation against the expected construct |
| Analytical HPLC or CE | Estimate purity and detect major product-related impurities | Most fixed-sequence aptamers and modified constructs after purification | A single method may not resolve every impurity class or prove functional folding | Purity trace and reported result under the agreed method |
| UV Quantitation | Determine oligonucleotide concentration or amount using sequence-dependent absorbance | Routine material release, concentration setup, and preparation of assay-ready solutions | Extinction coefficients and attached chromophores must be accounted for appropriately | Quantity or concentration result with formulation details |
| Folding Review | Define a practical refolding and handling plan for the intended binding assay | Structure-sensitive aptamers, multivalent constructs, and sequences transferred into a new buffer system | Chemical identity and purity do not by themselves establish target-binding performance | Suggested refolding conditions and test controls based on available project information |
The workflow below is structured for sequence-defined aptamers, candidate panels, and randomized libraries. Activities are adjusted according to chemistry, length, labeling, conjugation, purity, quantity, and downstream use.
We collect the sequence or library architecture, aptamer type, target class, intended assay, requested quantity, modification map, purity expectation, and formulation needs. This establishes whether the project is routine, modification-sensitive, or requires a dedicated feasibility review.
The sequence is reviewed for length, base composition, self-complementarity, structural motifs, difficult couplings, label position, and conjugation risk. We then recommend a synthesis route, purification plan, and analytical package that protect the intended aptamer function as far as chemical production can support.
The final construct map, scale, purity target, analytical methods, delivery format, and project boundaries are documented before work begins. This step prevents ambiguity around terminal groups, linker orientation, modification notation, and whether functional binding testing is included.
Aptamers are produced using the selected chemistry, followed by cleavage, deprotection, desalting, and preparative purification as applicable. Process choices are adjusted for RNA sensitivity, long sequences, hydrophobic labels, conjugates, and other project-specific risks.
The material is evaluated using the agreed identity, purity, and quantity methods. It is then dried or formulated in the specified buffer or counterion, with attention to concentration, light sensitivity, nuclease exposure, and handling requirements.
Customers receive the aptamer material and project documentation covering sequence configuration, modifications, purification, analytical results, and formulation. Post-delivery support addresses reconstitution, refolding, control design, and practical next steps without overstating binding performance that has not been experimentally verified.
Aptamer projects often fail at the transition from a published or selected sequence to a reproducible physical reagent. Our approach connects oligonucleotide chemistry with the structural and application requirements that make aptamers distinct from standard primers or probes.
Custom aptamer synthesis supports research workflows that depend on selective molecular recognition, programmable nucleic acid structure, or integration with optical, electrochemical, surface-based, and cargo-delivery systems.
Share your aptamer sequence or library design, DNA or RNA format, modification map, required quantity, purity expectation, intended assay, and preferred delivery format. Our team will review sequence feasibility, identify chemistry or purification risks, and recommend a practical synthesis and analytical plan. Whether the project involves a simple DNA aptamer, a nuclease-resistant RNA construct, a fluorescent sensor reagent, a surface-binding aptamer, a multivalent design, or a complex conjugate, we can coordinate the work from specification through technical handoff. Contact us to request a project review and quotation.
Aptamers offer superior stability, easier chemical synthesis, customizable modifications, minimal batch-to-batch variation, and the ability to target molecules that are challenging for antibody development.
Aptamers can be selected to bind diverse targets including small molecules, proteins, peptides, carbohydrates, and cellular components through systematic evolution of ligands by exponential enrichment (SELEX) technology.
Rigorous quality control includes HPLC purification, mass spectrometry verification, binding affinity assessment via SPR/BLI, specificity testing, and stability evaluation under various conditions.
Yes, sequence optimization, chemical modifications, and conjugation with functional groups can enhance aptamer stability, binding affinity, and application suitability.
Various backbone modifications, including 2'-fluoro, 2'-O-methyl, and phosphorothioate linkages, significantly enhance nuclease resistance and thermal stability.
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