Click & Bioorthogonal Chemistry

How this supports a project

Click chemistry selection starts with the exact reaction pair, target matrix, handle concentration, required reaction time, and stability of each installed handle. The term bioorthogonal does not make every reagent suitable for every biological sample.

Choose a reaction pair, not a general label

SPAAC joins an azide with a strained cyclooctyne without a copper catalyst. IEDDA commonly joins a tetrazine with a strained alkene such as trans-cyclooctene. CuAAC joins an azide and terminal alkyne using a copper catalyst and normally requires separate review of catalyst, ligand, reducing conditions, removal, and target compatibility.

Reaction rate is only one selection variable. Handle stability before reaction, hydrolysis or isomerization, steric size, hydrophobicity, nonspecific interaction, reagent concentration, competing functionality, and stability of the product bond all affect a workflow. TCO and tetrazine studies show that higher reactivity can introduce stability trade-offs, so the exact derivative matters.

Typical reaction-pair workflow

Define the two molecular partners

Provide the exact biomolecule, surface, material, reporter, or payload on each side and identify the groups that must remain functional.

Select complementary handles

Choose azide-cyclooctyne, tetrazine-TCO, azide-terminal alkyne, or another defined pair based on environment, concentration, and required kinetics.

Assign each handle to a partner

Consider handle size, hydrophobicity, synthesis route, storage stability, exposure time, and whether installation changes partner function.

Define installation chemistry

Specify how each handle is attached, the site or distribution, spacer, protecting groups, reaction order, and purification of handle-bearing intermediates.

Run the ligation with controls

Set stoichiometry, concentration, solvent or buffer, pH, temperature, time, and negative controls for nonspecific association or background reaction.

Characterize product and retained function

Confirm conversion, identity, remaining free partners, handle loss or side products, site or distribution, stability, and the intended binding, labeling, or material function.

Inputs for platform review

Reaction environment

Purified buffer, cell lysate, live-cell, surface, polymer, particle, or other matrix; concentrations, temperature, pH, and permitted additives.

Molecular partners

Exact identities or structures, available sites, amount, formulation, size, and known sensitivity to copper, reducing agents, solvent, light, or oxidation.

Kinetic requirement

Expected partner concentrations, acceptable reaction time, whether a pretargeting or pulse-labeling window exists, and how conversion will be measured.

Handle stability

Required shelf life, storage form, aqueous exposure time, susceptibility to isomerization, reduction, oxidation, hydrolysis, or nonspecific reaction.

Analytical plan

Methods for handle installation, conversion, free reagents, identity, site or distribution, product stability, and retained target function.

Where this platform applies

This platform covers azide, alkyne, cyclooctyne, tetrazine, TCO, and related handle building blocks and conjugation planning. It does not claim universal bioorthogonality, a reaction rate in the customer matrix, quantitative conversion, site specificity, live-cell compatibility, imaging performance, biological activity, safety, clinical use, or regulatory status. Those outcomes require testing of the installed handles and final product in the intended system.

Core considerations

SPAAC handle selection
IEDDA reaction-pair planning
Labeling and immobilization handles

Related catalog and technical pages

Click chemistry and bioconjugation reagentsBrowse azides, alkynes, DBCO, BCN, TCO, tetrazines, and functionalized intermediates.Conjugation chemistry and linkersReview attachment sites, spacer design, reaction order, purification, and final-conjugate analysis.Labeling and imaging chemistryReview reporter identity, labeling stoichiometry, probe purification, and retained-function testing.DBCO versus BCNCompare two strained cyclooctyne handles by structure, steric profile, solubility, and project fit.SPAAC versus IEDDACompare azide-cyclooctyne and tetrazine-TCO systems by kinetics, stability, and workflow requirements.