Radiopharmaceuticals

How this supports a project

CHEMOS supplies cold, non-radioactive chelators, bifunctional handles, targeting-ligand intermediates, and precursor building blocks. The radionuclide, radiolabeling process, radioactive handling, and finished radiopharmaceutical are outside this site scope.

Start with the radionuclide and targeting vector

Chelator selection is metal-specific. The oxidation state, preferred coordination environment, complex stability, labeling temperature, pH, reaction time, and compatibility with the targeting vector must be considered together. DOTA, NOTA, DFO, and related chelators are not interchangeable labels for the same function.

A bifunctional chelator also needs a second, independently usable group for attachment to a peptide, antibody, small-molecule ligand, or other carrier. The attachment position, linker, chelator loading, and conjugation method can change labeling behavior and the properties of the resulting conjugate.

Typical precursor-planning workflow

Define the radionuclide or metal pair

Record the intended radionuclide, metal oxidation state, purpose, required labeling window, and whether a non-radioactive metal analogue is needed for method development.

Define the targeting vector

Provide the exact peptide, antibody, small molecule, or other carrier and identify the attachment site and groups that must remain available for binding.

Select a chelator family

Match donor atoms, denticity, ring size, kinetic behavior, and practical labeling conditions to the chosen metal instead of selecting by platform name alone.

Choose the conjugation handle and spacer

Match NHS ester, isothiocyanate, maleimide, click, or another handle to the carrier and define any spacer needed to separate chelation from target binding.

Prepare the cold precursor

Confirm structure, metal-binding groups, conjugation site, identity, purity, residual metals or reagents, water content, and storage conditions.

Qualify radiolabeling externally

A licensed radiochemistry team must establish labeling yield, radiochemical purity, molar activity, stability, carrier binding, biodistribution, dosimetry, and suitability for the intended use.

What to define before an inquiry

Metal and use case

Intended radionuclide or non-radioactive analogue, imaging or therapy objective, labeling site, and expected preparation timeline.

Labeling conditions

Acceptable pH, temperature, reaction time, buffer, precursor concentration, and sensitivity of the targeting vector.

Targeting vector

Exact identity or structure, attachment position, binding-critical groups, available reactive groups, and material quantity.

Chelator and linker format

Preferred chelator family, bifunctional handle, spacer length or composition, protection state, and conjugation order.

Analytical requirements

Identity, purity, residual-metal limits, chelator-to-vector ratio, free chelator, aggregation where relevant, and storage-stability methods.

Application boundary

All materials described here are cold and non-radioactive. This page does not offer radionuclides, radioactive materials, radiolabeling, radioactive transport, dose preparation, clinical manufacture, imaging or therapeutic performance, dosimetry, safety, or regulatory approval. Final chelator choice and radiochemistry must be established by the project team for the specific metal and targeting vector.

Related catalog and technical pages

Radiopharmaceutical chelators and precursorsBrowse cold chelators, bifunctional derivatives, targeting-ligand intermediates, and non-radioactive precursor building blocks.Radiopharmaceutical chelator chemistryReview metal-chelator matching, bifunctional handles, precursor planning, and scope boundaries.Conjugation chemistry and linkersReview attachment handles, spacer design, coupling order, and analytical questions for carrier conjugation.DOTA, NOTA, and DFO comparisonReview why chelator choice starts with the intended metal, labeling conditions, carrier, and stability requirements.Click chemistry and bioconjugation reagentsBrowse azide, alkyne, cyclooctyne, tetrazine, NHS ester, and maleimide handles used in precursor assembly.