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Linker Design and Synthesis Service

The linker is the spacer part between a cargo molecule, consisting of radionuclide and chelator, and the targeting molecule, constructing a covalent bond between them. Linker, as an important part of RDC (Radionuclide Drug Conjugate), has a great effect on the bioactivity of RDC.

Since the structure and design of the linker are critical to the success of RDC, Rdcthera, focused on linker development for decades, offers professional linker design and high-quality synthesis for customers to ensure the later RDC development.

Overview of Linkers in RDC

RDC is composed of four parts, including radionuclide, chelator, linker, and targeting biomolecule. After the connection between radioactive particle and chelator, this complex needed to binding to the targeting molecule by a linker to avoid interferences between bioactive groups in RDC. The linker in the RDC, also named as PKM (Pharmacokinetic Modifying) linker, has a significant effect on radiotracer excretion kinetics of RDC to improve the T/B (target-to-background) ratios of the radiopharmaceutical.

Examples of Linkers in RDC

Several linkers have been successfully designed including cationic, anionic, neutral, and metabolically cleavable linkers. Depending on the specific needs, the relatively best linker can be chosen. The following linkers shown in the chart are part of our linker library. With years of linker design service, our professional team can help you find the most suitable linker for your RDC.

Linkers for modification of pharmacokinetics of radiopharmaceuticalsFig.1 Linkers for modification of pharmacokinetics of radiopharmaceuticals.
(Liu S., Adv Drug Deliv Rev., 2008)

Influence of Linker in RDC

Different kinds of linkers have different influences on the bioactive properties of RDC, depending on the specific radioactive particle, chelator, and targeting molecule you design. The linkers of RDC have the following influences.

  • Increasing lipophilicity
  • Slowing of cellular uptake
  • Modifying pharmacokinetics
  • Minimizing accumulation
  • Improving hydrophilicity
  • Changing biodistribution
  • Increasing tumor/liver ratios
  • Improving excretion kinetics

For example, it is found that different linkers, with the same radionuclide, chelator, and targeting molecule, can cause different half-lives and calculated biological half-lives of RDC. As a result, the design of the linker is essential for the successful development of RDC.

Fig.2 Comparison of half-lives (t1/2(eff)/h) and calculated biological half-lives (t1/2(biol)/h) between different linkers.Fig.2 Comparison of half-lives (t1/2(eff)/h) and calculated biological half-lives (t1/2(biol)/h) between different linkers. (Guillou A, et al., Bioconjug Chem, 2021)

Our Service

  • Linker Design Service
  • The linker is one of the most crucial parts of RDC. With a wealth of knowledge in RDC development and years of experience in linker synthesis and manufacture, Rdcthera, grouped by extensive experience and senior scientists, is committed to designing the most appropriate linker for your project and saving your time. The linker designed by us has the following three benefits.

    • Stabilize the Radioactive Particle
    • Reduce the Interactions Between Radionuclide and the Targeting Molecule
    • Modify the Excretion Kinetics of RDC
  • Linker Synthesis Service

Moreover, with an advanced chemistry platform and top-notch equipment worldwide, we guarantee a high-quality and extreme pure linker with the best synthesis pathway will be chosen.

Project Workflow

Project Workflow

Why Choose Us

Rdcthera has been working on linker development for years. We concentrate on linker design, screening, and synthesis for years. After getting the suitable linker, we also provide other services. We can offer you RDC conjugation service and RDC analysis service.

Industrial Leadership

Cost Efficient

Highly Customizable

Premium Quality

We are pleased to share our experience, acknowledgment, and technology with you and help you screen for the best-fit linker for your RDC. We are committed to promoting your RDC development project. Please contact us for more information.


  1. Liu S. Bifunctional coupling agents for radiolabeling of biomolecules and target-specific delivery of metallic radionuclides[J]. Adv Drug Deliv Rev. 2008 Sep;60(12):1347-70.
  2. Guillou A, Earley DF, Klingler S, Nisli E, Nüesch LJ, Fay R, Holland JP. The Influence of a Polyethylene Glycol Linker on the Metabolism and Pharmacokinetics of a 89Zr-Radiolabeled Antibody[J]. Bioconjug Chem. 2021 Jul 21;32(7):1263-1275.
For research use only. Not intended for any clinical use.

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