Inquiry

Radiolabeling Technique

Radiolabeling service

Radiolabeling is a sensitive and reliable tracking method widely used in biology, genetic engineering, pharmacy, and medicine. The analytes can be intrinsically labeled by replacing atoms in the molecular structure with its own radioisotope or chemically modified with an extra radionuclide contained residue. The commonly used radioactive isotopes are 3H, 14C, 35S, 111In, 125I, and so on. As regards to PEG and PEGylated conjugates, radiolabeling is also a very effective tool to determine their pharmacokinetics in vivo.

Principles

Typically, a radioisotope is introduced to the PEG or PEGylated molecules by replacing one or several corresponding atoms with radioisotope, and is administrated in small amounts to minimize interference with the experimental system. The radionuclide atom continually emits radiation so that produces a copy of the conjugate with the same distribution path in the body, which can be detected and quantified by a γ-counter, liquid scintillation counter, Geiger counter or positron emission tomography computed tomography/computed tomography (PET/CT). Since the radioisotope labeling does not change the structure of the molecule and endows the analyte with fast identical physicochemical property, it can be used as a precise and sensitive tool to detect the pharmacokinetic behavior of the analytes. Up to date, radiolabeling has been successfully utilized in the studies of the in vivo absorption, distribution, metabolism, and excretion (ADME) processes of PEG, PEGylated small molecules, PEGylated peptides, PEGylated proteins, and PEGylated nanoparticles.

Radioisotopes Commonly Used

Radioisotopes commonly used

Methods for PEGs or PEG Derivatives Radiolabeling

Since methoxy-PEG (mPEG) is difficult to be directly labeled with radioisotope, it is necessary to use other functional end groups for radiolabeling.

  • Amine-PEG
  • Process demonstration of radiolabeling of amino PEG Fig. 1 Process demonstration of radiolabeling of amino-PEG. (Bioconjugate chemistry, 2012, 23(5): 881-899)

    Amine-PEG can be directly labeled with 125I using Bolton Hunter reagent, as illustrated in the Fig. 1. Similarly, the PEG chain can react with 125I-labeled tyrosine (using the chloramine T method) through the terminal hydroxyl group, thereby being radioactive.

  • Bi-functional PEG
  • Process demonstration of radiolabeling through a chelating agent Fig. 2 Process demonstration of radiolabeling through a chelating agent. (Bioconjugate chemistry, 2012, 23(5): 881-899)

    Chelating agents can be directly introduced to one end of a bifunctional PEG molecule to allow chelation of an isotope and covalent attachment to the target protein or peptide. As shown in Fig. 2, an amine-PEG-succinimidyl ester first react with a cyclic peptide and then react with DOTA sulfosuccinimydyl ester to expose the terminal -NH2 group for labeling with 64Cu.

  • PEGylated Peptides/Proteins
  • Process demonstration of radiolabeling of PEGylated peptides proteins through click reaction Fig. 3 Process demonstration of radiolabeling of PEGylated peptides/proteins through click reaction. (Bioconjugate chemistry, 2012, 23(5): 881-899)

    Click reaction, for example, Cu(I)-catalyzed azide−alkyne cycloaddition, can be sufficiently utilized to label PEGylated peptides/proteins for pharmacokinetic studies in tumor imaging application.

  • PEGylated Micelles/Liposomes
  • Process illustration of surface radiolabeling of PEGylated liposomes Fig. 4 Process illustration of surface radiolabeling of PEGylated liposomes. (Bioconjugate chemistry, 2012, 23(5): 881-899)

    There are two major approaches to achieve the surface labeling of PEGylated liposomes or micelles: one is to use membrane-soluble chelating agents to incorporate radioisotopes into the conjugates, and the other choice is to covalently attach the chelating agents to the surface.

  • PEGylated Nanoparticles
  • Inorganic nanoparticles, like Superparamagnetic iron oxide nanoparticles (SPION) and quantum dots (QDs), could also be reacted with the amine group at the PEG termini for binding of radioisotope, such as 64Cu. The biodistribution of these nanoparticles in mice could be followed by PET or magnetic resonance imaging (MRI).

Strengths & Weaknesses of Radiolabeling

Strengths and Weaknesses of Radiolabeling

References

  1. Zhang Z, Zhang Y, et al. Recent advances in the bioanalytical methods of polyethylene glycols and PEGylated pharmaceuticals. Journal of Separation Science, 2020, 43(9-10): 1978-1997.
  2. Cheng T L, Chuang K H, et al. Analytical measurement of PEGylated molecules. Bioconjugate chemistry, 2012, 23(5): 881-899.

Why BOC Sciences?

  • Large Stock

    More than 2000+ products in inventory

  • Global Delivery

    Warehouses in multiple cities to ensure fast delivery

  • mg to kg

    Multi specification for academic research and industrial production

  • 24/7 Technical Support

    Strict process parameter control to ensure product quality

Products

Resources

Our Feature

BOC Sciences supplies a unique variety of PEG derivatives and functional PEG polymers. Our products offer the most diverse collection of reactivity, ready-to-use functionality, and molecular weight options that you will not find anywhere else.

  • Our Feature icon1
  • Our Feature icon2
  • Our Feature icon3
  • Our Feature icon4
PEGylation of Peptides and Proteins

PEGylation of Peptides
and Proteins

Reduce the Immunogenicity of Peptide/Protein Drugs

Learn More

APPLICATIONS

APPLICATIONS

PEG linkers For Drug

Improved Circulation Half-Life

Learn More

Have Customer Reviewed On Us?

logo

Chat With Us

Online Inquiry

Verification code

Copyright © 2024 BOC Sciences. All rights reserved.