^99mTc-Radiolabeling Service

Dynamic in-vivo preclinical evaluation of molecular pathways and distribution through SPECT imaging is made possible through this ^99mTc radiolabeling service, which creates versatile, readily available tracers. Alfa Cytology is equipped with advanced knowledge and provides custom ^99mTc radiolabeling services, combined with state-of-the-art radiochemistry equipment, that fulfill the stringent quality and precision standards.

Introduction to ^99mTc Isotopes

Technetium-99m (^99mTc) is a metastable radionuclide and a key element of the workhorse of diagnostic nuclear medicine for single photon emission computed tomography (SPECT). It decays by emitting a gamma ray of 140 keV, which is perfectly suited for detection by standard gamma cameras and allows for excellent-quality images to be obtained. Among the key benefits of ^99mTc is its relatively short 6-hour half-life, which minimizes the amount of radiation subjects are exposed to and the ability to elute it from a Molybdenum-99/Technetium-99m generator, ensuring it is widely and reliably available for numerous diagnostic procedures.

^99mTc-Labeling for SPECT Imaging

The most important gamma-emitting radionuclide for SPECT is technetium-99m (^99mTc). Its convenient on-site availability from molybdenum-99/technetium-99m generators is a significant logistical advantage. The fact that isotopes have a physical property, that is, a half-life of only six hours, alongside emitting a photon with energy of 140 keV, means they can be used for high-resolution, single-day imaging studies. In radiopharmaceutical research, technetium plays an important role because of its stable bonds with targeting vectors and its sophisticated coordination chemistry.

Fig.1. ^99mTc-Pyrophosphate-based SPECT combined with multislice CT angiography. (Ilyushenkova, J, et al., 2020)

^99mTc Radiopharmaceutical

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Advantages of ^99mTc-Labeling

Our Services

Alfa Cytology has professional knowledge as well as sophisticated radiochemistry infrastructure, which allows us to offer specialized ^99mTc-radiolabeling services for many classes of molecules, including small organic chemicals and intricate biologics. The service is performed with thorough quality assurance, which provides high purity of the radiotracers, guaranteeing confidence and consistency of the data for the preclinical investigations that will follow.

Custom ^99mTc Conjugation Service

The custom ^99mTc conjugation service guarantees stable and efficient binding of technetium-99m to your specific molecule, be it a peptide, antibody, or small compound. This enables the transformation of your novel vector into a top-notch SPECT imaging agent, aimed at evaluating biodistribution and in vivo targeting characteristics.

Small-Molecule Radionuclide Conjugate (SMRC)

Antibody-Radionuclide Conjugate (ARC)

Peptide-Radionuclide Conjugate (PRC)

siRNA-Radionuclide Conjugate

Workflow for Developing ^99mTc-Radiolabeled Antibody Conjugates

^99mTc Custom Antibody Labeling

The foundation of our company's service offering starts with an individualized solution based on your specific antibody and research goals. We ensure and enhance the reproducibility and efficiency of the labeling process by working in a controlled environment.

• Strategy & Reagent Selection: Start with the assessment of your antibody properties, like the amino acid sequence, isoelectric point, and stability. We use this to consider and select the appropriate bifunctional chelator (BFC) to offer optimal binding affinity for ^99mTc, like HYNIC, MAG3, or DTPA, and then a conjugation strategy that ensures site-specificity or controlled random conjugation.
• Protocol Optimization: BFC is conjugated to your purified antibody using multiple chemical methods. This step optimizes for pH, molar ratio, and reaction time to achieve a consistent chelator to antibody ratio while maintaining the structure and immunoreactivity of the antibody.
• Custom Radiosynthesis: This is the stage where the ^99mTc-labeling synthesis is performed by a dedicated radiochemistry team. High radiochemical yield and optimal labeling efficiency are guaranteed with careful manipulation of pH, temperature, time, and concentration of the reaction mixture.

Purification & Quality Control

Each radiolabeling reaction's initial product has to undergo stringent purification and quality control to ensure that the product is as safe and effective as possible.

• Radiochemical Purity Evaluation Services: Radiochemical Purity (RCP) is a fundamental key concept, as the RCP defines a parameter as a percentage of the total radioactivity in a specific desired chemical form. We use several analyses and techniques to determine RCP and find possible radiochemical impurities: Instant Thin-Layer Chromatography (iTLC) and High-Performance Liquid Chromatography (HPLC).
• Stability Study Services: For practical usage, the final ^99mTc-labeled antibody conjugate needs to be stable. We perform stability assessment and predict its performance by serum stability or ligand challenges.

In Vitro Evaluation

In vitro tests are performed to evaluate the biological properties of the ^99mTc-labeled radiopharmaceutical. This includes studying its interaction with target receptors, cellular uptake, metabolic stability, and other pharmacological properties.

In Vivo Evaluation

This important step starts with evaluating the agent's biodistribution and performing pharmacokinetic (PK) studies, which help in the understanding of organ involvement and the rate of loss of the agent from circulation. Subsequently, SPECT imaging is performed in relevant disease models to visualize and validate the agent's specific target engagement and to assess, through in vivo blocking studies, the real diagnostic capability of the agent.

Applications of ^99mTc-Radiolabeling

Leveraging its versatile chemistry and ideal SPECT imaging properties, ^99mTc-radiolabeling is widely used in preclinical research to develop novel agents that visualize the real-time biodistribution and target engagement of small molecules, peptides, and biologics.

Why Choose Us?

We offer services that range from molecular design to preclinical testing, such that every stage of development is seamlessly integrated, ensuring efficiency, accuracy, and compliance with regulatory standards.

Experience in ^99mTc Chemistry

Full-Service Development

State-of-the-Art Facilities

Application-Specific Tailored Solutions

With our specialized knowledge in complex radiochemistry along with modern equipment, Alfa Cytology's team performs exceptional custom ^99mTc-radiolabeling tailored for specific research targets. In the case your team encounters any scientific or technical issues during your work, we invite you to consult with our specialists. We are confident in our ability to navigate challenges and co-develop effective solutions.

Reference

1. Waaijer, S.J., et al. (2018). Molecular Imaging of Radiolabeled Bispecific T-Cell Engager ⁸⁹Zr-AMG211 Targeting CEA-Positive Tumors. Clinical Cancer Research. 24, 4988 - 4996.

For research use only. Not intended for any clinical use.