Customized Targeted Nano-tracer Development

Molecular imaging is constantly growing in different areas of preclinical biomedical research. Along with great progress in single domain antibody (sdAb) generation and antibody labeling strategies, different sdAb-based probes have been generated and applied to a variety of imaging modalities, ranging from in vitro and in vivo preclinical imaging to super-resolution microscopy. Creative Biolabs has developed a reliable platform that allows us to use sdAb to trace changes in the living body due to age, genotype, activation or in response to therapy and to map these changes onto a standard atlas or images from different techniques. We provide customized sdAb-based imaging tools (Nano-tracer) development services for worldwide customers according to specific project demands.

SdAbs as Imaging Tools

SdAbs have emerged as important tools for both in vitro and in vivo imaging modalities. Desirable properties include their specificity, superior affinity, stability, fast clearance of unbound sdAb from the circulation, a pharmacokinetic and production profile compatible with short-lived radioisotopes, and ease of production. Several imaging techniques have been successfully optimized for sdAb imaging applications. The majority of in vivo molecular imaging studies have been performed using positron emission tomography (PET) and single photon emission computed tomography (SPECT), labeling sdAbs with positron-emitting nuclides (such as ⁶⁸Ga, ¹⁸F or ⁸⁹Zr) and γ-emitting nuclide (^99mTc), respectively. In ultrasound imaging, sdAbs have been tagged to contrast agents such as microbubbles or nanobubbles and are mainly used for the visualization of the systemic vasculature. Besides, optical imaging is used to visualize surface lesions during endoscopic examinations.

Fig.1 SdAbs as imaging tool for the visualization of different pathological conditions.^1,4

Application Fields

The availability of commercial sources to perform camelid immunizations and the production of a library will continue to improve access. Besides immuno-oncology, sdAbs have been developed to image a range of other events such as infectious disease, central nervous system (CNS) diseases, autoimmunity, and cardiovascular and inflammatory conditions. Imaging subjects including but not limited to the following:

One-stop Solution

• Generation and modification of sdAb: Optional imaging techniques and imaging modality
• Design of sdAb tracers: tailored conjugation strategy-random or site-specific
• Molecular imaging with Nano-tracer- In vivo biodistribution analysis
• Statistics analysis

If you are interested in our customized imaging nano-tracer development services, please directly contact us and consult our technical supports online.

Published Data

1. Targeted PET imaging of CD70 expression with a Site-Specific ⁶⁸Ga-labeled nanobody

Fig.2 PET/CT imaging in tumor models.^2,4

This study developed a gallium-68 (⁶⁸Ga) radiolabeled single-domain antibody fragment (sdAb) targeting CD70 for in vivo PET imaging of CD70 expression. The radiotracer, [⁶⁸Ga]Ga-NOTA-anti-CD70 VHH, was obtained with a high radiochemical yield (30.4 ± 1.7%) and purity (> 94%) and demonstrated excellent stability. In vitro, it showed specific binding to CD70_high 786-O cells, with significantly higher cell-associated activity compared to blocking conditions (p < 0.0001) and CD70_low NCl-H1975 cells (p < 0.0001). PET imaging revealed selective accumulation in CD70-expressing human tumor xenografts, significantly inhibited by unlabeled anti-CD70 VHH (p = 0.0029). Uptake in CD70_high tumors was significantly higher than in CD70_low tumors (p < 0.0001), and autoradiography matched immunohistochemistry results. Additionally, [⁶⁸Ga]Ga-NOTA-anti-CD70 VHH demonstrated exceptional in vivo specificity for targeting CD70 in human cancer xenograft models. This [⁶⁸Ga]Ga-NOTA-anti-CD70 VHH shows promise for non-invasive PET imaging and monitoring of patients for anti-CD70 therapies.

2. Nanobodies Conjugated to Quantum Dots for High-Resolution Single- and Two-Photon Imaging of Human Micrometastases and Disseminated Tumor Cells

Fig.3 Deep tissue imaging of metastatic breast tumor samples with sdAbs–QD probes.^3,4

This study demonstrated the application of sdAb-conjugated fluorescent quantum dots (QDs) for visualizing human micrometastases and disseminated tumor cells in ex vivo breast and pancreatic cancer mouse models expressing HER2 or CEA, enabling single- and two-photon imaging. Researchers stained thin (5-10 µm) paraffin and thick (50 µm) agarose tissue sections, successfully identifying the infiltration and metastasis of HER2- and CEA-positive tumor cells in various organs, including the brain, lungs, and lymph nodes. Compared to conventional fluorescent antibodies, sdAb-HER2-QD and sdAb-CEA-QD nanoprobes offered superior sensitivity, with lower photobleaching and higher fluorescence brightness for clearer signal discrimination. The high two-photon absorption cross-section and small size of these QDs enabled efficient imaging of thick tissue sections, making them ideal for visualizing small metastases and complex structures. These nanobody–QD probes will help to improve cancer diagnosis and monitor tumor progression.

References

1. Erreni, Marco, et al. "Nanobodies as versatile tool for multiscale imaging modalities." Biomolecules 10.12 (2020): 1695.
2. Dewulf, Jonatan, et al. "Site-specific ⁶⁸Ga-labeled nanobody for PET imaging of CD70 expression in preclinical tumor models." EJNMMI Radiopharmacy and Chemistry 8.1 (2023): 8.
3. Ramos-Gomes, Fernanda, et al. "Single-and two-photon imaging of human micrometastases and disseminated tumour cells with conjugates of nanobodies and quantum dots." Scientific Reports 8.1 (2018): 4595.
4. Distributed under Open Access license CC BY 4.0, without modification.

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