Nanobody: The “Magic Bullet” for Molecular Imaging?

Abstract

Molecular imaging involves the non-invasive investigation of biological processes in vivo at the cellular and molecular level, which can play diverse roles in better understanding and treatment of various diseases. Recently, single domain antigen-binding fragments known as 'nanobodies' were bioengineered and tested for molecular imaging applications. Small molecular size (~15 kDa) and suitable configuration of the complementarity determining regions (CDRs) of nanobodies offer many desirable features suitable for imaging applications, such as rapid targeting and fast blood clearance, high solubility, high stability, easy cloning, modular nature, and the capability of binding to cavities and difficult-to-access antigens. Using nanobody-based probes, several imaging techniques such as radionuclide-based, optical and ultrasound have been employed for visualization of target expression in various disease models. This review summarizes the recent developments in the use of nanobody-based probes for molecular imaging applications. The preclinical data reported to date are quite promising, and it is expected that nanobody-based molecular imaging agents will play an important role in the diagnosis and management of various diseases.

Recent Advances in the Development of PET/SPECT Probes for Atherosclerosis Imaging

“…In addition, IgG, even without an affinity for any specific target molecule, accumulates in pro-inflammatory M1 macrophages probably via Fcγ receptors [54]. To overcome these limitations of a radiolabeled antibody (IgG), several attempts using a variety of antibody fragments have been conducted [55,56]. In one of these attempts, Broisat et al [57] Tc-anti-VCAM1 nanobody.…”

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“…In contrast to Fab fragments, which must be expressed in mammalian or insect cells, Nbs are easy to express and manipulate in Escherichia coli. As a result of their favourable characteristics Nbs are also increasingly being used in imaging, where they can be labelled with GFP or fluorescent dyes (Chakravarty et al, 2014;Rothbauer et al, 2006). Covalent attachment of fluorescent dyes to Nbs has proven to be effective using NHS ester, isothiocyanate or maleimide functional groups, with maleimide labelling being superior to NHS ester dyes when comparing background staining in cellpermeabilizing imaging (Pleiner et al, 2015;Rö der et al, 2017).…”