Nanobodies (VHH Single Domain Antibodies)

At approximately 15 kDa, a nanobody is roughly one-tenth the molecular weight of a conventional IgG. This small size lets nanobodies diffuse rapidly through tissue and access densely packed cellular environments, which is part of why they are well suited to super-resolution microscopy techniques such as STORM and STED, where the 10 to 15 nm linkage error of an IgG-secondary antibody system can limit spatial resolution.

A nanobody consists of a single VHH domain with three complementarity-determining regions. The CDR3 loop is frequently longer than the equivalent loop in a conventional VH domain, which lets it reach into enzyme clefts and other recessed sites. A conventional IgG instead relies on a paired heavy and light chain to form its antigen-binding site.

Nanobodies are the preferred choice where the epitope of interest sits within an enzyme active site or a conformationally restricted receptor pocket that is sterically inaccessible to a full-size IgG. This also makes them useful in high-resolution imaging settings where secondary antibody background is a problem.

The disulfide-stabilised core of a VHH domain gives it stability characteristics distinct from a full-length antibody. This favours nanobodies for competitive assay formats or protocols that involve harsher fixation or extended incubation at elevated temperature.

All nanobodies in our range are produced recombinantly, which removes the batch-to-batch variability associated with hybridoma-derived antibodies and gives a consistent, traceable reagent for repeat experiments. Recombinant production also makes it straightforward to engineer Fc fusions, enzyme conjugates or fluorescent protein fusions.

A nanobody's size and stability under live-cell conditions support real-time protein tracking, including as the antigen-binding half of a genetically encoded chromobody fusion expressed inside the cell itself. See our fluorescent protein nanobodies below.

Because a nanobody is a single genetic construct rather than a paired heavy and light chain, it is comparatively simple to fuse to an Fc region, an enzyme or a fluorescent protein. See our Chimeric Antibodies range for nanobody-Fc fusion formats.