# Tiny tools closing the gap: nanobodies in research and therapy

## TL;DR

Nanobodies are small, versatile antibody fragments used in research and therapy for their ability to access hard-to-reach targets and enable detailed protein studies.

## Contribution

This review highlights recent advancements in nanobody technology and their expanding roles in bioimaging, therapy, and intracellular research.

## Key findings

- Nanobodies can access cryptic sites and penetrate tissues better than conventional antibodies.
- They are ideal for high-resolution imaging due to minimal linkage errors when conjugated to fluorophores.
- Nanobodies can be expressed in living cells to study proteins in their native context.

## Abstract

Nanobodies, also known as single-domain antibodies, have become powerful tools in research, diagnosis, and therapy. Sourced from the heavy chain of camelid heavy chain-only antibodies, this domain retains many important characteristics of full-length antibodies while being ∼10 times smaller in molecular weight. Nanobody discovery has seen expansive development over the recent past, through both conventional antigen-exposed and completely synthetic repertoires. Along these lines, binding properties of candidates can be evolved by subsequent mutation and selection cycles to adjust their specificity and avidity. Due to their small size and compact structure, nanobodies can reach cryptic sites not accessible to conventional antibodies and also show superior tissue penetration. This penetrance, alongside their ease of handling, has made nanobodies ideal candidates for a myriad of immunotherapeutic and drug delivery applications. Furthermore, their small size imparts minimal linkage errors when conjugated to a fluorophore, making nanobodies ideal tools for high-resolution imaging techniques. Most importantly, nanobodies can be stably expressed in living cells to bind, block, or modify intracellular targets, enabling study of proteins in a native context at unprecedented detail. In this review, we present the latest developments in nanobody technology and discuss applications in bioimaging, therapy, and intracellular protein study.