UV Photocrosslinking (UV-NBS)

Creative Biolabs develops a novel method for site-specific conjugation, UV photocrosslinking (UV-NBS), which utilizes the nucleotide binding site (NBS) for linking functional moieties to antibodies.

UV photocrosslinking (UV-NBS) Figure: The two-step method of UV-NBS

UV-NBS is an innovative method for site-specific conjugation. NBS is conserved and located in the variable region of the antibody Fab arm. IBA (indole-3-butyric acid) is a small molecule that has affinity for the NBS and can be crosslinked to antibodies upon UV energy exposure. Therefore, payloads featuring IBA moiety can be linked to an antibody by synthesizing IBA conjugated versions including affinity tags, peptides, imaging molecules and chemotherapeutics, etc. UV-NBS is a simple process to reproduce and it takes advantages of all the benefits of photocrosslinking techniques. Firstly, in the UV-NBS conjugation, the sample can receive defined amount energy. It is easy to achieve a high crosslinking yield due to the efficient radical activation. Moreover, based on UV-NBS, a two-step conjugation strategy can be implemented to facilitate more molecules conjugate to the antibody. In this method, the first step is to generate an IBA conjugated version of cysteine (IBA-Thiol), which can be photocrosslinked to antibodies at the NBS. Then the thiol group functions as a moiety for site-specific conjugation of any ligand that possesses either a thiol or a maleimide moiety. Although IBA- and thiol- active group are both UV sensitive, it has been proved that after UV exposure, the thiol moiety attached to IBA can still remain active and the IBA conjugation/NBS interaction results in highly efficient photocrosslinking. Moreover, the pattern of crosslinking does not affect the antibody-antigen binding activity. The two-step strategy provides a universal technique for conjugation of all payloads including UV sensitive molecules.

Based on the full understanding of antibodies, linkers and payloads in ADCs, scientists from Creative Biolabs can perform accurately controlled processes and deliver high quality products to clients. Our custom services will facilitate and accelerate your researches about ADCs.

There are various strategies used for antibody modification and conjugation:


  1. Nathan J Alves, et al. Conjugation of a reactive thiol at the nucleotide binding site (NBS) for site-specific antibody functionalization. Bioconjugate Chem., 2014, 25(7): 1198–1202.

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

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