Single Domain Antibody-Quantum Dots Conjugation Service

Creative Biolabs is the leading service provider that focuses on single domain antibody (sdAb) conjugation. In order to help our clients for the research of early cancer detection and diagnosis, we have established a special sdAb-quantum dots conjugation service based on our mature protein engineering platform. With years of experience, our technical scientists can not only accomplish the special task but also design unique experimental project to achieve our clients’ goals.

Quantum dots (QDs) are very small semiconductor particles, only several nanometers in size, so small that their optical and electronic properties differ from those of larger particles. QDs are characterized by good light stability, broad excitation spectra and narrow emission spectra, larger Stokes displacement, good biocompatibility, long fluorescent lifetime, and the emission spectra of quantum dots can be controlled by changing the size of quantum dots. In general, quantum dots have novel electronic and optical properties that can be used in many important areas such as electronics, optoelectronics, photovoltaic, and biomedical.

Nowadays, the common method to achieve the target of detection and diagnostics is to conjugate QDs with monoclonal antibodies (mAbs). However, the large size of mAbs largely limits the number of ligands that can be linked to the surface of ODs, obstructs the intracellular and intracellular penetration, and limits intra-tumor distribution due to interstitial tumor stress and limits.

Single domain antibodies (sdAbs) are antibody fragment consisting of a single monomeric variable antibody domain, derived from the heavy-chain-only antibodies produced by camelids and sharks, or the specific developed human VH and VL domain. Compared with conventional antibody molecule, the small size of sdAbs (12-15kDa) allows it to bind epitopes inaccessible, decorate thinner and more distal segments, and cover the antigens more delicately. Exist as monomers, sdAbs diffuse much better in tissues than full-length antibody. What’s more, sdAbs show high stability in extreme conditions such as chemical detergents, extreme pHs, high temperature, and proteolysis. SdAbs can be produced easily by E. coli bacteria results in a relatively lower cost. A series of advantages make sdAbs the best capture to conjugate with QDs and play an important role in the application of detection and diagnostics.

SdAb-quantum dots conjugationFig.1 SdAb-quantum dots conjugation

In our service, we can engineer ultrasmall nanoprobes through oriented conjugation of QDs with sdAbs derived from llama IgG. The coupling method can be sulfo-SMCC and PMPI. Finally, sdAb-QDs conjugates would be used to detect cancer cells. This method has excellent fluorescence properties and strong penetration of ultra-small single domain antibodies, thus greatly improving the detection sensitivity.

SdAbs conjugated with sulfo-SMCC and PMPIFig.2 SdAbs conjugated with sulfo-SMCC and PMPI

Creative Biolabs has been a long-term expert in the field of sdAb conjugation. With the rich experience and advanced platform, we are pleased to offer the best service and the most competitive price for our customers all over the world. If you are interested in our single domain antibody-quantum dots conjugation service, please do not hesitate to inquire our experts for more details.


  1. Sukhanova, A.; et al. Oriented conjugates of single-domain antibodies and quantum dots: toward a new generation of ultrasmall diagnostic nanoprobes. Nanomedicine Nanotechnology Biology & Medicine. 2012, (8.4):516-525.

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