Latex beads vs K-One® coated gold nanoparticles
LFA/bioconjugates

Latex beads vs K-One® coated gold nanoparticles

13/5/2024

Claude Nogues

5 min read

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Highlights

Improving the Limit of Detection of an infectious disease rapid antigen test: Latex beads vs K-One® coated gold nanoparticles

Products & applications

Kimialys develops custom bioconjugates for Lateral Flow Assay (LFA), leveraging its patented surface chemistry, K-One®. K-One® optimises the immobilisation of ligands (such as antibody, antigen or protein) on the nanoparticle surface, while fully protecting the remaining surface against non-specific interactions. With this double benefit, Kimialys’ K-One® coating allows LFA developers to reach their target Limit ofDetection (LoD), while maintaining the reliability of their assays, but without requiring any further adjustments to the assay manufacturing parameters. This application note provides a case study of Kimialys’ technology integrated into a rapid diagnostic test targeting an infectious disease protein marker.

Proof of Concept

The performance of a rapid antigen test in dipstick format (no sample pads or conjugate pads) was compared as a function of the bioconjugates used: latex beads versus Kimialys’ gold nanoparticles, with all other components remaining the same (strip, absorption pad, migration buffer, target antigen, capture antibody). The latex bioconjugates were optimised by a third party through passive adsorption of the capture antibody, while Kimialys’ gold bioconjugates relied on K-One covalent chemistry. The size of the latex beads was not known, while Kimialys’ gold nanoparticles had a diameter of 40nm ± 3nm. All experiments were carried out in the provided migration buffer.

Latex Bioconjugates

Figure 1. Detection carried out with latex bioconjugates

Kimialys’ Bioconjugates

Figure 2. Detection carried out with Kimialys bioconjugates
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Conclusion

This short study in dipstick format highlights the 3 main advantages of Kimialys’ K-One® surface chemistry applied to LFA:

Gain in sensitivity: K-One® coated gold nanoparticles generate an 8-fold gain in LoD compared to latex beads. This results from optimal orientation of the capture antibodies pointing the recognition site (paratope) towards the solution, thereby maximising capture efficiency.

Background noise removal: No background noise is observed on the strip after the migration of K-One® based bioconjugates, while latex bead migration leads to a faint pink staining. This showcases the optimal protection of the surface brought by K-One® against non-specific interactions.

No R&D transfer cost: switching from latex beads to K-One® gold bioconjugates does not require any change to the other test parameters (membrane, pads, buffers).

References

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