Aptamer-modified gold nanoparticles for rapid aggregation-based detection of inflammation: an optical assay for interleukin-6

Susan Giorgi-Call (Lead Author), Maria J. Marin (Lead Author), Olajumoke Sule, Peter J. Hutchinson, Keri L. H. Carpenter

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A proof-of-concept aptamer-based optical assay is described for the determination of the immuno signalling molecule interleukin-6 (IL-6), a key marker of acute inflammation. The optical assay is based on the aggregation of gold nanoparticles (AuNP) coated in two complimentary "sandwich-style" aptamers, each with different IL- 6 target moieties. IL-6 will recognise the complimentary aptamer pair and bind to it, thereby causing the aggregation of the corresponding functionalised nanoparticles. The aggregation of the AuNPs after exposure to IL-6 induces a visible colour change from red to pink, with a corresponding change in the absorption maximum from 520 to 540 nm. The change in the absorption maximum can be monitored visually, or by using a spectrophotometer or a plate reader. The optimal size and functionalisation of aptamer-coated AuNPs, and the potential assay formats were investigated using UV-vis spectrophotometry, transmission electron microscopy, and dynamic light scattering. The optical assay was applied for detecting mouse IL-6 in a mixed protein solution as a representative biological sample. The assay works in the 3.3 to 125 mu g.mL(-1) IL-6 concentration range, and the detection limit (at S/N = 3) is 1.95 mu g.mL(-1). This study was performed as a proof-ofconcept demonstration of this versatile assay design, with a view to developing a similar assay for use in clinical samples in future.

Original languageEnglish
Article number13
Number of pages11
JournalMicrochimica Acta
Early online date4 Dec 2019
Publication statusPublished - 1 Jan 2020


  • Cytokines
  • colorimetric
  • metal nanoparticles
  • sepsis
  • diagnostics
  • point-of-care assay

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