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

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Giorgi-Coll, Susan 
Sule, Olajumoke 
Hutchinson, Peter J 
Carpenter, Keri LH 


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 μg·mL-1 IL-6 concentration range, and the detection limit (at S/N = 3) is 1.95 μg·mL-1. This study was performed as a proof-of-concept demonstration of this versatile assay design, with a view to developing a similar assay for use in clinical samples in future. Graphical abstractSchematic representation of the aggregation of aptamer-functionalised nanoparticles in the presence of interleukin-6 (IL-6). The presence of mouse IL-6 in a mixed protein solution leads to a visible colour change, and a change in the absorption spectrum of the nanoparticles.



Colorimetry, Cytokines, Diagnostics, Metal nanoparticles, Point-of-care assay, Sepsis, Aptamers, Nucleotide, Biosensing Techniques, Gold, Inflammation, Interleukin-6, Kinetics, Metal Nanoparticles

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Mikrochim Acta

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Springer Science and Business Media LLC


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Cambridge University Hospitals NHS Foundation Trust (CUH) (unknown)
Cambridge University Hospitals NHS Foundation Trust (CUH) (146281)
This work was supported by seed-corn funding from the National Institute for Health Research Brain Injury Healthcare Technology Co-operative (NIHR-HTC). SGC and KLHC are funded from the NIHR Biomedical Research Centre, Cambridge (Neuroscience Theme; Brain Injury and Repair Theme). PJH is funded by a NIHR Research Professorship, Academy of Medical Sciences/Health Foundation Senior Surgical Scientist Fellowship and the National Institute for Health Research Biomedical Research Centre, Cambridge. The authors gratefully acknowledge Dr Giorgio Divitini (Department of Materials Science and Metallurgy, University of Cambridge) for transmission electron microscope access and assistance, and Prof Yorgo Modis and Ms Stephanie Reikine (Department of Medicine, University of Cambridge; Molecular Immunity Unit, MRC Laboratory for Molecular Biology) for dynamic light scattering access and assistance.