Compact plasmonic optical biosensors based on nanostructured gradient index lenses integrated into microfluidic cells

We report on a compact and cost-effective integrated label-free biosensor configuration which is based on the refractive index sensitivity of the localized surface plasmon resonance (LSPR) of gold nanostructures. Aiming for compactification and miniaturization of the sensor, arrays of nanodiscs were...

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Bibliographic Details
Published in:Nanoscale 2017-11, Vol.9 (44), p.17378-17386
Main Authors: Horrer, A, Haas, J, Freudenberger, K, Gauglitz, G, Kern, D. P, Fleischer, M
Format: Article
Language:English
Subjects:
Biosensing Techniques
Biosensors
Gold
Immunoassay
Lenses
Microfluidics - instrumentation
Miniaturization
Nanostructure
Nanostructures
Optical Imaging
Refractivity
Sensitivity analysis
Sensor arrays
Substrates
Surface Plasmon Resonance
Testosterone
Testosterone - analysis
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Summary:We report on a compact and cost-effective integrated label-free biosensor configuration which is based on the refractive index sensitivity of the localized surface plasmon resonance (LSPR) of gold nanostructures. Aiming for compactification and miniaturization of the sensor, arrays of nanodiscs were fabricated on the planar surface of a gradient index (GRIN) lens, which acts as a substrate as well as an imaging objective for the light scattered by the gold structures. Integration of the lens into a microfluidic flow cell enabled the controlled exchange of liquid media at the sensor surface. The light scattered by the nanostructures was investigated spatially and spectrally resolved making use of the imaging properties of the GRIN lens. Dynamic spectral analysis during refractive index changes was conducted, revealing high sensitivities of up to 372 nm per refractive index unit for the shift of the LSPR. Biosensing capabilities were demonstrated by the detection of binding of an analyte by means of a testosterone-immunoassay. Compact sensors for the detection of biomolecules were developed by combining plasmonic nanostructures with gradient-index lenses.
ISSN:2040-3364
2040-3372
DOI:10.1039/c7nr04097k