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- Chen, Si, 1985, et al.
(författare)
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Ultrahigh sensitivity made simple : nanoplasmonic label-free biosensing with an extremely low limit-of-detection for bacterial and cancer diagnostics.
- 2009
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Ingår i: Nanotechnology. - : Institute of Physics (IOP). - 0957-4484 .- 1361-6528. ; 20:43
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Tidskriftsartikel (refereegranskat)abstract
- We present a simple and robust scheme for biosensing with an ultralow limit-of-detection down to several pg cm(-2) (or several tens of attomoles cm(-2)) based on optical label-free biodetection with localized surface plasmon resonances. The scheme utilizes cost-effective optical components and comprises a white light source, a properly functionalized sensor surface enclosed in a simple fluidics chip, and a spectral analyzer. The sensor surface is produced by a bottom-up nanofabrication technique with hole mask colloidal lithography. Despite its simplicity, the method is able to reliably detect protein-protein binding events at low picomolar and femtomolar concentrations, which is exemplified by the label-free detection of the extracellular adherence protein (EAP) found on the outer surface of the bacterium Staphylococcus aureus and of prostate-specific antigen (PSA), which is believed to be a prostate cancer marker. These experiments pave the way towards an ultra-sensitive yet compact biodetection platform for point-of-care diagnostics applications.
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- Dahlin, Andreas, 1980, et al.
(författare)
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High-Resolution Microspectroscopy of Plasmonic Nanostructures for Miniaturized Biosensing
- 2009
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Ingår i: Analytical Chemistry. - : American Chemical Society. - 0003-2700 .- 1520-6882. ; 81:16, s. 6572-6580
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we demonstrate how to perform microscale spectroscopy of plasmonic nanostructures in order to minimize the noise when determining the resonance peak wavelength. This is accomplished using an experimental setup containing standard optical components mounted on an ordinary light microscope. We present a detailed comparison between extinction spectroscopy in transmission mode and scattering spectroscopy under dark field illumination, which shows that extinction measurements provide higher signal-to-noise in almost all situations. Furthermore, it is shown that rational selection of nanostructure, hardware components, and data analysis algorithms enables tracking of the particle plasmon resonance wavelength from a 10 mu m x 50 mu m area with a resolution of 10(-3) nm in transmission mode. We investigate how the temporal resolution, which can be improved down to 17 Ins, affects, the noise characteristics. In addition, we show how data can be acquired from an area as small as 2 mu m x 10 mu m (similar to 240 particles) at the expense of higher noise on longer time scales. In comparison with previous work on macroscopic sensor designs, this represents a sensor miniaturization of 5 orders of magnitude, without any loss in signal-to-noise performance. As a model system, we illustrate biomolecular detection using gold nanodisks prepared by colloidal lithography. The microextinction measurements of nanodisks described here provide detection of protein surface coverages as low as 40 pg/cm(2) (less than0.1% of saturated binding). In fact, the miniaturized system provides a detection limit in terms of surface coverage comparable to state of the art macroscopic sensors, while simultaneously being as close to single protein molecule detection as sensors based on a single nanoparticle.
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- Reimhult, Kristina, et al.
(författare)
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Characterization of QCM sensor surfaces coated with molecularly imprinted nanoparticles
- 2008
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 23:12, s. 1908-1914
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Tidskriftsartikel (refereegranskat)abstract
- Molecularly imprinted polymers (MIPs) are gaining great interest as tailor-made recognition materials for the development of biomimetic sensors. Various approaches have been adopted to interface MIPs with different transducers, including the use of pre-made imprinted particles and the in situ preparation of thin polymer layers directly on transducer surfaces. In this work we functionalized quartz crystal microbalance (QCM) sensor crystals by coating the sensing surfaces with pre-made molecularly imprinted nanoparticles. The nanoparticles were immobilized on the QCM transducers by physical entrapment in a thin poly(ethylene terephthalate) (PET) layer that was spin-coated on the transducer surface. By controlling the deposition conditions, it was possible to gain a high nanoparticle loading in a stable PET layer, allowing the recognition sites in nanoparticles to be easily accessed by the test analytes. In this work, different sensor surfaces were studied by micro-profilometry and atomic force microscopy and the functionality was evaluated using quartz crystal microbalance with dissipation (QCM-D). The molecular recognition capability of the sensors were also confirmed using radioligand binding analysis by testing their response to the presence of the test compounds, (R)- and (S)-propranolot in aqueous buffer.
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- Svedendahl, Mikael, et al.
(författare)
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Refractometric sensing using propagating versus localized surface plasmons : a direct comparison
- 2009
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:12, s. 4428-4433
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Tidskriftsartikel (refereegranskat)abstract
- We present a direct experimental comparison between the refractive index sensing capabilities of localized surface plasmon resonances (LSPRs) in gold nanodisks and propagating surface plasmon resonances (SPRs) on 50 nm gold films. The comparison is made using identical experimental conditions, and for the same resonance wavelength, lambda(SP) congruent with 700 nm. Biosensing experiments with biotin-avidin coupling reveal that the two sensing platforms have very similar performance, despite a superior bulk refractive index sensing figure of merit for the SPR sensor. The results demonstrate that LSPR sensing based on simple transmission or reflection measurements is a highly competitive technique compared to the traditional SPR sensor.
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