Fig 1: Imaging improves dynamic range over spectroscopic approach.a Schematic of the simplified workflow of a digital assay using random particle arrays of gold nanoparticles imaged in-situ with sample. Scale bar 20 µm. Neural network graphic adapted from Wikimedia Commons artwork45 b Design of particle aggregation assay towards C-reactive protein. c/d Traditional absorbance-based methods for inference of analyte concentration. c Spectra of samples with increasing CRP concentrations with associated decrease in 555 nm absorbance and simultaneous red-shifting. d Titration of CRP concentration against spectral shifts. e Example images using 20x darkfield to image the nanoparticle aggregates in the presence of increasing CRP concentration. Scale bar is 10 µm. f Titration of CRP concentration against quantification of aggregate size. Analysis was on raw images, but images shown here are contrast enhanced. Error bars represent SEM.
Fig 2: Image-based CRP assay in whole blood.Human blood samples, containing native (endogenous) analyte, were spiked with exogenous C-reactive Protein. a Plot of mean cluster size of nanoparticles against added concentration of CRP in blood samples. Error bars represent SEM. b Representative image of baseline nanoparticle clustering (no CRP added) in response to endogenous CRP. c Representative image of nanoparticle clustering in the presence of endogenous +200 mg/L exogenous CRP. Scale bars are 6 µm. Analysis was on raw images, but images shown here are contrast enhanced.
Supplier Page from Abcam for Recombinant Human C-Reactive Protein/CRP Protein