Glycosylated gold nanoparticle libraries for label-free multiplexed lectin biosensing

Glycosylated nanoparticle libraries are developed to enable ‘barcode’ sensing of lectins and toxins.


Particle size determination by Dynamic Light Scattering (DLS)
400 μL of glycoAuNPs in a disposable low volume cuvette. 3 measurements comprised of 10 runs were made of each sample at 25 °C. Average size and distribution were recorded.

Lectin induced aggregation studies by pixel intensity
The plates were then scanned using a canon flatbed scanner, the images were converted to a HSB stack and the saturation image was used for tiff image file uploaded into the opensource image processing package ImageJ (version 1.46a) where a region of interest was drawn around every well. The colour (RGB) image was then converted into a hue saturation and brightness (HSB) stack of images and the saturation image used. The regions of interest drawn on the original image were added to the saturation image using the ROI manager and average pixel intensity in each region of interest was measured using an inbuilt function in ImageJ.

Linear discriminant analysis
A fixed concentration of 6.25 μg.mL -1 lectin was added to glycoAuNPs. 5 repeats were made for each carbohydrate functionalised particle and the absorbance at 450 nm and 750 nm were recorded for linear discriminant analysis.
Every lectin was added to every surface as described in the lectin binding assay section. This was repeated 4 times to generate a training data matrix of 6 particles x 6 lectins x 5 replicates, which was then subjected to a classical linear discriminant analysis (LDA) in R (version 2.14.1).

Additional Figures
Size determination of goldnanoparticles by DLS. Before functionalisation (60 nm) and after functionalisation with carbohydrate terminated polymers. There is a size increase of about 5 nm.   Table 1 from the main article.
Size increase of over time of glycogoldnanoparticles upon addition of 200 nM SBA. Figure S4: DLS: Kinetic increase in particle size due to aggregation induced by addition of