Software includes ratiometric calculation for the SoPRano™ Label-Free assay
The SoPRano™ label-free assay is based upon Localized Surface Plasmon Resonance (LSPR) which can be found in substances such as Gold Nano Rods (GNRs). GNRs have a specific absorbance maximum (λmax) and when proteins are subsequently bound to the GNRs, this λmax shifts to the red region of the spectrum. This means that different proteins and different protein concentrations bound to the GNRs will have a different change in λmax. Therefore the λmax and the change in λmax must be determined for each new SoPRano™ assay. To help with the data analysis, Pharma Diagnostics has created a ratiometric method that accurately measures this change in λmax.
After determining the λmax of the SoPRano™ assay using fast, full-spectrum analysis, the λmax+80 is determined. This OD is then divided by the λmax OD to get ODλmax+80/ODλmax. Figure 1 shows graphically the λmax+80 changes that can be measured and Figure 2 shows the binding curves that can be created using the OD ratio. As pointed out earlier, these calculations are now easily done with BMG LABTECH’s MARS v2.40 or higher. In addition, a SoPRano™ MARS calculation template is available upon request. This template can be imported into MARS 2.40 and it will do all of the necessary calculations with one press of a button.