Assays benefit from CCD spectrometer technology

With this label-free assay platform, IC/EC₅₀s and K_ds can be determined for biological interactions such as protein-protein or antibody-antigen.

Based upon on Surface Plasmon Resonance (SPR) technology that has previously only been found in expensive dedicated biosensing equipment, the SoPRano label-free technology uses Localised Surface Plasmon Resonance (LSPR) – active Gold Nano Rods (GNRs) that can detect the binding of molecules to the GNR surface in a concentration dependent manner.

A key feature to the SoPRano label-free assay is that an absorbance microplate reader can be used to measure the change in the LSPR signal upon binding, which manifests as a red-shift in the maximum absorbance wavelength (lmax).

The specific spectral change upon ligand interaction depends upon the nature of the interactants. These specific changes provide both qualitative and quantitative information, therefore, full spectrum, far-red measurements (600-1000 nm) are necessary to fully analyze the SoPRano label-free assay.

“Since the whole absorbance spectrum red-shifts when molecules bind to the SoPRano GNR surface, a whole spectrum needs to be measured. In less than 1 second per well and at a resolution of 1 nm, our CCD spectrometer microplate readers can instantly capture an entire absorbance spectrum (220-1000 nm).

“Other microplate readers have to ‘build’ the spectrum, this can take tens of seconds (or even minutes) and it is usually at a lower resolution. This makes BMG LABTECH’s CCD spectrometer microplate readers perfect for the SoPRano label-free assay,” said Dr. E.J. Dell, BMG LABTECH’s International Marketing Director.

BMG LABTECH has also added a feature to its MARS Data Analysis software that allows for the SoPRano^TM ratiometric data analysis to be done quickly and efficiently. After performing these ratiometric calculations, one-site binding curves are plotted and K_ds and IC/EC₅₀s are determined.