CIELab chromaticity evolution to measure the binding free energy of non-colored biomolecules to gold nanoparticles

We explore the possibilities of the CIELab chromaticity system parameters' evolution in order to study the interaction between two non-colored biological reactants, lysozyme and adenosine, and the red-colored, non-functionalized citrate gold nanoparticles. By measuring and quantifying the AuNP color changes, which are strongly dependant on their aggregation state, binding free energies are obtained for the first time for these two systems. Results are confirmed via an alternate fitting method which makes use of deconvolution parameters from experimental absorbance spectra. Binding free energies obtained through the use of both means are in good agreement with each other.