Differential light scattering spectroscopy for studying biospeciric assembling of gold nanoparticles with protein or oligonucleotide probes

A new method is proposed for studying biospecific interactions in systems of conjugates of colloidal gold nanoparticles. The method is based on measuring the differential spectra of light scattered at 900 within wavelength range 350-800 nm. Addition of complementary component to bioconjugate probe results in the nanoparticle aggregation that can be monitored by the light scattering or extinction spectra. To this end, we developed a special attachment to a Specord M-40 spectrophotometer and a corresponding measurement procedure called by us the differential light scattering spectroscopy. The method is compared with the common spectrophotometry as applied to colloidal gold conjugates to various polymers including proteins and oligonucleotides. Our experiments with the gold nanoparticles of different sizes showed a higher potential sensitivity of the suggested method as compared to spectrophotornetry. It is expected that the differential light scattering spectroscopy can be used to develop sensitive analytical biospecific test for various biopolymers.