Ultrasensitive antigen quantification with functionlized Ag nanoparticles

Estocolmo

Conferencia; Baltic Conference Series 2017; 2017

International Association of Advanced Materials

In this presentation we will give our recent developments for the quantification of antigens of relevance in medicine and food science using the optical properties of Ag nanoparticles. Using a functionalization strategy of plasmonic nanoparticle probes it is demonstrated that it is possible to detect sub-picomolar concentrations of specific antigens directly in clinical as well as in food samples. This novel ultrasensitive optical bionanosensor, denoted as Intensity depletion Immunolinked Assay (IDILA) has a widespread capability for antigens detection and is based on the strong interaction of the streptavidin-biotin system combined with the high specific biomolecular recognition of immunoglobulin. The biosensor works on two main principles A) the controlled agglomeration of Ag nanospheres generated in the presence of a biotinylated immunoglobulin which acts as a linker between functionalized Ag nanoparticles B) The inhibition of the agglomeration process in the presence of the specific antigen to be detected .The amount of Au NP aggregates decreases by increasing the antigen concentration. As a consequence the intensity of the UV-Vis spectra of monomers decreases, and the depletion is extremely sensitive to the antigen concentration. The IDILA methodology allowed specific detection of various antigens of relevance in Medicine as well as in Food Science, with significantly improved sensitivity over the standard ELISA (Enzyme-lLnked Immunosorbent Assay). In particular,we demonstrate that this methodology could be used to detect several cytokines, which play an important role in the activation, proliferation and differentiation of B and T cells, macrophages, dendritic cells, granulocytes and various other cells that participate in the immune response and that have been implicated in the pathogenesis of rheumatoid arthritis.In the field of Food Science we show how this methodology can be applied for the ultrasensitive detection of gliadin in food samples, a protein responsible for causing celiac disease, an autoimmune disease that causes gluten intolerance. For a signal readout, we use a common UV-Vis spectrometer and we evaluate the applicability of the method using standard equipment commonly used to perform ELISA (microplate reader), showing that IDILA requires smaller volumes of sample for processing and is capable of supporting rapid operation.