Analytical features of particle counting sensor based on plasmon assisted microscopy of nano objects

We present a new analytical method for concentration measurements of nano objects of different nature such as polystyrene nanoparticles or viruses. The method is based on counting single particles of interest bound to a functionalized sensor surface. The counting rate was used for concentration measurements. For polystyrene particles, the counting rate was found to be in good agreement with the theoretically predicted one. Binding of human immunodeficiency virus (HIV) virus-like particles (VLPs) to the sensor surface functionalized with antibodies was observed. The concentration of HIV–VLP was estimated by means of well-characterized solutions of artificial nanoparticles as a reference material. The results are in a good agreement with standard enzyme-linked immunosorbent assay (ELISA) analysis. Factors are discussed which determine the detection power of the method.