Scattering performance analysis of reflectance photometer for quantifying gold labeled test strips

Gold labeled immunochromatography assay is widely used in many fields. Quantitative test can be realized by using a reflectance photometer. However, theoretical analysis of the strip and the photometer has seldom been reported. In this paper, the microstructure of immunochromatographic strip labeled by nanogold particles is analyzed with scanning electron microscope (SEM). Based on the SEM images of the strip, Mie's scattering theory is used to investigate the scattering behaviors of particles in the strip, and Lambert cosine law is applied to analyze the diffuse reflection of porous strip. Besides, a reflectance photometer for gold labeled test strip has been developed for fast quantification of immunochromatography assay in our group. Theoretical model is achieved by introducing the parameter of the developed reflectance photometer. The calculated scattering signal distribution is well consistent with that measured by the reflectance photometer.