Particle size analysis

Author: admin     Date: February 21, 2024

Effect of the Refractive Index on the Light Scattering Detection

Based on the theory of Rayleigh scattering, the scattering cross-section of a nanoparticle is not only dominated by the particle size but also influenced by the refractive index contrast, which is the ratio of the refractive index of the particle to that of the medium. A silica nanoparticle scatters 3.8-fold less light than a polystyrene nanoparticle of the same size at a wavelength of 532 nm, with refractive indices of 1.46 and 1.59, respectively.

The exact refractive index of viruses is not known, but it can be assumed to be 1.45 or 1.46, similar to that of proteins and DNA. The effect of the refractive index on the light scattering detection of single viruses is examined using the bacteriophage T7, a bacterial virus with an icosahedral capsid head of ~60 nm in diameter, along with silica nanospheres and polystyrene nanobeads of a comparable size.

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Discrimination and Size Measurement of Viruses in a Mixture

Nano-sized biological agents and pathogens, such as viruses, are known to be responsible for a wide variety of human diseases, such as the flu, AIDS, and herpes. They have also been used as biowarfare agents. Viral size plays a substantial role in transmission dynamics, disease outbreaks, and outcomes. Rapid and accurate detection and characterization of single viral particles have become increasingly important for virology research, disease diagnosis and treatment, and biotechnology applications.

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