Limits...
A method based on light scattering to estimate the concentration of virus particles without the need for virus particle standards.

Makra I, Terejánszky P, Gyurcsányi RE - MethodsX (2015)

Bottom Line: Most often the determination of the concentration of virus particles is rendered difficult by the availability of proper standards.Instead, as standards, well-characterized polymeric nanoparticle solutions are used.The method is especially relevant for preparation of virus particle concentration standards and to vaccine formulations based on attenuated or inactivated virus particles where the classical plaque forming assays cannot be applied.

View Article: PubMed Central - PubMed

Affiliation: MTA-BME "Lendület" Chemical Nanosensors Research Group, Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, Budapest 1111, Hungary.

ABSTRACT
Most often the determination of the concentration of virus particles is rendered difficult by the availability of proper standards. We have adapted a static light scattering based method for the quantification of virus particles (shown for poliovirus) without the need of virus particle standards. Instead, as standards, well-characterized polymeric nanoparticle solutions are used. The method is applicable for virus particles acting as Rayleigh scatterers, i.e., virus particles with equivalent diameters up to ca. 1/10th of the wavelength of the scattered monochromatic light (∼70 nm diameter). Further limitations may arise if the refractive index of the virus is unavailable or cannot be calculated based on its composition, such as in case of enveloped viruses. The method is especially relevant for preparation of virus particle concentration standards and to vaccine formulations based on attenuated or inactivated virus particles where the classical plaque forming assays cannot be applied. The method consists of: •Measuring the intensity of the light scattered by viruses suspended in an aqueous solution.•Measuring the intensity of the light scattered by polymeric nanoparticles of known concentration and comparable size with the investigated virus particle.•The concentration of virus nanoparticles can be calculated based on the two measured scattered light intensities by knowing the refractive index of the dispersing solution, of the polymer and virus nanoparticles as well as their relative sphere equivalent diameters.

No MeSH data available.


Related in: MedlinePlus

The scattered light intensity stemming from different sized standard nanoparticles as a function of their concentration (note the log–log scale). Lines are fitted to the linear range of the respective dependencies.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4487338&req=5

fig0015: The scattered light intensity stemming from different sized standard nanoparticles as a function of their concentration (note the log–log scale). Lines are fitted to the linear range of the respective dependencies.

Mentions: Fig. 3 shows the scattered light intensity (in kcps, kilo count-per-second) as a function of latex nanoparticle concentration in aqueous solution for various size nanoparticles. Given that most DLS instruments use red laser (633 nm in case of Zetasizer Nano ZS) the 25, 45 and 73 nm diameter nanoparticles can be considered as Rayleigh scatterers, while the 330 nm nanoparticle clearly exceeds the size limit. Owing to the strong () dependency of the scattered light intensity on the particle diameter the linear range of scattered light intensity vs. nanoparticle concentration curves is shifting towards lower concentration. The limits of the linear range at low concentrations where the scattered intensity from the particles falls below about 200 kcps is given by the detection limit of the instrument while at high concentrations multiple scattering events occur that will artificially lower the scattered light intensity reaching the detector. Fig. 3 shows clearly why it is recommended to check whether the concentration of the particle standard is in the linear range.


A method based on light scattering to estimate the concentration of virus particles without the need for virus particle standards.

Makra I, Terejánszky P, Gyurcsányi RE - MethodsX (2015)

The scattered light intensity stemming from different sized standard nanoparticles as a function of their concentration (note the log–log scale). Lines are fitted to the linear range of the respective dependencies.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487338&req=5

fig0015: The scattered light intensity stemming from different sized standard nanoparticles as a function of their concentration (note the log–log scale). Lines are fitted to the linear range of the respective dependencies.
Mentions: Fig. 3 shows the scattered light intensity (in kcps, kilo count-per-second) as a function of latex nanoparticle concentration in aqueous solution for various size nanoparticles. Given that most DLS instruments use red laser (633 nm in case of Zetasizer Nano ZS) the 25, 45 and 73 nm diameter nanoparticles can be considered as Rayleigh scatterers, while the 330 nm nanoparticle clearly exceeds the size limit. Owing to the strong () dependency of the scattered light intensity on the particle diameter the linear range of scattered light intensity vs. nanoparticle concentration curves is shifting towards lower concentration. The limits of the linear range at low concentrations where the scattered intensity from the particles falls below about 200 kcps is given by the detection limit of the instrument while at high concentrations multiple scattering events occur that will artificially lower the scattered light intensity reaching the detector. Fig. 3 shows clearly why it is recommended to check whether the concentration of the particle standard is in the linear range.

Bottom Line: Most often the determination of the concentration of virus particles is rendered difficult by the availability of proper standards.Instead, as standards, well-characterized polymeric nanoparticle solutions are used.The method is especially relevant for preparation of virus particle concentration standards and to vaccine formulations based on attenuated or inactivated virus particles where the classical plaque forming assays cannot be applied.

View Article: PubMed Central - PubMed

Affiliation: MTA-BME "Lendület" Chemical Nanosensors Research Group, Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, Budapest 1111, Hungary.

ABSTRACT
Most often the determination of the concentration of virus particles is rendered difficult by the availability of proper standards. We have adapted a static light scattering based method for the quantification of virus particles (shown for poliovirus) without the need of virus particle standards. Instead, as standards, well-characterized polymeric nanoparticle solutions are used. The method is applicable for virus particles acting as Rayleigh scatterers, i.e., virus particles with equivalent diameters up to ca. 1/10th of the wavelength of the scattered monochromatic light (∼70 nm diameter). Further limitations may arise if the refractive index of the virus is unavailable or cannot be calculated based on its composition, such as in case of enveloped viruses. The method is especially relevant for preparation of virus particle concentration standards and to vaccine formulations based on attenuated or inactivated virus particles where the classical plaque forming assays cannot be applied. The method consists of: •Measuring the intensity of the light scattered by viruses suspended in an aqueous solution.•Measuring the intensity of the light scattered by polymeric nanoparticles of known concentration and comparable size with the investigated virus particle.•The concentration of virus nanoparticles can be calculated based on the two measured scattered light intensities by knowing the refractive index of the dispersing solution, of the polymer and virus nanoparticles as well as their relative sphere equivalent diameters.

No MeSH data available.


Related in: MedlinePlus