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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: 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).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

Intensity distribution plot of the 45 nm diameter nanoparticle standard at 1014 (green) and 1010 (red) mL−1 concentrations. It is apparent that at the lower concentration the scattered light intensity from other particles (e.g., impurities) becomes significant and the total light intensity needs to be corrected with the percentage stemming from the standards. At higher concentration however the peak of the standard particles is the dominant one and the total intensity of the scattered light can be used for calculation.
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fig0005: Intensity distribution plot of the 45 nm diameter nanoparticle standard at 1014 (green) and 1010 (red) mL−1 concentrations. It is apparent that at the lower concentration the scattered light intensity from other particles (e.g., impurities) becomes significant and the total light intensity needs to be corrected with the percentage stemming from the standards. At higher concentration however the peak of the standard particles is the dominant one and the total intensity of the scattered light can be used for calculation.

Mentions: As the solution may contain particles that differ from the standards but also scatter light, one needs to calculate the scattered light intensity stemming only from the standard nanoparticles. For this first the size distribution of the particles in the solution should be measured by DLS. The results should be plotted as intensity percent (intensity percent vs. size) and the peak corresponding to the standard particles should be identified (Fig. 1). The area of the peak corresponds to the percent of the intensity of the scattered light stemming from the nanoparticle standard. Multiplying with this percentage value the total intensity of the scattered light (stemming from all particles in the solution) results in the light intensity scattered by the standards. For the specific case of using the Malvern Zetasizer Nano ZS see the procedure detailed in the Supplementary information.


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)

Intensity distribution plot of the 45 nm diameter nanoparticle standard at 1014 (green) and 1010 (red) mL−1 concentrations. It is apparent that at the lower concentration the scattered light intensity from other particles (e.g., impurities) becomes significant and the total light intensity needs to be corrected with the percentage stemming from the standards. At higher concentration however the peak of the standard particles is the dominant one and the total intensity of the scattered light can be used for calculation.
© Copyright Policy - CC BY
Related In: Results  -  Collection

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

fig0005: Intensity distribution plot of the 45 nm diameter nanoparticle standard at 1014 (green) and 1010 (red) mL−1 concentrations. It is apparent that at the lower concentration the scattered light intensity from other particles (e.g., impurities) becomes significant and the total light intensity needs to be corrected with the percentage stemming from the standards. At higher concentration however the peak of the standard particles is the dominant one and the total intensity of the scattered light can be used for calculation.
Mentions: As the solution may contain particles that differ from the standards but also scatter light, one needs to calculate the scattered light intensity stemming only from the standard nanoparticles. For this first the size distribution of the particles in the solution should be measured by DLS. The results should be plotted as intensity percent (intensity percent vs. size) and the peak corresponding to the standard particles should be identified (Fig. 1). The area of the peak corresponds to the percent of the intensity of the scattered light stemming from the nanoparticle standard. Multiplying with this percentage value the total intensity of the scattered light (stemming from all particles in the solution) results in the light intensity scattered by the standards. For the specific case of using the Malvern Zetasizer Nano ZS see the procedure detailed in the Supplementary information.

Bottom Line: 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).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