The average number of dengue viruses that were observed in the SEM images.

<p>Standard deviation in brackets.</p

Illustration of experimental methods.

<p>A: The flow direction and the division of the hydroxyapatite (HAp) column into 3 parts. After removing the HAp particles from the column, HAp particles were collected in each part of the column. Column head: lower position of the column (upstream side); Mid-column: middle position of the column; Column end: upper position of the column (downstream side). B: Virus elution and incubation processes of HAp columns. Detailed conditions are described in the Materials and methods, section 3–6.</p

Observation of HAp surfaces that were incubated under 3 different conditions.

<p>Column D: no incubation; Column E: incubated at 2°C for 7 days; Column F: incubated at 37°C for 7 days. HAp particles of the column head were observed with scanning electron microscopy. The white triangles indicate spherical-shaped viruses. The black triangles indicate flat-shaped viruses.</p

SEM images of control HAp surfaces. A: Untreated HAp particles; B: HAp particles after loading of cell culture fluid (virus-free).

<p>SEM images of control HAp surfaces. A: Untreated HAp particles; B: HAp particles after loading of cell culture fluid (virus-free).</p

The average number of dengue viruses that were observed and counted separately as spherical viruses and flat viruses on the SEM images.

<p>Standard deviation in brackets.</p