Microparticles

Microparticles in Microscopy

Latex microspheres have been visualized by light microscopy in unembedded coverslip monolayers, in fixed or unfixed frozen sections, in paraffin sections, and glycol methacrylate kits. For paraffin sections, n-butyl alcohol must be used for clearing and deparaffination since the typical organic solvents, such as toluene, THF, or ethyl acetate, will destroy the beads. The beads cannot be embedded in methyl or butyl methacrylate media. TEM embedments in Epon and Spurrs have been successful. The dye is mostly located near to the surface of particles.


Determination of Particle Numbers

Diameter (mm) Particles/ml (2.5% solids-latex)
1.00 4.55 x 1010
1.50 1.35 x 1010
2.00 5.68 x 109
3.00 1.68 x 109
4.50 4.99 x 108
6.00 2.10 x 108
10.0 4.55 x 107
15.0 1.35 x 107
20.0 5.68 x 106
   
25.0 2.91 x 106
45.0 4.99 x 105
75.0 1.08 x 105
90.0 6.24 x 104


The following equation can be used to calculate the number of particles per ml:

Number of particles per ml = 6W x 1012 / p x P x X3
W = grams of polymer per ml in latex (0.025 g/ml for 2.5% solids)

  • X = diameter in microns of latex particles
  • p = density of polymer in grams per ml (1.05 for polystyrene)