I don't know the amount of particles you need. If it not too big amount is needed, sputtering them of the surface of the Diatom into a suitable liquid by laser could be a solution. In this case the
Laser Zentrum Hannover e.V.
Telefon : +49-(0) 511 2788 -0
Fax : +49-(0) 511 2788-100
is a highly experienced group to do this.