Hi Jorge, 

I'm not an expert with viruses in particular, but with nanoparticles normally we get good results by using sonication on the nanoparticle suspension. A more diluted suspension usually helps. But I suppose you already tried this...

Another option would find a suitable liquid-air interface, similar to what is done here

http://pubs.acs.org/doi/abs/10.1021/la100591h

where they get a uniform arrangements of nanoparticles by placing them at the toluene-air interface, and then by letting toluene evaporate.

Hi Jorge

Sonication is indeed a good idea. The particules agregation can be due to electrostatic interactions. So you could try to decrease the ionic strength of your solution to increase particules repulsion. pH could also be considered, try to decrease pH in order to increase the particule repulsion.

Then you could try to direct the assembly of your viruses on the surface. But this is more difficult and maybe out of the scope of your work.

Hope it helps

All the best

Hi Jorge

I happened to see a brief report "Disaggregation of Vaeeinia Virus with Ultrasonic Cleaners" by G. Muller in 1976. The paper shows the comparing pictures with and without sonication. It shows that sonication is indeed a good way. Viruses are well distributed on the surface. Hope it helps.

Hi Jorge,

We have studied a lot of viruses by AFM. Usually we use the sonication for disaggregation. Just take a small piece of the light foam rubber, make a hole, put the eppendorf with virus in this hole and put it to an ultrasonic bath on 10 minutes.

Good luck!    

Thank you all! It seems that sonication is the answer. I've sonicated, but I've been careful  since I had no idea about how resistent the virus are. Apparently their structures are pretty resistant!

Best wishes!