Colloids and nanoparticles
Colloidal crystals, nanoparticle films, gold-on-DNA arrays, and particle self-assembly movies in the digests use particles from tens of nanometers to tens of micrometers, suspended in liquid.
What exists today
- Gold and silver nanoparticles in many sizes and coatings, sold as ready-to-use suspensions.
- Polystyrene and silica microspheres with tight size control, plain or fluorescent, and with chemical handles on the surface.
- Magnetic (paramagnetic) beads for steering particles with a magnet.
- Janus particles (two different halves) in larger sizes. Smaller ones are mostly made in research labs.
- Surfactants and stabilizers (soap-like molecules) from general chemical suppliers.
Example vendors
| Need | Examples (verified links) | Notes |
|---|---|---|
| Gold and silver nanoparticles | Cytodiagnostics , nanoComposix (Fortis Life Sciences) | Many sizes and surface coatings |
| Polystyrene and silica microspheres | Bangs Laboratories , microParticles GmbH , Spherotech | Size standards, fluorescent, magnetic |
| Janus microspheres (45 µm and up) | Cospheric custom Janus particles | Half-coated spheres. Too big for most colloid physics, good for demos |
| Surfactants, salts, solvents | Thermo Fisher , VWR | General lab chemical catalogs |
Maturity
- Plain particles: industrial. They are widely used in diagnostics and coatings.
- Functionalized particles (DNA-coated, patchy, shape-controlled): university-lab. Usually made in-house.
- Programmable colloidal materials as products: not yet available.
Bottlenecks and gaps
- Patchy and shaped particles (sticky spots in chosen places) are the heart of programmable colloids, and there is almost no catalog supply.
- Batch-to-batch variation in size and surface chemistry changes how particles assemble.
- Seeing the result needs microscopy, and below about 200 nm you need electron microscopes.
What would need to exist for scale-up
Catalogs of standard patchy and DNA-coated particles, shared size and surface-chemistry standards, and inline optical checks during assembly.
Safety notes
- Dry nanopowders can be breathed in. Buy particles already suspended in liquid when you can, and never handle dry nanopowders outside a fume hood or proper enclosure.
- NIOSH recommends caution with free, unbound nanoparticles. See NIOSH nanotechnology guidance .
- Some solvents used with particles are flammable or toxic. Follow the Safety Data Sheet that comes with every product.
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