Silica nanoparticles encapsulating near-infrared emissive cyanine dyes.

We show that efficient near-infrared (NIR) cyanine fluorophores (1 and 2) can be encapsulated into silica nanoparticles providing a highly versatile and unique platform for in vivo diagnostics. Utilizing this platform, multiple fluorophores can be loaded within a single particle allowing the light absorption and emission properties of the nanoparticle to be controlled independent of particle size. Furthermore, such dyed nanoparticles may have extinction coefficients as high as about 100 x 10(6) Lmol(-1)cm(-1) in the NIR (on a per mole of particles basis), with quantum yields from about 8-10%.

Controlled, simultaneous assembly of polyethylenimine onto nanoparticle silica colloids.

A novel precision-assembly methodology is described on the basis of the controlled, simultaneous assembly (CSA) of a core nanoparticle substrate and polyelectrolyte solutions. The method is capable of assembly rates at least as fast as 10(16) core particles s(-1) L(-1) and affords concentrated suspensions of stable colloids with an adsorbed polyelectrolyte. The resulting dispersions are highly homogeneous, have a low viscosity and narrow particle-size distribution, and are stable colloids, even at solid concentrations of at least 33 wt %.