A Princeton University-led research team has invented an innovative technique for the rapid assembly of nanoparticles designed to deliver drugs or imaging agents deep into the body.
Other applications include pesticides and herbicides that enable more uniform coverage on foliage. Advanced printer inks, in which smaller pigment particles lead to more vibrant colours, are also a possibility, as are sunscreens that allow better coverage with hydrophobic UV blocking compounds.
In Flash NanoPrecipitation, two streams of liquid are directed toward each other in a confined area. The first stream typically consists of an organic solvent containing a mixture of active ingredients and polymers, while the other stream is pure water.
When the streams collide, the active ingredients and polymers precipitate out of solution in an attempt to avoid the water molecules. The polymers immediately self-assemble onto the active clusters to form a coating that has the hydrophobic portion attached to the nanoparticle core, and the hydrophilic part stretching out into the water. Particle size is controlled by adjusting the concentrations of the streams, and the mixing speed.
‘Our process is unique in being able to prepare nanoparticles in the size range of 80–300 nm with high loadings of hydrophobic drugs with controlled surface functionality,’ says Robert Prud’homme. ‘Equally important is the fact that the process is scalable. We can run research studies in our lab with 3 mg of Paclitaxel [an anti-cancer agent derived from yew bark], but the results scale to production runs of 1,000 kg/day in processes run by BASF.’
‘Flash NanoPrecipitation produces high surface area nanoparticles with enhanced dissolution rates that offer the potential of higher bioavailability of poorly water soluble drugs’ says Keith Johnston, a chemist at the University of Texas. ‘Given that 40% or more of discovered drugs are poorly water soluble, this improvement offers the potential to lead to significant improvement in drug efficacy for a wide range of diseases including cancer, heart disease and many others.’
Figure: Schematic of a Flash NanoPrecipitation process in which an active organic ingredient and an amphiphilic diblock copolymer are mixed rapidly with an anti-solvent (e.g., water), resulting in nanoparticles of the active ingredient (© Australian Journal of Chemistry).
Further reading: Flash NanoPrecipitation of Organic Actives and Block Copolymers using a Confined Impinging Jets Mixer, Johnson & Prud’homme, Aus. J. Chem. 56, 1021 (2003) (subscription required).
Article first published in Nanomaterials News.