At Fraunhofer IGB, molecularly imprinted polymer nanoparticles are represented by miniemulsion polymerization with typical particle sizes in the range of 50 to 300 nm. This process is a heterophase polymerization in which two immiscible liquid phases are homogeneously and stably emulsified under the influence of high shear forces, the use of surfactants and co-stabilizers. The resulting nanodroplets of monomer, template molecule and osmotic reagent form nanoreactors in which the polymerization takes place. The resulting polymer nanoparticles are direct images of the emulsion droplets in terms of size and morphology.
This technique of synthesizing molecularly imprinted polymer nanoparticles, which has been patented by Fraunhofer IGB, offers the advantage over other common methods of polymer nanoparticle synthesis such as emulsion polymerization or precipitation polymerization that the synthesis - although complex - is carried out in a single step with quantitative yield and independent of the diffusion of the educts.
In addition to classical miniemulsion polymerization, which is used for the molecular imprinting of hydrophobic molecules, the process can be carried out in an inverse miniemulsion polymerization. This technique can be used to produce nanoparticles for the molecular recognition of hydrophilic molecules such as peptides and proteins.