After particles are formed, they are purified, either by tangential flow filtration (top) or by centrifugation (not shown) to remove excess polymer and unencapsulated cargo.  Finally, organic solvent is evaporated (bottom).

Our lab usually prepares particles by emulsion, as illustrated here.  In the first step (top), an aqueous solution containing particle cargo is added to an organic solution containing the polymer strands that will encapsulate the cargo.  As the mixture is stirred (middle), the mixture forms an emulsion: droplets of the aqueous solution are surrounded by the organic solution.  To keep the two components from separating, a stabilizer such as polyvinyl alcohol is added (bottom).

We have shown that fiber optic ATR-FTIR spectroscopy accurately measures release of protein from hydrogels and nanoparticles in real time.  This scheme illustrates the setup: the ATR-FTIR probe measures changes in the solution as conditions are manipulated (for example, by addition of acid) and monitored (in this case, using a pH electrode).

Our inflammation responsive nanoparticles are stable at low concentrations of reactive oxygen species (ROS) such as peroxide, swell at higher concentrations of ROS, and disintegrate in the presence of both mildly acidic pH and disease state levels of ROS.