Long-term stability of PBCA nanoparticle suspensions

In this study, the stability of poly(butyl cyanoacrylate) (PBCA) nanopartic le suspensions was examined for up to 1 year by measuring the nanoparticle sizes. The nanoparticles were prepared with different stabilizers (dextran 70.000, poloxamer 188, or polysorbate 85), and the particle size was determ ined before and after purification by centrifugation and after dilution wit h different solutions (0.1 N HCl, 0.01 N HCl, H2O, and PBS). The most const ant sizes were with the untreated acidic nanoparticle suspensions. In all o ther cases, agglomeration of the particles occurred: the extent of this agg lomeration and the time at which the agglomeration occurred depended on the experimental conditions. Nanoparticle polymer degradation, as indicated by size decrease, was not observed. Thus, PBCA nanoparticles can be stored as suspensions, making the lyophilization and the sometimes problematic resus pension by ultrasonication, unnecessary, which is advantageous for clinical applications.