Encapsulation, permeability, and cellular uptake characteristics of hollownanometer-sized conductive polymer capsules

The use of nanometer-sized gold particles as templates for the synthesis of hollow poly(pyrrole), poly(N-methylpyrrole), and poly(3-methylthiophene) i s described in this paper. Diffusion coefficients of small molecules throug h the capsule shell were found to vary by almost 3 orders of magnitude depe nding on the polymer, polymer oxidation state, and counteranion incorporate d during polymer synthesis. A small molecule (anthraquinone) and an enzyme (horseradish peroxidase) were trapped inside hollow capsules by attaching t hem to the template particle prior to polymerization and particle etching. A thin poly(pyrrole) shell protected the enzyme 2 times longer in neat tolu ene compared to unencapsulated enzyme. Finally, the potential for using con ductive polymer nanoparticles for intracellular delivery or diagnostics was examined by administering partice suspensions to 3T3 murine fibroblasts. P articles ranging in size from 25 to 100 nm were engulfed by fibroblasts wit hout compromising cell viability.