The Effects of Poly(ethylene glycol) Chain Length on the Presentation of Species on the Surface of Poly(styrene-b-ethylene oxide) Nanoparticles

Abstract

Nanoparticles (NPs) are increasingly attractive in therapeutic and diagnostic medical applications, such as drug delivery or imaging contrast agents. In addition to enabling multiple methods of delivery (oral and inhalation), NPs can increase bioavailability, allow for controlled release, and reduce potential side effects. Applications in medicine may be enhanced through NP surface modifications, including functional chain ends such as peptides, antibodies, or drugs. Functionalized NPs allow drug aggregation towards specific sites in the body, potentially reducing side effects and drug toxicity. This approach may be particularly effective in targeting tumors, which can cause significant damage to healthy cells in the body. However, functionalized NP effectiveness is dependent on the presentation of molecules attached to chain ends at the surface of NPs, allowing for binding to target surfaces or proteins. Hence, the effectiveness of surface modifications may be reduced by migration or incorporation of functionalized ends to the NP corona or NP core. In order to verify that functionalized nanoparticle surface chains are available, PEG chains were modified with Nile Red and the fluorescence of NP constructed with these chains was measured. Because the emitted wavelengths depend on the local environment of the dye, this technique allows for the determination of chain end migration to the either the NP core or corona. These experiments were able to differentiate between dye aggregation in various NP regions during formation and were used to measure migration of Nile Red after synthesis. Chain length effects on dye accumulation within NPs were determined to inform future work in designing and implementing NPs for more effective medical applications.