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. Author manuscript; available in PMC: 2015 Nov 1.
Published in final edited form as: Biomaterials. 2014 Aug 8;35(34):9343–9354. doi: 10.1016/j.biomaterials.2014.07.043

Figure 1. Surface modification of MLNPs.

Figure 1

Schematic for the step-by-step fabrication and surface modifications of multi-layered nanoparticles (MLNPs). A–B. Camptothecin was encapsulated into poly(lactic-co-glycolic) (PLGA) nanoparticles. C–D. The PLGA nanoparticles were complexed with polyethyleneimine (PEI) which results in a net positive surface charge on the MLNPs. E–F. Plasmid DNA was then complexed onto the positive surface of the MLNPs. G–H. Another layer of PEI was subsequently complexed onto the MLNPs. I–J. A heterobifunctional polyethylene glycol (PEG) linker was then conjugated to the outer PEI layer. K–L. Finally, a cell penetrating peptide, specifically modified antennapedia, was conjugated to the PEG linker.