Paclitaxel-Loaded SCK Nanoparticles: An Investigation of Loading Capacity and Cell Killing Abilities <i>in Vitro</i>

Block copolymer nanoparticles having two different hydrodynamic diameters (120 nm vs 50 nm) and core diameters (60 nm vs 20 nm) with variable paclitaxel loading (5 to 20 wt % with respect to polymer weight, 4.4 μg/mL to 21.7 μg/mL paclitaxel concentrations in ultrapure water) were prepared for their <i>in vitro</i> cytotoxicity evaluation. Empty nanoparticles did not show any inherent cytotoxicity even at their highest concentration, whereas paclitaxel-loaded nanoparticles resulted in IC₅₀ values that were better than free paclitaxel at 2 h (0.021 μM vs 0.046 μM) incubation periods, and approximately equal to free paclitaxel at 72 h (0.004 μM vs 0.003 μM) continuous incubation. Confocal fluorescence microscopy images demonstrated that the drug-loaded nanoparticles internalized into KB cells within 2 h and released their payload, resulting in cytotoxicity as evident from the fragmented nuclei present. Functionalization of the nanoparticle surfaces with poly­(ethylene oxide) (2 kDa PEO, 5 PEO per block copolymer chain) did not affect the loading of paclitaxel or cell kill ability. No free paclitaxel was found in these nanoparticle formulations indicated by analytical assays

Hierarchically Assembled Theranostic Nanostructures for siRNA Delivery and Imaging Applications

Dual functional hierarchically assembled nanostructures, with two unique functions of carrying therapeutic cargo electrostatically and maintaining radiolabeled imaging agents covalently within separate component building blocks, have been developed via the supramolecular assembly of several spherical cationic shell cross-linked nanoparticles clustered around a central anionic shell cross-linked cylinder. The shells of the cationic nanoparticles and the hydrophobic core domain of the anionic central cylindrical nanostructure of the assemblies were utilized to complex negatively charged nucleic acids (siRNA) and to undergo radiolabeling, respectively, for potential theranostic applications. The assemblies exhibited exceptional cell transfection and radiolabeling efficiencies, providing an overall advantage over the individual components, which could each facilitate only one or the other of the functions