Bioresponsive Polymer Coating on Targeted Drug Nanorods

Non-specific delivery and ineffective drug release at the target site are among the top challenges to effective treatment. The first challenge reflects the fact that interactions with carriers (i.e., nanoparticles) can denature the active ingredients of drugs by shear stress. The second challenge is low affinity for specific receptor proteins overexpressed on the target cell surface. The third challenge of ineffective drug release can be overcome by exploiting the disease microenvironment. Here, we report a one-step process to prepare bioresponsive polymer coated drug nanorods (NRs) from liquid precursors using the solvent diffusion method. A thin layer (10.3 ± 1.4 nm) of poly(e-caprolactone) (PCL) polymer coating was deposited on the surface of camptothecin (CPT) anti-cancer drug NRs. The mean size of PCL-coated CPT NRs was 500.9 ± 91.3 nm length x 122.7 ± 10.1 nm width. The PCL polymer coating was biodegradable at acidic pH 6 as determined by Fourier Transform Infrared (FT-IR) spectroscopy. CPT drugs were released up to 51.5% when PCL coating dissolved into non-toxic carboxyl and hydroxyl groups. Trastuzumab (TTZ), a humanized IgG monoclonal antibody, was conjugated to the NR surface for breast cancer cell targeting. Combination treatments using CPT and TTZ decreased the HER-2 positive BT-474 breast cancer cells by 66.9 ± 5.3 % in vitro. These results suggest highly effective combination treatments of breast cancer cells using bioresponsive polymer coated specific drug delivery.