Hydrophobic myristic acid modified PAMAM dendrimers augment the delivery of tamoxifen to breast cancer cells

Abstract

In the present study, cationic generation 5 polyamido amine (G5 PAMAM) dendrimers were hydrophobically modified by grafting the surface with lipid-like myristic acid (My) tails to augment their potential as a drug delivery vector in vitro. Nuclear magnetic resonance (¹H NMR) measurements confirmed the presence of myristic acid tails at the dendrimer periphery (My-g-G5). Tamoxifen (TAM) an estrogen agonist, was entrapped in the My-g-G5 domains to impart them with anticancer properties. Transmission electron microscopy (TEM) observations indicate these My-g-G5/TAM complexes to be around 6–8 nm in size. Further, in vitro drug release studies ascertained the ability of My-g-G5/TAM complexes to release TAM in a sustained fashion under acidic conditions (pH 5.5). Cellular uptake studies revealed lysosomes as the target organelles of these nanocomplexes. MTT assay suggested good cell viability of My-g-G5 dendrimers and strong inhibitory effects of My-g-G5/TAM complexes in MCF-7 (human breast adenocarcinoma, estrogen receptor (ER) positive) cells. Dual fluorescence staining, reactive oxygen species (ROS) generation, cell cycle analysis, field emission scanning electron microscopy (FE-SEM), change in mitochondrial membrane potential (MMP, ΔΨ) and gene expression studies revealed the apoptosis-inducing ability of My-g-G5/TAM in MCF-7 cells. Based on our findings, we present these hydrophobically modified G5 PAMAM dendrimers as prospective nanocarriers for TAM delivery for anticancer applications.