Hyperbranched Polymer-Functionalized Magnetic Nanoparticle-Mediated Hyperthermia and Niclosamide Bimodal Therapy of Colorectal Cancer Cells

Functionalized magnetic nanoparticles (MNPs) have attracted particular interest as potential drug delivery carriers as they offer dual advantage of delivering drugs to the target site complemented with magnetic hyperthermia-mediated therapy. Hyperbranched polymer-functionalized MNPs have the potential to perform a dual role of killing cancer cells by hyperthermia (by magnetite core) with apoptosis (by loaded niclosamide). These are formed by the co-precipitation of iron salts followed by aminocellulose grafting, branch growth, and PEGylation. NP formation was investigated by determining particle size, zeta potential, and microscopic (transmission electron microscopy, field-emission scanning electron microscopy, and atomic force microscopy) studies. Results showed that these nanocarriers were 107 +/- 57 nm in size with a zeta potential of -18 mV and exist as NPs. Drug loading and encapsulation efficiency were calculated as 15.28 +/- 2.72 and 76.41 +/- 1.84%, respectively, using UV-vis spectroscopy. NPs were internalized into HCT116 cells as investigated using confocal microscopy and flow cytometry. Blank NPs at the dose of 200 mu g/mL were found to be cytocompatible using hTERT cells and hemocompatible. The cell viability study suggested that niclosamide-loaded functionalized magnetic nanoparticles (NFMNPs) were more effective (7 times) than free niclosamide in killing colon cancer cells. Moreover, NFMNPs induced apoptosis in an immunofluorescence study of cleaved caspase-3. Exposure of NFMNPs to an alternating magnetic field (AMF) resulted in a slight increase in the rate of niclosamide release. AMF exposure drastically reduced cell viability due to dual effects of hyperthermia and niclosamide after treatment with NFMNPs. The potentiation of cell death due to dual effects of hyperthermia and niclosamide was further confirmed by Annexin-V/propidium iodide assay using flow cytometry. The results imply that niclosamide delivery through hyperbranched polymer-functionalized MNPs may serve as an effective strategy for the treatment of colorectal cancer.