Superparamagnetic Iron Oxide Nanotheranostics for Targeted Cancer Cell Imaging and pH-Dependent Intracellular Drug Release

Abstract

Purpose-To develop antibody-and fluorescence-labeled superparamagnetic iron oxide nanoparticle (SPIO) "nanotheranostics" for magnetic resonance imaging (MRI) and fluorescence imaging of cancer cells and pH-dependent intracellular drug release.Method-SPIO nanoparticles (10 nm) were coated with amphiphilic polymers and PEGylated. The antibody HuCC49ΔCH2 and fluorescent dye 5-FAM were conjugated to the PEG of IONPs. Anticancer drugs doxorubicin (Dox), and azido-doxorubicin (Adox), MI-219, 17-DMAG containing primary amine, azide, secondary amine, and tertiary amine, respectively, were encapsulated into IONPs. The encapsulation efficiency and drug release at various pHs were determined using an LC-MS/MS. The cancer targeting and imaging were monitored using MRI and fluorescent microscopy in colon cancer cell line (LS174T). The pH-dependent drug release, intracellular distribution, and cytotoxicity were evaluated using microscopy and MTS assay.Results-The pegylation of SPIO and conjugation with antibody and 5-FAM increased SPIO size from 18 nm to 44 nm. Fluorescent imaging, magnetic resonance imaging (MRI) and Prussian blue staining demonstrated that HuCC49ΔCH2-SPIO increased cancer cell targeting. HuCC49ΔCH2-SPIO "nanotheranostics" decreased the T 2 values in MRI of LS174T cells from 117.3±1.8 ms to 55.5±2.6 ms. The loading capacities of Dox, Adox, MI-219, and 17-DMAG were 3.16 ± 0.77%, 6.04± 0.61%, 2.22± 0.42%, and 0.09±0.07%, respectively. Dox, MI-219 and 17-DMAG showed pH-dependent release while Adox didn't. Fluorescent imaging demonstrated the accumulation of HuCC49ΔCH2-SPIO "nanotheranostics" in endosomes/lysosomes. The encapsulated Dox was released in acidic lysosomes and diffused into cytosol and nuclei. In contrary, the encapsulated Adox only showed limited release in endosomes/lysosomes. HuCC49ΔCH2-SPIO "nanotheranostics" targetedly delivered more Dox to LS174T cells than nonspecific IgG-SPIO and resulted in a lower IC 50 (1.44 μM v.s. 0.44 μM).* To whom correspondence should be addressed: Duxin Sun, PhD, Department of Pharmaceutical Sciences, College of Pharmacy, The University of Michigan, 428 Church Street, Ann Arbor, MI 48109, duxins@umich Conclusion-The developed HuCC49ΔCH2-SPIO "nanotheranostics" provides an integrated platform for cancer cell imaging, targeted anticancer drug delivery and pH-dependently drug release.

The Upcoming Field of Theranostic Nanomedicine: An Overview

“…Targeted nanocarriers exhibited IC 50 value of 0.44 M which was significantly lower than that of the non-targeted nanocarriers (1.42 M). 104 …”

pH‐Responsive Drug‐Delivery Systems

“…DOX was then conjugated to the Fe 3 O 4 colloidal nanocrystal clusters through a hydrazone bond to provide a pH-sensitive drug release capability, and the release rate of DOX was dramatically improved in low pH environments, whereas almost no DOX was released at neutral pH values. Zou et al [91] prepared superparamagnetic iron oxide nanoparticles (SPIO, 10 nm) coated with amphiphilic polymers and PEGylated. The antibody HuCC49DCH 2 and fluorescent dye 5-FAM were conjugated to the PEG on iron oxide nanoparticles, and the anticancer drugs DOX, azido-doxorubicin (Adox), MI-219, and 17-DMAG, which contain primary amine, azide, secondary amine, and tertiary amine, respectively, were encapsulated into the iron oxide nanoparticles.…”

Responsive Theranostic Systems: Integration of Diagnostic Imaging Agents and Responsive Controlled Release Drug Delivery Carriers

“…Therapeutic agents that contain amine groups have demonstrated pH-dependent release; hypothesized to be a result of the amine group protonation 10 . Zou et al 10 recently reported the development of a novel antibody- and fluorescence-labeled superparamagnetic iron oxide nanoparticle (SPIO) nanotheranostic carrier for MRI and fluorescent imaging, and pH-dependent intracellular drug release. To create a dual-imaging particle, the group conjugated the fluorescent dye 5-FAM to the PEG polymer coating iron oxide nanoparticles (IONPs).…”