A graphene-sandwiched DNA nano-system: regulation of intercalated doxorubicin for cellular localization

Abstract

Control of the sub-cellular localization of nanoparticles (NPs) with enhanced drug-loading capacity, employing graphene oxide (GO), iron oxide (Fe₃O₄) NPs and sandwiched deoxyribonucleic acid (DNA) bearing intercalated anticancer drug doxorubicin (DOX) has been investigated in this work. The nanosystems G–DNA–DOX–Fe₃O₄ and Fe₃O₄–DNA–DOX differentially influence serum protein binding and deliver DOX to lysosomal compartments of cervical cancer (HeLa) cells with enhanced retention. Stern–Volmer plots describing BSA adsorption on the nanosystems demonstrated the quenching constants, K_sv for G–DNA–DOX–Fe₃O₄ and Fe₃O₄–DNA–DOX (0.025 mL μg⁻¹ and 0.0103 mL μg⁻¹ respectively). Nuclear DOX intensity, measured at 24 h, was ∼2.0 fold higher for Fe₃O₄–DNA–DOX in HeLa cells. Parallelly, the cytosol displayed ∼2.2 fold higher DOX intensity for Fe₃O₄–DNA–DOX compared to G–DNA–DOX–Fe₃O₄. Fe₃O₄–DNA–DOX was more efficacious in the cytotoxic effect than G–DNA–DOX–Fe₃O₄ (viability of treated cells: 33% and 49% respectively). The DNA:nanosystems demonstrated superior cytotoxicity compared to mole-equivalent free DOX administration. The results implicate DNA:DOX NPs in influencing the cellular uptake mechanism and were critically subject to cellular localization. Furthermore, cell morphology analysis evidenced maximum deformation attributed to free-DOX with 34% increased cell roundness, 63% decreased cell area and ∼1.9 times increased nuclear-to-cytoplasmic (N/C) ratio after 24 h. In the case of Fe₃O₄–DNA–DOX, the N/C ratio increased 1.2 times and a maximum ∼37% decrease in NSA was noted suggesting involvement of non-canonical cytotoxic pathways. In conclusion, the study makes a case for designing nanosystems with controlled and regulated sub-cellular localization to potentially exploit secondary cytotoxic pathways, in addition to optimized drug-loading for enhanced anticancer efficacy and reduced adverse effects.