Co-delivery of paclitaxel and indocyanine green by PEGylated graphene oxide: a potential integrated nanoplatform for tumor theranostics

Abstract

Herein, we have prepared PEGylated nano graphene oxide (NGO-PEG) that co-delivers paclitaxel (PTX) and indocyanine green (ICG) for tumor theranostics, integrating fluorescence imaging and chemotherapy. First, polyethylene glycol (PEG) with a dual-terminal amine was covalently conjugated with NGO to obtain the NGO-PEG. Furthermore, ICG, a near-infrared (NIR) Food and Drug Administration (FDA) approved fluorescent dye was covalently loaded onto NGO-PEG as a fluorescence contrast agent, NGO-PEG–ICG. PTX, a widely clinical used anti-cancer drug, was non-covalently immobilized onto the NGO surface via π–π stacking interaction and hydrogen bonding, giving the multifunctional nano-composite, NGO-PEG–ICG/PTX. The obtained nano-composite had great stability and biocompatibility. NGO-PEG showed (50 ± 2.1)% and (90 ± 1.6)% (w/w) of ICG and PTX loading ratios, respectively, which were determined from a UV-visible spectrometer. The fluorescence signal endowed by ICG was detected in the cytoplasm using confocal microscopy, demonstrating the high-efficiency human osteosarcoma (MG-63) cell uptake of NGO-PEG–ICG/PTX. Moreover, NGO-PEG–ICG/PTX could cause decreased cell viability compared to the same concentration of free PTX, revealing the excellent chemotherapeutic effect of NGO-PEG–ICG/PTX in vitro. In vivo fluorescence imaging results indicated a high MG-63 tumor accumulation of NGO-PEG–ICG/PTX, which could reach the maximum content in tumors at about 29.1% dose per g tissue at 24 h post injection with about eight days of tumor retention. Based on these encouraging results, the NGO-PEG–ICG/PTX was tail vein injected into tumor-bearing mice at day one and day eight, and the tumor-bearing mice showed complete tumor suppression or no relapse and treatment-induced major organ lesions over one-month of treatment. These results suggested that the synthesized versatile NGO-PEG–ICG/PTX with a high fluorescence contrast and chemotherapeutic effect can be a potential tumor theranostic nanoplatform.