DOX-Assisted Functionalization of Green Tea Polyphenol Nanoparticles for Effective Chemo-Photothermal Cancer Therapy

Recently, chemo-photothermal cancer therapy has drawn more and more attention due to its non-invasiveness, low adverse effects and high therapeutic efficiency. Green tea catechins (GTC) including (−)-epigallocatechin-3-gallate (EGCG) are a kind of natural polyphenolic compounds with antitumor activity. In this work, we fabricated nanoparticles loaded with doxorubicin hydrochloride (DOX) and coordinated with Fe(III) for effective chemo-photothermal cancer therapy in which, in a dual role, DOX provided the chemotherapeutic effect and also assisted in achieving nanoparticles with photothermal properties. The GTC nanoparticles (GTCs) were obtained from EGCG and polyethylenimine modified by poly(ethylene glycol) (PEI–PEG) in the presence of formaldehyde. The anticancer drug DOX was encapsulated in GTCs to prepare DOX@GTCs nanoparticles by electrostatic and π–π stacking interactions. After simply mixing with FeCl3 solutions, EGCG–Fe(III) networks successfully emerged to give nanoparticles with photothermal capacity. In vitro experiments indicated that the prepared DOX@GTCs and DOX@GTCs-Fe nanostructures could be effectively internalized into HT-29 cells and that DOX@GTCs-Fe could destroy these cancer cells by hyperthermia in comparison with DOX@GTCs. The animal experiments demonstrated that tumors of mice injected intravenously with both groups of nanoparticles could be effectively inhibited with minimal side effects, confirming their accumulation at tumor sites. Furthermore, the DOX@GTCs-Fe nanoparticles completely ablated the tumor under near-infrared irradiation. Our work indicated that both nanoparticles could achieve targeted drug delivery and that DOX@GTCs-Fe nanoparticles possessed the capability to combine chemo- and photothermal therapy.