A Hybrid Nanomaterial for the Controlled Generation of Free Radicals and Oxidative Destruction of Hypoxic Cancer Cells

Abstract

Anticancer modalities based on oxygen free radicals, including photodynamic therapy and radiotherapy, have emerged as promising treatments in the clinic. However, the hypoxic environment in tumor tissue prevents the formation of oxygen free radicals. Here we introduce a novel strategy that employs oxygen-independent free radicals generated from a polymerization initiator for eradicating cancer cells. The initiator is mixed with a phase-change material and loaded into the cavities of gold nanocages. Upon irradiation by a near-infrared laser, the phase-change material is melted due to the photothermal effect of gold nanocages, leading to the release and decomposition of the loaded initiator to generate free radicals. The free radicals produced in this way are highly effective in inducing apoptosis in hypoxic cancer cells.

Synthesis of CaO2 Nanocrystals and Their Spherical Aggregates with Uniform Sizes for Use as a Biodegradable Bacteriostatic Agent

“…[1,2] It is the oxidative stress induced by reactive oxygen species (ROS) that plays the essential role in enabling the antimicrobial capability of these nanoparticles. [3,4] However, the low concentration of oxygen in an anaerobic environment prevents the formation of ROS, [5] reducing the antimicrobial activity of most metal and solvent in an effort to mitigate the hydrolysis of CaO 2 nanoparticles. When H 2 O 2 is added into an ethanol solution containing CaCl 2 and PVP, CaO 2 primary nanocrystals of 2-15 nm in size are formed immediately, followed by their assembly into spherical aggregates with a uniform size (Scheme 1).…”

Multifunctional Nanotherapeutics for Photothermal Combination Therapy of Cancer

“…However, the prognosis of PDT is always limited by the hypoxia microenvironment at the tumor site, because oxygen is indispensable for PDT. [82] In their design, an azo compound is loaded to the hollow cavity of gold nanocages and lauric acid (melting point 44°C) is used to fix the azo compound inside the nanocages (Figure 5c). Last year, Xia and coworkers first reported a photothermal approach to generate free radicals without oxygen.…”

“…Cancer vaccines aim at promoting the maturation and differentiation of antigen presenting cells, mainly dendritic cells (DCs), [87] which accelerate presenting tumor antigens to lymphocytes and . [82] Copyright 2017, Wiley-VCH. [75] Copyright 2016, Wiley-VCH.…”

“…Last year, Xia and coworkers first reported a photothermal approach to generate free radicals without oxygen. [82] In their design, an azo compound is loaded to the hollow cavity of gold nanocages and lauric acid (melting point 44°C) is used to fix the azo compound inside the nanocages (Figure 5c). Upon laser irradiation, gold nanocages generate heat, melting lauric acid and the azo compound is released and subsequently decomposes under thermal stimulation to produce alkyl radicals.…”

“…Reproduced with permission. [82] Copyright 2017, Wiley-VCH. e) Left: Time-dependent tumor volume changes after the photothermal-dynamic treatment.…”