Gold nanorods-conjugated TiO2 nanoclusters for the synergistic combination of phototherapeutic treatments of cancer cells

Jooran Lee,Joon Sig Choi,Ki Soo Chang,Minjoong Yoon,Young Hwa Lee,Chan Bae Jeong

doi:10.1186/s12951-018-0432-4

Jooran Lee, Joon Sig Choi + Show 4 more

Open Access

https://doi.org/10.1186/s12951-018-0432-4

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Abstract

BackgroundRecently, a combination of photodynamic therapy (PDT) and photothermal therapy (PTT) to generate reactive oxygen species (ROS) and heat to kill cancer cells, respectively has attracted considerable attention because it gives synergistic effects on the cancer treatment by utilizing the radiation of nontoxic low-energy photons such as long wavelength visible light and near IR (NIR) penetrating into subcutaneous region. For the effective combination of the phototherapies, various organic photosensitizer-conjugated gold nanocomplexes have been developed, but they have still some disadvantages due to photobleaching and unnecessary energy transfer of the organic photosensitizers.ResultsIn this study, we fabricated novel inorganic phototherapeutic nanocomplexes (Au NR–TiO2 NCs) by conjugating gold nanorods (Au NRs) with defective TiO2 nanoparticle clusters (d-TiO2 NP clusters) and characterized their optical and photothermal properties. They were observed to absorb a broad range of visible light and near IR (NIR) from 500 to 1000 nm, exhibiting the generation of ROS as well as the photothermal effect for the simultaneous application of PDT and PTT. The resultant combination of PDT and PTT treatments of HeLa cells incubated with the nanocomplexes caused a synergistic increase in the cell death compared to the single treatment.ConclusionThe higher efficacy of cell death by the combination of PDT and PTT treatments with the nanocomplexes is likely attributed to the increases of ROS generation from the TiO2 NCs with the aid of local surface plasma resonance (LSPR)-induced hot electrons and heat generation from Au NRs, suggesting that Au NR–TiO2 NCs are promising nanomaterials for the in vivo combinatorial phototherapy of cancer.

Highlights

A combination of photodynamic therapy (PDT) and photothermal therapy (PTT) to generate reactive oxygen species (ROS) and heat to kill cancer cells, respectively has attracted considerable attention because it gives synergistic effects on the cancer treatment by utilizing the radiation of nontoxic low-energy photons such as long wavelength visible light and near IR (NIR) penetrating into subcutaneous region
D-TiO2 NPs were synthesized by hydrothermal reaction of liposome-TiO2 composites as previously reported [18], and their surfaces were modified by binding with APTES
When Au NR–TiO2 NCs were dispersed in deionized water at pH 7.0 at a concentration of 1 mg mL−1, they were found to have an average diameter of 317 nm which is appropriate size for their efficient uptake into cells as is within the known range from about

Summary

Introduction

A combination of photodynamic therapy (PDT) and photothermal therapy (PTT) to generate reactive oxygen species (ROS) and heat to kill cancer cells, respectively has attracted considerable attention because it gives synergistic effects on the cancer treatment by utilizing the radiation of nontoxic low-energy photons such as long wavelength visible light and near IR (NIR) penetrating into subcutaneous region. The most common types of cancer treatments [1,2,3,4] are chemotherapy, radiation therapy and/or surgery Such treatments have many well-known disadvantages, including relatively poor specificity toward malignant tissues, drug resistance and side effects [5, 6]. Many researchers have attempted to apply the combination of PDT and PTT to enhance the therapeutic efficiency synergistically against malignant carcinomas as compared to PDT or PTT alone [10, 23,24,25]

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