Multifunctional porous iron oxide nanoagents for MRI and

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Multifunctional porous iron oxide nanoagents for MRI and photothermal/chemo synergistic therapy Yayun Hu, Hai Hu, Jun Yan, Chao Zhang, Yonggang Li, Mengyun Wang, Weiyi Tan, Jian Liu, and Yue Pan Bioconjugate Chem., Just Accepted Manuscript • DOI: 10.1021/acs.bioconjchem.8b00052 • Publication Date (Web): 05 Feb 2018 Downloaded from http://pubs.acs.org on February 7, 2018

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Bioconjugate Chemistry

Multifunctional porous iron oxide nanoagents for MRI and photothermal/chemo synergistic therapy Yayun Hu,† Hai Hu,¶* Jun Yan, § Chao Zhang, † Yonggang Li, ǁ Mengyun Wang, ǁ Weiyi Tan, † Jian Liu,§* Yue Pan†,¶* †

State and Local Joint Engineering Laboratory for Novel Functional Polymeric

Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China. ¶

Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and

Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, China. §

Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key

Laboratory for Carbon-based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu Province 215123, China. ǁ

Department of Radiology, The First Affiliated Hospital of Soochow University,

Soochow University, Suzhou, 215006, China.

Corresponding Author * Yue Pan, E-mail: [email protected] * Jian Liu, E-mail: [email protected] * Hai Hu, E-mail: [email protected] 1 ACS Paragon Plus Environment

Bioconjugate Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Table of Content

The as-prepared Fe3O4 nanoparticles with high biocompatibility exhibited good photothermal effect and more DOX release content under near infrared laser irradiation. Combined NIR laser with DOX, the as-synthesized nanoparticles could kill the cancer cells effectively.

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ABSTRACT. Nanoagents of integrating multiple imaging and therapeutic modalities have attracted tremendous attention for biomedical applications. Herein, we synthesize porous hollow Fe3O4 as a theranostic agent for MRI and combined photothermal/chemo cancer therapy. The as-prepared porous iron oxide nanoagents allow for T2-weighted MR imaging. Interestingly, we demonstrate that the porous structure endows the nanoagents an outstanding photothermal property for cancer cell killing, in comparison with other types of iron oxide nanomaterials. Under the exposure of NIR laser, the heat produced by porous Fe3O4 can accelerate the release of the loaded drug (e.g. DOX) to enhance chemotherapeutic efficacy, promoting the ablating of cancer cells with synergistic photothermal/chemo therapy.



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Introduction

Photothermal therapy (PTT) is a hyperthermia treatment of cancer based on photo-absorbing materials which can effectively convert the optical energy of near infrared (NIR) laser to localized heat to kill cancer cells without affecting normal tissues1-3. Owing to its less invasive feature, PTT has attracted attention increasingly in biomedical applications. In the development of biomedical nanoagents with an excellent photothermal effect, there are two critical issues which must be met: (1) high efficiency in transforming optical energy to heat; (2) good biocompatibility. Many efforts have been devoted to explore various nanomaterials, such as metal sulfides4-6, NIR dyes7-9, noble metal-based nanomaterials10-13 and carbon-based nanomaterials14-16. However, there are still serious concerns that many current photothermal agents (PTAs) can hardly be bio-degraded in vivo, thus limiting their translation into clinics. Therefore, it is indispensable to develop more biocompatible PTAs for phtothermal ablation of cancer. Chemotherapy has been widely used to treat cancer patients, but the patients still suffer from severe side effects17-20. Well-designed therapies by combination of several different treatment methods simultaneously may produce a synergistic effect on killing cancer cells21-23, which promise therapeutic enhancement and alleviation of side effects. For instance, combining chemotherapy with PTT can improve therapeutic efficiency24-26. The dosage of the chemotherapeutic drugs can be cut down, which is benefit from the synergistic effect of the photothermal therapy. Hence, the development of biocompatible nano-platforms with multiple functionalities to 4 ACS Paragon Plus Environment

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combine chemotherapy with hyperthermia would have significant potential for clinical cancer treatment. Due to their excellent superparamagnetic and bio-degraded properties, iron oxide nanoparticles27,28, especially Fe3O4 nanoparticles, have been used for magnetic resonance imaging (MRI) contrast agents29-31 and hyperthermia under an alternating magnetic field32-34. In the past few years, Fe3O4 nanoparticles with broad absorption in the NIR region have been reported with good optical-thermal converting efficiency. Chu et al. studied the photothermal properties of Fe3O4 with different concentrations and different shapes by using NIR laser35. Recently, Yang’s group has investigated that Fe3O4 nanoclusters can produce more heat than separated nanoparticles with the same Fe concentration36. Unfortunately, either the laser power density (5 W cm-2) or the concentration of iron oxide (8 mg L-1) employed in experiments are too high to avoid side effects. In addition, Peng et al. revealed that the size of the iron oxide nanoparticles would have an positive correlation effect on the near infrared absorption, consequently leading to tunable photothermal effect37. Herein, we report the preparation of porous iron oxide nanoparticles (PIONs) for MRI and synergistic photothermal/chemo therapy. This porous structure, composed of smaller iron oxide particles, have relative large specific surface area which is favorable for loading of doxorubicin hydrochloride (DOX). Polyacrylamide (PAM) modified on the surface of PIONs could not only produce good solubility38 but also prevent PIONs from being oxidized to Fe2O3 and make them exhibit more stable photothermal effect37. Under NIR laser exposure, the local heat generated by the 5 ACS Paragon Plus Environment


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nanoagents can facilitate the release of DOX to promote the cancer cell apoptosis and thus improve the treatment effect (Scheme 1).

Scheme 1. The illustration of PIONs used as theranostic agents for MRI and synergistic photothermal/chemo therapy.

Results and Discussion

In typical experiments, bigger PIONs with uniform size distribution were synthesized by previous work with modification39,40. The surface of the synthesized product was modified with PAM which not only enhanced PIONs water solubility with good biocompatibility but also prevented it from being oxidized37,38. Figure 1A shows a typical TEM image of the synthesized PIONs, in which a batch of spheres all have light central regions in contrast to dark edges, suggesting that the spheres are hollow. As shown in high-resolution TEM (HRTEM) image (Figure 1B), the interplanar crystal spacing of the PIONs is 0.296 nm, which matches well with the plane of 220. The SEM image (Figure 1C) shows that the product consists of well dispersed spheres roughly 260 nm in diameters with a coarse surface. The crack on 6 ACS Paragon Plus Environment

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the surface of the materials indicates that they have a porous structure. Combining with the results of TEM and SEM supports that as-prepared particles are uniform porous hollow spheres. The XRD pattern (Figure 1D) for synthesized materials contains a number of peaks that can be well-indexed to Fe3O4 (JCPDS 75-0033).

Figure 1. (A) Low-resolution TEM images (B) high-resolution TEM images and (C) SEM images of as-prepared PIONs (D) XRD patterns.

In order to evaluate the porosity of PIONs, we measured the specific surface area of PIONs. Figure 2A and 2B exhibit the N2 adsorption-desorption isotherm and pore size distribution curve of the PIONs. The adsorption-desorption isotherm can be classified as type IV with an apparent hysteresis loop in the range 0.5-1.0 P/P0, indicating the presence of pores. The BET specific surface area and pore volume of the sample were determined to be 39.79 m2 g-1 and 0.14 g cm-3, respectively. The relative high BET surface area and pore volume support the feature of porous hollow structure for the nanoparticles. The results also suggest that the PIONs are promising



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nanomaterials for drug delivery applications. The plot of pore size distribution determined by the Barrett-Joyner-Halenda (BJH) method shows that the pore size is around 10 nm, attributed to the interparticles spaces. The sharp distribution of the pores around 10 nm indicates that the PIONs are featured with monodispersed pores.

We further evaluated the photothermal properties of the materials. Firstly, the light absorption capacity of the materials in the near infrared region from 680 nm to 980 nm was tested using a UV-Vis-NIR spectrophotometer. The aqueous solution of PIONs exhibited broad absorption ranging from the UV to NIR region (Figure 2C). With the increase of the PIONs concentration, the absorption intensity was increased (maximum absorption up to 1.575), it indicated a potential good photothermal conversion. The photothermal conversion capacity was further validated by dilutions of the PIONs (different concentrations including 0, 25, 50, 100, 150, 200 µg Fe mL-1) and exposed to 808 nm NIR laser (1 W cm-2) for 600 s. In Figure 2D and Figure S2, the temperature of solution containing PIONs with various concentrations displayed a distinctly rise and the maximum temperature change reached 31 oC during laser irradiation. In contrast, under the identical experimental condition, the value of water temperature did not show apparent change. From Figure S3A-3C, we can found that the bigger diameter PIONs have better photothermal effect than smaller one. In order to further explore the reason why PIONs have a good photothermal property, we have synthesized Fe3O4 nanoclusters with a diameter of 250 nm (Figure S4A, Figure S4B)41. The results in Figure S4C and Figure S4D suggest that PIONs have a better UV-Vis-NIR absorbance than the Fe3O4 nanoclusters and can convert more light 8 ACS Paragon Plus Environment

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energy into heat. Therefore, the porous hollow structure is an important feature with correlation to the good photothermal property. For the purpose of assessing the photothermal stability of PIONs, five cycles of photothermal measurements at the power density of 1 W cm-2 were carried out. In Figure S5, the increase of temperature after laser irradiation was displayed no obvious attenuation during 5 cycles, which demonstrated that PIONs have excellent photothermal stability.

Figure 2. (A) N2 adsorption-desorption isotherms of the PIONs. (B) Pore size distribution plot. (C) UV-Vis-NIR absorption spectra in aqueous solution with different Fe concentrations. (D) The temperature rising curves of solution and water under 808 nm laser irradiation at a power density of 1 W cm-2 for 10 min.

In general, iron-based materials with magnetic properties can be used as MRI contrast agents42,43. To investigate the MR contrasting performance of PIONs, a 3.0 T clinical MR scanner was used for T2-weighted MRI. With the increase of iron concentration, T2 signal intensity gradually decreased (Figure 3). The gradually



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darken image indicates that T2 signal intensity gradually reduced, revealing the concentration-dependent effect. In the plot of the relationship between the transverse relaxation (1/T2) and Fe concentration, the r2 of PIONs is calculated to be 119.66 mM-1S-1, which is close to that of the commercial MRI contrast agent44. The result demonstrated that PIONs can act as an efficacious T2-weighted MR contrast agent for cancer therapy.

Figure 3. T2-weighted MRI photographs of the dispersions with different Fe concentrations at room temperature. The T2 relaxation rate (1/T2) of the dispersion is as a function of Fe concentration.

Owing to the hollow porous structure, PIONs can be used as drug delivery vehicles. In our study, PIONs were mixed up with DOX and shaken for 24 h at room temperature to reach equilibrium, and then PBS (pH=7.4) was utilized to wash the PIONs. The release of DOX loaded in PIONs was examined in PBS with different pH 10 ACS Paragon Plus Environment

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values. Figure 4A exhibits the cumulative DOX release profile over 48 h in PBS (pH=7.4) and PBS (pH=5.0) at room temperature. At the beginning of experiment, the cumulative release rate of DOX was relatively fast, and then decreased with the extension of time. It exhibited a time-dependent releasing manner. The quantity difference of release in pH 5.0 and pH 7.4 demonstrated an important role of pH value in DOX release. From the cumulative release profile at different pH, lower pH is beneficial to drug emancipation. This is due to the increasing solubility of DOX in acidic environment, attributed to re-protonation of the -NH2 groups of DOX45. To further evaluate the effect of thermal energy to DOX release, the NIR laser with the power density of 1 W cm-2 was employed. The PIONs loaded with DOX were irradiated by the laser for 10 min and then cooled for 60 min. Radiated by NIR, the amount of releasing drug was increased obviously, which was observed in Figure 4B. This enhancement of drug release was ascribed to the elevation of the temperature caused by the PIONs and the radiation which can promote the DOX release46. In this way, the pH value and photothermal responsive drug release of as-synthesized PIONs-DOX

composites

could

be

used

as

a

candidate

for

synergistic

photothermal/chemo therapy to reduce side effects of chemotherapeutics.



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Figure 4. (A) The cumulative release profile for DOX loaded PIONs nanocomposites measured in PBS (pH=7.4) and PBS (pH=5.0) at room temperature. (B) DOX release profile in PBS (pH=5.0) with intermittent NIR laser irradiation. The data are shown as mean ± standard deviation (SD). Error bars are based on 3 times measurements.

The potential cytotoxicity of PIONs was examined by using 4T1 murine breast cancer cells. The 4T1 cells were cultured in a 96-well microplate with PIONs at various concentrations for 24 h. Then the standard CTG assay was used to evaluate relative viability of the cells. As shown in Figure 5A, with the increase of Fe concentration, the cells maintained good cell viability. Until the Fe concentration reach 200 µg mL-1, the relative survival of the cells were still higher than 85%, indicating an excellent biocompatibility for the PIONs. We further tested the ability of PIONs to ablate tumor cells under laser irradiation. At the beginning, 4T1 cells were incubated with different concentrations of PIONs for 4 h, then the cells solutions were divided into two portions, which were treated with or without 808 nm laser (10 min, 1.5 W cm-2), respectively. As illustrated in Figure 5B, the cells show high viability in the absence of light. By contrast, with the Fe concentration increasing from 0 to 200 µg mL-1, the relative survival proportion decreases from ~100% to less than 20%. In order to visually assess therapeutic efficiency of PIONs for cancer cells, we utilized Calcein AM and propidium iodide (PI) to co-stain 4T1 cells to distinguish between apoptotic (red) and live (green) cells. As shown in Figure 5F, almost all cells cultured with PIONs (200 µg Fe mL-1) and illuminated by NIR laser (1.5 W cm-2, 10 min) were stained into red, which means PIONs under NIR laser exposure for 10 min can 12 ACS Paragon Plus Environment

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effectively kill cancer cells. While, 4T1 cells incubated with or without the same concentration of PIONs or exposed to identical power density NIR laser solely has little effect to cell apoptosis as dominated color observed in Figure 5C, 5D and 5E is green. Thus, PIONs with good biocompatibility could ablate cancer cells under NIR laser.

Figure 5. Cell viability of 4T1 cells (A) incubated with PIONs at different concentrations, (B) treated with different concentrations of PIONs with and without laser illumination. Live-dead staining images of 4T1 cells cultured with(C) no treatment, (D) NIR irradiation (1.5 W cm-2, 10 min), (E) PIONs (200 µg Fe mL-1), (F) PIONs (200 µg Fe mL-1) plus NIR irradiation. The data are shown as mean ± standard deviation (SD). Error bars are based on 6 times measurements. The scale bar is 100 µm. 13 ACS Paragon Plus Environment


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In view of the fact that the laser irradiation may promote the release of DOX loaded in PIONs, we assessed the therapeutic efficiency of synergistic effects combining photothermal with chemotherapy on tumor therapy. As shown in Figure 6A, individual hyperthermia and chemotherapy cannot effectively kill tumor cells at the concentration of 150 µg Fe per mL. For PIONs loaded with DOX, lower than 25% of 4T1 cells could be killed without NIR exposure at the Fe concentration of 150 µg mL-1. Around 60% of cells were still alive at the same Fe concentration when treated with laser alone. However, PIONs loaded with DOX were radiated by laser and the cell viability decreases to around 25%, which indicated that combination with photothermal and chemotherapy can induce cell apoptosis significantly (Figure 6B). In order to further evaluate the synergistic effect of photothermal therapy and chemotherapy, we multiplied the cell viability of hyperthermia by the cell viability of chemotherapy to obtain an expected added value. Comparing the relative survival of combined therapy with the expected added value, we can conclude that PTT and chemotherapy triggered by PIONs would show a synergistically enhanced therapeutic effect for cancer therapy.


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Figure 6. (A) Cell viability of 4T1 cells with PIONs at different concentrations with or without NIR laser and DOX (B) Synergistic therapeutic effect on 4T1 cells that have taken up PIONs (150 µg Fe mL-1) subjected to NIR, DOX and the combined NIR/DOX treatments. The data are shown as mean ± standard deviation (SD). Error bars are based on 6 times measurements.

Conclusions

In conclusion, we have developed a facile approach for the synthesis of PIONs as theranostic nanoagents. The synthesized nanoagents have been demonstrated to be a good candidate for PTT because they not only have a measurable absorption in NIR 15 ACS Paragon Plus Environment


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region and good photothermal stability, but also presented good biocompatibility. Due to the porous hollow characteristics, the PIONs are capable of serving as drug carriers to load DOX for chemotherapy and PTAs of cancer cells. The release rate of drug loaded in PIONs can be accelerated under exposure to radiation at cancer cells microenvironment, and displayed an enhanced tumor inhibition rate. Moreover, PIONs are able to provide obvious contrast enhancement for MRI. Overall, PIONs with low toxicity and good photothermal effect are potential multifunctional nanoplatforms for cancer therapy because of the synergistic effect between photothermal and chemotherapy.

Experimental Section

Materials All reagents were used without further purification. Iron chloride (FeCl3), trisodium citrate dehydrate (C8H5Na3O7·2H2O), urea, polyacrylamide (PAM), disodium phosphate dodecahydrate, absolute ethanol, potassium dihydrogen phosphate, dimethyl sulfoxide (DMSO) are analytically pure and were purchased from Shanghai Chemical Reagents Company, DOX was obtained from J&K Scientific CO., Ltd. High Q water was used throughout the research. Synthesis of PIONs

The multifunctional PIONs were prepared by modified procedure. Briefly, FeCl3 (1.3 g), sodium citrate (C8H5Na3O7·2H2O) (4.7 g) and urea (1.8 g) were added in 160 mL distilled water and stirred for 30 min. Then, PAM (1.0 g) was added slowly with 16 ACS Paragon Plus Environment

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vigorous stirring until it dissolved completely. The resulting solution was transferred into a 200 mL Teflon-lined autoclave and maintained at 200 oC for 12 h. Afterwards, the product was collected by centrifugation and washed with water and absolute ethanol for several times.

Characterizations

The morphologies and sizes were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM was performed on a Hitachi S-4700 cold field-emission scanning electron microscope operated at 30 kV, and TEM was performed on a Tecnai G220 microscope (FEI, USA). Wide angle powder X-ray diffraction (XRD) patterns were recorded on an X'Pert-Pro MPD diffractometer (Netherlands PANalytical) with a Cu Kα X-ray source (λ = 1.540598 Å). The specific surface areas and pore size distribution was calculated by the Barrett-Joyner-Halenda (BJH) method. UV-Vis-NIR absorption spectra were obtained on TU-1810 (Persee, China). The temperature of the solution at each time point was measured by an Infrared Radiation (IR) thermal camera (Fotric 225s). Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis was done by using a Thermo Scientific iCAP6300 (Thermo Fisher Scientific, US).

PTT experiment in aqueous solutions

In order to investigate the PTT effect of the synthesized PIONs, the solution of the sample was diluted to different concentrations (0, 25, 50, 100, 150 and 200 µg Fe mL-1) and then illuminated by a beam of 808 nm NIR laser with the power density of 17 ACS Paragon Plus Environment


1 W cm-2 for 10 min. Running temperature of solution was recorded by an IR thermal imaging camera.

To further assess the photothermal property of the material, five cycles of NIR laser radiation were performed. Briefly, PIONs at the Fe concentration of 200 µg mL-1 were illuminated by 808 nm laser (1 W cm-2) for 10 min, and then turned off light source for another 10 min. This process was repeated for 5 times to estimate the photothermal stability of PIONs.

DOX load and release

Typically, DOX was dissolved in 2 mL DMSO containing 10 mg PIONs, and then the mixture was shaken at 37 oC for 12 h to reach equilibrium. Afterwards, the PIONs loaded with DOX were collected by a magnet and washed with phosphate buffer saline (PBS) twice to remove free DOX Then, the supernatant solution was collected. The quantity of DOX loaded into PIONs was determined by measuring the amounts of DOX in the supernatant by UV-Vis-NIR spectra with an absorption peak at 480 nm.

In the experiment of examining the amount of released DOX, 1 mg PIONs plus DOX complexes were dispersed in 1 mL PBS (pH=7.4) and 1 mL PBS (pH=5), respectively. Then the supernatant of the forming solutions were collected by a magnet at different time under gentle oscillation. In addition, laser-induced release studies were also carried out. The as-prepared sample dispersed in PBS (pH=5) were treated with intermittent laser for 10 min and the power density of laser is 1 W cm-2. 18 ACS Paragon Plus Environment

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To determine the amounts of released DOX, the same method, which used to acquire the loading capacity of PIONs, was used.

Cytotoxicity assay of PIONs

The cytotoxicity of the PIONs was evaluated by CellTiter-Glo® (CTG) assay with the 4T1 (mice breast cancer) cells. Briefly, 4T1 cells were preseeded into a 96-well plate with the density of 1 × 104 cells per well in an atmosphere of 5% CO2 and 95% air for 24 h. Subsequently, the culture medium was removed and new culture media with a series of concentrations (25, 50, 100, 150, 200 µg Fe mL-1) of PIONs was added to incubate the cells for another 24 h. Then, CTG Reagent was directly added to cells cultured in serum-supplemented medium without cells washing and medium removing. After 20 min incubation at room temperature, luminescent signal was recorded by a CCD camera to obtain the data about cells viability.

Photothermal experiments of the PIONs

To quantitatively evaluate the photothermal effect of PIONs to cells, 4T1 cells were seeded into 96-well plates and cultured at 37 oC for 24 h. Then, different concentrations of PIONs which were dissolved in 100 µL culture medium were added to the cells and incubated for another 6 h. Afterwards, the cells were irradiated by NIR laser for 10 min and further incubated for 8 h. The relative viability of 4T1 cells were determined by CTG assay.

The effect of DOX 19 ACS Paragon Plus Environment


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4T1 cells were seeded in 96-well plates and incubated for 24h at 37 oC with 95% air and 5% CO2. Then, a series of DOX loaded in PIONs were added to incubate the cells for additional 12 h. Afterwards, CTG assay was used to evaluate the cell viability.

Combined photothermal and chemotherapy experiments of the PIONs

4T1 cells were incubated in 96-well plates with culture medium for 24 h and then different concentrations of PIONs loaded with DOX were added. After 6 h incubation, the cells were illuminated by a laser with power density of 1.5 W cm-2 for 10 min and incubated for another 8 h. The relative viability of 4T1 cells were measured by CTG assay.

ASSOCIATED CONTENT

Supporting Information. Temperature elevation of different concentrations PIONs. Photos of PIONs in water and PBS buffer. TEM, SEM and temperature rising of PIONs with diameter of 180 nm. TEM, SEM, UV-Vis-NIR spectra and temperature rising of Fe3O4 nanocluster. Photothermal stability of PIONs after five cycles and process of calculation of photothermal conversion efficiency (η) are included in Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author 20 ACS Paragon Plus Environment

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* Yue Pan, E-mail: [email protected]

* Jian Liu, E-mail: [email protected]

ACKNOWLEDGMENT The authors acknowledge financial support from National Natural Science Foundation of China (51402203, 21575095), the Natural Science Foundation of Jiangsu Province (BK20140326), the Science and Technology Program of Suzhou (SYG201736), the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions, the 111 project, and a project by Collaborative Innovation Centre of Suzhou Nano Science and Technology The Project is also sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University.

NOTES The authors declare no competing financial interest. ABBREVIATIONS DOX, doxorubicin hydrochloride; NIR, near infrared; PTT, photothermal therapy; PTAs, photothermal agents; MRI, magnetic resonance imaging; PIONs, porous iron oxide nanoparticles; PAM, polyacrylamide; PBS, phosphate buffer saline; HRTEM, high-resolution transmission electron microscopy; PI, propidium iodide; SEM, scanning electron microscopy; XRD, X-ray diffraction; ICP-OES, inductively coupled plasma optical emission spectrometry; BJH, Barrett-Joyner-Halenda. REFERENCES (1) Cheng, L., Wang, C., Feng, L., Yang, K., Liu, Z. (2014) Functional nanomaterials for phototherapies of cancer. Chem. Rev. 114, 10869-10939.



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Cu9S5@mSiO2@Fe3O4-PEG nanocomposites for combined MR imaging and chemo/photothermal synergistic therapy. Nanoscale. 8, 12560-12569.


Multifunctional porous iron oxide nanoagents for MRI and

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