Preparation of Polycarbonate-ZnO Nanocomposite Films: Surface Investigation after UV Irradiation.

Polycarbonate (PC)-ZnO films with different percentages of ZnO were prepared by a solution stirring technique and subjected to ultraviolet (UV; λ = 254 nm) irradiation. Structural parameters of the samples and the effects of UV irradiation on the surface properties of the PC and PC-ZnO nanocomposites were evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), water contact angle (WCA) measurements, and a Vickers microhardness (HV) tester. The XRD patterns of the nanocomposite films were found to show an increase in crystallinity with the increasing ZnO nanoparticles percentage. The WCA was found to be reduced from 90° to 17° after 15 h of UV irradiation, which could be ascribed to the oxidation of the surface of the samples during the irradiation and exposure of the ZnO nanoparticles, a result that is also supported by the obtained XPS data. The microhardness value of the PC-ZnO films including 30 wt.% ZnO enhanced considerably after UV radiation, which can also be attributed to the exposition of the ZnO nanoparticles after photodegradation of the PC superficial layer of the nanocomposite films.

Cobalt ferrite nanoparticles supported on reduced graphene oxide sheets: optical, magnetic and magneto-antibacterial studies.

The development of antibacterial nanomaterials has emerged as a strategy to control bacterial activity, due to the growth and spread of antibiotic-resistant pathogen microorganisms. Graphene-based nanocarbons, as one of the most attractive materials, given their extraordinary physical and chemical properties, are promising candidate nanomaterials for biomedical applications. In this study, cobalt ferrite nanoparticles (NPs) supported on reduced graphene oxide (rGO) sheets to form metal nanocomposites (MNCs) known as CoFe2O4@rGO MNCs with different rGO contents (0, 10, 25 and 40 wt%) have been synthesized by a one-step process. The structures, morphology, optical, magnetic and antibacterial properties of the CoFe2O4@rGO were investigated by x-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy images, Raman, Fourier transform infrared (FTIR) and UV-Vis spectroscopies, vibration sample magnetometry and antibacterial tests as a function of rGO content. The particle sizes of the CoFe2O4 NPs supported on the different rGO contents were below 10 nm. The band gap energy of the samples decreased from about 3.1 to 1.7 eV with reducing rGO content. The results prove the effective reduction of graphene oxide to rGO and also the support of CoFe2O4 on rGO sheets by a one-step hydrothermal reaction. The increase in rGO content in the samples reduced their saturated magnetization from about 15 to 7 emu g-1. The CoFe2O4@rGO MNCs have shown magneto-antibacterial activity against gram-negative bacteria (Escherichia coli), whose efficacy depends on the value of the rGO content. In contrast, the CoFe2O4@rGO MNC (25 wt% rGO) which was synthesized by the one-step hydrothermal method not only has a narrow band gap energy (for photocatalytic applications), but also significant magneto-antibacterial activity was observed.

Mg(1-x)CuxFe2O4 superparamagnetic nanoparticles as nano-radiosensitizer agents in radiotherapy of MCF-7 human breast cancer cells.

Magnesium-doped copper spinel ferrite superparamagnetic nanoparticles (Mg(1-x)CuxFe2O4 SPMNPs, 0.2 ≤ x ≤ 0.8) were successfully synthesized by a hydrothermal method. The cytotoxicity effects and cell viability of MCF-7 on human breast cancer cells pre and post exposure to the Mg1-xCuxFe2O4 SPMNPs at different concentrations of 0.1, 1, 10 and 100 µg ml-1 under radiotherapy were studied by MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. Here, x-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-visible spectrophotometry, Fourier transform infrared spectroscopy and vibrating-sample magnetometry were evaluated for the crystal structure, morphology, optical and magnetic property of the Mg(1-x)CuxFe2O4 SPMNPs. The results showed that the Mg(1-x)CuxFe2O4 SPMNPs all at x values had no significant cytotoxicity at concentrations of 0.1,1 and 10 µg ml-1, but were enhanced by increasing of Cu content. Furthermore, cell destruction of MCF-7 human breast cancer cells post exposure to Mg(1-x)CuxFe2O4 SPMNPs under x-ray irradiation was enhanced by increasing the Cu content and concentration. Superparamagnetic properties of the Mg(1-x)CuxFe2O4 SPMNPs cause their localization and elimination, by only an external magnetic field. In conclusion, the Mg(1-x)CuxFe2O4 SPMNPs with optimum values of x = 0.2 (10 µg ml-1) and x = 0.6 (1 µg ml-1) can be considered as a nano-radiosensitizer because of the synergistic treatment effect without cytotoxicity on the MCF-7 cells.

ZnFe2O4 nanoparticles as radiosensitizers in radiotherapy of human prostate cancer cells.

Nanoparticles of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe2O4) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanoparticles showed fast separation from solutions (e.g., ~1 min for 2 mg mL(-1) of the nanoparticles in ethanol) by applying an external magnetic field (~1T). The ZnFe2O4 nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high radioresistant cells) under gamma irradiation of (60)Co source. The nanoparticles exhibited no significant effects on the cancer cells up to the high concentration of 100 µg mL(-1), in the absence of gamma irradiation. The gamma irradiation alone (2Gy dose) also showed no significant effects on the cells. However, gamma irradiation in the presence of 100 µg mL(-1) ZnFe2O4 nanoparticles resulted in ~53% inactivation of the cells (~17 times higher than the inactivation that occurred under gamma irradiation alone) after 24h. The higher cell inactivation was assigned to interaction of gamma radiation with nanoparticles (photoelectric effect), resulting in a high level electron release in the media of the radioresistant cells. Our results indicated that ZnFe2O4 nanoparticles not only can be applied in increasing the efficiency of radiotherapy, but also can be easily separated from the cell environment by using an external magnetic field after the radiotherapy.

Zinc ferrite spinel-graphene in magneto-photothermal therapy of cancer.

A magneto-photothermal therapy for cancer (in vitro photothermal therapy of prostate cancer cells and in vivo photothermal therapy of human glioblastoma tumors in the presence of an external magnetic field) was developed using superparamagnetic zinc ferrite spinel (ZnFe2O4)-reduced graphene oxide (rGO) nanostructures (with various graphene contents). In vitro application of a low concentration (10 µg mL-1) of the ZnFe2O4-rGO (20 wt%) nanostructures under a short time period (∼1 min) of near-infrared (NIR) irradiation (with a laser power of 7.5 W cm-2) resulted in an excellent destruction of the prostate cancer cells, in the presence of a magnetic field (∼1 Tesla) used for localizing the nanomaterials at the laser spot. However, in the absence of a magnetic field, ZnFe2O4-rGO and also rGO alone (10 µg mL-1) resulted in only ∼50% cell destruction at the most in the short photothermal therapy and also in a typical radiotherapy (∼2 min gamma irradiation with a dose of 2 Gy). The minimum concentrations required for the successful application of the nanostructures in the photothermal and radiotherapeutic methods were found to be ∼100 and 1000 µg mL-1, while in the proposed magneto-photothermal therapy it was only ∼10 µg mL-1. The in vivo feasibility of this method was also examined on mice bearing glioblastoma tumors. Furthermore, the localization of the magnetic nanomaterials injected into the tumors was studied in the presence and absence of an external magnetic field. These results will stimulate more applications of magnetic graphene-containing composites in highly efficient photothermal therapy.