Chemothermal therapy is widely used in clinical applications for the treatment of tumors. However, the major challenge is the use of a multifunctional nano platform for significant regression of the tumor. In this study, a simple synthesis of highly aqueous stable, carboxyl enriched, PEGylated mesoporous iron platinum-iron(ii,iii) oxide (FePt-Fe3O4) composite nanoassemblies (CNAs) by a simple hydrothermal approach is reported. CNAs exhibit a high loading capacity ∼90 wt% of the anticancer therapeutic drug, doxorubicin (DOX) because of its porous nature and the availability of abundant negatively charged carboxylic groups on its surface. DOX loaded CNAs (CNAs + DOX) showed a pH responsive drug release in a cell-mimicking environment. Furthermore, the release was enhanced by the application of a alternating current magnetic field. CNAs show no appreciable cytotoxicity in mouse fibroblast (L929) cells but show toxic effects in cervical cancer (HeLa) cells at a concentration of ∼1 mg mL(-1). A suitable composition of CNAs with a concentration of 2 mg mL(-1) can generate a hyperthermic temperature of ∼43 °C. Also, CNAs, because of their Fe and Pt contents, have an ability to generate reactive oxygen species (ROS) in the presence of hydrogen peroxide inside the cancer cells which helps to enhance its therapeutic effects. The synergistic combination of chemotherapy and ROS is very efficient for killing cancer cells.

This work reports the fabrication of magnetite (Fe3O4) nanoparticles (NPs) coated with various biocompatible surfactants such as glutamic acid (GA), citric acid (CA), polyethylene glycol (PEG), polyvinylpyrrolidine (PVP), ethylene diamine (EDA) and cetyl-trimethyl ammonium bromide (CTAB) via co-precipitation method and their comparative inductive heating ability for hyperthermia (HT) applications. X-ray and electron diffraction analyses validated the formation of well crystallined inverse spinel structured Fe3O4 NPs (crystallite size of ~ 8–10 nm). Magnetic studies confirmed the superparamagnetic (SPM) behaviour for all the NPs with substantial magnetisation (63–68 emu/g) and enhanced magnetic susceptibility is attributed to the greater number of occupations of Fe2+ ions in the lattice as revealed by X-ray photoelectron spectroscopy (XPS). Moreover, distinctive heating response (specific absorption rate, SAR from 130 to 44 W/g) of NPs with similar size and magnetisation is observed. The present study was successful in establishing a direct correlation between relaxation time (~ 9.42–15.92 ns) and heating efficiency of each surface functionalised NPs. Moreover, heat dissipated in different surface grafted NPs is found to be dependent on magnetic susceptibility, magnetic anisotropy and magnetic relaxation time. These results open very promising avenues to design surface functionalised magnetite NPs for effective HT applications.

No abstract

No abstract

No abstract

Luminescence intensity of rare-earth doped materials can be varied depending on shape of particles, capping agent, and heat-treatment. This is related to the non-radiative rate possessed by the material. Here, we observed the high quenching of the luminescence intensity of Eu3+ doped GdPO4 prepared in water (H2O) medium. On the contrary, in ethylene glycol (EG) medium, it shows high luminescence. Luminescence intensity is recovered when Eu3+ doped GdPO4 nanorods prepared in H2O medium is heated above 700 °C. This transforms hexagonal to monoclinic structure following the removal of water. Luminescence intensity is enhanced by changing the medium from H2O to D2O and also if core-shell formation occurs. Also, we found significant variation in bending and stretching vibrations of O-H and microstructure in this material prepared in H2O and EG. Two types of O-H stretching frequencies are observed at 3450 and 3520 cm−1 in H2O medium prepared sample which are assigned to the O-H having the hydrogen bonding (surface water) and the confined water, respectively. The formation of nanorods is due to the presence of water on the surface of particles or/and inside the pores of compound. The available water in the nanoparticles pores can be utilized for the efficient killing of mass cells tumor by generating reactive free radicals (H· and OH·) through the application of laser near infrared (NIR) source and the subsequent irradiation of gamma ray. This proposed mechanism is quite different from the conventional treatment of mass cell/malignant tumor using gamma ray radiation. Sample is highly paramagnetic and it will be useful for magnetic resonance imaging contrast agent.

No abstract

Herein we report the enhanced green emission from Tb 3+ -doped GdPO 4 nanorods sensitized with Ce 3+ . The increase in the rate of nonradiative transition processes in sensitizer due to efficient energy transfer to activator is realized from steady-state and dynamic luminescence studies. Luminescence quenching due to cross relaxation is least significant up to 20 at. % Ce 3+ and 7 at. % Tb 3+ concentration. The quantum yield of the sample with maximum luminescence, i.e., GdPO 4 :Tb 3+ (5 at. %)/Ce 3+ (7 at. %), is found to be 28%. Also, samples are readily redispersible in water and could be easily incorporated in polymer-based films that show strong green light emission under UV excitation. The luminescence switching (ON and OFF) behavior is examined using alternately an oxidizing agent (KMnO 4 ) and then a reducing agent (ascorbic acid) through a redox reaction (Ce 3+ /Ce 4+ ). Both GdPO 4 :Tb 3+ and GdPO 4 :Tb 3+ / Ce 3+ are observed to be paramagnetic.