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To overcome the problems of thermal, moisture and photo-stability of existing methylammonium based perovskites, formamidinium-based compositions are introduced for photovoltaic application. Formamidinium lead iodide (FAPbI3) and methylammonium lead bromide (MAPbBr3) mixed compositions of hybrid organic–inorganic perovskite type solar cells have shown the highest efficiency of 22.1%. For FAPbI3, two different polymorphs exist at room temperature: one is the hexagonal non-perovskite phase (δ-phase) and the other is the perovskite cubic phase (α-phase). The non-perovskite phase can be detrimental to the solar cell performance. To eradicate the undesired phase, a systematic evaluation of phase formation and crystallization is necessary. Here, we investigated the room temperature crystallization of the perovskite and non-perovskite phases of FAPbI3 by solvent and antisolvent induced crystallization methods using a two-step sequential deposition method. For each phase, the volume fraction is estimated using the X-ray diffraction technique. At room temperature, the δ-phase is found to grow as long one-dimensional nanorods and its volume fraction increases with the dipping time. It is observed that the presence of an antisolvent has a moderate control on the δ-phase growth. Experimentally, with the detailed solvent-induced time dependent crystallization study, we have proved the effective elimination of the δ-phase and the stability of the FA1−xMAxPbI3 perovskite phase. [ABSTRACT FROM AUTHOR]

Polyacrylic acid functionalized Fe3O4 nanoparticles (PAA-MNPs) of average size of 10 nm are prepared by a simple soft chemical approach. These PAA-MNPs are conjugated with folic acid through peptide bonding between the carboxylic group on the surface of PAA-MNPs and the amine group of folic acid. The good colloidal stability of FA conjugated MNPs makes it a promising candidate for targeted drug delivery, hyperthermia and as a MRI contrast agent with a transverse relaxivity R2 value of 105 mM−1 s−1. Folic acid conjugated magnetic nanoparticles (FA-MNPs) achieved ∼95% loading efficiency of doxorubicin (DOX) which could be due to strong electrostatic interaction of highly negatively charged FA-MNPs and the positively charged DOX. The drug release study shows a pH-dependent behavior and is higher in acidic pH (4.3 and 5.6) as compared to the physiological pH (7.3). Flow cytometry and confocal microscopic image analysis reveal that around 75–80% of HeLa cells undergo apoptosis due to DNA disintegration upon incubation with DOX-MNPs for 24 h. DOX-MNPs exhibit the synergistic effect due to the combination of DOX induced apoptosis and magnetic hyperthermia treatment (MHT) which enhance the cell death ∼95.0%. Thus, this system may serve as a potential pH sensitive nanocarrier for synergistic chemo-thermal therapy as well as a possible MRI contrast agent. [ABSTRACT FROM AUTHOR]

Fluorescein isothiocyanate (FITC)-encapsulated ZnO nanocomposite has been synthesized using the soft chemical approach. X-ray diffraction reveals the formation of highly crystalline single-phase hexagonal wurtzite nanostructure. TEM and SEM micrographs indicate the formation of spherical porous nanoassembly of ZnO of size ∼ 100–400 nm. On the other hand, FITC–ZnO nanocomposite is spherical and porous but with a uniform size of ∼150 nm. The size of single particles is ∼20 nm for the ZnO nanoassembly and ∼15 nm for FITC–ZnO nanocomposite. The UV-visible, fluorescence, FTIR and XPS spectra confirm the formation of FITC–ZnO nanocomposite. The FITC–ZnO nanocomposite demonstrates excellent selectivity in preferential killing of cervical (HeLa) and breast (MCF-7) cancer cells with minimal toxicity to normal fibroblast cells (L929). Apoptotic cells are observed and analyzed by confocal microscopy and flow cytometry. Our results show that cytotoxicity of FITC–ZnO nanocomposite towards cancer cells is due to the generation of reactive oxygen species (ROS) and preferential dissolution of Zn2+ ions in an acidic cancer microenvironment. Furthermore, generated ROS and dissolved Zn+2 ions induce cellular apoptosis, DNA fragmentation, and depolarization of mitochondrial membrane and cell cycle arrest in S phase. The FITC encapsulated multifunctional ZnO nanocomposite can be used as smart nanostructures for cell imaging and cancer therapy. [ABSTRACT FROM AUTHOR]

Supercapacitors have attracted significant attention in the last few years as they have the capability to fulfill the demand for both power and energy density in many energy storage applications. In this study, an in situ carbon-supported titanium oxide (ICS-TiO 2 ) electrode has been prepared using sucrose and TiO 2 powder. The ICS-TiO 2 powder was prepared by slipcasting, followed by the annealing of the TiO 2 slurry. Sucrose was added to the TiO 2 slurry as a soluble carbon source, and was converted into carbon at 600 °C then coated on the TiO 2 particles. The morphological and structural evolution of the electrode was investigated by FEG-SEM, FEG-TEM, XRD, BET, FTIR, XPS and Raman spectroscopy. The electrochemical characterization of ICS-TiO 2 demonstrated that this material exhibits an efficient value of specific capacitance (277.72 F g -1 at 25 mV s -1 ) for charge storage. ISC-TiO 2 also exhibits a specific capacitance of 180 F g -1 at 2 A g -1 in a 1 M Na 2 SO 4 aqueous electrolyte. The results suggest that ICS-TiO 2 can be utilized as a high-performance electrode material for supercapacitors with desirable electrochemical properties., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Dye sensitized solar cells (DSSCs) are low cost solar cells and their fabrication process is easy relative to silicon based solar cells. Platinum can be replaced with carbon materials as counter electrodes in DSSCs because of their good catalytic properties and low cost. A carbon material was produced by carbonization of an organic ligand (2 methyl 8-hydroxy quinolinol (Mq)) at high temperature in flowing argon gas. Polyvinylpyrrolidone (PVP) was used as a surfactant for making carbon slurry from carbon produced using Mq. For the fabrication of the counter electrode, a carbon coating was prepared by using the doctor blading technique and the carbon slurry was coated on the FTO substrate. DSSCs based on the carbon counter electrode exhibit a higher V oc of 0.75 V than that of the Pt counter electrode (0.69 V). DSSCs based on the carbon material showed a power conversion efficiency (PCE) of 4.25% and fill factor (FF) of 0.51 which are slightly lower than those of the platinum (Pt) based counter electrode which showed a PCE of 5.86% and FF of 0.68., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Polyacrylic acid functionalized Fe3O4 nanoparticles (PAA-MNPs) of average size of 10 nm are prepared by a simple soft chemical approach. These PAA-MNPs are conjugated with folic acid through peptide bonding between the carboxylic group on the surface of PAA-MNPs and the amine group of folic acid. The good colloidal stability of FA conjugated MNPs makes it a promising candidate for targeted drug delivery, hyperthermia and as a MRI contrast agent with a transverse relaxivity R2 value of 105 mM(-1) s(-1). Folic acid conjugated magnetic nanoparticles (FA-MNPs) achieved ∼ 95% loading efficiency of doxorubicin (DOX) which could be due to strong electrostatic interaction of highly negatively charged FA-MNPs and the positively charged DOX. The drug release study shows a pH-dependent behavior and is higher in acidic pH (4.3 and 5.6) as compared to the physiological pH (7.3). Flow cytometry and confocal microscopic image analysis reveal that around 75-80% of HeLa cells undergo apoptosis due to DNA disintegration upon incubation with DOX-MNPs for 24 h. DOX-MNPs exhibit the synergistic effect due to the combination of DOX induced apoptosis and magnetic hyperthermia treatment (MHT) which enhance the cell death ∼ 95.0%. Thus, this system may serve as a potential pH sensitive nanocarrier for synergistic chemo-thermal therapy as well as a possible MRI contrast agent.