Targeted delivery of superparamagnetic iron oxide nanoparticles (SPIONs) could facilitate their accumulation in metastatic cancer cells in peripheral tissues, lymph nodes and bones and enhance the sensitivity of magnetic resonance imaging (MRI). The specificities of luteinizing hormone releasing hormone (LHRH) and luteinizing hormone/chorionic gonadotropin (LH/CG)- bound SPIONs were tested in human breast cancer cells in vitro and were found to be dependent on the receptor expression of the target cells, the time of incubation and showed saturation kinetics. In incubations with MDA-MB-435S.luc cells, the highest iron accumulation was 452.6 pg Fe/cell with LHRH-SPIONs, 203.6 pg Fe/cell with beta-CG-SPIONs and 51.3 pg Fe/cell with SPIONs. Incubations at 4 degrees C resulted in 1.1 pg Fe/cell. Co-incubation with the same ligands (betaCG or LHRH) decreased the iron accumulation in each case. LHRH-SPIONs were poorly incorporated by macrophages. Tumors and metastatic cells from breast cancer xenografts were targeted in vivo in a nude mouse model. LHRH-SPION specifically accumulated in cells of human breast cancer xenografts. The amount of LHRH-SPION in the lungs was directly dependent on the number of metastatic cells and amounted to 77.8 pg Fe/metastastic cell. In contrast, unconjugated SPIONs accumulated in the liver, showed poor affinity to the tumor, and were not detectable in metastatic lesions in the lungs. LHRH-SPION accumulated in the cytosolic compartment of the target cells and formed clusters. LHRH-SPIONs did not accumulate in livers of normal mice. In conclusion, LHRH conjugated SPIONs may serve as a contrast agent for MR imaging in vivo and increase the sensitivity for the detection of metastases and disseminated cells in lymph nodes, bones and peripheral organs.

A porous magnetic hollow silica nanosphere (MHSN) is a new nanostructured drug carrier for increasing drug loading capability. Keeping the magnetic nanoparticles in the hollow core will limit the toxicity and degradation in a biosystem. In this paper, we report a synthesis of porous MHSNs by sol−gel method. CaCO3/Fe3O4 composite particles were first fabricated by embedding Fe3O4 nanoparticles into CaCO3 using the rotating packed bed (RPB) method. Tetraethoxysilane (TEOS) was then added as precursor to form a silica (SiO2) layer on the surface of CaCO3/Fe3O4 composite particles. Hexadecyltrimethylammonium bromide (CTAB) and octane act as second templates for the formation of porous silica shells. After removing the surfactants by calcination and etching away the CaCO3 particles, porous MHSNs with magnetite (Fe3O4) nanoparticles inside the cores were formed. The pore size can be tuned by adjusting the amount of the cationic surfactant absorbed on the surface of the composite particles to form self-assembled nanochannels. Ibuprofen was loaded on or into the porous MHSNs, and the drug encapsulation and release were investigated. A slow release was observed for the porous MHSNs, which demonstrated MHSNs are potential carriers for controlled releasing in nanomedicine application.

Carbon-based perovskite solar cells (PVSCs) without hole transport materials are promising for their high stability and low cost, but the electron transporting layer (ETL) of TiO is notorious for inflicting hysteresis and instability. In view of its electron accepting ability, C is used to replace TiO for the ETL, forming a so-called all carbon based PVSC. With a device structure of fluorine-doped tin oxide (FTO)/C /methylammonium lead iodide (MAPbI )/carbon, a power conversion efficiency (PCE) is attained up to 15.38% without hysteresis, much higher than that of the TiO ones (12.06% with obvious hysteresis). The C ETL is found to effectively improve electron extraction, suppress charge recombination, and reduce the sub-bandgap states at the interface with MAPbI . Moreover, the all carbon based PVSCs are shown to resist moisture and ion migration, leading to a much higher operational stability under ambient, humid, and light-soaking conditions. To make it an even more genuine all carbon based PVSC, it is further attempted to use graphene as the transparent conductive electrode, reaping a PCE of 13.93%. The high performance of all carbon based PVSCs stems from the bonding flexibility and electronic versatility of carbon, promising commercial developments on account of their favorable balance of cost, efficiency, and stability.

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Improvement in stability and an economical processing technique are the main aspects of the commercialization of perovskite solar cells (PSCs). In this study, a 425 nm‐thick CsPbI2Br film with a high crystalline, smooth, and uniform surface morphology is obtained by Pb(SCN)2 passivating the grain boundaries under low temperature (150 °C). The results of a series of electrochemical analyses, including space‐charge‐limited‐current (SCLC), open‐circuit voltage decay (OCVD), electrical impedance spectroscopy (EIS), intensity‐modulated photocurrent spectroscopy (IMPS), and intensity‐modulated photovoltage spectroscopy (IMVS), demonstrate that the trap density of the CsPbI2Br film is greatly reduced with Pb(SCN)2, which effectively inhibits the interface recombination and promotes charge transport in CsPbI2Br PSC. Efficiencies of 12.22% and 10.44% are achieved for low‐temperature‐processed CsPbI2Br planar‐architecture PSCs with ITO/SnO2/CsPbI2Br/ poly(3‐hexylthiophene) (P3HT)/Ag and ITO/SnO2/CsPbI2Br/carbon, respectively. This low‐cost, high‐efficiency carbon‐based inorganic PSC shows potential industrial application, especially for tandem solar cells.

Nanoindentation has recently emerged to be the primary method to study the mechanical behavior and reliability of human enamel. Its hardness and elastic modulus were generally reported as average values with standard deviations that were calculated from the results of multiple nanoindentation testing. In such an approach, it is assumed that the mechanical properties of human enamel are constant, independent of testing parameters, like indent depth and loading rate. However, little is known if they affect the measurements. In this study, we investigated the dependence of the hardness and elastic modulus of human enamel on the indent depth. We found that in a depth range from 100 to 2000 nm the elastic moduli continuously decreased from approximately 104 to 70 GPa, and the hardnesses decreased from approximately 5.7 to 3.6 GPa. We then considered human enamel as a fiber-reinforced composite, and used the celebrated rule of mixture theory to quantify the upper and lower bounds of the elastic moduli, which were shown to cover the values measured in the current study and previous studies. Accordingly, we attributed the depth dependence of the hardness and modulus to the continuous microstructure evolution induced by the nanoindenter tip.