Upconversion nanoparticles (UCNPs) with superior optical and chemical features have been broadly employed for in vivo cancer imaging. Generally, UCNPs are surface modified with ligands for cancer active targeting. However, nanoparticles in biological fluids are known to form a long-lived “protein corona”, which covers the targeting ligands on nanoparticle surface and dramatically reduces the nanoparticle targeting capabilities. Here, for the first time, we demonstrated that by coating UCNPs with red blood cell (RBC) membranes, the resulting cell membrane-capped nanoparticles (RBC-UCNPs) adsorbed virtually no proteins when exposed to human plasma. We further observed in various scenarios that the cancer targeting ability of folic acid (FA)-functionalized nanoparticles (FA-RBC-UCNPs) was rescued by the cell membrane coating. Next, the FA-RBC-UCNPs were successfully utilized for enhanced in vivo tumor imaging. Finally, blood parameters and histology analysis suggested that no significant systematic toxicity was induced by the injection of biomimetic nanoparticles. Our method provides a new angle on the design of targeted nanoparticles for biomedical applications.Keywords: cancer targeting; diagnosis and therapy; drug delivery; protein corona; red blood cell membrane; upconversion nanoparticle;

Strontium (Sr) doped TiO2 nanoparticles are investigated with a view to studying the performance parameters of dye sensitized solar cells (DSSCs). Sr is used in trace levels (parts per million, ppm hereafter). The Sr doped TiO2 and undoped TiO2 nanoparticles are synthesized by the hydrothermal method and thin films of TiO2 electrodes are prepared using these particles (average grain size of 24 nm). The electrodes are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), surface area (BET) and UV-vis absorption spectrometry. DSSCs are fabricated using the doped and undoped TiO2 nanoparticle photoanodes. Their photovoltaic characteristics are studied by employing J–V measurements and electrochemical impedance spectroscopy (EIS). XRD studies reveal that the doping of Sr into the TiO2 lattice slightly inhibits the growth of the particles and causes lattice distortions. The optical studies indicate a reduction in band-gap upon doping of TiO2 films and a simultaneous enhancement in the photocurrent density (Jsc) and the photovoltage (Voc). The photoanode doped with 50 ppm Sr exhibits the highest power conversion efficiency (PCE) of about 7.88% which is 12.73% higher than that of undoped TiO2 cells. The effect of the Sr dopant on electron transport is studied by using EIS measurements. An improvement in electron life time is observed on the doping of TiO2.

AbstractUpconversion nanoparticles (UCNPs), with fascinating optical and chemical features, are a promising new generation of fluorescent probes. Although UCNPs have been widely used in diagnosis and therapy, there is an unmet need for a simple and effective surface engineering method that can produce cancer-targeting UCNPs. Here, we show that by coating particles with macrophage membranes, it becomes possible to utilize the adhesion between macrophages and cancer cells for effective cancer targeting. Natural macrophage membranes along with their associated membrane proteins were reconstructed into vesicles and then coated onto synthetic UCNPs. The resulting macrophage membrane-camouflaged particles (MM-UCNPs) exhibited effective cancer targeting capability inherited from the source cells and were further used for enhanced in vivo cancer imaging. Finally, the blood biochemistry, hematology testing and histology analysis results suggested a good in vivo biocompatibility of MM-UCNPs. The combination of synthetic nanoparticles with biomimetic cell membranes embodies a novel design strategy toward developing biocompatible nanoprobes for potential clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 521–530, 2017.

A novel composite nanostructured titanium dioxide (TiO2) based electron-transport layer (ETL) is designed by combining size blended nanoparticles (SBNP) and nanoarrays (NA) for efficient perovskite solar cell (PSC) applications. The composite nanostructured (SBNP + NA) ETL is successfully employed in hole-conductor free PSCs, there by achieving a stable device with a maximum efficiency of 13.5%. The improvement in the performance is attributed to the better charge transport and lower recombination in the SBNP + NA ETL. Despite the stable high efficiency, SBNP + NA ETL based PSCs are advantageous owing to their low cost, ease of all-solution fabrication process in an open environment and good reproducibility.

•Mesoporous SiO2 is prepared by spin-coating.•SiO2 layer can act as an efficient insulating layer.•Higher power conversion efficiency is obtained with TiO2/SiO2 films.A mesoporous SiO2 layer is successfully introduced into the hole transport material free perovskite solar cells by spin-coating a SiO2 paste onto the TiO2 scaffold layer. This SiO2 layer can act as an insulating layer and effectively inhibit the charge recombination between the TiO2 layer and carbon electrode. The variation of power conversion efficiencies with the thickness of SiO2 layer is studied here. Under optimized SiO2 thickness, perovskite solar cell fabricated on the TiO2/SiO2 film shows a superior power conversion efficiency of ∼12% and exhibits excellent long time stability for 30 days.

•A simple solvent treatment process is introduced.•Morphology of PbI2 film is modified by the solvent treatment.•More complete conversion of PbI2 to CH3NH3PbI3 is observed.•Enhanced performance and reproducibility is obtained.The morphology of PbI2 film plays a critical role in determining the quality of the resultant CH3NH3PbI3 film and power conversion efficiency of CH3NH3PbI3 perovskite solar cell. Here, we propose a solvent treatment method in the two-step sequential deposition process to control the morphology of PbI2 film, which leads to enhanced power conversion efficiency. Hole transport material free perovskite solar cell is chosen as a paradigm to demonstrate this idea. Solvent (isopropanol, chlorobenzene, or ethanol) treated PbI2 films exhibit dendrite-like or flake-like morphologies, which facilitate more complete conversion of PbI2 to CH3NH3PbI3 perovskite in ambient atmosphere with a relative high humidity. Therefore, enhanced performance is obtained with the solvent treated PbI2 films. Average power conversion efficiency has been improved from 9.42% in the traditional two-step sequential deposition to 11.22% in solar cells derived from ethanol treated PbI2 films.

Assays toward analysis of rare heterogeneous cells among identical specimen raise a significant challenge in many cell biological studies and clinical diagnosis applications. In this work, we report a disk-like hydrogel bead-based stratagem for rare cell researches at single cell level after a facile microfluidic-based particle synthesis approach. Cells of interested can be encapsulated into alginate droplets which are subsequently solidified into disk-like calcium alginate hydrogel beads and the bead size and cell number inside can be precisely controlled. Due to stability, permeability and disk-like shape of calcium alginate beads, cells immobilized in the disk-like beads can be treated with different chemicals with limited mechanical or fluidic operation influences and observed without distortion comparing with conventional methods or droplet microfluidic methods. Identification of circulating tumor cells, related to early-stage cancer diagnosis, is targeted to demonstrate the potential of our technique in rare cell analysis. This hydrogel bead-based stratagem is performed in immunofluorescence staining treatment and observation of cancer cells from normal hematological cells in blood sample. This method would have a great potential in single cell immobilization, manipulations and observation for biochemical cellular assays of rare cells.

The novel concept of introducing intermediate band into the mesoporous TiO2 backbone of dye-sensitized solar cells (DSSCs) is proposed to take full advantage of the sunlight and enhance the power conversion efficiency. Nominal trace amount W-doped TiO2 nanocrystralline films were prepared with the purpose of forming intermediate band in the bandgap of TiO2. A notable improvement of the device performance was obtained when N-type W-doped TiO2 films were applied as the photoanode of DSSCs. The short-circuit current density (Jsc) increased from 12.40 mA cm–2 to 15.10 mA cm–2, and the conversion efficiency increased from 6.64 to 7.42% when nominal 50 ppm (ppm) W-doped TiO2 was adopted.

Interfacial tension plays an important role in microfluidic emulsification, which is the process of preparing emulsions. A promising method which controls droplet behavior according to the function of the interfacial tension in the process of microfluidic emulsification is reported. The droplet size and generation frequency changed regularly to obtain appropriate concentrations of surfactant. This method could be of great help for setting up the size-controllable droplet generation systems, and ameliorating the emulsification technology. The interfacial tension effect was first analyzed by computational simulation before the real experiment, which significantly improved the efficiency of the whole research process.

A valve-based microfluidic micromixer was developed for multiply component droplets generation, manipulation and active mixing. By integrating pneumatic valves in microfluidic device, droplets could be individually generated, merged and well mixed automatically. Moreover, droplet volume could be controlled precisely by tuning loading pressure or the flow rate of the oil phase, and certain droplets fusion conditions were also investigated by adjusting the droplet driving times and oil flow rates. In these optimized conditions, fluorescence enhancement of droplets was used to detect Hg (II) ions in droplet by mixing with probe droplets (Rhodamine B quenched by gold nanoparticle). This method would have powerful potential for tiny volume sample assay or real-time chemical reaction study.