Efficient passivation of SnO2 nano crystallites by Indoline D-149 via dual chelation

For the first time in SnO₂ based dye solar cells, here we report, efficiency exceeding 3% of the cells consisting with Indoline D-149 dye with unmodified SnO₂ nano-crystallites. The cells sensitized with metal free D-149 dye together with liquid electrolyte comprising with 0.5 M tetrapropyl ammonium iodide and 0.05 M iodine in a mixture of acetonitrile and ethylene carbonate (1:4 by volume) delivered a short circuit current density of 10.4 mA cm^?2 with an open circuit voltage of 530 mV under the illumination of 100 mW cm^?2 (AM1.5) having an efficiency of 3.1%. As evident from the FTIR measurement, strong surface passivation of recombination centers of SnO₂ crystallites due to the dual mode of attachment of dye molecules to the surface of SnO₂ via both COOH and S–O direct bond might be the possible reason for this enhancement in these SnO₂ based cells.     

Selective trapping of single mammalian breast cancer cells by insulator-based dielectrophoresis

The trapping or immobilization of individual cells at specific locations in microfluidic platforms is essential for single cell studies, especially those requiring cell stimulation and downstream analysis of cellular content. Selectivity for individual cell types is required when mixtures of cells are analyzed in heterogeneous and complex matrices, such as the selection of metastatic cells within blood samples. Here, we demonstrate a microfluidic device based on direct current (DC) insulator-based dielectrophoresis (iDEP) for selective trapping of single MCF-7 breast cancer cells from mixtures with both mammalian peripheral blood mononuclear cells (PBMC) as well MDA-MB-231 as a second breast cancer cell type. The microfluidic device has a teardrop iDEP design optimized for the selective capture of single cells based on their differential DEP behavior under DC conditions. Numerical simulations adapted to experimental device geometries and buffer conditions predicted the trapping condition in which the dielectrophoretic force overcomes electrokinetic forces for MCF-7 cells, whereas PBMCs were not trapped. Experimentally, selective trapping of viable MCF-7 cells in mixtures with PBMCs was demonstrated in good agreement with simulations. A similar approach was also executed to demonstrate the selective trapping of MCF-7 cells in a mixture with MDA-MB-231 cells, indicating the selectivity of the device for weakly invasive and highly invasive breast cancer cells. The DEP studies were complemented with cell viability tests indicating acceptable cell viability over the course of an iDEP trapping experiment.

Synthesis-enabled exploration of chiral and polar multivalent quaternary sulfides

An innovative method of synthesis is reported for the large and diverse (RE)₆(TM)_x(Tt)₂S₁₄ (RE = rare-earth, TM = transition metals, Tt = Si, Ge, and Sn) family of compounds (∼1000 members, ∼325 contain Si), crystallizing in the noncentrosymmetric, chiral, and polar P6₃ space group. Traditional synthesis of such phases involves the annealing of elements or binary sulfides at elevated temperatures. The atomic mixing of refractory components technique, presented here, allows the synthesis of known members and vastly expands the family to nearly the entire transition metal block, including 3d, 4d, and 5d TMs with oxidation states ranging from 1+ to 4+. Arc-melting of the RE, TM, and tetrel elements of choice forms an atomically-mixed precursor, which readily reacts with sulfur providing bulk powders and large single crystals of the target quaternary sulfides. Detailed in situ and ex situ experiments show the mechanism of formation, which involves multiphase binary sulfide intermediates. Crystal structures and metal oxidation states were corroborated by a combination of single crystal X-ray diffraction, elemental analysis, EPR, NMR, and SQUID magnetometry. The potential of La₆(TM)_x(Tt)₂S₁₄ compounds for non-linear optical applications was also demonstrated.

Synthesis from atomically-mixed precursors opens up a phase space to hundreds of chiral and polar sulfide semiconductors with almost any transition metal in variable oxidation states.     

Simple polymerization through oxygen at reduced volumes using oil and water

An enduring question is: what is the simplest and easiest way to obtain tailored polymers? This communication explores a robust photoiniferter polymerization with only two active ingredients that requires no prior deoxygenation and can be performed on the milliliter scale or sub-milliliter scale. Rather than leaving headspace in the polymerization vessel or scaling reactions up to fill the vessel, this approach fills the headspace of the reaction vessel with mineral oil or inert solvents. This approach can also be applied to polar monomers in aqueous media, using oil as the inert solvent, or to hydrophobic monomers with water as the inert solvent. This method removes enough ambient oxygen that the photoiniferter reaction proceeds with no deoxygenation step, and achieves high conversion and good molecular weight control in 10–20 h in both aqueous and organic solvents. Complex polymer architectures such as multiblock copolymers and gradient polymers were successfully synthesized by this approach.     

In‐situ Chemiluminescence‐Driven Reversible Addition–Fragmentation Chain‐Transfer Photopolymerization

The power of chemical light generation (chemiluminescence) is used to drive polymerization reactions. A biphasic reaction is developed such that light‐generating reactions are confined to the organic phase and photopolymerization occurs in the aqueous phase. Well‐defined RAFT‐capped polymers are synthesized and the kinetics are shown to be dictated by light generation.