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.

Magnetic-field-induced spin excitations and renormalized spin gap of the underdoped La1.895Sr0.105CuO4 superconductor

High-resolution neutron inelastic scattering experiments in applied magnetic fields have been performed on La1.895Sr0.105CuO4 (LSCO). In zero field, the temperature dependence of the low-energy peak intensity at the incommensurate momentum transfer QIC=(0.5,0.5+/-delta,0),(0.5+/-delta,0.5,0) exhibits an anomaly at the superconducting Tc which broadens and shifts to lower temperature upon the application of a magnetic field along the c axis. A field-induced enhancement of the spectral weight is observed, but only at finite energy transfers and in an intermediate temperature range. These observations establish the opening of a strongly downward renormalized spin gap in the underdoped regime of LSCO. This behavior contrasts with the observed doping dependence of most electronic energy features.     

Design,synthesis and evaluation of spermine-based pH-sensitive amphiphilic gene delivery systems: Multifunctional non-viral gene carriers

Design and development of efficient non-viral gene delivery systems is critical to overcome various barriers for effective intracellular gene delivery.Eight new spermine-based protonatable surfactants were designed,synthesized and evaluated as non-viral pH-sensitive gene carriers.These carriers formed stable complexes with plasmid DNA at an N/P ratio as low as 2.The sizes of the carrier/pDNA nanoparticles (N/P = 12) were in the range of 90–130 nm,smaller than that of Lipofectamine2000/pDNA nanoparticles.The...     

Simple and versatile selective synthesis of neutral and cationic copper(I) N-heterocyclic carbene complexes using an electrochemical procedure

An electrochemical approach for the preparation of copper(I) N-heterocyclic carbene complexes has been developed to include a diverse range of ligand precursors. Importantly, the method is effective for a ligand precursor that contains several acidic protons and for which traditional methods of carbene formation are not suitable.     

Phase transitions in hadronic systems and thermodynamics of a system with an exponential spectrum

Both nuclear matter and hadronic matter at high excitations can be described by a liquid-vapor phase transition. For the hadronic systems, a system with an exponential mass spectrum (Hagedorn-like or bag-like) leads to a thermodynamics which is identical to that of a two phase coexistence at a fixed temperature.     

Lifetime measurement of the first excited 2+ state in 16C

The lifetime of the 2_+(1) state in 16C has been measured with the recoil distance method using the 9Be(9Be,2p) fusion-evaporation reaction at a beam energy of 40 MeV. The mean lifetime was measured to be 11.7(20) ps corresponding to a B(E2;2_+(1)-->0+) value of 4.15(73)e_2 fm_4 [1.73(30) W.u.], consistent with other even-even closed shell nuclei. Our result does not support an interpretation for "decoupled" valence neutrons.     

Application of Bis-Sulfonamides in Asymmetric Catalysis. Addition of Diethylzinc to Prochiral Aldehydes

The review summarizes the authors' and published data on the Ti(OPr-i)₄-catalyzed addition of diethylzinc to prochiral aldehydes in the presence of bis-sulfonamides. The effect of bis-sulfonamide structure and other factors on the enantioselectivity of formation of secondary alcohols is discussed.