A simple approach to electrospinning has been developed that enables the collection of polymer, ceramic, and multiphase composite fibers, in quantity, with a high degree of spatial orientation. It has been demonstrated that a careful choice of solvent effectively eliminates the onset of the characteristic ''bending'' instability that is commonly associated with the electrospinning process. This allows collection of spatially oriented submicron electrospun fibers on a rotating drum without the need for elaborate mechanical or electrostatic manipulation of the electrospinning jet and/or collection target (Deitzel, J. M.; Kleinmeyer, J. D. et al. Polymer 2001, 42, 8163, Zussman, E.; et al. Appl Phys Lett 2003, 82, 973, and Li, D. Wang, Y. L.; et al. Nano Lett 2003, 3, 1167. Fibers have been electrospun from a series of model polyethylene oxide/CHCl 3 solutions with a range of conductivities. The experimental data confirms theoretical predictions that the onset of the bending instability is a function of the available ''free'' charge in the solution, which in turn is strongly influenced by the dielectric constant of the solvent. The results show that fiber orientation becomes random as the conductivity increases, indicating the need for the surface charge density to exceed a critical threshold in order for the bending instability to initiate. This method has been experimentally demonstrated with other lowdielectric constant solvents and other common polymer, ceramic, and composite materials. Furthermore, it has been demonstrated that fibers electrospun from these solutions can be mechanically drawn to submicron dimensions ($ 200-500 nm) by controlling drum speed.
CD22, a member of Siglec family of sialic acid binding proteins, has restricted expression on B cells. Antibody‐based agents targeting CD22 or CD20 on B lymphoma and leukemia cells exhibit clinical efficacy for treating these malignancies, but also attack normal B cells leading to immune deficiency. Here, we report a chemoenzymatic glycocalyx editing strategy to introduce high‐affinity and specific CD22 ligands onto NK‐92MI and cytokine‐induced natural killer cells to achieve tumor‐specific CD22 targeting. These CD22‐ligand modified cells exhibited significantly enhanced tumor cell binding and killing in vitro without harming healthy B cells. For effective lymphoma cell killing in vivo, we further functionalized CD22 ligand‐modified NK‐92MI cells with the E‐selectin ligand sialyl Lewis X to promote trafficking to bone marrow. The dual‐functionalized cells resulted in the efficient suppression of B lymphoma in a xenograft model. Our results suggest that natural killer cells modified with glycan ligands to CD22 and selectins promote both targeted killing of B lymphoma cells and improved trafficking to sites where the cancer cells reside, respectively.
Polymer-embedded La2/3Sr1/3MnO3 (LSMO) composites,
(LSMO)1 −x(PPP)x (PPP is polyparaphenylene, and
x is
the weight fraction of PPP), were prepared by mixing pre-prepared LSMO
and PPP powders. Thermogravimetric analysis, x-ray diffraction, and
infrared spectra show that the composites are stable when calcined at
400̂C. Significant enhancement in the magnetoresistance (MR) effect
over a wide temperature range is observed for the composites compared
with the parent LSMO. The MR enhancement reaches its maximum at
x = 0.2.
The magnetotransport is mainly attributed to intergrain spin-polarized tunnelling.
We argue that the introduction of PPP gives rise to magnetic disorder and hence
an enhanced tunnelling effect, which is responsible for the MR enhancement.
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