Cell surface engineering provides access to custom-made
cell interfaces
with desirable properties and functions. However, cell-selective covalent
labeling methods that can simultaneously install multiple molecules
with different functions are scarce. Herein, we report an aptamer-enabled
proximity catalytic covalent labeling platform for multifunctional
surface reconfiguration of target cells in mixed cell populations.
By conjugating peroxidase with cell-selective aptamers, the probes
formed can selectively bind target cells and catalyze target-cell-localized
covalent labeling in situ. The universal applicability
of the platform to different phenol-modified functional molecules
allows us to perform a variety of manipulations on target cells, including
labeling, tracking, assembly regulation, and surface remodeling. In
particular, the platform has the ability of multiplexed covalent labeling,
which can be used to install two mutually orthogonal click reactive
molecules simultaneously on the surface of target cells. We thus achieve
“multitasking” in complex multicellular systems: programming
and tracking specific cell–cell interactions. We further extend
the functional molecules to carbohydrates and perform ultrafast neoglycosylation
on target living cells. These newly introduced sugars on the cell
membrane can be recognized and remodeled by a glycan-modifying enzyme,
thus providing a method package for cell-selective engineering of
the glycocalyx.
Transmission characteristics of two-dimensional magnetized magnetic photonic crystals (MPCs) have been studied by electromagnetic simulation and experiments in microwave frequencies. MPCs with square and hexagonal lattices are made of ferrites, and their transmission coefficients are measured in the X waveband with an applied static magnetic field. For the lattices, a stop-band and a band shift with the applied static magnetic field are observed. The experimental results are in good agreement with those of electromagnetic simulations when magnetic anisotropy of ferrites is represented by a tensor but deviate from the simulation results when the anisotropy is modelled by an effective permeability of TMz mode.
The intrinsic antiferromagnetic topological insulator MnBi2Te4 undergoes a metamagnetic transition in a c-axis magnetic field. It has been predicted that ferromagnetic MnBi2Te4 is an ideal Weyl semimetal with a single pair of Weyl nodes. Here we report measurements of quantum oscillations detected in the field-induced ferromagnetic phase of MnBi2-xSbxTe4, where Sb substitution tunes the majority carriers from electrons to holes. Single frequency Shubnikov-de Haas oscillations were observed in a wide range of Sb concentrations (0.54 ≤ x ≤ 1.21). The evolution of the oscillation frequency and the effective mass shows reasonable agreement with the Weyl semimetal band-structure of ferromagnetic MnBi2Te4 predicted by density functional calculations. Intriguingly, the quantum oscillation frequency shows a strong temperature dependence, indicating that the electronic structure sensitively depends on magnetism.
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