Micromotors hold exciting prospects in biomedical applications but still face a great challenge. To date, there have been few reports of micromotors with high safety, flexible controllability, and full biocompatibility. Here, a multifunctional method based on an optical tweezer system is presented to realize controllable cellular micromotors. The method not only satisfies all of the above criteria but is also independent of the cell types and materials. Optical tweezers are used to generate a dynamic scanning optical trap along a given circular trajectory, which can trap and drive a microparticle or a single cell to move along the trajectory and thus generate a microvortex. Cells within the microvortex will be controllably rotated under an action of shear stress or torque and their rotation rate and direction can be controlled by changing the scanning frequency and direction of the dynamic optical trap. The proposed method is effective for both immotile target cells and swimming target cells. Additionally, it is further applied to realize synchronous translation and rotation of cellular micromotors and to assemble controllable and fully biocompatible cellular micromotor assays. The proposed method is believed to have potential applications in targeted drug delivery, biological microenvironment monitoring and sensing, and biomedical treatment.
Characteristics like air-stability and high carrier mobility
make
non-van-der-Waals layered Bi2O2Se a good prospect
for planar integrated nanosystems. However, experimental investigation
about its analogue Bi2O2Te is rather rare due
to difficulty in synthesis. Herein, a low-pressure CVD process is
proposed that is adjusted to the rigorous growth condition required,
with large-scale Bi2O2Te ultrathin film obtained.
Magneto-transport behavior reveals a very large anisotropic nonsaturating
low-temperature magnetoresistance (∼1133% under 9 T magnetic
field). Despite the contradiction between high conductivity and ferroelectricity
in principle (mobile electrons screen electrostatic forces between
ions), the high-conductive Bi2O2Te film here
is revealed experimentally as another intrinsic ferroelectric with
the polarization switchable by external electric field (predicted
in Nano Lett.
2017, 17, 6309). These
results prove that Bi2O2Te possesses a very
narrow bandgap (∼0.15 eV), high conductivity, large magnetoresistance,
and room-temperature ferroelectricity, displaying great potential
as a high-performance nanoelectronic two-dimensional semiconductor
and, in advanced functional devices, working in the mid-infrared region.
In the fabric finishing field, the water repellents have received increasing interest in recent years and the development of a fluorine-free water repellent has become an attractive prospect.
Following logic in the silicon semiconductor industry, the existence of native oxide and suitable fabrication technology is essential for 2D semiconductors in planar integronics, which are surface-sensitive to typical coating technologies. To date, very few types of integronics are found to possess this feature. Herein, the 2D Bi 2 O 2 Te developed recently is reported to possess large-area synthesis and controllable thermal oxidation behavior toward single-crystal native oxides. This shows that surface-adsorbed oxygen atoms are inclined to penetrate across [Bi 2 O 2 ] n 2n+ layers and bond with the underlying [Te] n 2n− at elevated temperatures, transforming directly into [TeO 4 ] n 2n− with the basic architecture remaining stable. The oxide can be adjusted to form in an accurate layer-by-layer manner with a low-stress sharp interface. The native oxide Bi 2 TeO 6 layer (bandgap of ≈2.9 eV) exhibits visible-light transparency and is compatible with wet-chemical selective etching technology. These advances demonstrate the potential of Bi 2 O 2 Te in planar-integrated functional nanoelectronics such as tunnel junction devices, field-effect transistors, and memristors.
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