Micro/nanomotors (MNMs) have emerged as active micro/nanoplatforms that can move and perform functions at small scales. Much of their success, however, hinges on the use of functional properties of new materials. Liquid metals (LMs), due to their good electrical conductivity, biocompatibility, and flexibility, have attracted considerable attentions in the fields of flexible electronics, biomedicine, and soft robotics. The design and construction of LM‐based motors is therefore a research topic with tremendous prospects, however current approaches are mostly limited to macroscales. Here, the fabrication of an LM‐MNM (made of Galinstan, a gallium–indium–tin alloy) is reported and its potential application as an on‐demand, self‐targeting welding filler is demonstrated. These LM‐MNMs (as small as a few hundred nanometers) are half‐coated with a thin layer of platinum (Pt) and move in H2O2 via self‐electrophoresis. In addition, the LM‐MNMs roaming in a silver nanowire network can move along the nanowires and accumulate at the contact junctions where they become fluidic and achieve junction microwelding at room temperature by reacting with acid vapor. This work presents an intelligent and soft nanorobot capable of repairing circuits by welding at small scales, thus extending the pool of available self‐propelled MNMs and introducing new applications.
As
a typical, classical, but powerful biochemical sensing technology
in analytical chemistry, enzyme-linked immunosorbent assay (ELISA)
shows excellence and wide practicability for quantifying analytes
of ultralow concentration. However, long incubation time and burdensome
laborious multistep washing processes make it inefficient and labor-intensive
for conventional ELISA. Here, we propose rod-like magnetically driven
nanorobots (MNRs) for use as maneuverable immunoassay probes that
facilitate a strategy for an automated and highly efficient ELISA
analysis, termed nanorobots enabled ELISA (nR-ELISA). To prepare the
MNRs, the self-assembled chains of Fe3O4 magnetic
particles are chemically coated with a thin layer of rigid silica
oxide (SiO2), onto which capture antibody (Ab1) is grafted
to further achieve magnetically maneuverable immunoassay probes (MNR-Ab1s).
We investigate the fluid velocity distribution around the MNRs at
microscale using numerical simulation and empirically identify the
mixing efficiency of the actively rotating MNRs. To automate the analysis
process, we design and fabricate by 3-D printing a detection unit
consisting of three function wells. The MNR-Ab1s can be steered into
different function wells for required reaction or wishing process.
The actively rotating MNR-Ab1s can enhance the binding efficacy with
target analytes at microscale and greatly decrease incubation time.
The integrated nR-ELISA system can significantly reduce the assay
time, more importantly during which process manpower input is greatly
minimized. Our simulation of the magnetic field distribution generated
by Helmholtz coils demonstrates that our approach can be scaled up,
which proves the feasibility of using current strategy to construct
high throughput nR-ELISA detection instrument. This work of taking
magnetic micro/nanobots as active immunoassay probes for automatic
and efficient ELISA not only holds great potential for point-of-care
testing (POCT) in future but also extends the practical applications
of self-propelled micro/nanorobots into the field of analytical chemistry.
Honokiol, a well-tolerated natural product, can inhibit the proliferation of cancer cells. But its water insolubility hampers its systemic administration for therapy of cancer. As a drug delivery system, the pegylated liposome (PEGL) can increase the water solubility and targeting of the drug. Honokiol has been successfully encapsulated by PEGL in our laboratory. We wondered whether the combination treatment with pegylated liposomal honokiol (H-PEGL) and cisplatin (DDP) could improve the antitumor efficacy in ovarian carcinoma. H-PEGL could introduce apoptosis of SKOV3 cells in vitro, which was quantified by flow cytometric analysis, and the cellular morphologic changes were determined by propidium iodide staining. In a human ovarian carcinoma mouse model, combination treatment with H-PEGL (0.4 mg/day for 30 days; intraperitoneal) and DDP (5 mg/kg on days 7, 11, 15, 19; intraperitoneal) acted synergistically to inhibit tumor growth by 91.48% without notable toxicity, but H-PEGL and DDP alone only inhibit tumor growth by 66.83% and 52.5% as compared to the NaCl solution control, respectively. Assessment of microvessel density and apoptosis index by CD31 and terminal deoxynucleotidyl transferase-mediated nick end labeling immunohistochemistry respectively suggested that the antitumor activity of H-PEGL is mediated by angiogenesis inhibition and introduction of apoptosis. Our results showed us a splendid prospect of the clinical application of combination treatment on patients suffering from ovarian cancer with H-PEGL and DDP.
The degradation behaviors including oxidation and hydrolysis of silicone modified polycarbonate urethanes were thoroughly investigated. These polyurethanes were based on polyhexamethylene carbonate (PHMC)/polydimethylsiloxane (PDMS) mixed macrodiols with molar ratio of PDMS ranging from 5% to 30%. It was proved that PDMS tended to migrate toward surface and even a small amount of PDMS could form a silicone-like surface. Macrophages-mediated oxidation process indicated that the PDMS surface layer was desirable to protect the fragile soft PHMC from the attack of degradative species. Hydrolysis process was probed in detail after immersing in boiling buffered water using combined analytical tools. Hydrolytically stable PDMS could act as protective shields for the bulk to hinder the chain scission of polycarbonate carbonyls whereas the hydrolysis of urethane linkages was less affected. Although the promoted phase separation at higher PDMS fractions lead to possible physical defects and mechanical compromise after degradation, simultaneously enhanced oxidation and hydrolysis resistance could be achieved for the polyurethanes with proper PDMS incorporation.
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