Microfluidic-Based Droplet and Cell Manipulations Using Artificial Bacterial Flagella.

Herein, we assess the functionality of magnetic helical microswimmers as basic tools for the manipulation of soft materials, including microdroplets and single cells. Their ability to perform a range of unit operations is evaluated and the operational challenges associated with their use are established. In addition, we also report on interactions observed between the head of such helical swimmers and the boundaries of droplets and cells and discuss the possibilities of assembling an artificial swimming microorganism or a motorized cell.

3D Printed Microtransporters: Compound Micromachines for Spatiotemporally Controlled Delivery of Therapeutic Agents.

Functional compound micromachines are fabricated by a design methodology using 3D direct laser writing and selective physical vapor deposition of magnetic materials. Microtransporters with a wirelessly controlled Archimedes screw pumping mechanism are engineered. Spatiotemporally controlled collection, transport, and delivery of micro particles, as well as magnetic nanohelices inside microfluidic channels are demonstrated.

Controlled in vivo swimming of a swarm of bacteria-like microrobotic flagella.

In vivo imaging and actuation of a swarm of magnetic helical microswimmers by external magnetic fields (less than 10 mT) in deep tissue is demonstrated for the first time. This constitutes a major milestone in the field, yielding a generation of micrometer-scale transporters with numerous applications in biomedicine including synthetic biology, assisted fertilization, and drug/gene delivery.

The biocompatibility and anti-biofouling properties of magnetic core-multishell Fe@C NWs-AAO nanocomposites.

Soft-magnetic core-multishell Fe@C NWs-AAO nanocomposites were synthesized using anodization, electrodeposition and low-pressure chemical vapour deposition (CVD) at 900 °C. High chemical and mechanical stability is achieved by the conversion from amorphous to θ- and δ-Al2O3 phases above 600 °C. Moreover, the surface properties of the material evolve from bioactive, for porous AAO, to bioinert, for Fe@C NW filled AAO nanocomposite. Although the latter is not cytotoxic, cells do not adhere onto the surface of the magnetic nanocomposite, thus proving its anti-biofouling character.

Noncytotoxic artificial bacterial flagella fabricated from biocompatible ORMOCOMP and iron coating.

Magnetic microrobots have potential use in biomedical applications such as minimally invasive surgery, targeted diagnosis and therapy. Inspired by nature, artificial bacterial flagella (ABFs) are a form of microrobot powered by magnetic helical propulsion. For the promise of ABFs to be realized, issues of biocompatibility must be addressed and the materials used in their fabrication should be carefully considered. In this work, we fabricate the helical bodies of ABFs from a commercially available biocompatible photoresist, ORMOCOMP, by subsequently coating them with Fe for magnetic actuation. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays show that Fe-coated ORMOCOMP layers do not undermine the cell viability during 72 hours of incubation compared to control substrates. Cells exhibit normal morphology on ABF arrays and show good lamellipodial and filopodial interactions with the ABF surfaces. The swimming performance of Fe-coated ABFs is characterized using a three-pair Helmholtz coil arrangement. ABFs exhibit a maximum forward speed of 48.9 µm s-1 under a field of 9 mT at a frequency of 72 Hz. In summary, our Fe-coated ABFs exhibit little cytotoxicity and have potential for in vivo applications, especially those involving difficult to access regions within the human body.

Fabrication and characterization of magnetic microrobots for three-dimensional cell culture and targeted transportation.

Magnetically manipulated microrobots are demonstrated for targeted cell transportation. Full three-dimensional (3D) porous structures are fabricated with an SU-8 photoresist using a 3D laser lithography system. Nickel and titanium are deposited as a magnetic material and biocompatible material, respectively. The fabricated microrobots are controlled in the fluid by external magnetic fields. Human embryonic kidney 239 (HEK 239) cells are cultivated in the microrobot to show the possibility for targeted cell transportation.

Magnetic helical micromachines.

Helical microrobots have the potential to be used in a variety of application areas, such as in medical procedures, cell biology, or lab-on-a-chip. They are powered and steered wirelessly using low-strength rotating magnetic fields. The helical shape of the device allows propulsion through numerous types of materials and fluids, from tissue to different types of bodily fluids. Helical propulsion is suitable for pipe flow conditions or for 3D swimming in open fluidic environments.

Promotional effects of carbon nanotubes on V2O5/TiO2 for NOX removal.

A series of V(2)O(5)/TiO(2)-carbon nanotube (CNT) catalysts were synthesized by sol-gel method, and their activities for NO(X) removal were compared. A catalytic promotional effect was observed by adding CNTs to V(2)O(5)/TiO(2). The catalyst V(2)O(5)/TiO(2)-CNTs (10wt.%) showed an NO(X) removal efficiency of 89% at 300°C under a GHSV of 22,500h(-1). Based on X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, NH(3)-temperature-programmed desorption, temperature-programmed reduction, Brunauer-Emmett-Teller surface area measurements, differential scanning calorimetry, and thermogravimetric analysis, the increased acidity and reducibility, which could promote NH(3) adsorption and oxidation of NO to NO(2), respectively, contributed to this promotion.