Zinc Microrocket Pills: Fabrication and Characterization toward Active Oral Delivery

Here the fabrication of a zinc (Zn) microrocket pill is reported, and its unique features toward active and enhanced oral delivery application are demonstrated. By loading Zn-based tubular microrockets into an orally administrable pill formulation, the resulting Zn microrocket pill can rapidly dissolve in the stomach, releasing numerous encapsulated Zn microrockets that are instantaneously activated and then propel in the gastric fluid. The released Zn microrockets display efficient propulsion without being affected by the presence of the inactive excipient materials of the pill. An in vivo retention study performed in mice clearly shows that the active pill dissolution and powerful acid-driven Zn microrocket propulsion greatly enhance the microrocket retention within the gastric tissue without causing toxic effects. By combining the active delivery feature of Zn microrockets with the oral administration of a pill, the Zn microrocket pill holds considerable potential for active oral delivery of various therapeutics for diverse medical applications.

Small-Scale Propellers Deliver Miniature Versions of Themselves

Small-scale actuators and propellers have benefited from advances in materials and manufacturing to become more lifelike. Inspired by animal species, multi-generational chemically powered artificial propellers that carry small versions of themselves and deliver them "on-the-fly" are described. The released replicas are capable of autonomous propulsion and propelling immediately after detachment. Release occurs without human involvement and relies solely on sacrificial layers separating the carriers and replicas. These layers are composed of transient natural polymers, which dissolve under the swimming conditions to release the confined replicas. Judicious selection of the responsive transient materials, layer thickness, and solution conditions (e.g., pH), leads to programmable delivery of the replicas. Finally, the ability of the same carrier propellers to carry and transport multiple generations of propellers and deliver them at predetermined times is demonstrated.

Harnessing bistability for directional propulsion of soft, untethered robots

In most macroscale robotic systems, propulsion and controls are enabled through a physical tether or complex onboard electronics and batteries. A tether simplifies the design process but limits the range of motion of the robot, while onboard controls and power supplies are heavy and complicate the design process. Here, we present a simple design principle for an untethered, soft swimming robot with preprogrammed, directional propulsion without a battery or onboard electronics. Locomotion is achieved by using actuators that harness the large displacements of bistable elements triggered by surrounding temperature changes. Powered by shape memory polymer (SMP) muscles, the bistable elements in turn actuate the robot's fins. Our robots are fabricated using a commercially available 3D printer in a single print. As a proof of concept, we show the ability to program a vessel, which can autonomously deliver a cargo and navigate back to the deployment point.

Fuel-Free Synthetic Micro-/Nanomachines

Inspired by the swimming of natural microorganisms, synthetic micro-/nanomachines, which convert energy into movement, are able to mimic the function of these amazing natural systems and help humanity by completing environmental and biological tasks. While offering autonomous propulsion, conventional micro-/nanomachines usually rely on the decomposition of external chemical fuels (e.g., H₂ O₂ ), which greatly hinders their applications in biologically relevant media. Recent developments have resulted in various micro-/nanomotors that can be powered by biocompatible fuels. Fuel-free synthetic micro-/nanomotors, which can move without external chemical fuels, represent another attractive solution for practical applications owing to their biocompatibility and sustainability. Here, recent developments on fuel-free micro-/nanomotors (powered by various external stimuli such as light, magnetic, electric, or ultrasonic fields) are summarized, ranging from fabrication to propulsion mechanisms. The applications of these fuel-free micro-/nanomotors are also discussed, including nanopatterning, targeted drug/gene delivery, cell manipulation, and precision nanosurgery. With continuous innovation, future autonomous, intelligent and multifunctional fuel-free micro-/nanomachines are expected to have a profound impact upon diverse biomedical applications, providing unlimited opportunities beyond one's imagination.

Continuous Microfluidic Self-Assembly of Hybrid Janus-Like Vesicular Motors: Autonomous Propulsion and Controlled Release

A microfluidic strategy is developed for the continuous fabrication of hybrid Janus vesicular motors that uniquely combine the capability of autonomous propulsion and externally controlled delivery of encapsulated payload.

Biodegradable protein-based rockets for drug transportation and light-triggered release

We describe a biodegradable, self-propelled bovine serum albumin/poly-l-lysine (PLL/BSA) multilayer rocket as a smart vehicle for efficient anticancer drug encapsulation/delivery to cancer cells and near-infrared light controlled release. The rockets were constructed by a template-assisted layer-by-layer assembly of the PLL/BSA layers, followed by incorporation of a heat-sensitive gelatin hydrogel containing gold nanoparticles, doxorubicin, and catalase. These rockets can rapidly deliver the doxorubicin to the targeted cancer cell with a speed of up to 68 μm/s, through a combination of biocatalytic bubble propulsion and magnetic guidance. The photothermal effect of the gold nanoparticles under NIR irradiation enable the phase transition of the gelatin hydrogel for rapid release of the loaded doxorubicin and efficient killing of the surrounding cancer cells. Such biodegradable and multifunctional protein-based microrockets provide a convenient and efficient platform for the rapid delivery and controlled release of therapeutic drugs.