Magnetoactive Soft Materials with Programmable Magnetic Domains for Multifunctional Actuators

Despite considerable progress having been made in the research of soft actuators, there remains a grand challenge in creating a facile manufacturing process that offers both extensive programmability and exceptional actuation capabilities. Taking inspiration from uncomplicated small organisms, this work aims to develop soft actuators that can be mobilized through straightforward design and control, similar to caterpillars or inchworms. They execute intricate actions and functions to meet survival needs in the most efficient manner possible. Here, a novel soft actuator with uniformly dispersed ferromagnetic microparticles but programmatic magnetic profile distribution is proposed by a convenient magnetization process. Benefiting from its high magnetic sensitivity and good matrix flexibility, the actuator can simultaneously achieve reversible, remote, and fast programmable shape transformation and controllable movement even in a magnetic field as low as 14 Gs. Complemented by intrinsic material properties and structural configuration, actuation employing spatial magnetization profiles can facilitate multiple modes of locomotion when subjected to magnetic fields, allowing for an efficient manipulation task of both solid and liquid media. More importantly, a finite element model is developed to assist in the design of the interaction between the alternating magnetic field and the magnetic torques. This advanced soft actuator would strongly push forward major breakthroughs in key applications such as intelligent sensors, disaster rescue, and wearable devices.

Magnetic Nanorobots as Maneuverable Immunoassay Probes for Automated and Efficient Enzyme Linked Immunosorbent Assay

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.

Step-by-Step Design of New Theranostic Nanoformulations: Multifunctional Nanovectors for Radio-Chemo-Hyperthermic Therapy under Physical Targeting

While investigating the possible synergistic effect of the conventional anticancer therapies, which, taken individually, are often ineffective against critical tumors, such as central nervous system (CNS) ones, the design of a theranostic nanovector able to carry and deliver chemotherapy drugs and magnetic hyperthermic agents to the target radiosensitizers (oxygen) was pursued. Alongside the original formulation of polymeric biodegradable oxygen-loaded nanostructures, their properties were fine-tuned to optimize their ability to conjugate therapeutic doses of drugs (doxorubicin) or antitumoral natural substances (curcumin). Oxygen-loaded nanostructures (diameter = 251 ± 13 nm, ζ potential = −29 ± 5 mV) were finally decorated with superparamagnetic iron oxide nanoparticles (SPIONs, diameter = 18 ± 3 nm, ζ potential = 14 ± 4 mV), producing stable, effective and non-agglomerating magnetic nanovectors (diameter = 279 ± 17 nm, ζ potential = −18 ± 7 mV), which could potentially target the tumoral tissues under magnetic driving and are monitorable either by US or MRI imaging.

Beyond Oncological Hyperthermia: Physically Drivable Magnetic Nanobubbles as Novel Multipurpose Theranostic Carriers in the Central Nervous System

Magnetic Oxygen-Loaded Nanobubbles (MOLNBs), manufactured by adding Superparamagnetic Iron Oxide Nanoparticles (SPIONs) on the surface of polymeric nanobubbles, are investigated as theranostic carriers for delivering oxygen and chemotherapy to brain tumors. Physicochemical and cyto-toxicological properties and in vitro internalization by human brain microvascular endothelial cells as well as the motion of MOLNBs in a static magnetic field were investigated. MOLNBs are safe oxygen-loaded vectors able to overcome the brain membranes and drivable through the Central Nervous System (CNS) to deliver their cargoes to specific sites of interest. In addition, MOLNBs are monitorable either via Magnetic Resonance Imaging (MRI) or Ultrasound (US) sonography. MOLNBs can find application in targeting brain tumors since they can enhance conventional radiotherapy and deliver chemotherapy being driven by ad hoc tailored magnetic fields under MRI and/or US monitoring.

Pushing of Magnetic Microdroplet Using Electromagnetic Actuation System

Treatment of certain diseases requires the administration of drugs at specific areas of tissues and/or organs to increase therapy effectiveness and avoid side effects that may harm the rest of the body. Drug targeting is a research field that uses various techniques to administrate therapies at specific areas of the body, including magnetic systems able to drive nano “vehicles”, as well as magnetically labeled molecules, in human body fluids and tissues. Most available actuation systems can only attract magnetic elements in a relatively small workspace, limiting drug target applications to superficial tissues, and leaving no alternative cases where deep targeting is necessary. In this paper, we propose an electromagnetic actuation system able to push and deflect magnetic particles at distance of ~10 cm, enabling the manipulation of magnetic nano- and microparticles, as well as administration of drugs in tissues, which are not eligible for localized drug targeting with state-of-the-art systems. Laboratory experiments and modeling were conducted to prove the effectiveness of the proposed system. By further implementing our device, areas of the human body that previously were impossible to treat with magnetically labeled materials such as drugs, cells, and small molecules can now be accessible using the described system.

Experimental measurement on movement of spiral-type capsule endoscope

Wireless capsule endoscope achieved great success, however, the maneuvering of wireless capsule endoscope is challenging at present. A magnetic driving instrument, including two bar magnets, a stepper motor, a motor driver, a motor controller, and a power supplier, was developed to generate rotational magnetic fields. Permanent magnet ring, magnetized as S and N poles radially and mounted spiral structure on the surface, acted as a capsule. The maximum torque passing to the capsule, rotational synchronization of capsule and motor, and the translational speed of capsule, were measured in ex vivo porcine large intestine. The experimental results illustrate that the rotational movement of the spiral-type capsule in the intestine is feasible and the cost of the magnetic driving equipment is low. As a result, the solution is promising in the future controllability.