A Biodegradable Magnetic Microrobot Based on Gelatin Methacrylate for Precise Delivery of Stem Cells with Mass Production Capability.

A great deal of research has focused on small-scale robots for biomedical applications and minimally invasive delivery of therapeutics (e.g., cells, drugs, and genes) to a target area. Conventional fabrication methods, such as two-photon polymerization, can be used to build sophisticated micro- and nanorobots, but the long fabrication cycle for a single microrobot has limited its practical use. This study proposes a biodegradable spherical gelatin methacrylate (GelMA) microrobot for mass production in a microfluidic channel. The proposed microrobot is fabricated in a flow-focusing droplet generator by shearing a mixture of GelMA, photoinitiator, and superparamagnetic iron oxide nanoparticles (SPIONs) with a mixture of oil and surfactant. Human nasal turbinate stem cells (hNTSCs) are loaded on the GelMA microrobot, and the hNTSC-loaded microrobot shows precise rolling motion in response to an external rotating magnetic field. The microrobot is enzymatically degraded by collagenase, and released hNTSCs are proliferated and differentiated into neuronal cells. In addition, the feasibility of the GelMA microrobot as a cell therapeutic delivery system is investigated by measuring electrophysiological activity on a multielectrode array. Such a versatile and fully biodegradable microrobot has the potential for targeted stem cell delivery, proliferation, and differentiation for stem cell-based therapy.

Magnetically Controlled Intraocular Delivery of Dexamethasone Using Silica-Coated Magnetic Nanoparticles.

Although the number of patients with eye diseases is increasing, efficient drug delivery to the posterior segment of the eyeball remains challenging. The reasons include the unique anatomy of the eyeball, the blood-aqueous barrier, the blood-retina barrier, and drug elimination via the anterior chamber and uveoscleral routes. Solutions to these obstacles for therapeutic delivery to the posterior segment will increase the efficacy, efficiency, and safety of ophthalmic treatment. Micro/nanorobots are promising tools to deliver therapeutics to the retina under the direction of an external magnetic field. Although many groups have evaluated potential uses of micro/nanorobots in retinal treatment, most experiments have been performed under idealized in vitro laboratory conditions and thus do not fully demonstrate the clinical feasibility of this approach. This study examined the use of magnetic nanoparticles (MNPs) to deliver dexamethasone, a drug widely used in retinal disease treatment. The MNPs allowed sustainable drug release and successful magnetic manipulation inside bovine vitreous humor and the vitreous humor of living rabbits. Therefore, controlled drug distribution via magnetic manipulation of MNPs is a promising strategy for targeted drug delivery to the retina.

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications.

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation. Metal-based degradable micromotor composed of magnesium (Mg), zinc (Zn), and iron (Fe) have promise due to their nontoxic fuel-free propulsion, favorable biocompatibility, and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media, efficient cargo delivery and favorable biocompatibility. A noteworthy number of degradable metal-based micromotors employ bubble propulsion, utilizing water as fuel to generate hydrogen bubbles. This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications. In addition, understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance. Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor. Here we review the design and recent advancements of metallic degradable micromotors. Furthermore, we describe the controlled degradation, efficient in vivo drug delivery, and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications. Moreover, we discuss micromotors' efficacy in detecting and destroying environmental pollutants. Finally, we address the limitations and future research directions of degradable metallic micromotors.