Micro-and nanorobots are promising devices for biomedical and environmental applications. The past few years have witnessed rapid developments in this field. This short review intends to address recent progress on magnetically driven micro-and nanorobots developed in our laboratory and by other research groups. Different designs such as helical swimmers, flexible swimmers, surface walkers, and others are categorized and discussed. Specific applications of these robots in the fields of biomedicine or environmental remediation are also reported. Finally, the use of magnetic fields for additional capabilities beyond manipulation is presented.

Neurodegenerative diseases generally result in irreversible neuronal damage and neuronal death. Cell therapy shows promise as a potential treatment for these diseases. However, the therapeutic targeted delivery of these cells and the in situ provision of a suitable microenvironment for their differentiation into functional neuronal networks remain challenging. A highly integrated multifunctional soft helical microswimmer featuring targeted neuronal cell delivery, on-demand localized wireless neuronal electrostimulation, and post-delivery enzymatic degradation is introduced. The helical soft body of the microswimmer is fabricated by two-photon lithography of the photocurable gelatin-methacryloyl (GelMA)-based hydrogel. The helical body is then impregnated with composite multiferroic nanoparticles displaying magnetoelectric features (MENPs). While the soft GelMA hydrogel chassis supports the cell growth, and is degraded by enzymes secreted by cells, the MENPs allow for the magnetic transportation of the bioactive chassis, and act as magnetically mediated electrostimulators of neuron-like cells. The unique combination of the materials makes these microswimmers highly integrated devices that fulfill several requirements for their future translation to clinical applications, such as cargo delivery, cell stimulation, and biodegradability. The authors envision that these devices will inspire new avenues for targeted cell therapies for traumatic injuries and diseases in the central nervous system.

Micro- and nanorobots have shown great potential for applications in various fields, including minimally invasive surgery, targeted therapy, cell manipulation, environmental monitoring, and water remediation. Recent progress in the design, fabrication, and operation of these miniaturized devices has greatly enhanced their versatility. In this report, the most recent progress on the manipulation of small-scale robots based on power sources, such as magnetic fields, light, acoustic waves, electric fields, thermal energy, or combinations of these, is surveyed. The design and propulsion mechanism of micro- and nanorobots are the focus of this article. Their fabrication and applications are also briefly discussed.

Metal-organic frameworks (MOFs) are a class of crystalline materials constructed from organic linkers and inorganic nodes. MOFs typically possess ultra-high surface areas and pore volumes; thus, they are ideal candidates for biomedical applications. Zinc Imidazolate Framework 8 (ZIF-8) has been widely established in the literature as a potential candidate for on-demand drug delivery applications due to its remarkable loading capacity, stability in physiological environments, and pH triggered controlled drug release. Using ZIF-8 for in vivo applications requires a clear understanding of the interaction of ZIF-8 with biological tissue. In this work, we investigated the biocompatibility of ZIF-8 towards six different cell lines representing various body parts (kidney, skin, breast, blood, bones, and connective tissue). Our results suggested that ZIF-8 has no significant cytotoxicity up to a threshold value of 30 µg/mL. Above 30 µg/mL the cytotoxicity is shown to result from the effect of released Zinc ions (Zn 2+) on the mitochondrial ROS production, causing cell cycle arrest in the G2/M phase due to irreversible DNA damage, and ultimately initiating cellular apoptosis pathways. Due to this insight, we then encapsulated the hormone insulin into ZIF-8 and compared its drug delivery capabilities to the aforementioned cytotoxicity values. Our results suggest that ZIF-8 is suitable for therapeutic applications and furthermore, establish a clear understanding of the interaction of ZIF-8 and its constituents with various cell lines including, and highlight the important biocompatibility factors that must be considered for future in vivo testing.

An FeGa@P(VDF-TrFE) wire-shaped magnetoelectric nanorobot is designed and fabricated to demonstrate a proof-of-concept integrated device, which features wireless locomotion and on-site triggered therapeutics with a single external power source (i.e., a magnetic field). The device can be precisely steered toward a targeted location wirelessly by rotating magnetic fields and perform on-demand magnetoelectrically assisted drug release to kill cancer cells.