Magnetically Driven Micro and Nanorobots

Manipulation and navigation of micro and nanoswimmers in different fluid environments can be achieved by chemicals, external fields, or even motile cells. Many researchers have selected magnetic fields as the active external actuation source based on the advantageous features of this actuation strategy such as remote and spatiotemporal control, fuel-free, high degree of reconfigurability, programmability, recyclability, and versatility. This review introduces fundamental concepts and advantages of magnetic micro/nanorobots (termed here as "MagRobots") as well as basic knowledge of magnetic fields and magnetic materials, setups for magnetic manipulation, magnetic field configurations, and symmetry-breaking strategies for effective movement. These concepts are discussed to describe the interactions between micro/nanorobots and magnetic fields. Actuation mechanisms of flagella-inspired MagRobots (i.e., corkscrew-like motion and traveling-wave locomotion/ciliary stroke motion) and surface walkers (i.e., surface-assisted motion), applications of magnetic fields in other propulsion approaches, and magnetic stimulation of micro/nanorobots beyond motion are provided followed by fabrication techniques for (quasi)spherical, helical, flexible, wire-like, and biohybrid MagRobots. Applications of MagRobots in targeted drug/gene delivery, cell manipulation, minimally invasive surgery, biopsy, biofilm disruption/eradication, imaging-guided delivery/therapy/surgery, pollution removal for environmental remediation, and (bio)sensing are also reviewed. Finally, current challenges and future perspectives for the development of magnetically powered miniaturized motors are discussed

Nano/Microrobots Line Up for Gastrointestinal Tract Diseases: Targeted Delivery, Therapy, and Prevention

Nano/microrobots (NMRs) are tiny devices that can convert energy into motion and operate at nano/microscales.54 Especially in biomedical research, NMRs have received much attention over the past twenty years because of their excellent capabilities and great potential in various applications, including on-demand drug delivery, gene and cell transport, and precise microsurgery. Reports published in recent years show that synthetic nano/microrobots have promising potential to function in the gastrointestinal (GI) region, particularly in terms of drug delivery. These tiny robots were able to be designed in such a way that they propel in their surroundings (biological media) with high speed, load cargo (drug) efficiently, transport it safely, and release upon request successfully. Their propulsion, retention, distribution, and toxicity in the GI tract of mice has been evaluated. The results envisage that such nano/microrobots can be further modified and developed as a new-generation treatment of GI tract diseases. In this minireview, we focus on the functionality of micro/nanorobots as a biomedical treatment system for stomach/intestinal diseases. We review the research progress from the first in vivo report in December 2014 to the latest in August 2021. Then, we discuss the treatment difficulties and challenges in vivo application (in general) and possible future development routes

Nano vanadium dioxide films deposited on biomedical titanium: a novel approach for simultaneously enhanced osteogenic and antibacterial effects

<p>Vanadium is a trace element in the human body, and vanadium compounds have a promising future in biological and medical applications due to their various biological activities and low toxicity. Herein, a novel pure vanadium dioxide (VO₂) nanofilm was deposited on a substrate of biomedical titanium by magnetron sputtering. The antibacterial effect of VO₂ against the methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) was validated <i>in vitro</i> and <i>in vivo</i>. Moreover, the biocompatibility of VO₂ and its osteogenic effects were systematically illustrated. A possible osteogenic mechanism involving the amelioration of highly reactive oxygen species (ROS) levels were investigated. According to the results of our present and previous studies, the simultaneous antibacterial and osteogenic effects of VO₂ are attributed to its differential regulation of ROS levels in rat bone marrow mesenchymal stem cells (rBMSCs) and bacteria. This study is the first to report the simultaneous effects of VO₂ on bactericidal and osteogenic activities through its differential modification of ROS activity in eukaryotic (rBMSCs) and prokaryotic (MRSA) cells. The findings in this work may yield a deeper understanding of the biological activities of vanadium compounds while also paving the way for the further investigation and application of VO₂ in biological and medical materials.</p

Enhanced Anti-Infective Efficacy of ZnO Nanoreservoirs through a Combination of Intrinsic Anti-Biofilm Activity and Reinforced Innate Defense

The increasing prevalence of implant-associated infections (IAIs) imposes a heavy burden on patients and medical providers. Bacterial biofilms are recalcitrant to antiseptic drugs and local immune defense and can attenuate host proinflammatory response to interfere with bacterial clearance. Zinc oxide nanoparticles (ZnO NPs) play a dual role in antibacterial and immunomodulatory activities but compromise the cytocompatibility because of their intracellular uptake. Here, ZnO NPs were immobilized on titanium to form homogeneous nanofilms (from discontinuous to continuous) through magnetron sputtering, and the possible antimicrobial activity and immunomodulatory effect of nano-ZnO films were investigated. Nano-ZnO films were found to prohibit sessile bacteria more than planktonic bacteria in vitro, and the antibacterial effect occurred in a dose-dependent manner. Using a novel mouse soft tissue IAI model, the in vivo results revealed that nano-ZnO films possessed outstanding antimicrobial efficacy, which could not be ascribed solely to the intrinsic anti-infective activity of nano-ZnO films observed in vitro. Macrophages and polymorphonuclear leukocytes (PMNs), two important factors in innate immune response, were cocultured with nano-ZnO and bacteria/lipopolysaccharide in vitro, and the nano-ZnO films could enhance the antimicrobial efficacy of macrophages and PMNs through promoting phagocytosis and secretion of inflammatory cytokines. This study provides insights into the anti-infective activity and mechanism of ZnO and consolidates the theoretical basis for future clinical applications of ZnO