Magnetic motors in interphases: Motion control and integration in soft robots.

Magnetic motors are a class of out-of-equilibrium particles that exhibit controlled and fast motion overcoming Brownian fluctuations by harnessing external magnetic fields. The advances in this field resulted in motors that have been used for different applications, such as biomedicine or environmental remediation. In this Perspective, an overview of the recent advancements of magnetic motors is provided, with a special focus on controlled motion.

Collagenase motors in gelatine-based hydrogels.

Nano/micromotors outperform Brownian motion due to their self-propulsive capabilities and hold promise as carriers for drug delivery across biological barriers such as the extracellular matrix. This study employs poly(2-(diethylamino)ethyl methacrylate) polymer brushes to enhance the collagenase-loading capacity of silica particle-based motors with the aim to systematically investigate the impact of gelatine viscosity, motors' size, and morphology on their propulsion velocity. Notably, 500 nm and 1 μm motors achieve similar speeds as high as ∼15 μm s in stiff gelatine-based hydrogels when triggered with calcium.

Artificial Cells and HepG2 Cells in 3D-Bioprinted Arrangements.

Artificial cells are engineered units with cell-like functions for different purposes including acting as supportive elements for mammalian cells. Artificial cells with minimal liver-like function are made of alginate and equipped with metalloporphyrins that mimic the enzyme activity of a member of the cytochrome P450 family namely CYP1A2. The artificial cells are employed to enhance the dealkylation activity within 3D bioprinted structures composed of HepG2 cells and these artificial cells.

Magnetic micromotors crossing lipid membranes.

Nano/micromotors are self-propelled particles that show enhanced motion upon being triggered by a stimulus. Their use in nanomedicine has been widely explored, with special focus on imaging or drug delivery. However, a thorough understanding of the requirements for more efficient locomotion is still lacking.

Surfaces Coated with Polymer Brushes Work as Carriers for Histidine Ammonia Lyase.

The immobilization of enzymes on solid supports is an important challenge in biotechnology and biomedicine. In contrast to other methods, enzyme deposition in polymer brushes offers the benefit of high protein loading that preserves enzymatic activity in part due to the hydrated 3D environment that is available within the brush structure. The authors equipped planar and colloidal silica surfaces with poly(2-(diethylamino)ethyl methacrylate)-based brushes to immobilize Thermoplasma acidophilum histidine ammonia lyase, and analyzed the amount and activity of the immobilized enzyme.

On Nanomachines and Their Future Perspectives in Biomedicine.

Nano/micromotors are a class of active matter that can self-propel converting different types of input energy into kinetic energy. The huge efforts that are made in this field over the last years result in remarkable advances. Specifically, a high number of publications have dealt with biomedical applications that these motors may offer.

Magnetically propelled chained nanocomposites for biologically relevant media exploration.

Elongated nanostructures to be remotely and magnetically propelled in biologically relevant media, have gained attention as offering themselves as effective tools or carriers in theragnostics applications. However, the magnetic actuation associated remains challenging due to the lack of mechanical information in the media of interest, taking into account biophysical or biomedical purposes. In this study, we detail the magnetic actuation of magnetically propelled chained nanocomposites considering their dynamics, in which their velocity can be modulated in terms of the viscosity of the medium considered, given a magnetic field gradient.

Manganese dioxide nanosheet-containing reactors as antioxidant support for neuroblastoma cells.

Supporting mammalian cells against reactive oxygen species such as hydrogen peroxide (HO) is essential. Bottom-up synthetic biology aims to integrate designed artificial units with mammalian cells. Here, we used manganese dioxide nanosheets (MnO-NSs) as catalytically active entities that have superoxide dismutase-like and catalase-like activities.

Locomotion of micromotors in paper chips.

Locomotion of nano/micromotors in non-aqueous environments remains a challenging task. We assembled magnetic micromotors with different surface coatings and explored their locomotion in paper chips. Poly(L-lysine) deposition resulted in positively charged micromotors.

Evaluation of Hybrid Vesicles in an Intestinal Cell Model Based on Structured Paper Chips.

Cell culture-based intestinal models are important to evaluate nanoformulations intended for oral drug delivery. We report the use of a floating structured paper chip as a scaffold for Caco-2 cells and HT29-MTX-E12 cells that are two established cell types used in intestinal cell models. The formation of cell monolayers for both mono- and cocultures in the paper chip are confirmed and the level of formed cell-cell junctions is evaluated.

Manganese Ferrite Nanoparticles Encapsulated into Vitamin E/Sphingomyelin Nanoemulsions as Contrast Agents for High-Sensitive Magnetic Resonance Imaging.

Magnetic resonance imaging (MRI) is one of the most powerful non-invasive imaging modalities used in clinics due to its great spatial resolution and excellent soft-tissue contrast, though still less sensitive than other techniques such as the nuclear imaging modalities. This lack of sensitivity can be improved with the use of contrast agents based on nanomaterials. In recent years, researchers have focused on the development of magnetic nanoparticles, given their role as enhancers of the contrast signal based on the magnetic resonance.

Surface polymerization induced locomotion.

Nano- and micromotors are self-navigating particles that gain locomotion using fuel from the environment or external power sources to outperform Brownian motion. Herein, motors that make use of surface polymerization of hydroxyethylmethylacrylate to gain locomotion are reported, synthetically mimicking microorganisms' way of propulsion. These motors have enhanced Brownian motion with effective diffusion coefficients up to ∼0.

Microswimmers with Heat Delivery Capacity for 3D Cell Spheroid Penetration.

Micro- and nanoswimmers are a fast emerging concept that changes how colloidal and biological systems interact. They can support drug delivery vehicles, assist in crossing biological barriers, or improve diagnostics. We report microswimmers that employ collagen, a major extracellular matrix (ECM) constituent, as fuel and that have the ability to deliver heat incorporated magnetic nanoparticles when exposed to an alternating magnetic field (AMF).

Raman spectroscopy to unravel the magnetic properties of iron oxide nanocrystals for bio-related applications.

Iron oxide nanocrystals have become a versatile tool in biomedicine because of their low cytotoxicity while offering a wide range of tuneable magnetic properties that may be implemented in magnetic separation, drug and heat delivery and bioimaging. These capabilities rely on the unique magnetic features obtained when combining different iron oxide phases, so that an important portfolio of magnetic properties can be attained by the rational design of multicomponent nanocrystals. In this context, Raman spectroscopy is an invaluable and fast-performance tool to gain insight into the different phases forming part of the nanocrystals to be used, allowing correlation of the magnetic properties with the envisaged bio-related applications.

Clusters of Magnetite-Maghemite Nanocrystals with a Chemically-Tailored Average Diameter.

Clusters of magnetic nanocrystals are very advantageous if keeping the superparamagnetic state of the individual nanocrystals while taking advantage of a large total magnetic moment, as very convenient in sensing, catalysis and bio-related applications. Herein, we demonstrate how the molecular weight of poly(ethylene glycol) exerts a dominant role in controlling the final size of the clusters and individual crystallites forming them, which delineate the final magnetic properties and their potential applications.

Double-Fueled Janus Swimmers with Magnetotactic Behavior.

Self-propelled particles attract a great deal of attention due to the auspicious range of applications for which nanobots can be used. In a biomedical context, self-propelled swimmers hold promise to autonomously navigate to a desired location in an attempt to counteract cell/tissue defects either by releasing drugs or by performing surgical tasks. The vast majority of prior reports deal with single engine assemblies, often utilizing fuel molecules which are considered to be highly cytotoxic.