Medical micro- and nanomotors in the body

Modified Au:Fe-Ni magnetic micromotors improve drug delivery and diagnosis in MCF-7 cells and spheroids

Nano/micromotors hold immense potential for revolutionizing drug delivery and detection systems, especially in the realm of cancer diagnosis and treatment, owing to their distinctive features, including precise propulsion, maneuverability, and meticulously designed surface modifications. In this study, we explore the capabilities of modified and magnetically driven micromotors as active drug delivery systems within 2D and 3D cell culture environments and cancer diagnosis. We synthesized gold (Au) and iron-nickel (Fe-Ni) metallic-based magnetic micromotors (Au:Fe-Ni MMs) through electrochemical methods, equipping them with functionalities for controlled doxorubicin (DOX) release and cancer cell recognition. In 2D and spheroids of MCF-7 adenocarcinoma cells, the Au segment of these micromotors was utilized to help DOX loading through poly(sodium-4-styrenesulfonate) (PSS) functionalization, and the attachment of antiHER2 antibodies for specific recognition. This innovative approach enabled controlled drug release within the cancerous microenvironment, coupled with magnetic (Fe-Ni) propulsion for biocompatible drug delivery to MCF-7 cells. Furthermore, antiHER2 immobilized Au:Fe-Ni MMs effectively interacted with receptors, capitalizing on the overexpression of HER2 antigens on MCF-7 cells. Encouraging outcomes were observed, particularly in spheroid models, underscoring the remarkable potential of these multifunctional micromotors for advancing intelligent drug delivery methodologies and diagnostic purposes.

Magnetically Powered Microrobotic Swarm for Integrated Mechanical/Photothermal/Photodynamic Thrombolysis

Current thrombolytic drugs exhibit suboptimal therapeutic outcomes and potential bleeding risks due to their limited circulation time, inadequate thrombus penetration, and off-target biodistribution. Herein, a photosensitizer-loaded, red cell membrane-encapsuled multiple magnetic nanoparticles aggregate is successfully developed for integrated mechanical/photothermal/photodynamic thrombolysis. Red cell membrane coating endows magnetic particles with prolonged blood circulation and superior biocompatibility. Under a preset rotating magnetic field (RMF), the aggregate with asymmetric magnetic distribution initiates rolling motion toward the blood clot interface, and because of magnetic dipole-dipole interactions, the aggregate tends to self-assemble into longer, flexible chain-like microrobotic swarm with powerful mechanical stir forces, thereby facilitating thrombus penetration and mechanical thrombolysis. Moreover, precise magnetic control enables targeted photosensitizer accumulation, allowing effective conversion of near-infrared (NIR) light into heat and reactive oxygen species (ROS) for thrombus phototherapy. In thrombolysis assays, the weight of thrombi is massively reduced by ≈90%. The work presents a safer and more promising combination of magnetic microrobotic technology and phototherapy for multi-modality thrombolysis.

Harnessing Disparities in Magnetic Microswarms: From Construction to Collaborative Tasks

Individual differences in size, experience, and task specialization in natural swarms often result in heterogeneity and hierarchy, facilitating efficient and coordinated task accomplishment. Drawing inspiration from this phenomenon, a general strategy is proposed for organizing magnetic micro/nanorobots (MNRs) with apparent differences in size, shape, and properties into cohesive microswarms with tunable heterogeneity, controlled spatial hierarchy, and collaborative tasking capability. In this strategy, disparate magnetic MNRs can be manipulated to show reversible transitions between synchronization and desynchronization by elaborately regulating parameter sets of the rotating magnetic field. Utilizing these transitions, alongside local robust hydrodynamic interactions, diverse heterospecific pairings of disparate magnetic MNRs can be organized into heterogeneous microswarms, and their spatial organization can be dynamically adjusted from egalitarian to leader-follower-like hierarchies on the fly, both in open space and complex microchannels. Furthermore, when specializing the disparate MNRs with distinct functions ("division of labor") such as sensing and drug carrying, they can execute precise drug delivery targeting unknown sites in a collaborative sensing-navigating-cargo dropping sequence, demonstrating significant potential for precise tumor treatment. These findings highlight the critical roles of attribute differences and hierarchical organization in designing efficient swarming micro/nanorobots for biomedical applications.

Recent advances in the development of tumor microenvironment-activatable nanomotors for deep tumor penetration

Cancer represents a significant threat to human health, with the use of traditional chemotherapy drugs being limited by their harsh side effects. Tumor-targeted nanocarriers have emerged as a promising solution to this problem, as they can deliver drugs directly to the tumor site, improving drug effectiveness and reducing adverse effects. However, the efficacy of most nanomedicines is hindered by poor penetration into solid tumors. Nanomotors, capable of converting various forms of energy into mechanical energy for self-propelled movement, offer a potential solution for enhancing drug delivery to deep tumor regions. External force-driven nanomotors, such as those powered by magnetic fields or ultrasound, provide precise control but often necessitate bulky and costly external equipment. Bio-driven nanomotors, propelled by sperm, macrophages, or bacteria, utilize biological molecules for self-propulsion and are well-suited to the physiological environment. However, they are constrained by limited lifespan, inadequate speed, and potential immune responses. To address these issues, nanomotors have been engineered to propel themselves forward by catalyzing intrinsic "fuel" in the tumor microenvironment. This mechanism facilitates their penetration through biological barriers, allowing them to reach deep tumor regions for targeted drug delivery. In this regard, this article provides a review of tumor microenvironment-activatable nanomotors (fueled by hydrogen peroxide, urea, arginine), and discusses their prospects and challenges in clinical translation, aiming to offer new insights for safe, efficient, and precise treatment in cancer therapy.

Magnetic/Acoustic Dual-Controlled Microrobot Overcoming Oto-Biological Barrier for On-Demand Multidrug Delivery against Hearing Loss

Multidrug combination therapy in the inner ear faces diverse challenges due to the distinct physicochemical properties of drugs and the difficulties of overcoming the oto-biologic barrier. Although nanomedicine platforms offer potential solutions to multidrug delivery, the access of drugs to the inner ear remains limited. Micro/nanomachines, capable of delivering cargo actively, are promising tools for overcoming bio-barriers. Herein, a novel microrobot-based strategy to penetrate the round window membrane (RWM) is presented and multidrug in on-demand manner is delivered. The tube-type microrobot (TTMR) is constructed using the template-assisted layer-by-layer (LbL) assembly of chitosan/ferroferric oxide/silicon dioxide (CS/Fe3O4/SiO2) and loaded with anti-ototoxic drugs (curcumin, CUR and tanshinone IIA, TSA) and perfluorohexane (PFH). Fe3O4 provides magnetic actuation, while PFH ensures acoustic propulsion. Upon ultrasound stimulation, the vaporization of PFH enables a microshotgun-like behavior, propelling the drugs through barriers and driving them into the inner ear. Notably, the proportion of drugs entering the inner ear can be precisely controlled by varying the feeding ratios. Furthermore, in vivo studies demonstrate that the drug-loaded microrobot exhibits superior protective effects and excellent biosafety toward cisplatin (CDDP)-induced hearing loss. Overall, the microrobot-based strategy provides a promising direction for on-demand multidrug delivery for ear diseases.

Bottle Nanomotors Amplify Tumor Oxidative Stress for Enhanced Calcium Overload/Chemodynamic Therapy

Developing multifunctional, stimuli-responsive nanomedicine is intriguing because it has the potential to effectively treat cancer. Yet, poor tumor penetration of nanodrugs results in limited antitumor efficacy. Herein, an oxygen-driven silicon-based nanomotor (Si-motor) loaded with MnO and CaO2 nanoparticles is developed, which can move in tumor microenvironment (TME) by the cascade reaction of CaO2 and MnO. Under acidic TME, CaO2 reacts with acid to release Ca2+ to induce mitochondrial damage and simultaneously produces O2 and H2O2, when the loaded MnO exerts Fenton-like activity to produce ·OH and O2 based on the produced H2O2. The generated O2 drives Si-motor forward, thus endowing active delivery capability of the formed motors in TME. Meanwhile, MnO with glutathione (GSH) depletion ability further prevents reactive oxygen species (ROS) from being destroyed. Such TME actuated Si-motor with enhanced cellular uptake and deep penetration provides amplification of synergistic oxidative stresscaused by intracellular Ca2 + overloading, GSH depletion induced by Mn2+, and Mn2+ mediated chemodynamic treatment (CDT), leading to excellent tumor cell death. The created nanomotor may offer an effective platform for active synergistic cancer treatment.

Thermal-Accelerated Urease-Driven Bowl-Like Polydopamine Nanorobot for Targeted Photothermal/Photodynamic Antibiotic-Free Antibacterial Therapy

The problem of antibiotic resistance seriously affects the treatment of bacterial infections, so there is an urgent need to develop novel antibiotic-independent antimicrobial strategies. Herein, a urease-driven bowl-like mesoporous polydopamine nanorobot (MPDA@ICG@Ur@Man) based on single-wavelength near-infrared (NIR) remote photothermal acceleration to achieve antibiotic-free phototherapy(photothermal therapy, PTT, plus photodynamic therapy, PDT) is first reported. The smart nanorobots can perform active movement by decomposing urea to produce carbon dioxide and ammonia. Particularly, the elevated local temperature during PTT can increase urease activity to enhance the autonomous movement and thus increase the contact between the antimicrobial substance and bacteria. Compared with a nanomotor propelled by urea only, the diffusion coefficient (De) of photothermal-accelerated nanorobots is increased from 1.10 to 1.26 µm2 s-1. More importantly, urease-driven bowl-like nanorobots with photothermal enhancement can specifically identify Escherichia coli (E. coli) and achieve simultaneous PTT/PDT at a single wavelength with 99% antibactericidal activity in vitro. In a word, the urease-driven bowl-like nanorobots guided by photothermal-accelerated strategy could provide a novel perspective for increasing PTT/PDT antibacterial therapeutic efficacy and be promising for various antibiotic-free sterilization applications.

Iron-Reduced Graphene Oxide Core-Shell Micromotors Designed for Magnetic Guidance and Photothermal Therapy under Second Near-Infrared Light

Core-shell micro/nanomotors have garnered significant interest in biomedicine owing to their versatile task-performing capabilities. However, their effectiveness for photothermal therapy (PTT) still faces challenges because of their poor tumor accumulation, lower light-to-heat conversion, and due to the limited penetration of near-infrared (NIR) light. In this study, we present a novel core-shell micromotor that combines magnetic and photothermal properties. It is synthesized via the template-assisted electrodeposition of iron (Fe) and reduced graphene oxide (rGO) on a microtubular pore-shaped membrane. The resulting Fe-rGO micromotor consists of a core of oval-shaped zero-valent iron nanoparticles with large magnetization. At the same time, the outer layer has a uniform reduced graphene oxide (rGO) topography. Combined, these Fe-rGO core-shell micromotors respond to magnetic forces and near-infrared (NIR) light (1064 nm), achieving a remarkable photothermal conversion efficiency of 78% at a concentration of 434 µg mL-1. They can also carry doxorubicin (DOX) and rapidly release it upon NIR irradiation. Additionally, preliminary results regarding the biocompatibility of these micromotors through in vitro tests on a 3D breast cancer model demonstrate low cytotoxicity and strong accumulation. These promising results suggest that such Fe-rGO core-shell micromotors could hold great potential for combined photothermal therapy.

Intelligent micro/nanorobots based on biotemplates

Intelligent micro/nanorobots based on natural materials as biotemplates are considered to be some of the most promising robots in the future in the microscopic field. Due to the advantages of biotemplates such as unique structure, abundant resources, environmental friendliness, easy removal, low price, easy access, and renewability, intelligent micro/nanorobots based on biotemplates can be endowed with both excellent biomaterial activity and unique structural morphology through biotemplates themselves and specific functions through artificial micro/nanotechnology. Thus, intelligent micro/nanorobots show excellent application potential in various fields from biomedical applications to environmental remediation. In this review, we introduce the advantages of using natural biological materials as biotemplates to build intelligent micro/nanorobots, and then, classify the micro/nanorobots according to different types of biotemplates, systematically detail their preparation strategies and summarize their application prospects. Finally, in order to further advance the development of intelligent micro/nanorobots, we discuss the current challenges and future prospects of biotemplates. Intelligent micro/nanorobots based on biotemplates are a perfect combination of natural biotemplates and micro/nanotechnology, which is an important trend for the future development of micro/nanorobots. We hope this review can provide useful references for developing more intelligent, efficient and safe micro/nanorobots in the future.

Buoyancy-Driven Micro/-Nanomotors: From Fundamentals to Applications

The progression of self-powered micro/-nanomotors (MNMs) has rapidly evolved over the past few decades, showing applications in various fields such as nanotechnology, biomedical engineering, microfluidics, environmental science, and energy harvesting. Miniaturized MNMs transduce chemical/biochemical energies into mechanical motion for navigating through complex fluidic environments with directional control via external forces fields such as magnetic, photonic, and electric stimuli. Among various propulsion mechanisms, buoyancy-driven MNMs have received noteworthy recognition due to their simplicity, efficiency, and versatility. Buoyancy force-driven motors harness the principles of density variation-mediated force to overcome fluidic resistance to navigate through complex environments. Restricting the propulsion in one direction helps to control directional movement, making it more efficient in isotropic solutions. The changes in pH, ionic strength, chemical concentration, solute gradients, or the presence of specific molecules can influence the motion of buoyancy-driven MNMs as evidenced by earlier reports. This review aims to provide a fundamental and detailed analysis of the current state-of-the-art in buoyancy-driven MNMs, aiming to inspire further research and innovation in this promising field.

A NIR-driven green affording-oxygen microrobot for targeted photodynamic therapy of tumors

Photodynamic therapy (PDT) is a light-activated local treatment modality that has promising potential in cancer therapy. However, ineffective delivery of photosensitizers and hypoxia in the tumor microenvironment severely restrict the therapeutic efficacy of PDT. Herein, phototactic Chlorella (C) is utilized to carry photosensitizer-encapsulated nanoparticles to develop a near-infrared (NIR) driven green affording-oxygen microrobot system (CurNPs-C) for enhanced PDT. Photosensitizer (curcumin, Cur) loaded nanoparticles are first synthesized and then covalently attached to C through amide bonds. An in vitro study demonstrates that the developed CurNPs-C exhibits continuous oxygen generation and desirable phototaxis under NIR treatment. After intravenous injection, the initial 660 nm laser irradiation successfully induces the active migration of CurNPs-C to tumor sites for higher accumulation. Upon the second 660 nm laser treatment, CurNPs-C produces abundant oxygen, which in turn induces the natural product Cur to generate more reactive oxygen species (ROS) that significantly inhibit the growth of tumors in 4T1 tumor-bearing mice. This contribution showcases the ability of a light-driven green affording-oxygen microrobot to exhibit targeting capacity and O2 generation for enhancing photodynamic therapy.

Light-Driven Biomimetic Nanomotors for Enhanced Photothermal Therapy

Nanotechnology-based strategy has recently drawn extensive attention for the therapy of malignant tumors due to its distinct strengths in cancer diagnosis and treatment. However, the limited intratumoral permeability of nanoparticles is a major hurdle to achieving the desired effect of cancer treatment. Due to their superior cargo towing and reliable penetrating property, micro-/nanomotors (MNMs) are considered as one of the most potential candidates for the coming generation of drug delivery platforms. Here, near-infrared (NIR)-actuated biomimetic nanomotors (4T1-JPGSs-IND) are fabricated successfully and we demonstrate that 4T1-JPGSs-IND selectively accumulate in homologous tumor regions due to the effective homing ability. Upon laser irradiation, hyperthermia generated by 4T1-JPGSs-IND leads to self-thermophoretic motion and photothermal therapy (PTT) to ablate tumors with a deep depth, thereby improving the photothermal therapeutic effect for cancer management. The developed nanomotor system with multifunctionalities exhibits promising potential in biomedical applications to fight against various diseases.

Focus on the performance enhancement of micro/nanomotor-based biosensors

Micro/nanomotors (MNMs) emerge as a vital candidate for biosensing due to its nano-size structure, high surface-to-area ratio, directional mobility, biocompatibility, and ease of functionalization, therefore being able to detect objects with high efficiency, precision, and selectivity. The driving mode, nanostructure, materials property, preparation technique, and biosensing applications have been thoroughly discussed in publications. To promote the MNMs-based biosensors from in vitro to in vivo, it is necessary to give a comprehensive discussion from the perspective of sensing performances enhancement. However, until now, there is few reviews dedicated to the systematic discussion on the multiple performance enhancement schemes and the current challenges of MNMs-based biosensors. Bearing it in mind and based on our research experience in this field, we summarized the enhancement methods for biosensing properties such as sensitivity, selectivity, detection time, biocompatibility, simplify system operation, and environmental availability. We hope that this review provides the readers with fundamental understanding on performance enhancement schemes for MNMs-based biosensors.

Microelectronic Morphogenesis: Smart Materials with Electronics Assembling into Artificial Organisms

Microelectronic morphogenesis is the creation and maintenance of complex functional structures by microelectronic information within shape-changing materials. Only recently has in-built information technology begun to be used to reshape materials and their functions in three dimensions to form smart microdevices and microrobots. Electronic information that controls morphology is inheritable like its biological counterpart, genetic information, and is set to open new vistas of technology leading to artificial organisms when coupled with modular design and self-assembly that can make reversible microscopic electrical connections. Three core capabilities of cells in organisms, self-maintenance (homeostatic metabolism utilizing free energy), self-containment (distinguishing self from nonself), and self-reproduction (cell division with inherited properties), once well out of reach for technology, are now within the grasp of information-directed materials. Construction-aware electronics can be used to proof-read and initiate game-changing error correction in microelectronic self-assembly. Furthermore, noncontact communication and electronically supported learning enable one to implement guided self-assembly and enhance functionality. Here, the fundamental breakthroughs that have opened the pathway to this prospective path are reviewed, the extent and way in which the core properties of life can be addressed are analyzed, and the potential and indeed necessity of such technology for sustainable high technology in society is discussed.

Light-driven micro/nanomotors in biomedical applications

Nanotechnology brings hope for targeted drug delivery. However, most current drug delivery systems use passive delivery strategies with limited therapeutic efficiency. Over the past two decades, research on micro/nanomotors (MNMs) has flourished in the biomedical field. Compared with other driven methods, light-driven MNMs have the advantages of being reversible, simple to control, clean, and efficient. Under light irradiation, the MNMs can overcome several barriers in the body and show great potential in the treatment of various diseases, such as tumors, and gastrointestinal, cardiovascular and cerebrovascular diseases. Herein, the classification and mechanism of light-driven MNMs are introduced briefly. Subsequently, the applications of light-driven MNMs in overcoming physiological and pathological barriers in the past five years are highlighted. Finally, the future prospects and challenges of light-driven MNMs are discussed as well. This review will provide inspiration and direction for light-driven MNMs to overcome biological barriers in vivo and promote the clinical application of light-driven MNMs in the biomedical field.

Metallic elements combine with herbal compounds upload in microneedles to promote wound healing: a review

Wound healing is a dynamic and complex restorative process, and traditional dressings reduce their therapeutic effectiveness due to the accumulation of drugs in the cuticle. As a novel drug delivery system, microneedles (MNs) can overcome the defect and deliver drugs to the deeper layers of the skin. As the core of the microneedle system, loaded drugs exert a significant influence on the therapeutic efficacy of MNs. Metallic elements and herbal compounds have been widely used in wound treatment for their ability to accelerate the healing process. Metallic elements primarily serve as antimicrobial agents and facilitate the enhancement of cell proliferation. Whereas various herbal compounds act on different targets in the inflammatory, proliferative, and remodeling phases of wound healing. The interaction between the two drugs forms nanoparticles (NPs) and metal-organic frameworks (MOFs), reducing the toxicity of the metallic elements and increasing the therapeutic effect. This article summarizes recent trends in the development of MNs made of metallic elements and herbal compounds for wound healing, describes their advantages in wound treatment, and provides a reference for the development of future MNs.

Microparticles and nanoparticles-based approaches to improve oral treatment of Helicobacter pylori infection

Helicobacter pylori is a gram-negative, spiral-shaped, flagellated bacterium that colonizes the stomach of half the world's population. Helicobacter pylori infection causes pathologies of varying severity. Standard oral therapy fails in 15-20% since the barriers of the oral route decrease the bioavailability of antibiotics and the intrinsic factors of bacteria increase the rates of resistance. Nanoparticles and microparticles are promising strategies for drug delivery into the gastric mucosa and targeting H. pylori. The variety of building blocks creates systems with distinct colloidal, surface, and biological properties. These features improve drug-pathogen interactions, eliminate drug depletion and overuse, and enable the association of multiple actives combating H. pylori on several fronts. Nanoparticles and microparticles are successfully used to overcome the barriers of the oral route, physicochemical inconveniences, and lack of selectivity of current therapy. They have proven efficient in employing promising anti-H. pylori compounds whose limitation is oral route instability, such as some antibiotics and natural products. However, the current challenge is the applicability of these strategies in clinical practice. For this reason, strategies employing a rational design are necessary, including in the development of nano- and microsystems for the oral route.

Antibacterial micro/nanomotors: advancing biofilm research to support medical applications

Multi-drug resistant (MDR) bacterial infections are gradually increasing in the global scope, causing a serious burden to patients and society. The formation of bacterial biofilms, which is one of the key reasons for antibiotic resistance, blocks antibiotic penetration by forming a physical barrier. Nano/micro motors (MNMs) are micro-/nanoscale devices capable of performing complex tasks in the bacterial microenvironment by transforming various energy sources (including chemical fuels or external physical fields) into mechanical motion or actuation. This autonomous movement provides significant advantages in breaking through biological barriers and accelerating drug diffusion. In recent years, MNMs with high penetrating power have been used as carriers of antibiotics to overcome bacterial biofilms, enabling efficient drug delivery and improving the therapeutic effectiveness of MDR bacterial infections. Additionally, non-antibiotic antibacterial strategies based on nanomaterials, such as photothermal therapy and photodynamic therapy, are continuously being developed due to their non-invasive nature, high effectiveness, and non-induction of resistance. Therefore, multifunctional MNMs have broad prospects in the treatment of MDR bacterial infections. This review discusses the performance of MNMs in the breakthrough and elimination of bacterial biofilms, as well as their application in the field of anti-infection. Finally, the challenges and future development directions of antibacterial MNMs are introduced.

Progress on Physical Field-Regulated Micro/Nanomotors for Cardiovascular and Cerebrovascular Disease Treatment

Cardiovascular and cerebrovascular diseases (CCVDs) are two major vasculature-related diseases that seriously affect public health worldwide, which can cause serious death and disability. Lack of targeting effect of the traditional CCVD treatment drugs may damage other tissues and organs, thus more specific methods are needed to solve this dilemma. Micro/nanomotors are new materials that can convert external energy into driving force for autonomous movement, which can not only enhance the penetration depth and retention rates, but also increase the contact areas with the lesion sites (such as thrombus and inflammation sites of blood vessels). Physical field-regulated micro/nanomotors using the physical energy sources with deep tissue penetration and controllable performance, such as magnetic field, light, and ultrasound, etc. are considered as the emerging patient-friendly and effective therapeutic tools to overcome the limitations of conventional CCVD treatments. Recent efforts have suggested that physical field-regulated micro/nanomotors on CCVD treatments could simultaneously provide efficient therapeutic effect and intelligent control. In this review, various physical field-driven micro/nanomotors are mainly introduced and their latest advances for CCVDs are highlighted. Last, the remaining challenges and future perspectives regarding the physical field-regulated micro/nanomotors for CCVD treatments are discussed and outlined.

Swarming Multifunctional Heater-Thermometer Nanorobots for Precise Feedback Hyperthermia Delivery

Micro-/nanorobots (MNRs) are envisioned to act as "motile-targeting" platforms for biomedical tasks due to their ability to propel and navigate in challenging, hard-to-reach biological environments. However, it remains a great challenge for current swarming MNRs to accurately report and regulate therapeutic doses during disease treatment. Here we present the development of swarming multifunctional heater-thermometer nanorobots (HT-NRs) and their application in precise feedback photothermal hyperthermia delivery. The HT-NRs are designed as photothermal-responsive photonic nanochains consisting of magnetic Fe3O4 nanoparticles arranged periodically in one dimension and encapsulated in a temperature-responsive hydrogel shell. The HT-NRs exhibit energetic and controllable swarming motions under a rotating magnetic field, while simultaneously functioning as motile nanoheaters and nanothermometers, utilizing their photothermal conversion and (photo)thermal-responsive structural color changes (photothermochromism). Consequently, the HT-NRs can be quickly deployed to a remote target area (e.g., a superficial tumor lesion) using their collective motion and selectively eliminate diseased cells in a specific targeted region by utilizing their self-reporting photothermochromism as visual feedback for precisely regulating external light irradiation. This work may inspire the development of intelligent multifunctional theranostic micro-/nanorobots and their practical applications in precise disease treatment.

Real-Time Micromotor Probe for Immune Neutrophil Activation State

Neutrophil activation is a hallmark of the immune response. Approaches to identify neutrophil activation in real time are necessary but are still lacking. In this study, magnetic Spirulina micromotors are used as label-free probes that exhibit differences in motility under different neutrophil activation states. This is correlated with different secretions into the extracellular environment by activated/non-activated cells and local environmental viscoelasticity. The micromotor platform can bypass non-activated immune cells while being stopped by activated cells. Thus, the micromotors can serve as label-free biomechanical probes of the immune cell state. They can detect the activation state of target immune cells in real time and with single-cell precision, which provides new ideas for the diagnosis and treatment of diseases while deepening understanding of the biomechanics of activated immune cells.

Recent progress of micro/nanomotors to overcome physiological barriers in the gastrointestinal tract

Oral administration is a convenient administration route for gastrointestinal disease therapy with good patient compliance. But the nonspecific distribution of the oral drugs may cause serious side effects. In recent years, oral drug delivery systems (ODDS) have been applied to deliver the drugs to the gastrointestinal disease sites with decreased side effects. However, the delivery efficiency of ODDS is tremendously limited by physiological barriers in the gastrointestinal sites, such as the long and complex gastrointestinal tract, mucus layer, and epithelial barrier. Micro/nanomotors (MNMs) are micro/nanoscale devices that transfer various energy sources into autonomous motion. The outstanding motion characteristics of MNMs inspired the development of targeted drug delivery, especially the oral drug delivery. However, a comprehensive review of oral MNMs for the gastrointestinal diseases therapy is still lacking. Herein, the physiological barriers of ODDS were comprehensively reviewed. Afterward, the applications of MNMs in ODDS for overcoming the physiological barriers in the past 5 years were highlighted. Finally, future perspectives and challenges of MNMs in ODDS are discussed as well. This review will provide inspiration and direction of MNMs for the therapy of gastrointestinal diseases, pushing forward the clinical application of MNMs in oral drug delivery.

Advances of medical nanorobots for future cancer treatments

Early detection and diagnosis of many cancers is very challenging. Late stage detection of a cancer always leads to high mortality rates. It is imperative to develop novel and more sensitive and effective diagnosis and therapeutic methods for cancer treatments. The development of new cancer treatments has become a crucial aspect of medical advancements. Nanobots, as one of the most promising applications of nanomedicines, are at the forefront of multidisciplinary research. With the progress of nanotechnology, nanobots enable the assembly and deployment of functional molecular/nanosized machines and are increasingly being utilized in cancer diagnosis and therapeutic treatment. In recent years, various practical applications of nanobots for cancer treatments have transitioned from theory to practice, from in vitro experiments to in vivo applications. In this paper, we review and analyze the recent advancements of nanobots in cancer treatments, with a particular emphasis on their key fundamental features and their applications in drug delivery, tumor sensing and diagnosis, targeted therapy, minimally invasive surgery, and other comprehensive treatments. At the same time, we discuss the challenges and the potential research opportunities for nanobots in revolutionizing cancer treatments. In the future, medical nanobots are expected to become more sophisticated and capable of performing multiple medical functions and tasks, ultimately becoming true nanosubmarines in the bloodstream.

FOF1-ATPase Motor-Embedded Chromatophore as Drug Delivery System: Extraction, Cargo Loading Ability and Mucus Penetration Ability

Mucosal drug delivery permits direct and prompt drug absorption, which is capable of reducing undesirable decomposition that occurs before absorption. However, mucus clearance of those mucosal drug delivery systems strongly retards their actual application. Herein, we propose chromatophore nanoparticles embedded with FOF1-ATPase motors to promote mucus penetration. The FOF1-ATPase motor-embedded chromatophores were firstly extracted from Thermus thermophilus by using a gradient centrifugation method. Then, the model drug (curcumin) was loaded onto the chromatophores. The drug loading efficiency and entrapment efficiency were optimized by using different loading approaches. The activity, motility, stability and mucus permeation of the drug-loaded chromatophore nanoparticles were thoroughly investigated. Both the in vitro and in vivo studies revealed that the FOF1-ATPase motor-embedded chromatophore successfully enhanced mucus penetration glioma therapy. This study indicates that the FOF1-ATPase motor-embedded chromatophore is a promising alternative as a mucosal drug delivery system.

Nanomotors-loaded microneedle patches for the treatment of bacterial biofilm-related infections of wound

The biofilms formed by bacteria at the wound site can effectively protect the bacteria, which greatly weakens the effect of antibiotics. Herein, a microneedle patch for wound treatment is designed, which can effectively penetrate the biofilms in a physical way because of the penetration ability of the microneedles and the motion behavior of the nanomotors, and deliver bacterial quorum sensing inhibitor luteolin (Le) and nanomotors with multiple antibacterial properties within biofilms. Firstly, the nanomotors-loaded microneedle patches are prepared and characterized. The results of in vitro and in vivo experiments show that the microneedle patches have good biosafety and antibacterial properties. Among them, Le can inhibit the growth of biofilms. Further, under near-infrared (NIR) irradiation, the nanomotors loaded with photosensitizer ICG and nitric oxide (NO) donor L-arginine (L-Arg) can move in the biofilms under the double driving effect of photothermal and NO, and can give full play to the multiple anti-biological infection effects of photothermal therapy (PTT), photodynamic therapy (PDT) and NO, and finally realize the effective removal of biofilms and promote wound healing. The intervention of nanomotor technology has brought about a new therapeutic strategy for bacterial biofilm-related infection of wound.

Steering Micromotors via Reprogrammable Optoelectronic Paths

Steering micromotors is important for using them in practical applications and as model systems for active matter. This functionality often requires magnetic materials in the micromotor, taxis behavior of the micromotor, or the use of specifically designed physical boundaries. Here, we develop an optoelectronic strategy that steers micromotors with programmable light patterns. In this strategy, light illumination turns hydrogenated amorphous silicon conductive, generating local electric field maxima at the edge of the light pattern that attracts micromotors via positive dielectrophoresis. As an example, metallo-dielectric Janus microspheres that self-propelled under alternating current electric fields were steered by static light patterns along customized paths and through complex microstructures. Their long-term directionality was also rectified by ratchet-shaped light patterns. Furthermore, dynamic light patterns that varied in space and time enabled more advanced motion controls such as multiple motion modes, parallel control of multiple micromotors, and the collection and transport of motor swarms. This optoelectronic steering strategy is highly versatile and compatible with a variety of micromotors, and thus it possesses the potential for their programmable control in complex environments.

Active therapy based on the byproducts of micro/nanomotors

Different from traditional colloidal particles based on Brownian motion, micro/nanomotors are micro/nanoscale devices capable of performing complex tasks in liquid media via transforming various energy sources into mechanical motion or actuation. Such unique self-propulsion endows motors with fantastic capabilities to access and enter the deep layer of targeted diseased tissue, which in turn breaks through the limitation of the poor permeability of traditional pharmaceutical preparations, thus providing giant prospects for active therapy. It is noteworthy that recently several studies, which utilized the byproducts generated in situ by micro/nanomotors to achieve active therapy, in a truly green zero-waste manner, have been carried out. In this minireview, we highlight the recent efforts with respect to active therapy based on the byproducts of micro/nanomotors, expecting to motivate readers to expand the practical biomedical application scope of micro/nanomotors in a broader horizon. Accompanied by ever booming enthusiasm and persevering exploration, micro/nanomotors are on their way to revolutionize conventional fields.

Micromotor Based Mini-Tablet for Oral Delivery of Insulin

Diabetes is a metabolic disorder characterized by hyperglycemia due to defective insulin secretion or its biological dysfunction. However, frequent subcutaneous injection of insulin often results in discomfort and local tissue infection. Herein, we demonstrate the successful fabrication of a mini-tablet system based on self-propelled micromotors with biocompatibility and biodegradability for oral colon administration of insulin. The insulin layer is first constructed onto the surface of a magnesium based micromotor via electrostatic interactions, followed by a tableting process. The resulting mini-tablets are then coated with esterified starch with colonic degradation capability, thus achieving controlled release of the embedded micromotors in the colon region. In the meantime, autonomous movement of the released micromotors with a speed up to 76.22 μm·s^-1 further results in enhanced colonic uptake and absorption of insulin, realizing long-term control of blood glucose for more than 5 h. Our micromotor based mini-tablet system can not only broaden the biomedical applications of emerging self-propelled micromotors but also offer an appealing strategy for oral administration of biomacromolecular drugs represented by insulin.

Microrobots for Targeted Delivery and Therapy in Digestive System

Untethered miniature robots enable targeted delivery and therapy deep inside the gastrointestinal tract in a minimally invasive manner. By combining actuation systems and imaging tools, significant progress has been made toward the development of functional microrobots. These robots can be actuated by external fields and fuels while featuring real-time tracking feedback toward certain regions and can perform the therapeutic process by rational exertion of the local environment of the gastrointestinal tract (e.g., pH, enzyme). Compared with conventional surgical tools, such as endoscopic devices and catheters, miniature robots feature minimally invasive diagnosis and treatment, multifunctionality, high safety and adaptivity, embodied intelligence, and easy access to tortuous and narrow lumens. In addition, the active motion of microrobots enhances local penetration and retention of drugs in tissues compared to common passive oral drug delivery. Based on the dissimilar microenvironments in the various sections of the gastrointestinal tract, this review introduces the advances of miniature robots for minimally invasive targeted delivery and therapy of diseases along the gastrointestinal tract. The imaging modalities for the tracking and their application scenarios are also discussed. We finally evaluate the challenges and barriers that retard their applications and hint on future research directions in this field.