Biosafety, Functionalities, and Applications of Biomedical Micro/nanomotors

Polymersome-based nanomotors: preparation, motion control, and biomedical applications

Polymersome-based nanomotors represent a cutting-edge development in nanomedicine, merging the unique vesicular properties of polymersomes with the active propulsion capabilities of synthetic nanomotors. As a vesicular structure enclosed by a bilayer membrane, polymersomes can encapsulate both hydrophilic and hydrophobic cargoes. In addition, their physical-chemical properties such as size, morphology, and surface chemistry are highly tunable, which makes them ideal for various biomedical applications. The integration of motility into polymersomes enables them to actively navigate biological environments and overcome physiological barriers, offering significant advantages over passive delivery platforms. Recent breakthroughs in fabrication techniques and motion control strategies, including chemically, enzymatically, and externally driven propulsion, have expanded their potential for drug delivery, biosensing, and therapeutic interventions. Despite these advancements, key challenges remain in optimizing propulsion efficiency, biocompatibility, and in vivo stability to translate these systems into clinical applications. In this perspective, we discuss recent advancements in the preparation and motion control strategies of polymersome-based nanomotors, as well as their biomedical-related applications. The molecular design, fabrication approaches, and nanomedicine-related utilities of polymersome-based nanomotors are highlighted, to envisage the future research directions and further development of these systems into effective, precise, and smart nanomedicines capable of addressing critical biomedical challenges.

Phosphatidylcholine Liposome Accelerated Platinum Nanomachines (PLANEs) With Enhanced Penetration Capability for Thrombus Mechanotherapy

Thrombotic cardiovascular diseases remain the leading cause of mortality worldwide. However, current thrombolytic therapeutics suffer from limited efficacy and a high risk of severe bleeding. Here, a phosphatidylcholine liposome accelerated platinum nanomachine (PLANE) for thrombus mechanotherapy is designed, constructed by encapsulating platinum nanomotors within isotropic, lubricating phosphatidylcholine (PC) liposomes. The precisely engineered PLANE exhibits superior lubricity and linear motion. Under laser irradiation and hydrogen peroxide treatment, PLANEs achieve significantly higher velocities than conventional platinum nanomotors, facilitating deep penetration into the thrombi. Further functionalization with thrombus-targeting peptides enables the cPLANEs to selectively accumulate at the thrombotic sites in vivo, demonstrating excellent thrombolytic efficacy. This work presents a novel surface modification strategy for optimizing the motion behavior of platinum nanomotors, offering a promising non-pharmaceutic approach for thrombotic disease treatment.

Janus-Structured Micro/Nanomotors: Self-Propelled Mechanisms and Biomedical Applications

Self-propelled micro/nanomotors (MNMs), which can convert other energy into mechanical motion, have attracted considerable attention due to their potential applications in diverse fields. Due to the asymmetric structures and 2 or more chemically discrepant composites constructed in the Janus nanoparticles, asymmetrical forces can be created in the physical environment. Thus, MNMs with Janus structures have been widely studied for revealing possible driving mechanisms. This tutorial review covers the most representative examples of Janus-structured MNMs developed so far, which are self-propelled by different mechanisms. We focus on Janus MNMs that exhibit self-propelled motion in liquid environments and their potential applications in biomedicine, including drug delivery, cancer therapy, bioimaging, and biosensing. The driving mechanisms and challenges associated with constructing asymmetric fields are deeply discussed, along with future opportunities for these versatile and promising MNMs. This review provides an overview of the rapidly evolving field of MNMs and their potential applications, serving as a valuable resource for researchers and others interested in this field.

Progress in enzyme-powered micro/nanomotors in diagnostics and therapeutics

Enzyme-powered micro/nanomotors (EMNMs) represent cutting-edge research taking advantage of enzymes as biocatalysts to provide a driving force for micro/nanomotors. Up to now, EMNMs have been designed to be powered by catalase, urease, lipase, collagenase, compound enzymes, etc. They not only have good biocompatibility and biosafety but also possess the unique ability to utilize physiologically relevant fuel to achieve autonomous propulsion through in vivo catalytic reactions. This innovation has opened exciting possibilities for medical applications of EMNMs. Given the fact that the human body is naturally abundant with substrates available for enzymatic reactions, EMNMs can effectively exploit the complex microenvironment associated with diseases, enabling the diagnosis and treatment of various medical conditions. In this review, we first introduce different kinds of EMNMs applied in specific environments for the diagnosis and treatment of diseases, while highlighting their advancements for revolutionizing healthcare practices. Then, we address the challenges faced in this rapidly evolving field, and at last, the potential future development directions are discussed. As the potential of EMNMs becomes increasingly evident, continued research and exploration are essential to unlock their full capabilities and to ensure their successful integration into clinical applications.

Janus micro/nanomotors for enhanced disease treatment through their deep penetration capability

Nanotherapeutic systems have provided an innovative means for the treatment of a wide range of diseases in modern medicine. However, the limited penetration of nanoparticles into focal tissues still greatly hampered their clinical application. With their unique two-sided structure and superior motility, Janus micro/nanomotors are expected to significantly improve the penetration of nanocarriers into organisms, thereby enhancing the therapeutic effects of diseases. This review introduces Janus micro/nanomotors with different morphologies and focuses on their propulsion mechanisms, including chemical field-driven, external physical field-driven, biologically-driven, and hybrid-driven mechanisms. We explore the research progress of Janus micro/nanomotors in various disease treatment areas (including cancer, cardiovascular diseases, neurological diseases, bacterial/fungal infections, and chronic inflammatory diseases) and elucidate the implementation strategies of Janus micro/nanomotors in facilitating disease therapies. Finally, we discuss the biosafety and biocompatibility of Janus micro/nanomotor, while exploring current challenges and opportunities in the field. We look forward to the Janus micro/nanomotor therapeutic platform demonstrating surprising therapeutic effects in the clinical treatment of diseases. STATEMENT OF SIGNIFICANCE: Micro/nanomotors are the highly promising nanotherapeutic systems due to their self-propelled motion capability. Janus micro/nanomotors possess an asymmetric structure with different physical or chemical properties on both sides. The flexibility of this bifunctional surface allows them to hold promise for improving the penetration of nanotherapeutic systems and enhancing therapeutic efficacy for complex diseases. This review focuses on the latest advancements in Janus micro/nanomotors for enhanced disease treatment, including the structural types and driving mechanisms, the enhancement effect to cope with different disease treatments, the biocompatibility and safety, the current challenges and possible solutions. These insights inform the design of deep-penetrating nanotherapeutic systems and the strategies of enhanced disease treatment.

Photothermal Cavitation-Driven Micromotor to Penetrate Cell Membrane

Photothermally driven micro/nanomotors efficiently convert light into mechanical motion, making them highly attractive for biomedical applications due to their exceptional biocompatibility and safety. However, one mystery of the photothermally driven micro/nanomotor is the wide range of reported light intensities applied, ranging from 1 W cm-2 to over 105 W cm-2. To address this mystery, we systematically investigated the propulsion of a carbon microbottle-based micromotor under three illumination conditions: continuous laser, pulsed laser, and scanning laser, where a new cavitation-driven mechanism is identified. Using a high-speed camera, we find that the instantaneous deposition of laser energy on the micromotors can lead to transient and localized evaporation of the solvent, creating cavitation bubbles to drive micromotors with ultrafast speed, where instantaneous velocity over 1 m s-1 is observed. Through precise modulation of the scanning orientation and intensity of the laser, directional propulsion and targeted explosions of the microbottles are achieved, where the instant force is strong enough to penetrate live cell membranes. Finally, the cavitation-driven micromotors are exploited as gene transfection tools, where targeted cytoplasmic transfection is demonstrated.

Ultrasound meets nanomedicine: towards disease treatment and medical imaging

As a kind of mechanical wave, ultrasound has been widely employed in the biomedical field due to its superiors of deep tissue penetration, non-destructiveness and non-toxicity. In this review, we highlight current progress and prospects in using ultrasound as a powerful tool for disease treatment and medical imaging, including (1) ultrasound as energy input for driving nano/micromotor in drug delivery, this part first introduces the synthesis and motion behavior of nano/micromotors, then reviews the small molecular and macromolecular compounds that the nano/micromotors are delivering; (2) sonosensitive nanomaterials for disease therapy, the sonodynamic, sonopiezoelectric, sonothermal, and sonomechanical therapy will all be covered; (3) ultrasound as a non-invasive technique for nano/micromotor tracking or medical imaging; (4) the sonoporation of nano/microbubble. Future challenges in using ultrasound for disease treatment or medical imaging will also be described in the conclusion part.

Metareview: a survey of active matter reviews

In the past years, the amount of research on active matter has grown extremely rapidly, a fact that is reflected in particular by the existence of more than 1000 reviews on this topic. Moreover, the field has become very diverse, ranging from theoretical studies of the statistical mechanics of active particles to applied work on medical applications of microrobots and from biological systems to artificial swimmers. This makes it very difficult to get an overview over the field as a whole. Here, we provide such an overview in the form of a metareview article that surveys the existing review articles and books on active matter. Thereby, this article provides a useful starting point for finding literature about a specific topic.

Recent Advances in Micro/Nanomotor for the Therapy and Diagnosis of Atherosclerosis

Atherosclerotic cardiovascular disease poses a significant global public health threat with a high incidence that can result in severe mortality and disability. The lack of targeted effects from traditional therapeutic drugs on atherosclerosis may cause damage to other organs and tissues, necessitating the need for a more focused approach to address this dilemma. Micro/nanomotors are self-propelled micro/nanoscale devices capable of converting external energy into autonomous movement, which offers advantages in enhancing penetration depth and retention while increasing contact area with abnormal sites, such as atherosclerotic plaque, inflammation, and thrombosis, within blood vessel walls. Recent studies have demonstrated the crucial role micro/nanomotors play in treating atherosclerotic cardiovascular disease. Hence, this review highlights the recent progress of micro/nanomotor technology in atherosclerotic cardiovascular disease, including the effective promotion of micro/nanomotors in the circulatory system, overcoming hemorheological barriers, targeting the atherosclerotic plaque microenvironment, and targeting intracellular drug delivery, to facilitate atherosclerotic plaque localization and therapy. Furthermore, we also describe the potential application of micro/nanomotors in the imaging of vulnerable plaque. Finally, we discuss key challenges and prospects for treating atherosclerotic cardiovascular disease while emphasizing the importance of designing individualized management strategies specific to its causes and microenvironmental factors.

Microwave-Responsive Engineered Platelet Microneedle Patch for Deep Tumor Penetration and Precision Therapy

Controllable and precise delivery of therapeutic agents is critical for effective tumor therapy. However, tumor targeting and the deep penetration of drugs remain among the most challenging issues in achieving controlled delivery. Herein, a novel engineered platelet microneedle patch with a microwave-responsive magnetic biometal-organic framework is proposed to facilitate the combination of the engineered platelet and microwave hyperthermia, enhancing deep drug penetration into tumors and enabling precision therapy. The prepared magnetic biometal-organic framework as nanomedicine exhibits excellent microwave thermal effects. The engineered platelets could be activated in the tumor microenvironment to release PMPs and nanomedicines combined with microwave hyperthermia for enhancing both cell uptake and deep drug penetration into tumors. The developed separable microneedle patch system allows the microneedle tip to be quickly detached from the backing layer and retained within the target tissue for repeated local cancer hyperthermia treatments. By integration of engineered platelets into the microneedle patch, the transdermal deep delivery of drugs could be effectively enhanced for local microwave thermochemotherapy of tumors. This work represents the first attempt to graft microwave-responsive inorganic nanomedicines onto platelets as cell drugs, offering a novel strategy for precise drug delivery activated by microwave thermal therapy.

Platinum micromotors for mucosal penetration and colorectal cancer therapy

The therapeutic outcomes of medications were restricted by the colonic mucosal barrier during the treatment of colorectal cancer (CRC). Micro/nanomotors can overcome the mucus barriers to reach deep colorectal tumors. In this study, we constructed a novel microsized PLGA-Pt micromotor (MM) driven by hydrogen peroxide (H2O2) to enhance drug delivery to the CRC tissues and achieve effective antitumor therapy. The PLGA-Pt MMs actively traversed the colonic mucosal barrier with the assist of gas propulsion, while continuously releasing Pt2+ ions within the tumor microenvironment. In vitro studies revealed that the PLGA-Pt MMs exhibited rapid movement in the presence of H2O2, achieving superior colonic mucosal penetration. It effectively delivered Pt2+ ions to the nuclei, forming DNA-Pt adducts that induced significant DNA damage and apoptosis of CRC cells. In vivo studies showed the PLGA-Pt MM significantly suppressed orthotopic tumor growth and activated antitumor immunity, enhancing the therapeutic effect against CRC. This study presents a micromotor capable of overcoming mucosal barriers for efficient treatment of orthotopic CRC.

A Bioinspired Virus-Like Mechano-Bactericidal Nanomotor for Ocular Multidrug-Resistant Bacterial Infection Treatment

Multidrug-resistant (MDR) bacteria and their associated biofilms are major causative factors in eye infections, often resulting in blindness and presenting considerable global health challenges. Presently, mechano-bactericidal systems, which combine distinct topological geometries with mechanical forces to physically induce bacterial apoptosis, show promising potential. However, the physical interaction process between current mechano-bactericidal systems and bacteria is generally based on passive diffusion or Brownian motion and lacks the force required for biofilm penetration; thus, featuring low antibacterial efficacy. Here, a biomimetic mechano-bactericidal nanomotor (VMSNT) is synthesized by functionalizing COOH-PEG-phenylboronic acid (PBA) on virus-like mesoporous silica, with subsequent partial coating of Au caps. Enhanced by self-thermophoresis capabilities and virus-like topological shapes, VMSNT significantly improves mechanical antibacterial effects and biofilm penetration. In addition, scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) analyses demonstrate that VMSNT can precisely target bacteria within the infection microenvironment, facilitated by PBA's ability to recognize and bind to the peptidoglycan on bacterial surfaces. Remarkably, VMSNT is also effective in eliminating MDR bacteria and reducing inflammation in mice models of methicillin-resistant Staphylococcus aureus (MRSA)-infected keratitis and endophthalmitis, with minimal adverse effects. Overall, such a nanomotor presents a promising approach for addressing the challenges of ocular MDR bacterial infections.

Breaking Through Physiological Barriers: Nanorobotic Strategies for Active Drug Delivery

Self-propelled micro/nanomotors (MNMs) represent a groundbreaking advancement in precision drug delivery, offering potential solutions to persistent challenges such as systemic toxicity, limited bioavailability, and nonspecific distribution. By transforming various energy sources into mechanical motion, MNMs are able to autonomously navigate through complex physiological environments, facilitating targeted delivery of therapeutic agents to previously inaccessible regions. However, to achieve efficient in vivo drug delivery, biomedical MNMs must demonstrate their ability to overcome crucial physiological barriers encompassing mucosal surfaces, blood flow dynamics, vascular endothelium, and cellular membrane. This review provides a comprehensive overview of the latest strategies developed to address these obstacles while also analyzing the broader challenges and opportunities associated with clinical translation. Our objective is to establish a solid foundation for future research in medical MNMs by focusing on enhancing drug delivery efficiency and advancing precision medicine, ultimately paving the way for practical theragnostic applications and wider clinical adoption.

AlgaeSperm: Microalgae-Based Soft Magnetic Microrobots for Targeted Tumor Treatment

Magnetic microrobots are significant platforms for targeted drug delivery, among which sperm-inspired types have attracted much attention due to their flexible undulation. However, mass production of sperm-like soft magnetic microrobots with high-speed propulsion is still challenging due to the need of more reasonable structure design and facile fabrication. Herein, a novel strategy is proposed for large-scale preparation of microalgae-based soft microrobots with a fully magnetic head-to-tail structure, called AlgaeSperm with robust propulsion and chemo-photothermal performance. This approach deposited Pd@Au nanoparticles (NPs) inside chlorella cells, which are further coated with Fe3O4 NPs and polydopamine layers to form the magnetic heads. Then, flexible flagella are grafted via magnetic assembly of Fe3O4@PVP NPs to construct the final AlgaeSperm. Under precessing magnetic fields, the AlgaeSperms can achieve a forward velocity up to 2.3 body length/s, the highest among sperm-like magnetic microrobots to the best of the knowledge. Besides, their flexible maneuverability in a swarm is also verified. In vitro anti-cancer experiments are conducted after loading doxorubicin (DOX) to confirm their excellent targeted chemo-photothermal performance. This work offers a significant paradigm for constructing sperm-like soft magnetic microrobots with great potential for targeted tumor treatment.

Multi-phoretic nanomotor with consistent motion direction for enhanced cancer therapy

Nanomotors have emerged as promising candidates for the deep penetration of loaded drugs into cancer stem cells (CSCs) located within the core of tumor tissues. A crucial factor in maximizing the clinical potential of nanomotors lies in their ability to respond dynamically to various stimuli in the tumor microenvironment. By adjusting their propulsion mechanisms in response to various stimuli, nanomotors can maintain directional movement, thus improving drug distribution and therapeutic efficacy. In this study, we present the design of a pH-responsive multi-phoretic propelled Janus nanomotor, comprising a SiO2@Pt core@shell nanosphere and half-wrapped acrylic acid polymers (PAA)-conjugated gold (Au) nanoparticles (JMSNs@Pt@P-Au). The JMSNs@Pt@P-Au catalyze endogenous H2O2 into O2, propelling the nanomotors into solid tumors. Within the tumor microenvironment, the contraction of PAA triggers contact between the Au and Pt layers, facilitating self-electrophoresis propulsion. Simultaneously, a local thermal gradient is generated on the Au layer under near-infrared light irradiation, propelling the nanomotor through thermophoresis. Exploiting the unique structure of JMSNs@Pt@P-Au, the driving forces generated by H2O2 catalysis, self-electrophoresis, and thermophoresis exhibit consistent motion directions. This consistency not only provides thrust for deep penetration but also enhances their targeted therapeutic efficiency against CSCs in vivo. This combination of nanomotor-driven power sources holds significant potential for designing intelligent, active drug delivery systems for effective CSC-targeted cancer therapy. STATEMENT OF SIGNIFICANCE: Deep penetration of nanomedicine in solid tumor tissue and cells is still an important challenge that restricts the therapeutic effect. Multiple-propelled nanomotors have been confirmed to be self-propulsive that overcome the limited penetration in solid tumor. However, their effective translation toward clinical applications is limited due to the inability to alter their propelled mechanisms in response to the actual physiological environment, resulting in speed and inconsistent movement directions. In this work, we designed a multi-phoretic propelled Janus nanomotor (JMSNs@Pt@P-Au) that exhibited three propelled mechanisms in response to the changes of pH value. Noteworthy is their heightened speed and remarkable tumor tissue penetration observed in vitro and in vivo without adverse effects. Such multi-phoretic propulsion offers considerable promise for developing advanced nanomachines with a stimuli-responsive switch of propulsion modes in biomedical applications.

A Lifetime of Catalytic Micro-/Nanomotors

Microscopic and nanoscopic motors, often referred to as micro-/nanomotors, are autonomous devices capable of converting chemical energy from their surroundings into mechanical motion or forces necessary for propulsion. These devices draw inspiration from natural biomolecular motor proteins, and in recent years, synthetic micro-/nanomotors have attracted significant attention. Among these, catalytic micro-/nanomotors have emerged as a prominent area of research. Despite considerable progress in their design and functionality, several obstacles remain, especially regarding the development of biocompatible materials and fuels, the integration of intelligent control systems, and the translation of these motors into practical applications. Thus, a comprehensive understanding of the current advancements in catalytic micro-/nanomotors is critical. This review aims to provide an in-depth overview of their fabrication techniques, propulsion mechanisms, key influencing factors, control methodologies, and potential applications. Furthermore, we examine their physical and hydrodynamic properties in fluidic environments to optimize propulsion efficiency. Lastly, we evaluate their biosafety and biocompatibility to facilitate their use in biological systems. The review also addresses key challenges and proposes potential solutions to advance their practical deployment.

Urease-powered nanomotor containing STING agonist for bladder cancer immunotherapy

Most non-muscle invasive bladder cancers have been treated by transurethral resection and following intravesical injection of immunotherapeutic agents. However, the delivery efficiency of therapeutic agents into bladder wall is low due to frequent urination, which leads to the failure of treatment with side effects. Here, we report a urease-powered nanomotor containing the agonist of stimulator of interferon genes (STING) for the efficient activation of immune cells in the bladder wall. After characterization, we perform in vitro motion analysis and assess in vivo swarming behaviors of nanomotors. The intravesical instillation results in the effective penetration and retention of nanomotors in the bladder. In addition, we confirm the anti-tumor effect of nanomotor containing the STING agonist (94.2% of inhibition), with recruitment of CD8+ T cells (11.2-fold compared with PBS) and enhanced anti-tumor immune responses in bladder cancer model in female mice. Furthermore, we demonstrate the better anti-tumor effect of nanomotor containing the STING agonist than those of the gold standard Bacille Calmette-Guerin therapy and the anti-PD-1 inhibitor pembrolizumab in bladder cancer model. Taken together, the urease-powered nanomotor would provide a paradigm as a next-generation platform for bladder cancer immunotherapy.

Antibacterial and Biofilm Removal Strategies Based on Micro/Nanomotors in the Biomedical Field

Bacterial infection, which can trigger varieties of diseases and tens of thousands of deaths each year, poses serious threats to human health. Particularly, the new dilemma caused by biofilms is gradually becoming a severe and tough problem in the biomedical field. Thus, the strategies to address these problems are considered an urgent task at present. Micro/nanomotors (MNMs), also named micro/nanoscale robots, are mostly driven by chemical energy or external field, exhibiting strong diffusion and self-propulsion in the liquid media, which has the potential for antibacterial applications. In particular, when MNMs are assembled in swarms, they become robust and efficient for biofilm removal. However, there is a lack of comprehensive review discussing the progress in this aspect. Bearing it in mind and based on our own research experience in this regard, the studies on MNMs driven by different mechanisms orchestrated for antibacterial activity and biofilm removal are timely and concisely summarized and discussed in this work, aiming to show the advantages of MNMs brought to this field. In addition, an outlook was proposed, hoping to provide the fundamental guidance for future development in this area.

Polysaccharide Based Self-Driven Tubular Micro/Nanomotors as a Comprehensive Platform for Quercetin Loading and Anti-inflammatory Function

Quercetin (QR) is a natural flavonoid with strong anti-inflammatory properties, but it suffers from poor water solubility and bioavailability. Micro/nanomotors (NMs) are tiny devices that convert external energy or chemical fuels into an autonomous motion. They are characterized by their small size, rapid movement, and self-assembly capabilities, which can enhance the delivery of bioactive ingredients. The study synthesized natural polysaccharide-based nanotubes (NTs) using a layer-by-layer self-assembly method and combined with urease (Ure), glucose oxidase (GOx), and Fe3O4 to create three types of NMs. These NMs were well-dispersed and biocompatible. In vitro experiments showed that NMs-Fe3O4 has excellent photothermal conversion properties and potential for use in photothermal therapy. Cellular inflammation model results demonstrated that QR-loaded NMs were not only structurally stable but also improved bioavailability and effectively inhibited the release of inflammatory mediators such as IL-1β and IL-6, providing a safe and advanced carrier system for the effective use of bioactive components in food.

Microfluidic-Enabled Assembly of Multicomponent Artificial Organelle for Synergistic Tumor Starvation Therapy

Artificial organelles (AOs) encapsulating enzymes are engineered to facilitate biocatalytic reactions for exerting therapeutic effects in various diseases. Exploiting the confinement effect, these catalytic properties exhibit significant enhancements without being influenced by the surrounding medium, enabling more efficient cascade reactions. In this study, we present a novel approach for synergistic tumor starvation therapy by developing multicomponent artificial organelles that combine enzymatic oncotherapy with chemotherapy. The construction process involves a microfluidic-based approach that enables the encapsulation of cationic cores containing doxorubicin (DOX), electrostatic adsorption of cascade enzymes, and surface assembly of the protective lipid membrane. Additionally, these multicomponent AOs possess multicompartment structures that enable the separation and sequential release of each component. By coencapsulating enzymes and chemotherapeutic agent DOX within AOs, we achieve enhanced enzymatic cascade reactions (ECR) and improved intrinsic permeability of DOX due to spatial confinement. Furthermore, exceptional therapeutic effects on 4T1 xenograft tumors are observed, demonstrating the feasibility of utilizing AOs as biomimetic implants in living organisms. This innovative approach that combines starvation therapy with chemotherapy using multicompartment AOs represents a promising paradigm in the field of precise cancer therapy.

Bacterial outer membrane vesicle nanorobot

Autonomous nanorobots represent an advanced tool for precision therapy to improve therapeutic efficacy. However, current nanorobotic designs primarily rely on inorganic materials with compromised biocompatibility and limited biological functions. Here, we introduce enzyme-powered bacterial outer membrane vesicle (OMV) nanorobots. The immobilized urease on the OMV membrane catalyzes the decomposition of bioavailable urea, generating effective propulsion for nanorobots. This OMV nanorobot preserves the unique features of OMVs, including intrinsic biocompatibility, immunogenicity, versatile surface bioengineering for desired biofunctionalities, capability of cargo loading and protection. We present OMV-based nanorobots designed for effective tumor therapy by leveraging the membrane properties of OMVs. These involve surface bioengineering of robotic body with cell-penetrating peptide for tumor targeting and penetration, which is further enhanced by active propulsion of nanorobots. Additionally, OMV nanorobots can effectively safeguard the loaded gene silencing tool, small interfering RNA (siRNA), from enzymatic degradation. Through systematic in vitro and in vivo studies using a rodent model, we demonstrate that these OMV nanorobots substantially enhanced siRNA delivery and immune stimulation, resulting in the utmost effectiveness in tumor suppression when juxtaposed with static groups, particularly evident in the orthotopic bladder tumor model. This OMV nanorobot opens an inspiring avenue to design advanced medical robots with expanded versatility and adaptability, broadening their operation scope in practical biomedical domains.

Light-driven rGO/Cu2 + 1O tubular nanomotor with active targeted drug delivery for combination treatment of cancer cells

The unprecedented navigation ability in micro/nanoscale and tailored functionality tunes micro/nanomotors as new target drug delivery systems, open up new horizons for biomedical applications. Herein, we designed a light-driven rGO/Cu2 + 1O tubular nanomotor for active targeting of cancer cells as a drug delivery system. The propulsion performance is greatly enhanced in real cell media (5% glucose cells isotonic solution), attributing to the introduction of oxygen vacancy and reduced graphene oxide (rGO) layer for separating photo-induced electron-hole pairs. The motion speed and direction can be readily modulated. Meanwhile, doxorubicin (DOX) can be loaded quickly on the rGO layer because of π-π bonding effect. The Cu2 + 1O matrix in the tiny robots not only serves as a photocatalyst to generate a chemical concentration gradient as the driving force but also acts as a nanomedicine to kill cancer cells as well. The strong propulsion of light-driven rGO/Cu2 + 1O nanomotors coupled with tiny size endow them with active transmembrane transport, assisting DOX and Cu2 + 1O breaking through the barrier of the cell membrane. Compared with non-powered nanocarrier and free DOX, light-propelled rGO/Cu2 + 1O nanomotors exhibit greater transmembrane transport efficiency and significant therapeutic efficacy. This proof-of-concept nanomotor design presents an innovative approach against tumor, enlarging the list of biomedical applications of light-driven micro/nanomotors to the superficial tissue treatment.

Nanomaterials-assisted gene editing and synthetic biology for optimizing the treatment of pulmonary diseases

The use of nanomaterials in gene editing and synthetic biology has emerged as a pivotal strategy in the pursuit of refined treatment methodologies for pulmonary disorders. This review discusses the utilization of nanomaterial-assisted gene editing tools and synthetic biology techniques to promote the development of more precise and efficient treatments for pulmonary diseases. First, we briefly outline the characterization of the respiratory system and succinctly describe the principal applications of diverse nanomaterials in lung ailment treatment. Second, we elaborate on gene-editing tools, their configurations, and assorted delivery methods, while delving into the present state of nanomaterial-facilitated gene-editing interventions for a spectrum of pulmonary diseases. Subsequently, we briefly expound on synthetic biology and its deployment in biomedicine, focusing on research advances in the diagnosis and treatment of pulmonary conditions against the backdrop of the coronavirus disease 2019 pandemic. Finally, we summarize the extant lacunae in current research and delineate prospects for advancement in this domain. This holistic approach augments the development of pioneering solutions in lung disease treatment, thereby endowing patients with more efficacious and personalized therapeutic alternatives.

H2S-Powered Nanomotors for Active Therapy of Tumors by Inducing Ferroptosis and Lactate-Pyruvate Axis Disorders

Disruption of the symbiosis of extra/intratumoral metabolism is a good strategy for treating tumors that shuttle resources from the tumor microenvironment. Here, we report a precision treatment strategy for enhancing pyruvic acid and intratumoral acidosis to destroy tumoral metabolic symbiosis to eliminate tumors; this approach is based on PEGylated gold and lactate oxidase-modified aminated dendritic mesoporous silica with lonidamine and ferrous sulfide loading (PEG-Au@DMSNs/FeS/LND@LOX). In the tumor microenvironment, LOX oxidizes lactic acid to produce pyruvate, which represses tumor cell proliferation by inhibiting histone gene expression and induces ferroptosis by partial histone monoubiquitination. In acidic tumor conditions, the nanoparticles release H2S gas and Fe2+ ions, which can inhibit catalase activity to promote the Fenton reaction of Fe2+, resulting in massive ·OH production and ferroptosis via Fe3+. More interestingly, the combination of H2S and LND (a monocarboxylic acid transporter inhibitor) can cause intracellular acidosis by lactate, and protons overaccumulate in cells. Multiple intracellular acidosis is caused by lactate-pyruvate axis disorders. Moreover, H2S provides motive power to intensify the shuttling of nanoparticles in the tumor region. The findings confirm that this nanomedicine system can enable precise antitumor effects by disrupting extra/intratumoral metabolic symbiosis and inducing ferroptosis and represents a promising active drug delivery system candidate for tumor treatment.

NIR-II light powered hydrogel nanomotor for intravesical instillation with enhanced bladder cancer therapy

Intravesical instillation is the common therapeutic strategy for bladder cancer. Besides chemo drugs, nanoparticles are used as intravesical instillation reagents, offering appealing therapeutic approaches for bladder cancer treatment. Metal oxide nanoparticle based chemodynamic therapy (CDT) converts tumor intracellular hydrogen peroxide to ROS with cancer cell-specific toxicity, which makes it a promising approach for the intravesical instillation of bladder cancer. However, the limited penetration of nanoparticle based therapeutic agents into the mucosa layer of the bladder wall poses a great challenge for the clinical application of CDT in intravesical instillation. Herein, we developed a 1064 nm NIR-II light driven hydrogel nanomotor for the CDT for bladder cancer via intravesical instillation. The hydrogel nanomotor was synthesized via microfluidics, wrapped with a lipid bilayer, and encapsulates CuO2 nanoparticles as a CDT reagent and core-shell structured Fe3O4@Cu9S8 nanoparticles as a fuel reagent with asymmetric distribution in the nanomotor (LipGel-NM). An NIR-II light irradiation of 1064 nm drives the active motion of LipGel-NMs, thus facilitating their distribution in the bladder and deep penetration into the mucosa layer of the bladder wall. After FA-mediated endocytosis in bladder cancer cells, CuO2 is released from LipGel-NMs due to the acidic intracellular environment for CDT. The NIR-II light powered active motion of LipGel-NMs effectively enhances CDT, providing a promising strategy for bladder cancer therapy.

Heterogeneous Sensor-Carrier Microswarms for Collaborative Precise Drug Delivery toward Unknown Targets with Localized Acidosis

Micro/nanorobots hold the potential to revolutionize biomedicine by executing diverse tasks in hard-to-reach biological environments. Nevertheless, achieving precise drug delivery to unknown disease sites using swarming micro/nanorobots remains a significant challenge. Here we develop a heterogeneous swarm comprising sensing microrobots (sensor-bots) and drug-carrying microrobots (carrier-bots) with collaborative tasking capabilities for precise drug delivery toward unknown sites. Leveraging robust interspecific hydrodynamic interactions, the sensor-bots and carrier-bots spontaneously synchronize and self-organize into stable heterogeneous microswarms. Given that the sensor-bots can create real-time pH maps employing pH-responsive structural-color changes and the doxorubicin-loaded carrier-bots exhibit selective adhesion to acidic targets via pH-responsive charge reversal, the sensor-carrier microswarm, when exploring unknown environments, can detect and localize uncharted acidic targets, guide itself to cover the area, and finally deploy therapeutic carrier-bots precisely there. This versatile platform holds promise for treating diseases with localized acidosis and inspires future theranostic microsystems with expandability, task flexibility, and high efficiency.

Biohybrid Flexible Sperm-like Microrobot for Targeted Chemo-Photothermal Therapy

Magnetic micro/nanorobots are promising platforms for targeted drug delivery, and their construction with soft and flexible features has received extensive attention for practical applications. Despite significant efforts in this field, facile fabrication of magnetic microrobots with flexible structures and versatility in targeted therapy remains a big challenge. Herein, we proposed a novel universal strategy to fabricate a biohybrid flexible sperm-like microrobot (BFSM) based on a Chlorella (Ch.) cell and artificial flagella, which showed great potential for targeted chemo-photothermal therapy for the first time. In this approach, microspherical Ch. cells were utilized to construct the microrobotic heads, which were intracellularly deposited with core-shell Pd@Au, extracellularly magnetized with Fe3O4, and further loaded with anticancer drug. The magnetic heads with excellent photothermal and chemotherapeutic capability were further assembled with flexible polypyrrole nanowires via biotin-streptavidin bonding to construct the BFSMs. Based on the exquisite head-to-tail structures, the BFSMs could be effectively propelled under precessing magnetic fields and move back and forth without a U-turn. Moreover, in vitro chemo-photothermal tests were conducted to verify their performance of targeted drug delivery toward localized HeLa cells. Due to this superior versatility and facile fabrication, the BFSMs demonstrated great potential for targeted anticancer therapy.

Piezo-enhanced near infrared photocatalytic nanoheterojunction integrated injectable biopolymer hydrogel for anti-osteosarcoma and osteogenesis combination therapy

Preventing local tumor recurrence while promoting bone tissue regeneration is an urgent need for osteosarcoma treatment. However, the therapeutic efficacy of traditional photosensitizers is limited, and they lack the ability to regenerate bone. Here, a piezo-photo nanoheterostructure is developed based on ultrasmall bismuth/strontium titanate nanocubes (denoted as Bi/SrTiO3), which achieve piezoelectric field-driven fast charge separation coupling with surface plasmon resonance to efficiently generate reactive oxygen species. These hybrid nanotherapeutics are integrated into injectable biopolymer hydrogels, which exhibit outstanding anticancer effects under the combined irradiation of NIR and ultrasound. In vivo studies using patient-derived xenograft models and tibial osteosarcoma models demonstrate that the hydrogels achieve tumor suppression with efficacy rates of 98.6 % and 67.6 % in the respective models. Furthermore, the hydrogel had good filling and retention capabilities in the bone defect region, which exerted bone repair therapeutic efficacy by polarizing and conveying electrical stimuli to the cells under mild ultrasound radiation. This study provides a comprehensive and clinically feasible strategy for the overall treatment and tissue regeneration of osteosarcoma.

Janus mesoporous organosilica/platinum nanomotors for active treatment of suppurative otitis media

We report a Janus mesoporous organosilica/platinum (MOS/Pt) nanomotor for active targeted treatment of suppurative otitis media, as a new type of multi-functional ear drop. The efficient propulsion of MOS/Pt nanomotors in hydrogen peroxide ear-cleaning drops significantly improves their binding efficiency with Staphylococcus aureus and enhances their antibacterial efficacy.

tPA-anchored nanorobots for in vivo arterial recanalization at submillimeter-scale segments

Micro/nanorobots provide a promising approach for intravascular therapy with high precision. However, blood vessel is a highly complex system, and performing interventional therapy in those submillimeter segments remains challenging. While micro/nanorobots can enter submillimeter segments, they may still comprise nonbiodegradable parts, posing a considerable challenge for post-use removal. Here, we developed a retrievable magnetic colloidal microswarm, composed of tPA-anchored Fe3O4@mSiO2 nanorobots (tPA-nbots), to archive tPA-mediated thrombolysis under balloon catheter-assisted magnetic actuation with x-ray fluoroscopy imaging system (CMAFIS). By deploying tPA-nbot transcatheter to the vicinity of the thrombus, the tPA-nbot microswarms were magnetically actuated to the blood clot at the submillimeter vessels with high precision. After thrombolysis, the tPA-nbots can be retrieved via the CMAFIS, as demonstrated in ex vivo organ of human placenta and in vivo carotid artery of rabbit. The proposed colloidal microswarm provides a promising robotic tool with high spatial precision for enhanced thrombolysis with low side effects.

Dual-Fuel Propelled Nanomotors with Two-Stage Permeation for Deep Bacterial Infection in the Treatment of Pulpitis

Bacterial infection-induced inflammatory response could cause irreversible death of pulp tissue in the absence of timely and effective therapy. Given that, the narrow structure of root canal limits the therapeutic effects of passive diffusion-drugs, considerable attention has been drawn to the development of nanomotors, which have high tissue penetration abilities but generally face the problem of insufficient fuel concentration. To address this drawback, dual-fuel propelled nanomotors (DPNMs) by encapsulating L-arginine (L-Arg), calcium peroxide (CaO2 ) in metal-organic framework is developed. Under pathological environment, L-Arg could release nitric oxide (NO) by reacting with reactive oxygen species (ROS) to provide the driving force for movement. Remarkably, the depleted ROS could be supplemented through the reaction between CaO2 with acids abundant in the inflammatory microenvironment. Owing to high diffusivity, NO achieves further tissue penetration based on the first-stage propulsion of nanomotors, thereby removing deep-seated bacterial infection. Results indicate that the nanomotors effectively eliminate bacterial infection based on antibacterial activity of NO, thereby blocking inflammatory response and oxidative damage, forming reparative dentine layer to avoid further exposure and infection. Thus, this work provides a propagable strategy to overcome fuel shortage and facilitates the therapy of deep lesions.

Effects of Size and Asymmetry on Catalase-Powered Silica Micro/nanomotors

Enzyme-powered micro/nanomotors that can autonomously move in biological environment are attractive in the fields of biology and biomedicine. The fabrication of enzyme-powered micro/nanomotors normally focuses on constructing Janus structures of micro/nanomaterials, based on the intuition that the Janus coating of enzymes can generate driving force from asymmetric catalytic reactions. Here, in the fabrication of catalase-powered silica micro/nanomotors (C-MNMs), an archetypical model of enzyme-powered micro/nanomotors, we find the silica size rather than asymmetric coating of catalase determines the motion ability of C-MNMs. The effects of size and asymmetry have been investigated by a series of C-MNMs at various sizes (0.5, 2, 5 and 10 μm) and asymmetric levels (full-, half- and most-coated with catalase). The motion performance indicates that 500 nm and 2 μm C-MNMs show obvious increases (varying from 134% to 618%) of diffusion coefficient, but C-MNMs bigger than 5 μm have no self-propulsion behaviour at all, regardless of asymmetric levels. In addition, although asymmetry facilitates enhanced diffusion of C-MNMs, only 2 μm C-MNMs are sensitive to asymmetric level. This work elucidates the primary and secondary roles of size and asymmetry in the preparation of C-MNMs, paving the way to fabricate enzyme-powered micro/nanomotors with high motion performance in future.

UCNPs-based nanoreactors with ultraviolet radiation-induced effect for enhanced ferroptosis therapy of tumor

The limitations of light source limit the clinical application of optical therapy technology. How to improve the application efficiency of radiant light has become the focus of researchers. Here, we synthesize a kind of UCNPs@PVP-GOx-PpIX-Fe3+ (UPGPF) nanoreactors with rare earth upconversion nanoparticles (UCNPs) as the substrate for the enhancement of ferroptosis effect by the synergistic starvation/photodynamic therapies. Firstly, glucose oxidase (GOx) and Fe3+ loaded in UPGPF nanoreactors are used to directly face the problems of insufficient H2O2 level in tumor tissue and low Fenton reaction efficiency. Further, UCNPs can absorb NIR light at 980 nm and convert low-energy photons into high-energy photons, thereby cleverly generating ultraviolet (UV) radiation induction in vivo, which can produce a synergistic effect of enhancing iron death. The in vivo experimental results of breast cancer model mice show that the UPGPF nanoreactors have significant anticancer effect and good biosafety. With the help of the optical conversion characteristics of UCNPs, this kind of treatment idea of building a UV radiation-induced microplatform in the tumor microenvironment, which leads to the synergistic enhancement of iron death effect, provides a promising innovative design strategy for tumor research.

Optically Programmable Living Microrouter in Vivo

With high reconfigurability and swarming intelligence, programmable medical micromachines (PMMs) represent a revolution in microrobots for executing complex coordinated tasks, especially for dynamic routing of various targets along their respective routes. However, it is difficult to achieve a biocompatible implantation into the body due to their exogenous building blocks. Herein, a living microrouter based on an organic integration of endogenous red blood cells (RBCs), programmable scanning optical tweezers and flexible optofluidic strategy is reported. By harvesting energy from a designed optical force landscape, five RBCs are optically rotated in a controlled velocity and direction, under which, a specific actuation flow is achieved to exert the well-defined hydrodynamic forces on various biological targets, thus enabling a selective routing by integrating three successive functions, i.e., dynamic input, inner processing, and controlled output. Benefited from the optofluidic manipulation, various blood cells, such as the platelets and white blood cells, are transported toward the damaged vessel and cell debris for the dynamic hemostasis and targeted clearance, respectively. Moreover, the microrouter enables a precise transport of nanodrugs for active and targeted delivery in a large quantity. The proposed RBC microrouter might provide a biocompatible medical platform for cell separation, drug delivery, and immunotherapy.

Strategies in design of self-propelling hybrid micro/nanobots for bioengineering applications

Micro/nanobots are integrated devices developed from engineered nanomaterials that have evolved significantly over the past decades. They can potentially be pre-programmed to operate robustly at numerous hard-to-reach organ/tissues/cellular sites for multiple bioengineering applications such as early disease diagnosis, precision surgeries, targeted drug delivery, cancer therapeutics, bio-imaging, biomolecules isolation, detoxification, bio-sensing, and clearing up clogged arteries with high soaring effectiveness and minimal exhaustion of power. Several techniques have been introduced in recent years to develop programmable, biocompatible, and energy-efficient micro/nanobots. Therefore, the primary focus of most of these techniques is to develop hybrid micro/nanobots that are an optimized combination of purely synthetic or biodegradable bots suitable for the execution of user-defined tasks more precisely and efficiently. Recent progress has been illustrated here as an overview of a few of the achievable construction principles to be used to make biomedical micro/nanobots and explores the pivotal ventures of nanotechnology-moderated development of catalytic autonomous bots. Furthermore, it is also foregrounding their advancement offering an insight into the recent trends and subsequent prospects, opportunities, and challenges involved in the accomplishments of the effective multifarious bioengineering applications.

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.

Magnetically Powered Immunogenic Macrophage Microrobots for Targeted Multimodal Cancer Therapy

Motile microrobots open a new realm for disease treatment. However, the concerns of possible immune elimination, targeted capability and limited therapeutic avenue of microrobots constrain its practical biomedical applications. Herein, a biogenic macrophage-based microrobot loaded with magnetic nanoparticles and bioengineered bacterial outer membrane vesicles (OMVs), capable of magnetic propulsion, tumor targeting, and multimodal cancer therapy is reported. Such cell robots preserve intrinsic properties of macrophages for tumor suppression and targeting, and bioengineered OMVs for antitumor immune regulation and fused anticancer peptides. Cell robots display efficient magnetic propulsion and directional migration in the confined space. In vivo tests show that cell robots can accumulate at the tumor site upon magnetic manipulation, coupling with tumor tropism of macrophages to greatly improve the efficacy of its multimodal therapy, including tumor inhibition of macrophages, immune stimulation, and antitumor peptides of OMVs. This technology offers an attractive avenue to design intelligent medical microrobots with remote manipulation and multifunctional therapy capabilities for practical precision treatment.

Intelligent sensing based on active micro/nanomotors

In the microscopic world, synthetic micro/nanomotors (MNMs) can convert a variety of energy sources into driving forces to help humans perform a number of complex tasks with greater ease and efficiency. These tiny machines have attracted tremendous attention in the field of drug delivery, minimally invasive surgery, in vivo sampling, and environmental management. By modifying their surface materials and functionalizing them with bioactive agents, these MNMs can also be transformed into dynamic micro/nano-biosensors that can detect biomolecules in real-time with high sensitivity. The extensive range of operations and uses combined with their minuscule size have opened up new avenues for tackling intricate analytical difficulties. Here, in this review, various driving methods are briefly introduced, followed by a focus on intelligent detection techniques based on MNMs. And we discuss the distinctive advantages, current issues, and challenges associated with MNM-based intelligent detection. It is believed that the future advancements of MNMs will greatly impact the diagnosis, treatment, and prevention of diseases.

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.

Probing the Biosafety of Implantable Artificial Secretory Granules for the Sustained Release of Bioactive Proteins

Among bio-inspired protein materials, secretory protein microparticles are of clinical interest as self-contained, slow protein delivery platforms that mimic secretory granules of the human endocrine system, in which the protein is both the drug and the scaffold. Upon subcutaneous injection, their progressive disintegration results in the sustained release of the building block polypeptides, which reach the bloodstream for systemic distribution and subsequent biological effects. Such entities are easily fabricated in vitro by Zn-assisted cross-molecular coordination of histidine residues. Using cationic Zn for the assembly of selected pure protein species and in the absence of any heterologous holding material, these granules are expected to be nontoxic and therefore adequate for different clinical uses. However, such presumed biosafety has not been so far confirmed and the potential protein dosage threshold not probed yet. By selecting the receptor binding domain (RBD) from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein as a model protein and using a mouse lab model, we have explored the toxicity of RBD-made secretory granules at increasing doses up to ∼100 mg/kg of animal weight. By monitoring body weight and biochemical blood markers and through the histological scrutiny of main tissues and organs, we have not observed systemic toxicity. Otherwise, the bioavailability of the material was demonstrated by the induction of specific antibody responses. The presented data confirm the intrinsic biosafety of artificial secretory granules made by recombinant proteins and prompt their further clinical development as self-contained and dynamic protein reservoirs.

Advancements in artificial micro/nanomotors for nucleic acid biosensing: a review of recent progress

Artificial micro/nanomotors represent a class of well-designed tools that exhibit dynamic motion and remote-control capabilities, endowing them with the capacity to perform complex tasks at the micro/nanoscale. Their utilization in nucleic acid biosensing has been paid significant attention, owing to their ability to facilitate targeted delivery of detection probes to designated sites and enhance hybridization between detection probes and target nucleic acids, thereby improving the sensitivity and specificity of biosensing. Within this comprehensive overview, we elucidate the advancement of nucleic acid biosensing through the integration of micro/nanomotors over the past decade. In particular, we provide an in-depth exploration of the diverse applications of micro/nanomotors in nucleic acid biosensing, including fluorescence recovery-based biosensing, velocity change-based biosensing, and aggregation-enhanced biosensing. Additionally, we outline the remaining challenges that impede the practical application of artificial micro/nanomotors in nucleic acid detection, and offer personal insights into prospective avenues for future development. By overcoming these obstacles, we anticipate that artificial micro/nanomotors will revolutionize conventional nucleic acid detection methodologies, providing enhanced sensitivity and reduced diagnostic timeframes, thereby facilitating more effective disease diagnosis.

Nanoparticles with transformable physicochemical properties for overcoming biological barriers

In recent years, tremendous progress has been made in the development of nanomedicines for advanced therapeutics, yet their unsatisfactory targeting ability hinders the further application of nanomedicines. Nanomaterials undergo a series of processes, from intravenous injection to precise delivery at target sites. Each process faces different or even contradictory requirements for nanoparticles to pass through biological barriers. To overcome biological barriers, researchers have been developing nanomedicines with transformable physicochemical properties in recent years. Physicochemical transformability enables nanomedicines to responsively switch their physicochemical properties, including size, shape, surface charge, etc., thus enabling them to cross a series of biological barriers and achieve maximum delivery efficiency. In this review, we summarize recent developments in nanomedicines with transformable physicochemical properties. First, the biological dilemmas faced by nanomedicines are analyzed. Furthermore, the design and synthesis of nanomaterials with transformable physicochemical properties in terms of size, charge, and shape are summarized. Other switchable physicochemical parameters such as mobility, roughness and mechanical properties, which have been sought after most recently, are also discussed. Finally, the prospects and challenges for nanomedicines with transformable physicochemical properties are highlighted.

Self-Propelled Enzymatic Nanomotors from Prodrug-Skeletal Zeolitic Imidazolate Frameworks for Boosting Multimodel Cancer Therapy Efficiency

Self-propelled nanomotors, which can autonomous propelled by harnessing others type of energy, have shown tremendous potential as drug delivery systems for cancer therapy. However, it remains challenging for nanomotors in tumor theranostics because of their structural complexity and deficient therapeutic model. Herein, glucose-fueled enzymatic nanomotors (GC6@cPt ZIFs) are developed through encapsulation of glucose oxidase (GOx), catalase (CAT), and chlorin e6 (Ce6) using cisplatin-skeletal zeolitic imidazolate frameworks (cPt ZIFs) for synergetic photochemotherapy. The GC6@cPt ZIFs nanomotors can produce O₂ through enzymatic cascade reactions for propelling the self-propulsion. Trans-well chamber and multicellular tumor spheroids experiments demonstrate the deep penetration and high accumulation of GC6@cPt nanomotors. Importantly, the glucose-fueled nanomotor can release the chemotherapeutic cPt and generate reactive oxygen species under laser irradiation, and simultaneously consume intratumoral over-expressed glutathione. Mechanistically, such processes can inhibit cancer cell energy and destroy intratumoral redox balance to synergistically damage DNA and induce tumor cell apoptosis. Collectively, this work demonstrates that the self-propelled prodrug-skeleton nanomotors with oxidative stress activation can highlight a robust therapeutic capability of oxidants amplification and glutathione depletion to boost the synergetic cancer therapy efficiency.

Small-Scale Robotics with Tailored Wettability

Small-scale robots (SSRs) have emerged as promising and versatile tools in various biomedical, sensing, decontamination, and manipulation applications, as they are uniquely capable of performing tasks at small length scales. With the miniaturization of robots from the macroscale to millimeter-, micrometer-, and nanometer-scales, the viscous and surface forces, namely adhesive forces and surface tension have become dominant. These forces significantly impact motion efficiency. Surface engineering of robots with both hydrophilic and hydrophobic functionalization presents a brand-new pathway to overcome motion resistance and enhance the ability to target and regulate robots for various tasks. This review focuses on the current progress and future perspectives of SSRs with hydrophilic and hydrophobic modifications (including both tethered and untethered robots). The study emphasizes the distinct advantages of SSRs, such as improved maneuverability and reduced drag forces, and outlines their potential applications. With continued innovation, rational surface engineering is expected to endow SSRs with exceptional mobility and functionality, which can broaden their applications, enhance their penetration depth, reduce surface fouling, and inhibit bacterial adhesion.

In vivo applications of micro/nanorobots

Untethered robots in the size range of micro/nano-scale offer unprecedented access to hard-to-reach areas of the body. In these challenging environments, autonomous task completion capabilities of micro/nanorobots have been the subject of research in recent years. However, most of the studies have presented preliminary in vitro results that can significantly differ under in vivo settings. Here, we focus on the studies conducted with animal models to reveal the current status of micro/nanorobotic applications in real-world conditions. By a categorization based on target locations, we highlight the main strategies employed in organs and other body parts. We also discuss key challenges that require interest before the successful translation of micro/nanorobots to the clinic.

Drug-Free Antimicrobial Nanomotor for Precise Treatment of Multidrug-Resistant Bacterial Infections

Manufacturing heteronanostructures with specific physicochemical characteristics and tightly controllable designs is very appealing. Herein, we reported NIR-II light-driven dual plasmonic (AuNR-SiO₂-Cu₇S₄) antimicrobial nanomotors with an intended Janus configuration through the overgrowth of copper-rich Cu₇S₄ nanocrystals at only one high-curvature site of Au nanorods (Au NRs). These nanomotors were applied for photoacoustic imaging (PAI)-guided synergistic photothermal and photocatalytic treatment of bacterial infections. Both the photothermal performance and photocatalytic activity of the nanomotors are dramatically improved owing to the strong plasmon coupling between Au NRs and the Cu₇S₄ component and enhanced energy transfer. The motion behavior of nanomotors promotes transdermal penetration and enhances the matter-bacteria interaction. More importantly, the directional navigation and synergistic antimicrobial activity of the nanomotors could be synchronously driven by NIR-II light. The marriage of active motion and enhanced antibacterial activity resulted in the expected good antibacterial effects in an abscess infection mouse model.

Photothermal-accelerated urease-powered human serum albumin nanomotor for rapid and efficient photothermal and photodynamic cancer combination therapy

Nanomotors, as a new type of micro-device, show good performance in terms of rapid transportation and deep penetration through their autonomous motion. However, their ability to efficiently break physiological barriers still remains a great challenge. Herein, we first developed a thermal-accelerated urease driven human serum albumin (HSA) nanomotor based on photothermal intervention (PTI) to achieve chemotherapy drugfree-phototherapy. The HANM@FI (HSA-AuNR@FA@Ur@ICG) is composed of a main body of biocompatible HSA, modified by gold nanorods (AuNR) and loaded with functional molecules of folic acid (FA) and indocyanine green (ICG). It promotes its own motion by breaking down urea to produce carbon dioxide and ammonia. In particular, the nanomotor is conveniently operated via near-infrared combined photothermal therapy (PTT)/ photodynamic therapy (PDT) to achieve an accelerated De value from 0.73 μm²s^-1 to 1.01μm²s^-1, and ideal tumor ablation at the same time. In contrast to customary urease-driven nanodrug-stacked engine, this HANM@FI has both targeting and imaging-guided capabilities, and finally achieves superior anti-tumor effects without chemotherapy drugs, through a "two-in-one" (motor mobility plus unique phototherapy in chemotherapy-drugfree phototherapy) strategy. This PTI effect with urease-driven nanomotors may offer further possibilities for future clinical applications of nanomedicines by enabling deep penetration and a subsequent chemotherapy-drugfree combination therapy strategy.

Copper Single-Atom Jellyfish-like Nanomotors for Enhanced Tumor Penetration and Nanocatalytic Therapy

Single-atom catalysts with extraordinary catalytic activity have been receiving great attention in tumor therapy. However, most single-atom catalysts lack self-propulsion properties, restricting them from actively approaching cancer cells or penetrating the interior of tumors. Herein, we design N-doped jellyfish-like mesoporous carbon nanomotors coordinated with single-atom copper (Cu-JMCNs). It is a combination of single-atom nanocatalytic medicine and nanomotor self-propulsion for cancer therapy. The Cu single atom can catalyze H₂O₂ into toxic hydroxyl radical (^•OH) for chemodynamic therapy (CDT). Near-infrared light triggers Cu-JMCNs to achieve self-thermophoretic motion because of the jellyfish-like asymmetric structure and photothermal property of carbon, which significantly improves the cellular uptake and the penetration of three-dimensional tumors. In vivo experiments indicate that the combination of single-atom Cu for CDT and near-infrared light propulsion can achieve over 85% tumor inhibition rate. This work sheds light on the development of advanced nanomotors with single-atom catalysts for biomedical applications.

Polydopamine nanomotors loaded indocyanine green and ferric ion for photothermal and photodynamic synergistic therapy of tumor

The limited penetration depth of nanodrugs in the tumor and the severe hypoxia inside the tumor significantly reduce the efficacy of photothermal-photodynamic synergistic therapy (PTT-PDT). Here, we synthesized a methoxypolyethylene glycol amine (mPEG-NH₂)-modified walnut-shaped polydopamine nanomotor (PDA-PEG) driven by near-infrared light (NIR). At the same time, it also loaded the photosensitizer indocyanine green (ICG) via electrostatic/hydrophobicinteractions and chelated with ferric ion (Fe³⁺). Under the irradiation of NIR, the asymmetry of PDA-PEG morphology led to the asymmetry of local photothermal effects and the formation of thermal gradient, which can make the nanomotor move autonomously. This ability of autonomous movement was proved to be used to improve the permeability of the nanomotor in three-dimensional (3D) tumor sphere. Fe³⁺ can catalyze endogenous hydrogen peroxide to produce oxygen, so as to overcome the hypoxia of tumor microenvironment and thereby generate more singlet oxygen to kill tumor cells. Animal experiments in vivo confirmed that the nanomotors had a good PTT-PDT synergistic treatment effect. The introduction of nanomotor technology has brought new ideas for cancer optical therapy.