Microalgae-Based Biohybrid Microrobot for Accelerated Diabetic Wound Healing

Micro/nanomotors for active inflammatory disease therapy

Inflammation is a carefully orchestrated response of the immune system to repair injured tissues and clear various damage factors. However, dysregulated inflammation can eventually contribute to the development and progression of various inflammatory diseases. Although anti-inflammatory drugs have demonstrated certain therapeutic efficacy in clinical settings, significant limitations still persist, highlighting the necessity for the development of improved approaches to address complex inflammatory conditions. Micro/nanomotors (MNMs) have shown significant promise for applications in the biomedical field due to their micro/nano-scale sizes and autonomous movement. Unlike traditional nanoparticles, which exhibit passive diffusion in biological fluids, MNMs can convert external energy into a driving force for self-propulsion. This capability not only enhances the tissue penetration depth and retention rates but also facilitates interaction with inflammatory lesions. Recent efforts have suggested that MNMs for inflammatory disease therapy could provide an efficient therapeutic effect. Herein, we mainly introduce the recent advances in inflammatory disease therapy based on MNMs. We conclude by discussing both the obstacles and potential opportunities for MNMs innovations in addressing inflammation.

Harnessing photosynthesis for materials, devices, and environmental technologies

Photosynthetic organisms convert solar light into chemical energy through the process of photosynthesis. The employment of photosynthetic organisms in novel materials and devices provides them with a solar-powered and sustainable functionality. In general, photosynthesis utilizes light, water, and CO2 to generate various organic compounds while releasing secondary valuable products such as O2, extracellular electrons, carbohydrates, or H2. The light-dependent inputs and outputs are harnessed for environmental purification, biomedical applications, and production of biofuel, electricity, nanomaterials, or bioplastics. In this review, we summarize photosynthesis-assisted materials and engineering applications based on the products and substrates of photosynthetic processes, and we highlight key challenges that remain to be addressed.

Living material-derived intelligent micro/nanorobots

Living materials, which include various types of cells, organelles, and biological components from animals, plants, and microorganisms, have become central to recent investigations in micro and nanorobotics. Living material-derived intelligent micro/nanorobots (LMNRs) are self-propelled devices that combine living materials with synthetic materials. By harnessing energy from external physical fields or biological sources, LMNRs can move autonomously and perform various biomedical functions, such as drug delivery, crossing biological barriers, medical imaging, and disease treatment. This review, from a biomimetic strategy perspective, summarized the latest advances in the design and biomedical applications of LMNRs. It provided a comprehensive overview of the living materials used to construct LMNRs, including mammalian cells, plants, and microorganisms while highlighting their biological properties and functions. Lastly, the review discussed the major challenges in this field and offered suggestions for future research that may help facilitate the clinical application of LMNRs in the near future.

Therapeutic potential of microalgae-derived natural compounds in diabetic wound healing: A comprehensive review

A variety of cell types and chemical systems are known to interact throughout the complex process of wound healing. In addition to being very uncomfortable for patients, wounds that do not heal properly or become chronic can place a heavy burden on society. The creation of novel treatment approaches can expedite the healing process, reduce the societal burden, and improve patient outcomes. Due to advancements in the field of biomedical science, microalgae have significant potential for use in diabetic wound healing and other wound healing applications. This review delves into the physiological process of wound healing, the use of microalgae in wound healing, and a detailed explanation of the wound healing roles of various microalgal originated bioactive compounds including alginate, pigments, fatty acids, proteins, polysaccharides, flavonoids and phenols. The study discusses the efficacy of photosynthetic hydrogels in drugs and oxygen delivery to the wounded area that is crucial for promoting a good healing process, as well as highlights the drawbacks and challenges involved in using microalgae for wound healing. Given the current state of the art in utilizing microalgae for wound care, this review provides new perspectives for further research, along with insightful advice and innovative suggestions for academics engaged in this area.

Advancements in Micro/Nanorobots in Medicine: Design, Actuation, and Transformative Application

In light of the ongoing technological transformation, embracing advancements that foster shared benefits is essential. Nanorobots, a breakthrough within nanotechnology, have demonstrated significant potential in fields such as medicine, where diagnostic and therapeutic applications are the primary focus areas. This review provides a comprehensive overview of nanotechnology, robots, and their evolving role in medical applications, particularly highlighting the use of nanorobots. Various design strategies and operational principles, including sensors, actuators, and nanocontrollers, are discussed based on prior research. Key nanorobot medical applications include biomedical imaging, biosensing, minimally invasive surgery, and targeted drug delivery, each utilizing advanced actuation technologies to enhance precision. The paper further examines recent progress in micro/nanorobot actuation and addresses important considerations for the future, including biocompatibility, control, navigation, delivery, targeting, safety, and ethical implications. This review offers a holistic perspective on how nanorobots can reshape medical practices, paving the way for precision medicine and improved patient outcomes.

Engineering Gas-Releasing Nanomaterials for Efficient Wound Healing

The escalating prevalence of tissue damage and its associated complications has elicited global apprehension. While nanomaterial-based wound healing exhibits significant potential in terms of curbing infections and surpassing conventional methods, unresolved concerns regarding nanomaterial controllability and precision remain unresolved, jeopardizing its practical applications. In recent years, a unique strategy for creating gas-releasing nanomaterials for wound repair has been proposed, involving the creation of gas-releasing nanomaterials to facilitate wound repair by generating gas donor moieties. The operational spatiotemporal responsiveness and broad-spectrum antibacterial properties of these gases, combined with their inability to generate bacterial resistance like traditional antibiotics, establish their efficacy in addressing chronic non-healing wounds, specifically diabetic foot ulcers (DFUs). In this review, we delve into the intricacies of wound healing process, emphasizing the chemical design, functionality, bactericidal activity, and potential of gas-release materials, encompassing NO, CO, H2S, O2, CO2, and H2, for effective wound healing. Furthermore, we explore the advancements in synergistic therapy utilizing these gases, aiming to enhance our overall comprehension of this field. The insights gleaned from this review will undoubtedly aid researchers and developers in the creation of promising gas-releasing nanomaterials, thus propelling efficient wound healing in the future.

Dual-strategy microneedles of bio‑oxygen therapy and artificial enzyme anti-oxidation for psoriasis treatment

Oxidative stress results from an imbalance between the production of free radicals by oxidants and their removal by antioxidants. Chronic oxidative stress is a key factor in inflammation, characterized by hypoxic microenvironments and elevated levels of reactive oxygen species (ROS). Psoriasis, a common chronic inflammatory skin disorder, profoundly impacts the physical and psychological well-being of affected individuals. In response to this, we have innovatively developed a core-shell structured Chlorella-Prussian Blue Complex (Z-PB), integrating dual therapeutic strategies of biological oxygen therapy and oxidative stress regulation to address psoriasis. The Z-PB leveraged the unique ability of Chlorella to generate dissolved oxygen under light, combined with the broad enzymatic activity of Prussian Blue (PB), to effectively ameliorate the oxidative stress in the chronic inflammatory microenvironment. Additionally, the Z-PB overcame challenges such as the survival of Chlorella in high ROS environments and the aggregation of nanoenzymes. The Z-PB-loaded hyaluronic acid microneedles (Z-PBHA/MNs) demonstrated excellent skin permeability, in vitro release profiles, and biocompatibility. These Z-PBHA/MNs had been shown to alleviate psoriasis induced by imiquimod (IMQ). Overall, the Z-PBHA/MNs incorporating both biological oxygen therapy and artificial enzyme antioxidants represented a promising and innovative therapeutic strategy for the treatment of psoriasis.

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.

Biohybrid Micro/Nanorobots: Pioneering the Next Generation of Medical Technology

Biohybrid micro/nanorobots hold a great potential for advancing biomedical research. These tiny structures, designed to mimic biological organisms, offer a promising method for targeted drug delivery, tissue engineering, biosensing/imaging, and cancer therapy, among other applications. The integration of biology and robotics opens new possibilities for minimally invasive surgeries and personalized healthcare solutions. The key challenges in the development of biohybrid micro/nanorobots include ensuring biocompatibility, addressing manufacturing scalability, enhancing navigation and localization capabilities, maintaining stability in dynamic biological environments, navigating regulatory hurdles, and successfully translating these innovative technologies into clinical applications. Herein, the recent advancements, challenges, and future perspectives related to the biomedical applications of biohybrid micro/nanorobots are described. Indeed, this review sheds light on the cutting-edge developments in this field, providing researchers with an updated overview of the current potential of biohybrid micro/nanorobots in the realm of biomedical applications, and offering insights into their practical applications. Furthermore, it delves into recent advancements in the field of biohybrid micro/nanorobotics, providing a comprehensive analysis of the current state-of-the-art technologies and their future applications in the biomedical field.

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.

Recent advances in microalgae encapsulation techniques for biomedical applications

Microalgae are microorganisms that are rich in bioactive compounds, including pigments, proteins, lipids, and polysaccharides. These compounds can be utilized for a number of biomedical purposes, including drug delivery, wound healing, and tissue engineering. Nevertheless, encapsulating microalgae cells and microalgae bioactive metabolites is vital to protect them and prevent premature degradation. This also enables the development of intelligent controlled release strategies for the bioactive compounds. This review outlines the most employed encapsulation techniques for microalgae, with a particular focus on their biomedical applications. These include ionic gelation, oil-in-water emulsions, and spray drying. Such techniques have been widely explored, due to their ability to protect sensitive compounds from degradation, enhance their stability, extend their shelf life, mask undesirable tastes or odours, control the release of bioactive compounds, and enable targeted delivery to specific sites within the body or environment. Moreover, a patent landscape analysis is also provided, allowing an overview of the microalgae encapsulation technology development applied to a variety of fields, including pharmaceuticals, cosmetics, food, and agriculture.

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.

Enhancing diabetic wound healing through anti-bacterial and promoting angiogenesis using dual-functional slow-release microspheres-loaded dermal scaffolds

Bacterial infections and the degeneration of the capillary network comprise the primary factors that contribute to the delayed healing of diabetic wounds. However, treatment modalities that cater to effective diabetic wounds healing in clinical settings are severely lacking. Herein, a dual-functional microsphere carrier was designed, which encapsulates polyhexamethylene biguanide (PHMB) or recombinant human vascular endothelial growth factor (rhVEGF) together. The in vitro release experiments demonstrated that the use of the microspheres ensured the sustained release of the drugs (PHMB or rhVEGF) over a period of 12 days. Additionally, the integration of these controlled-release microspheres into a dermal scaffold (DS-PLGA@PHMB/rhVEGF) imbued both antibacterial and angiogenic functions to the resulting material. Accordingly, the DS-PLGA@PHMB/rhVEGF scaffold exhibited potent antibacterial properties, effectively suppressing bacterial growth and providing a conducive environment for wound healing, thereby addressing the drawbacks associated with the susceptibility of rhVEGF to deactivation in inflammatory conditions. Additionally, the histological analysis revealed that the use of the DS-PLGA@PHMB/rhVEGF scaffold accelerated the process of wound healing by inhibiting inflammatory reactions, stimulating the production of collagen formation, and enhancing angiogenesis. This provides a novel solution for enhancing the antibacterial and vascularization capabilities of artificial dermal scaffolds, providing a beacon of hope for improving diabetic wound healing.

Light-Driven Microrobots for Targeted Drug Delivery

As a new micromanipulation tool with the advantages of small size, flexible movement and easy manipulation, light-driven microrobots have a wide range of prospects in biomedical fields such as drug targeting and cell manipulation. Recently, microrobots have been controlled in various ways, and light field has become a research hotspot by its advantages of noncontact manipulation, precise localization, fast response, and biocompatibility. It utilizes the force or deformation generated by the light field to precisely control the microrobot, and combines with the drug release technology to realize the targeted drug application. Therefore, this paper provides an overview of light-driven microrobots with drug targeting to provide new ideas for the manipulation of microrobots. Here, this paper briefly categorizes the driving mechanisms and materials of light-driven microrobots, which mainly include photothermal, photochemical, and biological. Then, typical designs of light-driven microrobots with different driving mechanisms and control strategies for multiple physical fields are summarized. Finally, the applications of microrobots in the fields of drug targeting and bioimaging are presented as well as the future prospects of light-driven microrobots in the biomedical field are demonstrated.

Metal-Organic Framework-Based Micro-/Nanomotors for Wastewater Remediation

Micro-/nanomotors (MNMs) in water remediation have garnered significant attention over the past two decades. More recently, metal-organic framework-based micro-/nanomotors (MOF-MNMs) have been applied for environmental remediation; however, a comprehensive summary of research in this research area is yet to be reported. Herein, a review is presented to cover the recent advances in MOF-MNMs and their various applications in wastewater remediation. The review presents a comprehensive introduction to MNMs, including different propulsion approaches, fabrication, and functionalization strategies, in addition to the unique features of MOF-MNMs. The conception and various synthetic routes of MOF-MNMs are extensively covered and the implementation of MOF-MNMs in water-related applications, including adsorption, degradation, sensing, and disinfection of different pollutants, is in depth discussed. Meanwhile, the propulsion and mechanism of action behind each MOF-MNM are systematically studied. Finally, the review provides insights into the challenges and perspectives to build more effective MOF-MNMs to cover versatile applications for wastewater treatment.

Biocompatible polymer-based micro/nanorobots for theranostic translational applications

Recently, micro/nanorobots (MNRs) with self-propulsion have emerged as a promising smart platform for diagnostic, therapeutic and theranostic applications. Especially, polymer-based MNRs have attracted huge attention due to their inherent biocompatibility and versatility, making them actively explored for various medical applications. As the translation of MNRs from laboratory to clinical settings is imperative, the use of appropriate polymers for MNRs is a key strategy, which can prompt the advancement of MNRs to the next phase. In this review, we describe the multifunctional versatile polymers in MNRs, and their biodegradability, motion control, cargo loading and release, adhesion, and other characteristics. After that, we review the theranostic applications of polymer-based MNRs to bioimaging, biosensing, drug delivery, and tissue engineering. Furthermore, we address the challenges that must be overcome to facilitate the translational development of polymeric MNRs with future perspectives. This review would provide valuable insights into the state-of-the-art technologies associated with polymeric MNRs and contribute to their progression for further clinical development.

3D-printed microrobots for biomedical applications

Microrobots, which can perform tasks in difficult-to-reach parts of the human body under their own or external power supply, are potential tools for biomedical applications, such as drug delivery, microsurgery, imaging and monitoring, tissue engineering, and sensors and actuators. Compared with traditional fabrication methods for microrobots, recent improvements in 3D printers enable them to print high-precision microrobots, breaking through the limitations of traditional micromanufacturing technologies that require high skills for operators and greatly shortening the design-to-production cycle. Here, this review first introduces typical 3D printing technologies used in microrobot manufacturing. Then, the structures of microrobots with different functions and application scenarios are discussed. Next, we summarize the materials (body materials, propulsion materials and intelligent materials) used in 3D microrobot manufacturing to complete body construction and realize biomedical applications (e.g., drug delivery, imaging and monitoring). Finally, the challenges and future prospects of 3D printed microrobots in biomedical applications are discussed in terms of materials, manufacturing and advancement.

Teicoplanin-Decorated Reduced Graphene Oxide Incorporated Silk Protein Hybrid Hydrogel for Accelerating Infectious Diabetic Wound Healing and Preventing Diabetic Foot Osteomyelitis

Developing hybrid hydrogel dressings with anti-inflammatory, antioxidant, angiogenetic, and antibiofilm activities with higher bone tissue penetrability to accelerate diabetic wound healing and prevent diabetic foot osteomyelitis (DFO) is highly desirable in managing diabetic wounds. Herein, the glycopeptide teicoplanin is used for the first time as a green reductant to chemically reduce graphene oxide (GO). The resulting teicoplanin-decorated reduced graphene oxide (rGO) is incorporated into a mixture of silk proteins (SP) and crosslinked with genipin to yield a physicochemically crosslinked rGO-SP hybrid hydrogel. This hybrid hydrogel exhibits high porosity, self-healing, shear-induced thinning, increased cell proliferation and migration, and mechanical properties suitable for tissue engineering. Moreover, the hybrid hydrogel eradicates bacterial biofilms with a high penetrability index in agar and hydroxyapatite disks covered with biofilms, mimicking bone tissue. In vivo, the hybrid hydrogel accelerates the healing of noninfected wounds in a diabetic rat and infected wounds in a diabetic mouse by upregulating anti-inflammatory cytokines and downregulating matrix metalloproteinase-9, promoting M2 macrophage polarization and angiogenesis. The implantation of hybrid hydrogel into the infected site of mouse tibia improves bone regeneration. Hence, the rGO-SP hybrid hydrogel can be a promising wound dressing for treating infectious diabetic wounds, providing a further advantage in preventing DFO.

Biohybrid Nanorobots Carrying Glycoengineered Extracellular Vesicles Promote Diabetic Wound Repair through Dual-Enhanced Cell and Tissue Penetration

Considerable progress has been made in the development of drug delivery systems for diabetic wounds. However, underlying drawbacks, such as low delivery efficiency and poor tissue permeability, have rarely been addressed. In this study, a multifunctional biohybrid nanorobot platform comprising an artificial unit and several biological components is constructed. The artificial unit is a magnetically driven nanorobot surface modified with antibacterial 2-hydroxypropyltrimethyl ammonium chloride chitosan, which enables the entire platform to move and has excellent tissue penetration capacity. The biological components are two-step engineered extracellular vesicles that are first loaded with mangiferin, a natural polyphenolic compound with antioxidant properties, and then glycoengineered on the surface to enhance cellular uptake efficiency. As expected, the platform is more easily absorbed by endothelial cells and fibroblasts and exhibits outstanding dermal penetration performance and antioxidant properties. Encouraging results are also observed in infected diabetic wound models, showing improved wound re-epithelialization, collagen deposition, angiogenesis, and accelerated wound healing. Collectively, a biohybrid nanorobot platform that possesses the functionalities of both artificial units and biological components serves as an efficient delivery system to promote diabetic wound repair through dual-enhanced cell and tissue penetration and multistep interventions.

Novel Biomaterials for Wound Healing and Tissue Regeneration

Skin is the first defense barrier of the human body, which can resist the invasion of external dust, microorganisms and other pollutants, and ensure that the human body maintains the homeostasis of the internal environment. Once the skin is damaged, the health threat to the human body will increase. Wound repair and the human internal environment are a dynamic process. How to effectively accelerate the healing of wounds without affecting the internal environment of the human body and guarantee that the repaired tissue retains its original function as much as possible has become a research hotspot. With the advancement of technology, researchers have combined new technologies to develop and prepare various types of materials for wound healing. This article will introduce the wound repair materials developed and prepared in recent years from three types: nanofibers, composite hydrogels, and other new materials. The paper aims to provide reference for researchers in related fields to develop and prepare multifunctional materials. This may be helpful to design more ideal materials for clinical application, and then achieve better wound healing and regeneration effects.

A Hemoglobin Bionics-Based System for Combating Antibiotic Resistance in Chronic Diabetic Wounds via Iron Homeostasis Regulation

Owing to the increased tissue iron accumulation in patients with diabetes, microorganisms may activate high expression of iron-involved metabolic pathways, leading to the exacerbation of bacterial infections and disruption of systemic glucose metabolism. Therefore, an on-demand transdermal dosing approach that utilizes iron homeostasis regulation to combat antimicrobial resistance is a promising strategy to address the challenges associated with low administration bioavailability and high antibiotic resistance in treating infected diabetic wounds. Here, it is aimed to propose an effective therapy based on hemoglobin bionics to induce disturbances in bacterial iron homeostasis. The preferred "iron cargo" is synthesized by protoporphyrin IX chelated with dopamine and gallium (PDGa), and is delivered via a glucose/pH-responsive microneedle bandage (PDGa@GMB). The PDGa@GMB downregulates the expression levels of the iron uptake regulator (Fur) and the peroxide response regulator (perR) in Staphylococcus aureus, leading to iron nutrient starvation and oxidative stress, ultimately suppressing iron-dependent bacterial activities. Consequently, PDGa@GMB demonstrates insusceptibility to genetic resistance while maintaining sustainable antimicrobial effects (>90%) against resistant strains of both S. aureus and E. coli, and accelerates tissue recovery (<20 d). Overall, PDGa@GMB not only counteracts antibiotic resistance but also holds tremendous potential in mediating microbial-host crosstalk, synergistically attenuating pathogen virulence and pathogenicity.

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.

A nano-composite hyaluronic acid-based hydrogel efficiently antibacterial and scavenges ROS for promoting infected diabetic wound healing

Diabetic wound infection brings chronic pain to patients and the therapy remains a crucial challenge owing to the disruption of the internal microenvironment. Herein, we report a nano-composite hydrogel (ZnO@HN) based on ZnO nanoparticles and a photo-trigging hyaluronic acid which is modified by o-nitrobenzene (NB), to accelerate infected diabetic wound healing. The diameter of the prepared ZnO nanoparticle is about 50 nm. X-ray photoelectron spectroscopy (XPS) analysis reveals that the coordinate bond binds ZnO in the hydrogel, rather than simple physical restraint. ZnO@HN possesses efficient antioxidant capacity and it can scavenge DPPH about 40 % in 2 h and inhibit H2O2 >50 % in 8 h. The nano-composite hydrogel also exhibits satisfactory antibacterial capacity (58.35 % against E. coli and 64.03 % against S. aureus for 6 h). In vitro tests suggest that ZnO@HN is biocompatible and promotes cell proliferation. In vivo experiments reveal that the hydrogel can accelerate the formation of new blood vessels and hair follicles. Histological analysis exhibits decreased macrophages, increased myofibroblasts, downregulated TNF-α expression, and enhanced VEGFA expression during wound healing. In conclusion, ZnO@HN could be a promising candidate for treating intractable infected diabetic skin defection.

Hypoxic environment of wounds and photosynthesis-based oxygen therapy

The hypoxic environment is among the most important factors that complicates the healing of chronic wounds, such as venous leg ulcers, pressure injuries and diabetic foot ulcers, which seriously affects the quality of life of patients. Various oxygen supply treatments are used in clinical practice to improve the hypoxic environment at the wound site. However, problems still occur, such as insufficient oxygen supply, short oxygen infusion time and potential biosafety risks. In recent years, artificial photosynthetic systems have become a research hotspot in the fields of materials and energy. Photosynthesis is expected to improve the oxygen level at wound sites and promote wound healing because the method provides a continuous oxygen supply and has good biosafety. In this paper, oxygen treatment methods for wounds are reviewed, and the oxygen supply principle and construction of artificial photosynthesis systems are described. Finally, research progress on the photosynthetic oxygen production system to promote wound healing is summarized.

Study on Structural Design and Motion Characteristics of Magnetic Helical Soft Microrobots with Drug-Carrying Function

Magnetic soft microrobots have a wide range of applications in targeted drug therapy, cell manipulation, and other aspects. Currently, the research on magnetic soft microrobots is still in the exploratory stage, and most of the research focuses on a single helical structure, which has limited space to perform drug-carrying tasks efficiently and cannot satisfy specific medical goals in terms of propulsion speed. Therefore, balancing the motion speed and drug-carrying performance is a current challenge to overcome. In this paper, a magnetically controlled cone-helix soft microrobot structure with a drug-carrying function is proposed, its helical propulsion mechanism is deduced, a dynamical model is constructed, and the microrobot structure is prepared using femtosecond laser two-photon polymerization three-dimensional printing technology for magnetic drive control experiments. The results show that under the premise of ensuring sufficient drug-carrying space, the microrobot structure proposed in this paper can realize helical propulsion quickly and stably, and the speed of motion increases with increases in the frequency of the rotating magnetic field. The microrobot with a larger cavity diameter and a larger helical pitch exhibits faster rotary advancement speed, while the microrobot with a smaller helical height and a smaller helical cone angle outperforms other structures with the same feature sizes. The microrobot with a cone angle of 0.2 rad, a helical pitch of 100 µm, a helical height of 220 µm, and a cavity diameter of 80 µm achieves a maximum longitudinal motion speed of 390 µm/s.

Dielectrophoretic characterization and selection of non-spherical flagellate algae in parallel channels with right-angle bipolar electrodes

Non-spherical flagellate algae play an increasingly significant role in handling problematic issues as versatile biological micro/nanorobots and resources of valuable bioproducts. However, the commensalism of flagellate algae with distinct structures and constituents causes considerable difficulties in their further biological utilization. Therefore, it is imperative to develop a novel method to realize high-efficiency selection of non-spherical flagellate algae in a non-invasive manner. Enthused by these, we proposed a novel method to accomplish the selection of flagellate algae based on the numerical and experimental investigation of dielectrophoretic characterizations of flagellate algae. Firstly, an arbitrary Lagrangian-Eulerian method was utilized to study the electro-orientation and dielectrophoretic assembly process of spindle-shaped and ellipsoid-shaped cells in a uniform electric field. Secondly, we studied the equilibrium state of spherical, ellipsoid-shaped, and spindle-shaped cells under positive DEP forces actuated by right-angle bipolar electrodes. Thirdly, we investigated the dielectrophoretic assembly and escape processes of the non-spherical flagellate algae in continuous flow to explore their influences on the selection. Fourthly, freshwater flagellate algae (Euglena, H. pluvialis, and C. reinhardtii) and marine ones (Euglena, Dunaliella salina, and Platymonas) were separated to validate the feasibility and adaptability of this method. Finally, this approach was engineered in the selection of Euglena cells with high viability and motility. This method presents immense prospects in the selection of pure non-spherical flagellate algae with high motility for chronic wound healing, bio-micromotor construction, and decontamination with advantages of no sheath, strong reliability, and shape-insensitivity.

AI-enhanced biomedical micro/nanorobots in microfluidics

Human beings encompass sophisticated microcirculation and microenvironments, incorporating a broad spectrum of microfluidic systems that adopt fundamental roles in orchestrating physiological mechanisms. In vitro recapitulation of human microenvironments based on lab-on-a-chip technology represents a critical paradigm to better understand the intricate mechanisms. Moreover, the advent of micro/nanorobotics provides brand new perspectives and dynamic tools for elucidating the complex process in microfluidics. Currently, artificial intelligence (AI) has endowed micro/nanorobots (MNRs) with unprecedented benefits, such as material synthesis, optimal design, fabrication, and swarm behavior. Using advanced AI algorithms, the motion control, environment perception, and swarm intelligence of MNRs in microfluidics are significantly enhanced. This emerging interdisciplinary research trend holds great potential to propel biomedical research to the forefront and make valuable contributions to human health. Herein, we initially introduce the AI algorithms integral to the development of MNRs. We briefly revisit the components, designs, and fabrication techniques adopted by robots in microfluidics with an emphasis on the application of AI. Then, we review the latest research pertinent to AI-enhanced MNRs, focusing on their motion control, sensing abilities, and intricate collective behavior in microfluidics. Furthermore, we spotlight biomedical domains that are already witnessing or will undergo game-changing evolution based on AI-enhanced MNRs. Finally, we identify the current challenges that hinder the practical use of the pioneering interdisciplinary technology.

Macrophages-Based Biohybrid Microrobots for Breast Cancer Photothermal Immunotherapy by Inducing Pyroptosis

Pyroptosis-based immunotherapy can escape drug resistance as well as inhibit metastasis. It is urgently required to develop a delivery platform to induce targeted tumor-specific pyroptosis for cancer immunotherapy. Herein, macrophages-based biohybrid microrobots (IDN@MC) are constructed with IR-macrophage and decitabine-loaded Metal-organic frameworks (DZNPs). The integration of fluorescence photosensitizers and pH-sensitive DZNPs endow the microrobots properties such as photothermal conversion, fluorescent navigation, targeted drug delivery, and controlled drug release. In light of the inherent tumor targeting, tumor accumulation of IDN@MC is facilitated. Due to the sustained release of decitabine from packaged DZNPs, the host macrophages are differentiated into M1 phenotypes to exert the tumor phagocytosis at the tumor site, directly transporting the therapeutic agents into cancer cells. With laser control, the rapid and durable caspase 3-cleaved gasdermin E (GSDME)-related tumor pyroptosis is achieved with combined photothermal-chemotherapy, releasing inflammatory factors such as lactate dehydrogenase and interleukin-18. Subsequently, the robust and adaptive immune response is primed with dendritic cell maturation to initiate T-cell clone expansion and modulation of the immune suppressive microenvironment, thus enhancing the tumor immunotherapy to inhibit tumor proliferation and metastasis. This macrophages-based biohybrid microrobot is an efficient strategy for breast cancer treatment to trigger photo-induced pyroptosis and augment the immune response.

Biomimetic hybrid nanovesicles improve infected diabetic wound via enhanced targeted delivery

Infected diabetic wounds have been raising the global medical burden because of its high occurrence and resulting risk of amputation. Impaired endothelium has been well-documented as one of the most critical reasons for unhealed wounds. Recently, endothelial cell-derived nanovesicles (NVs) were reported to facilitate angiogenesis, whereas their efficacy is limited in infected diabetic wounds because of the complex niche. In this study, extrusion-derived endothelial NVs were manufactured and then hybridized with rhamnolipid liposomes to obtain biomimetic hybrid nanovesicles (HNVs). The HNVs were biocompatible and achieved endothelium-targeted delivery through membrane CXCR4-mediated homologous homing. More importantly, the HNVs exhibited better penetration and antibacterial activity compared with NVs, which further promote the intrinsic endothelium targeting in infected diabetic wounds. Therefore, the present research has established a novel bioactive delivery system-HNV with enhanced targeting, penetration, and antibacterial activity-which might be an encouraging strategy for infected diabetic wound treatment.

Biohybrid Microalgae Robots: Design, Fabrication, Materials, and Applications

The integration of microorganisms and engineered artificial components has shown considerable promise for creating biohybrid microrobots. The unique features of microalgae make them attractive candidates as natural actuation materials for the design of biohybrid microrobotic systems. In this review, microalgae-based biohybrid microrobots are introduced for diverse biomedical and environmental applications. The distinct propulsion and phototaxis behaviors of green microalgae, as well as important properties from other photosynthetic microalga systems (blue-green algae and diatom) that are crucial to constructing powerful biohybrid microrobots, will be described first. Then the focus is on chemical and physical routes for functionalizing the algae surface with diverse reactive materials toward the fabrication of advanced biohybrid microalgae robots. Finally, representative applications of such algae-driven microrobots are presented, including drug delivery, imaging, and water decontamination, highlighting the distinct advantages of these active biohybrid robots, along with future prospects and challenges.

Photopolymerizable, immunomodulatory hydrogels of gelatin methacryloyl and carboxymethyl chitosan as all-in-one strategic dressing for wound healing

Microenvironment regeneration in wound tissue is crucial for wound healing. However, achieving desirable wound microenvironment regeneration involves multiple stages, including hemostasis, inflammation, proliferation, and remodeling. Traditional wound dressings face challenges in fully manipulating all these stages to achieve quick and complete wound healing. Herein, we present a VEGF-loaded, versatile wound dressing hydrogel based on gelatin methacryloyl (GelMA) and carboxymethyl chitosan (CMCS), which could be easily fabricated using UV irradiation. The newly designed GelMA-CMCS@VEGF hydrogel not only exhibited strong tissue adhesion capacity due to the interactions between CMCS active groups and biological tissues, but also possessed desirable extensible properties for frequently moving skins and joints. Furthermore, the hydrogel demonstrates exceptional abilities in blood cell coagulation, hemostasis and cell recruitment, leading to the promotion of endothelial cells proliferation, adhesion, migration and angiogenesis. Additionally, in vivo studies demonstrated that the hydrogel drastically shortened hemostatic time, and achieved satisfactory therapeutic efficacy by suppressing inflammation, modulating M1/M2 polarization of macrophages, significantly promoting collagen deposition, stimulating angiogenesis, epithelialization and tissue remodeling. This work contributes to the design of versatile hydrogel dressings for rapid and complete wound healing therapy.

CaO2-Cu2O micromotors accelerate infected wound healing through antibacterial functions, hemostasis, improved cell migration, and inflammatory regulation

During the wound tissue healing process, the relatively weak driving forces of tissue barriers and concentration gradients lead to a slow and inefficient penetration of bioactive substances into the wound area, consequently showing an impact on the effectiveness of deep wound healing. To overcome these challenges, we constructed biocompatible CaO2-Cu2O "micromotors". These micromotors reacted with the fluids at the wound site, releasing oxygen bubbles and propelling particles deep into the wound tissue. In vitro experimental results revealed that these micromotors not only exhibited antibacterial and hemostatic functions but also facilitated the migration of dermal fibroblasts and vascular endothelial cells, while modulating the inflammatory microenvironment. A methicillin-resistant Staphylococcus aureus infected full-thickness-wound model was created in rats, in which CaO2-Cu2O micromotors markedly expedited the wound healing process. Specifically, CaO2-Cu2O provided a sterile microenvironment for wounds and increased the amounts of M1-type macrophages during infection and inflammation. During the proliferation and remodeling stages, the amount of M1 macrophages gradually decreased, while the amount of M2 macrophages increased, and CaO2-Cu2O did not prolong the inflammatory period. Furthermore, the introduction of a regenerated silk fibroin (RSF) film on the wound surface successfully enhanced the therapeutic effects of CaO2-Cu2O against the infected wound. The combined application of oxygen-producing CaO2-Cu2O micromotors and a RSF film demonstrates significant therapeutic potential and emerges as a promising candidate for the treatment of infected wounds.

Construction of micro-nano robots: living cells and functionalized biological cell membranes

Micro-nano robots have emerged as a promising research field with vast potential applications in biomedicine. The motor is the key component of micro-nano robot research, and the design of the motor is crucial. Among the most commonly used motors are those derived from living cells such as bacteria with flagella, sperm, and algal cells. Additionally, scientists have developed numerous self-adaptive biomimetic motors with biological functions, primarily cell membrane functionalized micromotors. This novel type of motor exhibits remarkable performance in complex media. This paper provides a comprehensive review of the structure and performance of micro-nano robots that utilize living cells and functionalized biological cell membranes. We also discuss potential practical applications of these mirco-nano robots as well as potential challenges that may arise in future development.

Preparation of Antibacterial, Arginine-Modified Ag Nanoclusters in the Hydrogel Used for Promoting Diabetic, Infected Wound Healing

Diabetic foot ulcers with complex healing wounds accompanied by bacterial infection are considered a significant clinical problem which are made worse by the lack of effective treatments. Traditional antibiotics and dressings have failed to address wound infection and healing, and multifunctional combination therapies are attractive for treating chronic wounds. In this study, arginine (Arg) was loaded onto the surface of silver nanoclusters and encapsulated in a hydrogel to achieve antibacterial, anti-inflammatory, angiogenic, and collagen deposition functions through the slow release of Arg combined with silver nanoclusters. In vitro studies indicated that Arg-Ag@H composites inhibited methicillin-resistant Staphylococcus aureus and Escherichia coli by 94 and 97%, respectively. The inhibition of bacterial biofilms reached 85%, and the migration ability of human venous endothelial cells (HUVECs) increased by 50%. In vitro studies showed that Arg-Ag@H composites increased the healing area of wounds by 26% and resulted in a 98% skin wound-healing rate. Safety studies confirmed the excellent biocompatibility of Arg-Ag@H. The results suggest that Arg-Ag@H offers new possibilities for treating chronic diabetic wounds.

Microbial Cells as a Microrobots: From Drug Delivery to Advanced Biosensors

The presented review focused on the microbial cell based system. This approach is based on the application of microorganisms as the main part of a robot that is responsible for the motility, cargo shipping, and in some cases, the production of useful chemicals. Living cells in such microrobots have both advantages and disadvantages. Regarding the advantages, it is necessary to mention the motility of cells, which can be natural chemotaxis or phototaxis, depending on the organism. There are approaches to make cells magnetotactic by adding nanoparticles to their surface. Today, the results of the development of such microrobots have been widely discussed. It has been shown that there is a possibility of combining different types of taxis to enhance the control level of the microrobots based on the microorganisms' cells and the efficiency of the solving task. Another advantage is the possibility of applying the whole potential of synthetic biology to make the behavior of the cells more controllable and complex. Biosynthesis of the cargo, advanced sensing, on/off switches, and other promising approaches are discussed within the context of the application for the microrobots. Thus, a synthetic biology application offers significant perspectives on microbial cell based microrobot development. Disadvantages that follow from the nature of microbial cells such as the number of external factors influence the cells, potential immune reaction, etc. They provide several limitations in the application, but do not decrease the bright perspectives of microrobots based on the cells of the microorganisms.