Precise Control of Customized Macrophage Cell Robot for Targeted Therapy of Solid Tumors with Minimal Invasion

Magnetically actuated cisplatin-loaded nanoparticle collectives enhance drug penetration for potentiated ovarian cancer chemotherapy

Chemotherapy is the main clinical treatment for ovarian cancer, but still faces challenges of low drug targeting efficiency and insufficient drug permeability. Drug-loaded nanoparticle collectives, which are actuated by magnetic field, could be targeted to a designated location and achieve targeted drug delivery. In this work, we report a strategy that utilizes magnetic mesoporous silica nanoparticles loaded with cis-diaminodichloroplatinum (Fe3O4@SiO2-CDDP) for targeted delivery of chemotherapeutic drugs and enhances penetration into deep tumors. The Fe3O4@SiO2-CDDP collectives actively moved to the target tumor site, and this movement was regulated by a magnetic actuation system. Under the action of a torque-force hybrid magnetic field (TFMF), Fe3O4@SiO2-CDDP could further penetrate into the interior of tumors and achieve pH-responsive drug release in the tumor environment. The feasibility of this strategy was verified in three-dimensional cell spheres in vitro and in a tumor-bearing mouse model in vivo. This magnetically actuated nanoparticle collectives enhanced drug penetration strategy provides a new paradigm for targeted drug delivery and potentiated tumor therapy.

Stimuli-Mediated Macrophage Switching, Unraveling the Dynamics at the Nanoplatforms-Macrophage Interface

Macrophages play an essential role in immunotherapy and tissue regeneration owing to their remarkable plasticity and diverse functions. Recent bioengineering developments have focused on using external physical stimuli such as electric and magnetic fields, temperature, and compressive stress, among others, on micro/nanostructures to induce macrophage polarization, thereby increasing their therapeutic potential. However, it is difficult to find a concise review of the interaction between physical stimuli, advanced micro/nanostructures, and macrophage polarization. This review examines the present research on physical stimuli-induced macrophage polarization on micro/nanoplatforms, emphasizing the synergistic role of fabricated structure and stimulation for advanced immunotherapy and tissue regeneration. A concise overview of the research advancements investigating the impact of physical stimuli, including electric fields, magnetic fields, compressive forces, fluid shear stress, photothermal stimuli, and multiple stimulations on the polarization of macrophages within complex engineered structures, is provided. The prospective implications of these strategies in regenerative medicine and immunotherapeutic approaches are highlighted. This review will aid in creating stimuli-responsive platforms for immunomodulation and tissue regeneration.

ZIF-8-Encapsulated Pexidartinib Delivery via Targeted Peptide-Modified M1 Macrophages Attenuates MDSC-Mediated Immunosuppression in Osteosarcoma

Adoptive cellular therapy is a promising strategy for cancer treatment. However, the effectiveness of this therapy is limited by its intricate and immunosuppressive tumor microenvironment. In this study, a targeted therapeutic strategy for macrophage loading of drugs is presented to enhance anti-tumor efficacy of macrophages. K7M2-target peptide (KTP) is used to modify macrophages to enhance their affinity for tumors. Pexidartinib-loaded ZIF-8 nanoparticles (P@ZIF-8) are loaded into macrophages to synergistically alleviate the immunosuppressive tumor microenvironment synergistically. Thus, the M1 macrophages decorated with KTP carried P@ZIF-8 and are named P@ZIF/M1-KTP. The tumor volumes in the P@ZIF/M1-KTP group are significantly smaller than those in the other groups, indicating that P@ZIF/M1-KTP exhibited enhanced anti-tumor efficacy. Mechanistically, an increased ratio of CD4+ T cells and a decreased ratio of MDSCs in the tumor tissues after treatment with P@ZIF/M1-KTP indicated that it can alleviate the immunosuppressive tumor microenvironment. RNA-seq further confirms the enhanced immune cell function. Consequently, P@ZIF/M1-KTP has great potential as a novel adoptive cellular therapeutic strategy for tumors.

Engineering unactivated platelets for targeted drug delivery

As a vital component of blood, platelets play crucial roles in hemostasis and maintaining vascular integrity, and actively participate in inflammation and immune regulation. The unique biological properties of natural platelets have enabled their utilization as drug delivery vehicles. The advancement and integration of various techniques, including biological, chemical, and physicochemical methods, have enabled the preparation of engineered platelets. Platelets can serve as drug delivery platforms combined with immunotherapy and chemokine therapy to enhance their therapeutic impact. This review focuses on the recent advancements in the application of unactivated platelets for drug delivery. The construction strategies of engineered platelets are comprehensively summarized, encompassing internal loading, surface modification, and genetic engineering techniques. Engineered platelets hold vast potential for treating cardiovascular diseases, cancers, and infectious diseases. Furthermore, the challenges and potential considerations in creating engineered platelets with natural activity are discussed.

Rechargeable Afterglow Nanotorches for In Vivo Tracing of Cell-Based Microrobots

As one of the self-luminescence imaging approaches that require pre-illumination instead of real-time light excitation, afterglow luminescence imaging has attracted increasing enthusiasm to circumvent tissue autofluorescence. In this work, we developed organic afterglow luminescent nanoprobe (nanotorch), which could emit persistent luminescence more than 10 days upon single light excitation. More importantly, the nanotorch could be remote charged by 660 nm light in a non-invasive manner, which showed great potential for real-time tracing the location of macrophage cell-based microrobots.

Dual-Functional Laser-Guided Magnetic Nanorobot Collectives against Gravity for On-Demand Thermo-Chemotherapy of Peritoneal Metastasis

Combining hyperthermic intraperitoneal chemotherapy with cytoreductive surgery is the main treatment modality for peritoneal metastatic (PM) carcinoma despite the off-target effects of chemotherapy drugs and the ineluctable side effects of total abdominal heating. Herein, a laser-integrated magnetic actuation system that actively delivers doxorubicin (DOX)-grafted magnetic nanorobot collectives to the tumor site in model mice for local hyperthermia and chemotherapy is reported. With intraluminal movements controlled by a torque-force hybrid magnetic field, these magnetic nanorobots gather at a fixed point coinciding with the position of the localization laser, moving upward against gravity over a long distance and targeting tumor sites under ultrasound imaging guidance. Because aggregation enhances the photothermal effect, controlled local DOX release is achieved under near-infrared laser irradiation. The targeted on-demand photothermal therapy of multiple PM carcinomas while minimizing off-target tissue damage is demonstrated. Additionally, a localization/treatment dual-functional laser-integrated magnetic actuation system is developed and validated in vivo, offering a potentially clinically feasible drug delivery strategy for targeting PM and other intraluminal tumors.

Engineering Magnetic Soft and Reconfigurable Robots

Magnetic control has gained popularity recently due to its ability to enhance soft robots with reconfigurability and untethered maneuverability, among other capabilities. Several advancements in the fabrication and application of reconfigurable magnetic soft robots have been reported. This review summarizes novel fabrication techniques for designing magnetic soft robots, including chemical and physical methods. Mechanisms of reconfigurability and deformation properties are discussed in detail. The maneuverability of magnetic soft robots is then briefly discussed. Finally, the present challenges and possible future work in designing reconfigurable magnetic soft robots for biomedical applications are identified.

Biocompatible Ferrofluid-Based Millirobot for Tumor Photothermal Therapy in Near-Infrared-II Window

Ferrofluidic robots with excellent deformability and controllability have been intensively studied recently. However, most of these studies are in vitro and the use of ferrofluids for in vivo medicinal applications remains a big challenge. The application of ferrofluidic robots to the body requires the solution of many key problems. In this study, biocompatibility, controllability, and tumor-killing efficacy are considered when creating a ferrofluid-based millirobot for in vivo tumor-targeted therapy. For biocompatibility problems, corn oil is used specifically for the ferrofluid robot. In addition, a control system is built that enables a 3D magnetic drive to be implemented in complex biological media. Using the photothermal conversion property of 1064 nm, the ferrofluid robot can kill tumor cells in vitro; inhibit tumor volume, destroy the tumor interstitium, increase tumor cell apoptosis, and inhibit tumor cell proliferation in vivo. This study provides a reference for ferrofluid-based millirobots to achieve targeted therapies in vivo.

Cell-Based Micro/Nano-Robots for Biomedical Applications: A Review

Micro/nano-robots are powerful tools for biomedical applications and are applied in disease diagnosis, tumor imaging, drug delivery, and targeted therapy. Among the various types of micro-robots, cell-based micro-robots exhibit unique properties because of their different cell sources. In combination with various actuation methods, particularly externally propelled methods, cell-based microrobots have enormous potential for biomedical applications. This review introduces recent progress and applications of cell-based micro/nano-robots. Different actuation methods for micro/nano-robots are summarized, and cell-based micro-robots with different cell templates are introduced. Furthermore, the review focuses on the combination of cell-based micro/nano-robots with precise control using different external fields. Potential challenges, further prospects, and clinical translations are also discussed.

Macrophage-Based Microrobots for Anticancer Therapy: Recent Progress and Future Perspectives

Macrophages, which are part of the mononuclear phagocytic system, possess sensory receptors that enable them to target cancer cells. In addition, they are able to engulf large amounts of particles through phagocytosis, suggesting a potential "Trojan horse" drug delivery approach to tumors by facilitating the engulfment of drug-hidden particles by macrophages. Recent research has focused on the development of macrophage-based microrobots for anticancer therapy, showing promising results and potential for clinical applications. In this review, we summarize the recent development of macrophage-based microrobot research for anticancer therapy. First, we discuss the types of macrophage cells used in the development of these microrobots, the common payloads they carry, and various targeting strategies utilized to guide the microrobots to cancer sites, such as biological, chemical, acoustic, and magnetic actuations. Subsequently, we analyze the applications of these microrobots in different cancer treatment modalities, including photothermal therapy, chemotherapy, immunotherapy, and various synergistic combination therapies. Finally, we present future outlooks for the development of macrophage-based microrobots.

Magnetically Actuated Biodegradable Nanorobots for Active Immunotherapy

An efficient and cost-effective therapeutic vaccine is highly desirable for the prevention and treatment of cancer, which helps to strengthen the immune system and activate the T cell immune response. However, initiating such an adaptive immune response efficiently remains challenging, especially the deficient antigen presentation by dendritic cells (DCs) in the immunosuppressive tumor microenvironment. Herein, an efficient and dynamic antigen delivery system based on the magnetically actuated OVA-CaCO3 -SPIO robots (OCS-robots) is rationally designed for active immunotherapy. Taking advantage of the unique dynamic features, the developed OCS-robots achieve controllable motion capability under the rotating magnetic field. Specifically, with the active motion, the acid-responsiveness of OCS-robots is beneficial for the tumor acidity attenuating and lysosome escape as well as the subsequent antigen cross-presentation of DCs. Furthermore, the dynamic OCS-robots boost the crosstalk between the DCs and antigens, which displays prominent tumor immunotherapy effect on melanoma through cytotoxic T lymphocytes (CTLs). Such a strategy of dynamic vaccine delivery system enables the active activation of immune system based on the magnetically actuated OCS-robots, which presents a plausible paradigm for incredibly efficient cancer immunotherapy by designing multifunctional and novel robot platforms in the future.

Microrobots for Biomedicine: Unsolved Challenges and Opportunities for Translation

Microrobots are being explored for biomedical applications, such as drug delivery, biological cargo transport, and minimally invasive surgery. However, current efforts largely focus on proof-of-concept studies with nontranslatable materials through a "design-and-apply" approach, limiting the potential for clinical adaptation. While these proof-of-concept studies have been key to advancing microrobot technologies, we believe that the distinguishing capabilities of microrobots will be most readily brought to patient bedsides through a "design-by-problem" approach, which involves focusing on unsolved problems to inform the design of microrobots with practical capabilities. As outlined below, we propose that the clinical translation of microrobots will be accelerated by a judicious choice of target applications, improved delivery considerations, and the rational selection of translation-ready biomaterials, ultimately reducing patient burden and enhancing the efficacy of therapeutic drugs for difficult-to-treat diseases.

Microfluidic Approaches for Microactuators: From Fabrication, Actuation, to Functionalization

Microactuators can autonomously convert external energy into specific mechanical motions. With the feature sizes varying from the micrometer to millimeter scale, microactuators offer many operation and control possibilities for miniaturized devices. In recent years, advanced microfluidic techniques have revolutionized the fabrication, actuation, and functionalization of microactuators. Microfluidics can not only facilitate fabrication with continuously changing materials but also deliver various signals to stimulate the microactuators as desired, and consequently improve microfluidic chips with multiple functions. Herein, this cross-field that systematically correlates microactuator properties and microfluidic functions is comprehensively reviewed. The fabrication strategies are classified into two types according to the flow state of the microfluids: stop-flow and continuous-flow prototyping. The working mechanism of microactuators in microfluidic chips is discussed in detail. Finally, the applications of microactuator-enriched functional chips, which include tunable imaging devices, micromanipulation tools, micromotors, and microsensors, are summarized. The existing challenges and future perspectives are also discussed. It is believed that with the rapid progress of this cutting-edge field, intelligent microsystems may realize high-throughput manipulation, characterization, and analysis of tiny objects and find broad applications in various fields, such as tissue engineering, micro/nanorobotics, and analytical devices.

Chemotaxis-guided Self-propelled Macrophage Motor for Targeted Treatment of Acute Pneumonia

Immune cells exhibit great potential as carriers of nanomedicine, attributed to their high tolerance to internalized nanomaterials and targeted accumulation in inflammatory tissues. However, the premature efflux of internalized nanomedicine during systemic delivery and slow infiltration into inflammatory tissues have limited their translational applications. Herein, a motorized cell platform as a nanomedicine carrier for highly efficient accumulation and infiltration in the inflammatory lungs and effective treatment of acute pneumonia are reported. β-Cyclodextrin and adamantane respectively modified manganese dioxide nanoparticles are intracellularly self-assembled into large aggregates mediated via host-guest interactions, to effectively inhibit the efflux of nanoparticles, catalytically consume/deplete H₂ O₂ to alleviate inflammation, and generate O₂ to propel macrophage movement for rapid tissue infiltration. With curcumin loaded into MnO₂ nanoparticles, macrophages carry the intracellular nano-assemblies rapidly into the inflammatory lungs via chemotaxis-guided, self-propelled movement, for effective treatment of acute pneumonia via immunoregulation induced by curcumin and the aggregates.

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.

Ultrafast Miniature Robotic Swimmers with Upstream Motility

With the development of materials science and micro-nano fabrication techniques, miniature soft robots at millimeter or submillimeter size can be manufactured and actuated remotely. The small-scaled robots have the unique capability to access hard-to-reach regions in the human body in a noninvasive manner. To date, it is still challenging for miniature robots to accurately move in the diverse and dynamic environments in the human body (e.g., in blood flow). To effectively locomote in the vascular system, miniature swimmers with upstream swimming capability are required. Herein, we design and fabricate a miniature robotic swimmer capable of performing ultrafast swimming in a fluidic environment. The maximum velocity of the swimmer in water is 30 cm/s, which is 60 body lengths. Moreover, in a tubular environment, the swimmer can still obtain a swimming velocity of 17 cm/s. The swimmer can also perform upstream swimming in a tubular environment with a velocity of 5 cm/s when the flow speed is 10 cm/s. The ultrasound-guided navigation of the swimmer in a phantom mimicking a blood vessel is also realized. This work gives insight into the design of agile undulatory milliswimmers for future biomedical applications.

Biophysical heterogeneity of myeloid-derived microenvironment to regulate resistance to cancer immunotherapy

Despite the advances in immunotherapy for cancer treatment, patients still obtain limited benefits, mostly owing to unrestrained tumour self-expansion and immune evasion that exploits immunoregulatory mechanisms. Traditionally, myeloid cells have a dominantly immunosuppressive role. However, the complicated populations of the myeloid cells and their multilateral interactions with tumour/stromal/lymphoid cells and physical abnormalities in the tumour microenvironment (TME) determine their heterogeneous functions in tumour development and immune response. Tumour-associated myeloid cells (TAMCs) include monocytes, tumour-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and granulocytes. Single-cell profiling revealed heterogeneous TAMCs composition, sub-types, and transcriptomic signatures across 15 human cancer types. We systematically reviewed the biophysical heterogeneity of TAMC composition and pro/anti-tumoral and immuno-suppressive/stimulating properties of myeloid-derived microenvironments. We also summarised comprehensive clinical strategies to overcome resistance to immunotherapy from three dimensions: targeting TAMCs, reversing physical abnormalities, utilising nanomedicines, and finally, put forward futuristic perspectives for scientific and clinical research.

Nanocarriers for intracellular co-delivery of proteins and small-molecule drugs for cancer therapy

In the past few decades, the combination of proteins and small-molecule drugs has made tremendous progress in cancer treatment, but it is still not satisfactory. Because there are great differences in molecular weight, water solubility, stability, pharmacokinetics, biodistribution, and the ways of release and action between macromolecular proteins and small-molecule drugs. To improve the efficacy and safety of tumor treatment, people are committed to developing protein and drug co-delivery systems. Currently, intracellular co-delivery systems have been developed that integrate proteins and small-molecule drugs into one nanocarrier via various loading strategies. These systems significantly improve the blood stability, half-life, and biodistribution of proteins and small-molecule drugs, thus increasing their concentration in tumors. Furthermore, proteins and small-molecule drugs within these systems can be specifically targeted to tumor cells, and are released to perform functions after entering tumor cells simultaneously, resulting in improved effectiveness and safety of tumor treatment. This review summarizes the latest progress in protein and small-molecule drug intracellular co-delivery systems, with emphasis on the composition of nanocarriers, as well as on the loading methods of proteins and small-molecule drugs that play a role in cells into the systems, which have not been summarized by others so far.

Strategies for Advanced Oncolytic Virotherapy: Current Technology Innovations and Clinical Approaches

Oncolytic virotherapy is a type of nanomedicine with a dual antitumor mechanism. Viruses are engineered to selectively infect and lyse cancer cells directly, leading to the release of soluble antigens which induce systemic antitumor immunity. Representative drug Talimogene laherparepvec has showed promising therapeutic effects in advanced melanoma, especially when combined with immune checkpoint inhibitors with moderate adverse effects. Diverse viruses like herpes simplex virus, adenovirus, vaccina virus, and so on could be engineered as vectors to express different transgenic payloads, vastly expanding the therapeutic potential of oncolytic virotherapy. A number of related clinical trials are under way which are mainly focusing on solid tumors. Studies about further optimizing the genome of oncolytic viruses or improving the delivering system are in the hotspot, indicating the future development of oncolytic virotherapy in the clinic. This review introduces the latest progress in clinical trials and pre-clinical studies as well as technology innovations directed at oncolytic viruses. The challenges and perspectives of oncolytic virotherapy towards clinical application are also discussed.

Macrophage Cell Membrane-Cloaked Nanoplatforms for Biomedical Applications

Biomimetic approaches utilize natural cell membrane-derived nanovesicles to camouflage nanoparticles to circumvent some limitations of nanoscale materials. This emergent cell membrane-coating technology is inspired by naturally occurring intercellular interactions, to efficiently guide nanostructures to the desired locations, thereby increasing both therapeutic efficacy and safety. In addition, the intrinsic biocompatibility of cell membranes allows the crossing of biological barriers and avoids elimination by the immune system. This results in enhanced blood circulation time and lower toxicity in vivo. Macrophages are the major phagocytic cells of the innate immune system. They are equipped with a complex repertoire of surface receptors, enabling them to respond to biological signals, and to exhibit a natural tropism to inflammatory sites and tumorous tissues. Macrophage cell membrane-functionalized nanosystems are designed to combine the advantages of both macrophages and nanomaterials, improving the ability of those nanosystems to reach target sites. Recent studies have demonstrated the potential of these biomimetic nanosystems for targeted delivery of drugs and imaging agents to tumors, inflammatory, and infected sites. The present review covers the preparation and biomedical applications of macrophage cell membrane-coated nanosystems. Challenges and future perspectives in the development of these membrane-coated nanosystems are addressed.

Biomanufacturing Biotinylated Magnetic Nanomaterial via Construction and Fermentation of Genetically Engineered Magnetotactic Bacteria

Biosynthesis provides a critical way to deal with global sustainability issues and has recently drawn increased attention. However, modifying biosynthesized magnetic nanoparticles by extraction is challenging, limiting its applications. Magnetotactic bacteria (MTB) synthesize single-domain magnetite nanocrystals in their organelles, magnetosomes (BMPs), which are excellent biomaterials that can be biologically modified by genetic engineering. Therefore, this study successfully constructed in vivo biotinylated BMPs in the MTB Magnetospirillum gryphiswaldense by fusing biotin carboxyl carrier protein (BCCP) with membrane protein MamF of BMPs. The engineered strain (MSR−∆F−BF) grew well and synthesized small-sized (20 ± 4.5 nm) BMPs and were cultured in a 42 L fermenter; the yield (dry weight) of cells and BMPs reached 8.14 g/L and 134.44 mg/L, respectively, approximately three-fold more than previously reported engineered strains and BMPs. The genetically engineered BMPs (BMP−∆F−BF) were successfully linked with streptavidin or streptavidin-labelled horseradish peroxidase and displayed better storage stability compared with chemically constructed biotinylated BMPs. This study systematically demonstrated the biosynthesis of engineered magnetic nanoparticles, including its construction, characterization, and production and detection based on MTB. Our findings provide insights into biomanufacturing multiple functional magnetic nanomaterials.

Single-Step Synthesis of Highly Tunable Multifunctional Nanoliposomes for Synergistic Cancer Therapy

Cancer is still one of the major diseases that humans have not conquered yet. Nanotechnology has promoted the development of multifunctional nanoparticles, which integrate diagnostic and treatment abilities for tumor imaging and therapy. However, its preparation methods usually require complicated unit operations, which result in large batch-to-batch differences, poor reproducibility, high production costs, and difficulty in clinical transformation. Furthermore, precisely manufacturing nanoliposomes with different tunable features (e.g., size, surface charge, targeting ligands, and so forth) remains a challenge, limiting effective nanoliposome optimization for tumor therapy. Due to the accurate control of the synthesis process and continuous operation mode, microfluidic technology becomes an emerging approach for the manufacturing of nanoliposomes. However, there are few reports on the single-step preparation of complex nanoliposomes by precise tuning of the physical properties, while investigating the influence of anti-cancer efficiency. Herein, we have prepared multifunctional nanoliposomes with accurate tuning properties through a microfluidic device in a single step, with synergistic photodynamic and chemodynamic effects for targeted tumor therapy. The preparation method provides an effective way for the one-step preparation of multifunctional nanoparticles with controllable particle sizes and surface properties.

Cell-derived membrane biomimetic nanocarriers for targeted therapy of pulmonary disease

Pulmonary diseases are currently one of the major threats of human health, especially considering the recent COVID-19 pandemic. However, the current treatments are facing the challenges like insufficient local drug concentrations, the fast lung clearance and risks to induce unexpected inflammation. Cell-derived membrane biomimetic nanocarriers are recently emerged delivery strategy, showing advantages of long circulation time, excellent biocompatibility and immune escape ability. In this review, applications of using cell-derived membrane biomimetic nanocarriers from diverse cell sources for the targeted therapy of pulmonary disease were summarized. In addition, improvements of the cell-derived membrane biomimetic nanocarriers for augmented therapeutic ability against different kinds of pulmonary diseases were introduced. This review is expected to provide a general guideline for the potential applications of cell-derived membrane biomimetic nanocarriers to treat pulmonary diseases.

Magnetically Actuated Cell-Robot System: Precise Control, Manipulation, and Multimode Conversion

Border-nearing microrobots with self-propelling and navigating capabilities have promising applications in micromanipulation and bioengineering, because they can stimulate the surrounding fluid flow for object transportation. However, ensuring the biosafety of microrobots is a concurrent challenge in bioengineering applications. Here, macrophage template-based microrobots (cell robots) that can be controlled individually or in chain-like swarms are proposed, which can transport various objects. The cell robots are constructed using the phagocytic ability of macrophages to load nanomagnetic particles while maintaining their viability. The robots exhibit high position control accuracy and generate a flow field that can be used to transport microspheres and sperm when exposed to an external magnetic field near a wall. The cell robots can also form chain-like swarms to transport a large object (more than 100 times the volume). This new insight into the manipulation of macrophage-based cell robots provides a new concept by converting other biological cells into microrobots for micromanipulation in biomedical applications.

Parallel Manipulation and Flexible Assembly of Micro-Spiral via Optoelectronic Tweezers

Micro-spiral has a wide range of applications in smart materials, such as drug delivery, deformable materials, and micro-scale electronic devices by utilizing the manipulation of electric fields, magnetic fields, and flow fields. However, it is incredibly challenging to achieve a massively parallel manipulation of the micro-spiral to form a particular microstructure in these conventional methods. Here, a simple method is reported for assembling micro-spirals into various microstructures via optoelectronic tweezers (OETs), which can accurately manipulate the micro-/bio-particles by projecting light patterns. The manipulation force of micro-spiral is analyzed and simulated first by the finite element simulation. When the micro-spiral lies at the bottom of the microfluidic chip, it can be translated or rotated toward the target position by applying control forces simultaneously at multiple locations on the long axis of the micro-spiral. Through the OET manipulation, the length of the micro-spiral chain can reach 806.45 μm. Moreover, the different parallel manipulation modes are achieved by utilizing multiple light spots. The results show that the micro-spirulina can be manipulated by a real-time local light pattern and be flexibly assembled into design microstructures by OETs, such as a T-shape circuit, link lever, and micro-coil pairs of devices. This assembly method using OETs has promising potential in fabricating innovative materials and microdevices for practical engineering applications.

Magnetically Driven Soft Continuum Microrobot for Intravascular Operations in Microscale

Remotely controlled soft continuum robots with active steering capability have broad prospects in medical applications. However, conventional continuum robots have the miniaturization challenge. This paper presents a microscale soft continuum microrobot with steering and locomotion capabilities based on magnetic field actuation. The magnetically driven soft continuum microrobot is made of NdFeB particles and polydimethylsiloxane (PDMS), and it can be as small as 200 μm in diameter. Moreover, a hydrogel layer is covered on the surface of the microrobot, which not only overcomes the adhesion force between the microobjects and the soft tip but also reduces the friction between the microrobot and substrate. The performance test indicates the soft continuum microrobot featured excellent control and steering capabilities. The experimental results demonstrate that the soft continuum microrobot can travel through the microfluidic channel by its own vibration and flexibly steer in a bifurcation environment. Moreover, the micromanipulation of microbeads in the microfluidic channels proves that the proposed microscale soft continuum microrobot has a great potential for intravascular manipulation.

Multifaceted Engineered Biomimetic Nanorobots Toward Cancer Management

The noteworthy beneficiary to date in nanotechnology is cancer management. Nanorobots are developed as the result of advancements in the nanostructure, robotics, healthcare, and computer systems. These devices at the nanoscale level are beneficial in the prevention, diagnosis, and treatment of various health conditions notably cancer. Though these structures have distinct potentialities, the usage of inorganic substances in their construction can affect their performance and can cause health issues in the body. To overcome this, naturally inspired substances are incorporated in the fabrication process of nanorobots termed biomimetic nanorobots that can overcome the immunological responses and reduce the side effects with effective functionalization. These biomimetic nanorobots can widen the opportunities in cancer imaging and therapy. Herein, an up-to-date review of biomimetic nanorobots along with their applications in cancer management is provided. Furthermore, the safety issues and future directions of biomimetic nanorobots to achieve clinical translation are also stated.

Biosafety evaluation of dual-responsive neutrobots

Neutrobots carrying antitumor drugs facilitate considerable safety in vivo upon intravenous administration with high dose.