Gastrointestinal tract drug delivery using algae motors embedded in a degradable capsule

Smart Bioelectronics for Real-Time Diagnosis and Therapy of Body Organ Functions

Noncommunicable diseases (NCDs) associated with cardiovascular, neurological, and gastrointestinal disorders remain a leading cause of global mortality, sounding the alarm for the urgent need for better diagnostic and therapeutic solutions. Wearable and implantable biointegrated electronics offer a groundbreaking solution, combining real-time, high-resolution monitoring with innovative treatment capabilities tailored to specific organ functions. In this comprehensive review, we focus on the diseases affecting the brain, heart, gastrointestinal organs, bladder, and adrenal gland, along with their associated physiological parameters. Additionally, we provide an overview of the characteristics of these parameters and explore the potential of bioelectronic devices for in situ sensing and therapeutic applications and highlight the recent advancements in their deployment across specific organs. Finally, we analyze the current challenges and prospects of implementing closed-loop feedback control systems in integrated sensor-therapy applications. By emphasizing organ-specific applications and advocating for closed-loop systems, this review highlights the potential of future bioelectronics to address physiological needs and serves as a guide for researchers navigating the interdisciplinary fields of diagnostics, therapeutics, and personalized medicine.

Plant cell-inspired colon-targeted cargo delivery systems with dual-triggered release mechanisms

Plant cells represent smart cargo carriers with great socioeconomic potential in oral drug delivery applications. The two exterior barriers, featuring a rigid cell wall and a dense plasma membrane, are unique with complementary structural, mechanical, and chemical properties. Current strategies for producing therapeutic drugs within plant cells for oral delivery are efficient, but largely limited to recombinant pharmaceutical proteins, and involve complex genetic modification of plants. To address this, we engineer plant cell-inspired delivery systems with cellulose nanofiber-based shells and lipid layers through a bottom-up assembly strategy, which offers greater flexibility to encapsulate nonprotein compounds and nanoparticles. Notably, the layered shell structure resists degradation in acidic environments, and two barriers respond differently to external stimuli in simulated gastrointestinal medium, resulting in size-dependent dual-triggered release mechanisms. The cytocompatibility was shown by incubation with Caco-2 cells. Our results open avenues for developing next generation of bioinspired oral delivery systems for multisite-specific gastrointestinal release in a low-cost and sustainable manner.

Engineered probiotics remodel the intestinal epithelial barrier and enhance bacteriotherapy for inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are often associated with compromised epithelial barriers and dysregulated gut microbiota. In this study, we revealed the synergistic effect that zinc and indole-3-carbinol (I3C) have in restoring the epithelial barrier, and co-localized them on a ZI platform, which was further conjugated to the surface of Escherichia coli Nissle 1917 (EcN). The ZI@EcN formulation effectively delivered ZI to colon tissues and extended its retention in the intestines due to the colonic colonization effect of EcN, thereby promoting the sustained release of zinc and I3C for optimal synergistic effects on epithelial barrier remodeling. The restored epithelium acts as a protective barrier, preventing the infiltration of toxins and pathogens, which significantly reduces inflammation in colonic tissues. Additionally, EcN enriched the gut microbiome, increasing the abundance of beneficial bacteria while reducing that of pathogens, demonstrating its significant efficacy in gut microbiome regulation. In dextran sulfate sodium-induced mouse colitis models, ZI@EcN exhibited substantially improved prophylactic and therapeutic efficacy with favorable safety profiles, highlighting its potential for clinical applications. STATEMENT OF SIGNIFICANCE: This study highlighted the synergistic effects that zinc and indole-3-carbinol, both derived from dietary sources, have on restoring integrity of the intestinal epithelial barrier. A platform (ZI@EcN) was also developed for the targeted delivery and sustained release of zinc and indole-3-carbinol, specifically in colonic tissues, for colitis treatment. This platform not only restores the compromised intestinal epithelial barrier but also regulates the dysbiotic gut microbiota, promoting the recovery of a healthy intestinal microenvironment and showing promise in alleviating complex symptoms in a single formulation. Furthermore, the formulation demonstrated potent prophylactic and therapeutic efficacy against colitis, with favorable safety profiles, and a strong potential for clinical applications.

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.

Anisotropic Microcarriers: Fabrication Strategies and Biomedical Applications

Anisotropic microcarriers (AMs) have attracted increasing attention. Although significant efforts have been made to explore AMs with various morphologies, their full potential is yet to be realized, as most studies have primarily focused on materials or fabrication methods. A thorough analysis of the interactional and interdependent relationships between these factors is required, along with proposed countermeasures tailored for researchers from various backgrounds. These countermeasures include specific fabrication strategies for various morphologies and guidelines for selecting the most suitable AM for certain biomedical applications. In this review, a comprehensive summary of AMs, ranging from their fabrication methods to biomedical applications, based on the past two decades of research, is provided. The fabrication of various morphologies is investigated using different strategies and their corresponding biomedical applications. By systematically examining these morphology-dependent effects, a better utilization of AMs with diverse morphologies can be achieved and clear strategies for breakthroughs in the biomedical field are established. Additionally, certain challenges are identified, new frontiers are opened, and promising and exciting opportunities are provided for fabricating functional AMs with broad implications across various fields that must be addressed in biomaterials and biotechnology.

Synthetic and Biogenic Materials for Oral Delivery of Biologics: From Bench to Bedside

The development of nucleic acid and protein drugs for oral delivery has lagged behind their production for conventional nonoral routes. Over the past decade, the evolution of DNA- and RNA-based technologies combined with the innovation of state-of-the-art delivery vehicles for nucleic acids has brought rapid advancements to the biopharmaceutical field. Nucleic acid therapies have the potential to achieve long-lasting effects, or even cures, by inhibiting or editing genes, which is not possible with conventional small-molecule drugs. However, challenges and limitations must be addressed before these therapies can provide cures for chronic conditions and rare diseases, rather than only offering temporary relief. Nucleic acids and proteins face premature degradation in the acidic, enzyme-rich stomach environment and are rapidly cleared by the liver. To overcome these challenges, various delivery vehicles have been developed to transport therapeutic compounds to the intestines, where the active compounds are released and gut microbiota and mucosal immune system also play an important role. This review provides a comprehensive overview of the promises and pitfalls associated with the oral route of administration of biologics, current delivery systems, applications of orally delivered therapeutics, and the challenges and considerations for translation of nucleic acid and protein therapeutics into clinical practice.

Robotic micromotors transforming oral drug administration

Oral medication is preferred for its convenience; however, efficient drug delivery remains challenging due to issues such as poor solubility, and absorption caused by mucosal barriers, which result in low bioavailability. In this review, we discuss new strategies integrating robotic capabilities into oral formulations to enhance drug delivery. Such robotic pill systems leverage the efficient propulsion of biological and synthetic micromotors to accelerate pill disintegration and overcome mucosal barriers, increasing bioavailability with lower doses and fewer side effects. In addition, advanced bioinspired robotic capsules, including microneedles, microinjectors, and microjet systems, offer enhanced macromolecule bioavailability comparable with that achieved with subcutaneous injections. The future of precision medicine lies in encapsulating diverse micromotors (with unique capabilities) within pharmaceutical carriers, offering groundbreaking opportunities for enhanced therapeutic interventions.

De-Novo Design of Actively Spinning and Gyrating Spherical Micro-Vesicles

Self-propelled lipid-based artificial cells that can achieve controlled rotation and directed translation present significant potential for biomedical applications, yet their engineering poses considerable challenges. Lipid vesicles synthesized via solution-based methods naturally adopt isotropic spherical shapes. Active motion of these spherical objects requires symmetry breaking and rigidity. In this study, giant vesicles are employed as chassis, utilizing enzymes that undergo cyclic, non-reciprocal conformational changes as power sources. Weak, transient protein-protein interactions induce lipid ordering leading to rigidity and spontaneous symmetry breaking. Upon activation of enzyme reactions, these spherical vesicles demonstrate a variety of motion patterns, from pure spinning to 3D spiral trajectories. From experiments and simulations, it is demonstrated how such motion enables the vesicles to cross complex barriers. By utilizing biocompatible and scalable materials, The methodology establishes a solid framework for the design of such self-propelled systems. The work paves the way for advancements in biomedical and environmental technologies such as targeted drug delivery and active matter research.

Active microgel particle swarms for intrabronchial targeted delivery

Intrabronchial delivery of therapeutic agents is critical to the treatment of respiratory diseases. Targeted delivery is demanded because of the off-target accumulation of drugs in normal lung tissues caused by inhalation and the limited motion dexterity of clinical bronchoscopes in tortuous bronchial trees. Herein, we developed microrobotic swarms consisting of magnetic hydrogel microparticles to achieve intrabronchial targeted delivery. Under programmed magnetic fields, the microgel particle swarms performed controllable locomotion and adaptative structure reconfiguration in tortuous and air-filled environments. The swarms were further integrated with imaging contrast agents for precise tracking under x-ray fluoroscopy and computed tomography imaging. Magnetic navigation of the swarms in an ex vivo lung phantom and in vivo delivery into deep branches of the bronchial trees were achieved. The on-demand reconfiguration of swarms for avoiding the microgel particles from entering nontarget bronchi and the precise delivery into tilted bronchi through climbing motion were validated.

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.

Micro- and Nanomotors: Engineered Tools for Targeted and Efficient Biomedicine

Over the past two decades, nanotechnology has made significant progress toward the development and applications of micromotors (MMs) and nanomotors (NMs). Characterized by their capability to self-propel and swim in fluids, they have emerged as promising tools in various fields, particularly in biomedicine. This Review presents an overview of the current state of MMs and NMs, their motion in viscous media and complex environments, their interaction with biological barriers, and potential therapeutical applications. We identify the choice of appropriate administration routes to reach their target location as a key aspect of the success of MMs and NMs in biomedical applications. Looking ahead, we envision NMs playing a key role in treating diverse medical disorders, as recent proof-of-concept in vivo studies demonstrate their distinct capabilities and versatility. However, addressing regulatory, scalability, biocompatibility, and safety concerns remains imperative for the successful translation of NMs into clinical trials and industrial-scale production. This work provides a guideline for researchers, guiding them through the current landscape, challenges, and prospects of using MMs and NMs in biomedicine, thereby encouraging their responsible development and positioning in the future of nanomedicine. Furthermore, we outline critical areas for further research, including studies on biocompatibility, safety, and methods to overcome physical obstacles.

Microalgae in health care and functional foods: β-glucan applications, innovations in drug delivery and synthetic biology

Microalgae are emerging as a key player in healthcare, functional foods, and sustainable biotech due to their capacity to produce bioactive compounds like β-glucans, omega-3 fatty acids, and antioxidants in an eco-friendly manner. This review comprehensively discusses the role of microalgae in healthcare and functional foods, focusing particularly on β-glucan therapeutics, drug delivery innovations, and synthetic biology applications. In healthcare, microalgae-derived compounds show immense promise for treating diseases, boosting immunity, and tackling oxidative stress. Euglena-derived paramylon, a type of β-glucan, has shown potential in various medical applications, including immunomodulation and anticancer therapy. Synthetic biology and bioprocess engineering are enhancing microalgae's therapeutic and nutritional value, with applications in drug delivery and personalized medicine. To maximize the potential of microalgae, further research and development are needed to address scalability, regulatory alignment, and consumer acceptance, with a focus on interdisciplinary collaboration and sustainable practices to align healthcare innovation with environmental conservation.

Dual-responsive micromotor pill for targeted retention in the intestines in vivo

There has been considerable interest in the recent advances in synthetic micro/nanomotors in diverse biofluids due to their potential biomedical applications. However, the propulsion of existing micro/nanomotor platforms for delivery in the gastrointestinal (GI) tract is inefficient. Herein, we present a magnetically and chemically actuated micromotor-tableted pill that can be actively retained in the GI tract in vivo. A drug-loaded and water-powered magnesium Janus micromotor enveloped in an enteric polymer-protected magnetic pill was stable in the stomach. The movement of the micromotor pill (MP) was promoted using an external gradient alternating magnetic field with low frequency toward the targeted regions in the intestines. An alternating magnetic field with high frequency induces intensive water-powered propulsion of the micromotors though a magnetocaloric effect, and thus effectively prolongs retention in the intestines. The integration of the newly developed MP system enables active retention of micromotors in vivo and promises active drug delivery for GI therapy.

Living plastics from plasticizer-assisted thermal molding of silk protein

The pursuit of materials, particularly plastics, with a minimal ecological footprint throughout their circular lifecycle, is crucial for advancing sustainable materials development. Living materials composed of embedded yet active organisms can leverage endogenous biotic resources to achieve functional materials that align with sustainability goals. However, current living material systems face challenges such as weak mechanical properties, limited environmental adaptability, and restricted cellular functionality. In this study, we propose an approach to sustainable living materials by incorporating active organisms into silk-based plastics through a plasticizer-assisted thermal molding process. We investigate the mechanism of structure formation in these materials, correlating manufacturing performance to the resulting secondary structure. These silk-based plastics provide a protective matrix for probiotics, ensuring their survival through the harsh gastrointestinal tract and enhancing intestinal delivery. Similarly, soil rhizobacteria encapsulated within the plastics exhibit long-term protease activity, accelerating plastic degradation upon soil exposure. This work demonstrates the potential of sustainable plastics as a form of living materials, where active organisms are processed, entrapped, retain metabolic functions, and are protected in harsh environments.

Swarm Autonomy: From Agent Functionalization to Machine Intelligence

Swarm behaviors are common in nature, where individual organisms collaborate via perception, communication, and adaptation. Emulating these dynamics, large groups of active agents can self-organize through localized interactions, giving rise to complex swarm behaviors, which exhibit potential for applications across various domains. This review presents a comprehensive summary and perspective of synthetic swarms, to bridge the gap between the microscale individual agents and potential applications of synthetic swarms. It is begun by examining active agents, the fundamental units of synthetic swarms, to understand the origins of their motility and functionality in the presence of external stimuli. Then inter-agent communications and agent-environment communications that contribute to the swarm generation are summarized. Furthermore, the swarm behaviors reported to date and the emergence of machine intelligence within these behaviors are reviewed. Eventually, the applications enabled by distinct synthetic swarms are summarized. By discussing the emergent machine intelligence in swarm behaviors, insights are offered into the design and deployment of autonomous synthetic swarms for real-world applications.

Automated Actuation of Biodegradable and Self-Fluorescent Chlorella Swarms Using Magnetic Tweezers

Magnetic microrobot swarms have broad application prospects in human-targeted therapy. However, the automated assembly and actuation of functional large-volume swarms is a challenging topic. Chlorella with self-fluorescence and biodegradability is used in this paper as a template to prepare magnetic Chlorella-based microrobots through magnetron sputtering. The assembly and actuation of large-volume Chlorella swarms are realized using a magnetic tweezer system with a robust magnetic field. Experimental results indicate that the magnetic Chlorella swarms (MCS) possess excellent degradation capability and mobility, enabling automatic navigation in various scenarios. Notably, the MCS successfully moved on the spiral channel containing bovine serum and effectively crossed the simulated channel. Furthermore, in vitro studies of real articular cartilage fragments have revealed the motion capacity of the MCS. This research provides a functional microrobot swarm platform for targeted delivery and precision therapy.

Magneto-Thermal Hydrogel Swarms for Targeted Lesion Sealing

Magnetic microswarms capable of performing navigation to targeted lesions show great potential for in vivo medical applications. However, using the swarms for lesion cavity filling encounters challenges from precise delivery and sealing. Herein, this work develops a magneto-thermal hydrogel swarm consisting of magnetic hydrogel particles, which can perform phase transition induced by temperature change. The particles are prepared using a temperature-responsive hydrogel matrix, tissue adhesive monomers, and magnetic microparticles. The swarms can be remolded to various shapes, and it can be used to seal perforation in phantom and gastric tissue. The swarms can also serve as drug carriers, and their drug release profiles induced by temperature changes are characterized. Finally, the targeted delivery, adaptive filling, and sealing of a gastric ulcer using the swarms are achieved in ex vivo and in vivo environments.

NIR-II Ratiometric Optical Theranostic Capsule for In Situ Diagnosis and Precise Therapy of Intestinal Inflammation

Capsules were widely used in clinical settings for the oral delivery of various drugs, although it remains challenging to trace real-time drug release behavior and adjust dosages based on the therapeutic effect. To address these issues, we developed theranostic capsules that loaded two kinds of fluorescence nanoparticles, H2O2-responsive Janus Ag/Ag2S nanoparticles (Ag/Ag2S JNPs) and the downconversion nanoparticles (DCNPs), and the dexamethasone (Dex) drug. The Ag/Ag2S JNPs exhibit a highly sensitive fluorescence (FL) signal at 1250 nm in response to H2O2, while the FL signal from the DCNPs at 1550 nm remains stable under physiological conditions. The ratio of these two FL signals formed the ratiometric FL signal, which shows correlation with the H2O2 concentration with a detection limit of 1.7 μM. Moreover, the capsules can be precisely delivered into the intestine, where they release the JNPs and DCNPs simultaneously. The H2O2-triggered ratiometric FL signals and images can diagnose inflammation and indicate its location. Meanwhile, the encapsulated Dex is released in the disease region, with ratiometric imaging allowing for real-time tracking of therapeutic efficacy and providing guidance for ongoing treatment. The theranostic capsule system provides an approach for quantitative detection of disease biomarkers and further localized release of therapeutics, thereby avoiding overdose and reducing side effects.

Imaging-guided bioresorbable acoustic hydrogel microrobots

Micro- and nanorobots excel in navigating the intricate and often inaccessible areas of the human body, offering immense potential for applications such as disease diagnosis, precision drug delivery, detoxification, and minimally invasive surgery. Despite their promise, practical deployment faces hurdles, including achieving stable propulsion in complex in vivo biological environments, real-time imaging and localization through deep tissue, and precise remote control for targeted therapy and ensuring high therapeutic efficacy. To overcome these obstacles, we introduce a hydrogel-based, imaging-guided, bioresorbable acoustic microrobot (BAM) designed to navigate the human body with high stability. Constructed using two-photon polymerization, a BAM comprises magnetic nanoparticles and therapeutic agents integrated into its hydrogel matrix for precision control and drug delivery. The microrobot features an optimized surface chemistry with a hydrophobic inner layer to substantially enhance microbubble retention in biofluids with multiday functionality and a hydrophilic outer layer to minimize aggregation and promote timely degradation. The dual-opening bubble-trapping cavity design enables a BAM to maintain consistent and efficient acoustic propulsion across a range of biological fluids. Under focused ultrasound stimulation, the entrapped microbubbles oscillate and enhance the contrast for real-time ultrasound imaging, facilitating precise tracking and control of BAM movement through wireless magnetic navigation. Moreover, the hydrolysis-driven biodegradability of BAMs ensures its safe dissolution after treatment, posing no risk of long-term residual harm. Thorough in vitro and in vivo experimental evidence demonstrates the promising capabilities of BAMs in biomedical applications. This approach shows promise for advancing minimally invasive medical interventions and targeted therapeutic delivery.

Selectively Detachable Hydrogel Adhesion Enabled by Stimulus-Specific Cleavable Cross-Linkers

The development of detachable hydrogel adhesion presents an advancement in the fields of soft electronics and bioengineering as it offers additional functionalities to these applications. However, conventional methods typically rely on a single detachment trigger, so it is unclear whether unintentional detachment might occur in the specific environments of other detachment systems. This makes it difficult to directly introduce two independent detachment triggers directly. In this article, we present a strategy for selective detachable adhesion based on two types of cleavable cross-linkers, N,N'-bis(acryloyl)cystamine (BAC) and N,N'-(1,2-dihydroxyethylene)bis(acrylamide) (DHEBA), each with an independent cleavage trigger. BAC can be cleaved through the reduction of disulfide bonds using reducing agents, while DHEBA can be hydrolyzed through heating. We constructed stitching polymer networks for topological adhesion using two types of cleavable cross-linkers, allowing the networks to be selectively degraded depending on which cross-linker was used. Our findings show that the use of cleavable cross-linkers achieved selectively detachable adhesion in various hydrogels, with adhesion energy that reached up to 1223 J m-2 in polyacrylamide-alginate (PAAm-alginate) tough hydrogel. This strategy also proved versatile as it led to effective adhesion with various substrates, including aluminum, copper, glass, and polyester film (PET). Furthermore, we took advantage of the high programmability of this approach to construct hydrogel-based YES and AND logic gates, whose output changed depending on the applied input triggers. In addition, we designed a selective-release capsule model capable of dual-solution release, which emphasizes the potential of our strategy in creating programmable and responsive soft materials.

Micro/nanorobots for gastrointestinal tract

The application of micro/nanomotors (MNMs) in the gastrointestinal tract has become a Frontier in the treatment of gastrointestinal diseases. These miniature robots can enter the gastrointestinal tract through oral administration, achieving precise drug delivery and therapy. They can traverse mucosal layers and tissue barriers, directly targeting tumors or other lesion sites, thereby enhancing the bioavailability and therapeutic effects of drugs. Through the application of nanotechnology, these MNMs are able to accomplish targeted medication release, regulating drug release in response to either external stimuli or the local biological milieu. This results in reduced side effects and increased therapeutic efficacy. This review summarizes the primary classifications and power sources of current MNMs, as well as their applications in the gastrointestinal tract, providing inspiration and direction for the treatment of gastrointestinal diseases with MNMs.

Towards multifunctional robotic pills

Robotic pills leverage the advantages of oral pharmaceutical formulations-in particular, convenient encapsulation, high loading capacity, ease of manufacturing and high patient compliance-as well as the multifunctionality, increasing miniaturization and sophistication of microrobotic systems. In this Perspective, we provide an overview of major innovations in the development of robotic pills-specifically, oral pills embedded with robotic capabilities based on microneedles, microinjectors, microstirrers or microrockets-summarize current progress and applicational gaps of the technology, and discuss its prospects. We argue that the integration of multiple microrobotic functions within oral delivery systems alongside accurate control of the release characteristics of their payload provides a basis for realizing sophisticated multifunctional robotic pills that operate as closed-loop systems.

Microorganism microneedle micro-engine depth drug delivery

As a transdermal drug delivery method, microneedles offer minimal invasiveness, painlessness, and precise in-situ treatment. However, current microneedles rely on passive diffusion, leading to uncontrollable drug penetration. To overcome this, we developed a pneumatic microneedle patch that uses live Enterobacter aerogenes as microengines to actively control drug delivery. These microbes generate gas, driving drugs into deeper tissues, with adjustable glucose concentration allowing precise control over the process. Our results showed that this microorganism-powered system increases drug delivery depth by over 200%, reaching up to 1000 μm below the skin. In a psoriasis animal model, the technology effectively delivered calcitriol into subcutaneous tissues, offering rapid symptom relief. This innovation addresses the limitations of conventional microneedles, enhancing drug efficiency, transdermal permeability, and introducing a creative paradigm for on-demand controlled drug delivery.

Bulking up: the impact of polymer sterics on emulsion stability

Encapsulation of hydrophobic active ingredients is critical for targeted drug delivery as water-insoluble drugs dominate the pharmaceutical marketplace. We previously demonstrated hexadecane-in-water emulsions stabilized with a pH-tunable polymer, poly(acrylic acid) (PAA), via a steric layer preventing particle aggregation. Using vibrational sum frequency scattering spectroscopy (VSFSS), here we probe the influence of steric hindrance on emulsion colloidal stability by tailoring the molecular weight of PAA and by adding an additional methyl group to the polymer backbone via poly(methacrylic acid) (PMAA) at pH 2, 4, and 6. At low polymer molecular weight (2 and 10 kDa), PAA adsorption is entropy driven and akin to surfactant-mediated stabilization. With 450 kDa PAA, the longer polymer chain emphasizes enthalpically favored polymer-oil interactions to initially coat the surface, and forms layers at increasing molecular weight (1000 and 4000 kDa). PMAA exhibits better oil-solubility than PAA at low concentrations but cannot accommodate the steric hindrance at higher concentrations leading to disorder. Finally, we connect our molecular-level understanding of PAA ordering with temperature-dependent dynamic light scattering experiments and observe that emulsions coated with PAA at pH 2 and 4 maintain colloidal stability from 0-90 °C, making PAA a promising polymer for hydrophobic drug delivery.

Advanced materials for micro/nanorobotics

Autonomous micro/nanorobots capable of performing programmed missions are at the forefront of next-generation micromachinery. These small robotic systems are predominantly constructed using functional components sourced from micro- and nanoscale materials; therefore, combining them with various advanced materials represents a pivotal direction toward achieving a higher level of intelligence and multifunctionality. This review provides a comprehensive overview of advanced materials for innovative micro/nanorobotics, focusing on the five families of materials that have witnessed the most rapid advancements over the last decade: two-dimensional materials, metal-organic frameworks, semiconductors, polymers, and biological cells. Their unique physicochemical, mechanical, optical, and biological properties have been integrated into micro/nanorobots to achieve greater maneuverability, programmability, intelligence, and multifunctionality in collective behaviors. The design and fabrication methods for hybrid robotic systems are discussed based on the material categories. In addition, their promising potential for powering motion and/or (multi-)functionality is described and the fundamental principles underlying them are explained. Finally, their extensive use in a variety of applications, including environmental remediation, (bio)sensing, therapeutics, etc., and remaining challenges and perspectives for future research are discussed.

Oral administration microrobots for drug delivery

Oral administration is the most simple, noninvasive, convenient treatment. With the increasing demands on the targeted drug delivery, the traditional oral treatment now is facing some challenges: 1) biologics how to implement the oral treatment and ensure the bioavailability is not lower than the subcutaneous injections; 2) How to achieve targeted therapy of some drugs in the gastrointestinal tract? Based on these two issues, drug delivery microrobots have shown great application prospect in oral drug delivery due to their characteristics of flexible locomotion or driven ability. Therefore, this paper summarizes various drug delivery microrobots developed in recent years and divides them into four categories according to different driving modes: magnetic-controlled drug delivery microrobots, anchored drug delivery microrobots, self-propelled drug delivery microrobots and biohybrid drug delivery microrobots. As oral drug delivery microrobots involve disciplines such as materials science, mechanical engineering, medicine, and control systems, this paper begins by introducing the gastrointestinal barriers that oral drug delivery must overcome. Subsequently, it provides an overview of typical materials involved in the design process of oral drug delivery microrobots. To enhance readers' understanding of the working principles and design process of oral drug delivery microrobots, we present a guideline for designing such microrobots. Furthermore, the current development status of various types of oral drug delivery microrobots is reviewed, summarizing their respective advantages and limitations. Finally, considering the significant concerns regarding safety and clinical translation, we discuss the challenges and prospections of clinical translation for various oral drug delivery microrobots presented in this paper, providing corresponding suggestions for addressing some existing challenges.

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.

Processed microalgae: green gold for tissue regeneration and repair

As novel biomedical materials, microalgae have garnered significant interest because of their ability to generate photosynthetic oxygen, their antioxidant activity, and their favorable biocompatibility. Many studies have concentrated on the hypoxia-alleviating effects of microalgae within tumor microenvironments. However, recent findings indicate that microalgae can significantly increase the regeneration of various tissues and organs. To augment microalgae's therapeutic efficacy and mitigate the limitations imposed by immune clearance, it is essential to process microalgae through various processing strategies. This review examines common microalgal species in biomedical applications, such as Chlorella, Chlamydomonas reinhardtii, diatoms, and Spirulina. This review outlines diverse processing methods, including microalgae extracts, microalgae‒nanodrug composite delivery systems, surface modifications, and living microalgae‒loaded hydrogels. It also discusses the latest developments in tissue repair using processed microalgae for skin, gastrointestinal, bone, cardiovascular, lung, nerve, and oral tissues. Furthermore, future directions are presented, and research gaps for processed microalgae are identified. Collectively, these insights may inform the innovation of processed microalgae for various uses and offer guidance for ongoing research in tissue repair.

Reinforcement learning with thermal fluctuations at the nanoscale

Reinforcement Learning offers a framework to learn to choose actions in order to control a system. However, at small scales Brownian fluctuations limit the control of nanomachine actuation or nanonavigation and of the molecular machinery of life. We analyze this regime using the general framework of Markov decision processes. We show that at the nanoscale, while optimal control actions should bring an improvement proportional to the small ratio of the applied force times a length scale over the temperature, the learned improvement is smaller and proportional to the square of this small ratio. Consequently, the efficiency of learning, which compares the learning improvement to the theoretical optimal improvement, drops to zero. Nevertheless, these limitations can be circumvented by using actions learned at a lower temperature. These results are illustrated with simulations of the control of the shape of small particle clusters.

Arbitrary Construction of Versatile NIR-Driven Microrobots

Emerging light-driven micro/nanorobots (LMNRs) showcase profound potential for sophisticated manipulation and various applications. However, the realization of a versatile and straightforward fabrication technique remains a challenging pursuit. This study introduces an innovative bulk heterojunction organic semiconductor solar cell (OSC)-based spin-coating approach, aiming to facilitate the arbitrary construction of LMNRs. Leveraging the distinctive properties of a near-infrared (NIR)-responsive organic semiconductor heterojunction solution, this technique enables uniform coating across various dimensional structures (0D, 1D, 2D, 3D) to be LMNRs, denoted as "motorization." The film, with a slender profile measuring ≈140 nm in thickness, effectively preserves the original morphology of objects while imparting actuation capabilities exceeding hundreds of times their own weight. The propelled motion of these microrobots is realized through NIR-driven photoelectrochemical reaction-induced self-diffusiophoresis, showcasing a versatile array of controllable motion profiles. The strategic customization of arbitrary microrobot construction addresses specific applications, ranging from 0D microrobots inducing living crystal formation to intricate, multidimensional structures designed for tasks such as microplastic extraction, cargo delivery, and phototactic precise maneuvers. This study advances user-friendly and versatile LMNR technologies, unlocking new possibilities for various applications, signaling a transformative era in multifunctional micro/nanorobot technologies.

Dress me an outfit: advanced probiotics hybrid systems for intelligent IBD therapy

Inflammation bowel disease (IBD) has emerged as a public health challenge worldwide; with high incidence and rapid prevalence, it has troubled billions of people and further induced multitudinous systemic complications. Recent decade has witnessed the vigorous application of food-borne probiotics for IBD therapy; however, the complicated and changeable environments of digestive tract have forced probiotics to face multiple in vivo pressures, consequently causing unsatisfied prophylactic or therapeutic efficacy attributed to off-targeted arrival, damaged viability, insufficient colonization efficiency, etc. Fortunately, arisen hybrid technology has provided versatile breakthroughs for the targeted transplantation of probiotics. By ingeniously modifying probiotics to form probiotics hybrid systems (PHS), the biological behaviors of probiotics in vivo could be mediated, the interactions between probiotics with intestinal components can be facilitated, and diverse advanced probiotic-based therapies for IBD challenge can be developed, which attribute to the intelligent response to microenvironment of PHS, and intelligent design of PHS for multiple functions combination. In this review, various PHS were categorized and their intestinal behaviors were elucidated systematically, their therapeutic effects and intrinsic mechanism were further analyzed. Besides, shortages of present PHS and the corresponding solutions have been discussed, based on which the future perspectives of this field have also been proposed. The undeniable fact is that PHS show an incomparable future to bring the next generation of advanced food science.

Low-Friction Soft Robots for Targeted Bacterial Infection Treatment in Gastrointestinal Tract

Untethered and self-transformable miniature robots are capable of performing reconfigurable deformation and on-demand locomotion, which aid the traversal toward various lumens, and bring revolutionary changes for targeted delivery in gastrointestinal (GI) tract. However, the viscous non-Newtonian liquid environment and plicae gastricae obstacles severely hamper high-precision actuation and payload delivery. Here, we developed a low-friction soft robot by assembly of densely arranged cone structures and grafting of hydrophobic monolayers. The magnetic orientation encoded robot can move in multiple modes, with a substantially reduced drag, terrain adaptability, and improved motion velocity across the non-Newtonian liquids. Notably, the robot stiffness can be reversibly controlled with magnetically induced hardening, enabling on-site scratching and destruction of antibiotic-ineradicable polymeric matrix in biofilms with a low-frequency magnetic field. Furthermore, the magnetocaloric effect can be utilized to eradicate the bacteria by magnetocaloric effect under high-frequency alternating field. To verify the potential applications inside the body, the clinical imaging-guided actuation platforms were developed for vision-based control and delivery of the robots. The developed low-friction robots and clinical imaging-guided actuation platforms show their high potential to perform bacterial infection therapy in various lumens inside the body.

Biohybrid microrobots regulate colonic cytokines and the epithelium barrier in inflammatory bowel disease

Cytokines have been identified as key contributors to the development of inflammatory bowel disease (IBD), yet conventional treatments often prove inadequate and carry substantial side effects. Here, we present an innovative biohybrid robotic system, termed "algae-MΦNP-robot," for addressing IBD by actively neutralizing colonic cytokine levels. Our approach combines moving green microalgae with macrophage membrane-coated nanoparticles (MΦNPs) to efficiently capture proinflammatory cytokines "on the fly." The dynamic algae-MΦNP-robots outperformed static counterparts by enhancing cytokine removal through continuous movement, better distribution, and extended retention in the colon. This system is encapsulated in an oral capsule, which shields it from gastric acidity and ensures functionality upon reaching the targeted disease site. The resulting algae-MΦNP-robot capsule effectively regulated cytokine levels, facilitating the healing of damaged epithelial barriers. It showed markedly improved prevention and treatment efficacy in a mouse model of IBD and demonstrated an excellent biosafety profile. Overall, our biohybrid algae-MΦNP-robot system offers a promising and efficient solution for IBD, addressing cytokine-related inflammation effectively.

Biohybrid microrobots locally and actively deliver drug-loaded nanoparticles to inhibit the progression of lung metastasis

Lung metastasis poses a formidable challenge in the realm of cancer treatment, with conventional chemotherapy often falling short due to limited targeting and low accumulation in the lungs. Here, we show a microrobot approach using motile algae for localized delivery of drug-loaded nanoparticles to address lung metastasis challenges. The biohybrid microrobot [denoted "algae-NP(DOX)-robot"] combines green microalgae with red blood cell membrane-coated nanoparticles containing doxorubicin, a representative chemotherapeutic drug. Microalgae provide autonomous propulsion in the lungs, leveraging controlled drug release and enhanced drug dispersion to exert antimetastatic effects. Upon intratracheal administration, algae-NP(DOX)-robots efficiently transport their drug payload deep into the lungs while maintaining continuous motility. This strategy leads to rapid drug distribution, improved tissue accumulation, and prolonged retention compared to passive drug-loaded nanoparticles and free drug controls. In a melanoma lung metastasis model, algae-NP(DOX)-robots exhibit substantial improvement in therapeutic efficacy, reducing metastatic burden and extending survival compared to control groups.

Ultrafast light-activated polymeric nanomotors

Synthetic micro/nanomotors have been extensively exploited over the past decade to achieve active transportation. This interest is a result of their broad range of potential applications, from environmental remediation to nanomedicine. Nevertheless, it still remains a challenge to build a fast-moving biodegradable polymeric nanomotor. Here we present a light-propelled nanomotor by introducing gold nanoparticles (Au NP) onto biodegradable bowl-shaped polymersomes (stomatocytes) via electrostatic and hydrogen bond interactions. These biodegradable nanomotors show controllable motion and remarkable velocities of up to 125 μm s-1. This unique behavior is explained via a thorough three-dimensional characterization of the nanomotor, particularly the size and the spatial distribution of Au NP, with cryogenic transmission electron microscopy (cryo-TEM) and cryo-electron tomography (cryo-ET). Our in-depth quantitative 3D analysis reveals that the motile features of these nanomotors are caused by the nonuniform distribution of Au NPs on the outer surface of the stomatocyte along the z-axial direction. Their excellent motile features are exploited for active cargo delivery into living cells. This study provides a new approach to develop robust, biodegradable soft nanomotors with application potential in biomedicine.

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.

In Situ Formed Microalgae-Integrated Living Hydrogel for Enhanced Tumor Starvation Therapy and Immunotherapy through Photosynthetic Oxygenation

The effectiveness of various cancer therapies for solid tumors is substantially limited by the highly hypoxic tumor microenvironment (TME). Here, a microalgae-integrated living hydrogel (ACG gel) is developed to concurrently enhance hypoxia-constrained tumor starvation therapy and immunotherapy. The ACG gel is formed in situ following intratumoral injection of a biohybrid fluid composed of alginate, Chlorella sorokiniana, and glucose oxidase, facilitated by the crossing-linking between divalent ions within tumors and alginate. The microalgae Chlorella sorokiniana embedded in ACG gel generate abundant oxygen through photosynthesis, enhancing glucose oxidase-catalyzed glucose consumption and shifting the TME from immunosuppressive to immunopermissive status, thus reducing the tumor cell energy supply and boosting antitumor immunity. In murine 4T1 tumor models, the ACG gel significantly suppresses tumor growth and effectively prevents postoperative tumor recurrence. This study, leveraging microalgae as natural oxygenerators, provides a versatile and universal strategy for the development of oxygen-dependent tumor therapies.

Chemical multiscale robotics for bacterial biofilm treatment

A biofilm constitutes a bacterial community encased in a sticky matrix of extracellular polymeric substances. These intricate microbial communities adhere to various host surfaces such as hard and soft tissues as well as indwelling medical devices. These microbial aggregates form a robust matrix of extracellular polymeric substances (EPSs), leading to the majority of human infections. Such infections tend to exhibit high resistance to treatment, often progressing into chronic states. The matrix of EPS protects bacteria from a hostile environment and prevents the penetration of antibacterial agents. Modern robots at nano, micro, and millimeter scales are highly attractive candidates for biomedical applications due to their diverse functionalities, such as navigating in confined spaces and targeted multitasking. In this tutorial review, we describe key milestones in the strategies developed for the removal and eradication of biofilms using robots of different sizes and shapes. It can be seen that robots at different scales are useful and effective tools for treating bacterial biofilms, thus preventing persistent infections, the loss of costly implanted medical devices, and additional costs associated with hospitalization and therapies.

Untethered Microgrippers for Precision Medicine

Microgrippers, a branch of micro/nanorobots, refer to motile miniaturized machines that are of a size in the range of several to hundreds of micrometers. Compared with tethered grippers or other microscopic diagnostic and surgical equipment, untethered microgrippers play an indispensable role in biomedical applications because of their characteristics such as miniaturized size, dexterous shape tranformation, and  controllable motion, which enables the microgrippers to enter hard-to-reach regions to execute specific medical tasks for disease diagnosis and treatment. To date, numerous medical microgrippers are developed, and their potential in cell manipulation, targeted drug delivery, biopsy, and minimally invasive surgery  are explored. To achieve controlled locomotion and efficient target-oriented actions, the materials, size, microarchitecture, and morphology of microgrippers shall be deliberately designed. In this review, the authors summarizes the latest progress in untethered micrometer-scale grippers. The working mechanisms of shape-morphing and actuation methods for effective movement are first introduced. Then, the design principle and state-of-the-art fabrication techniques of microgrippers are discussed. Finally, their applications in the precise medicine are highlighted, followed by offering future perspectives for the development of untethered medical microgrippers.

Dual-Responsive Nanorobot-Based Marsupial Robotic System for Intracranial Cross-Scale Targeting Drug Delivery

Nanorobots capable of active movement are an exciting technology for targeted therapeutic intervention. However, the extensive motion range and hindrance of the blood-brain barrier impeded their clinical translation in glioblastoma therapy. Here, a marsupial robotic system constructed by integrating chemical/magnetic hybrid nanorobots (child robots) with a miniature magnetic continuum robot (mother robot) for intracranial cross-scale targeting drug delivery is reported. For primary targeting on macroscale, the continuum robot enters the cranial cavity through a minimally invasive channel (e.g., Ommaya device) in the skull and transports the nanorobots to pathogenic regions. Upon circumventing the blood-brain barrier, the released nanorobots perform secondary targeting on microscale to further enhance the spatial resolution of drug delivery. In vitro experiments against primary glioblastoma cells derived from different patients are conducted for personalized treatment guidance. The operation feasibility within organisms is shown in ex vivo swine brain experiments. The biosafety of the treatment system is suggested in in vivo experiments. Owing to the hierarchical targeting method, the targeting rate, targeting accuracy, and treatment efficacy have improved greatly. The marsupial robotic system offers a novel intracranial local therapeutic strategy and constitutes a key milestone in the development of glioblastoma treatment platforms.

Ultrasound robotics for precision therapy

In recent years, the application of microrobots in precision therapy has gained significant attention. The small size and maneuverability of these micromachines enable them to potentially access regions that are difficult to reach using traditional methods; thus, reducing off-target toxicities and maximizing treatment effectiveness. Specifically, acoustic actuation has emerged as a promising method to exert control. By harnessing the power of acoustic energy, these small machines potentially navigate the body, assemble at the desired sites, and deliver therapies with enhanced precision and effectiveness. Amidst the enthusiasm surrounding these miniature agents, their translation to clinical environments has proven difficult. The primary objectives of this review are threefold: firstly, to offer an overview of the fundamental acoustic principles employed in the field of microrobots; secondly, to assess their current applications in medical therapies, encompassing tissue targeting, drug delivery or even cell infiltration; and lastly, to delve into the continuous efforts aimed at integrating acoustic microrobots into in vivo applications.

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.

Platelet Membrane-Enclosed Bioorthogonal Catalysis for Combating Dental Caries

Platelets have shown promise as a means to combat bacterial infections, fostering the development of innovative therapeutic approaches. However, several challenges persist, including cargo loading issues, limited efficacy against biofilms, and concerns regarding the impact of payloads on the platelet carriers. Here, human platelet membrane vesicles (h-PMVs) encapsulating supramolecular metal catalysts (SMCs) as "nanofactories" to convert prodrugs into antimicrobial compounds within close proximity to bacteria are introduced. Having established the feasibility and effectiveness of the SMCs within h-PMVs, referred to as the PLT-reactor, to activate pro-antibiotic drugs (pro-ciprofloxacin and pro-moxifloxacin) using model organisms (Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923), the investigation is subsequently extended to oral biofilms, with a particular emphasis on Streptococcus mutans 3065. This "bind and kill" strategy demonstrates the potent antimicrobial specificity of the PLT-reactor through localized antibiotic production. h-PMVs play a pivotal role by enabling precise targeting of pathogenic biofilms on natural teeth while minimizing potential hemolytic effects. The finding indicates that platelet membrane-cloaked surfaces exhibit robust, multifaceted, and pathogen-specific binding affinity with excellent biocompatibility, making them a promising alternative to antibody-based therapies for infectious diseases.

Swarming magnetic nanorobots bio-interfaced by heparinoid-polymer brushes for in vivo safe synergistic thrombolysis

Biocompatible swarming magnetic nanorobots that work in blood vessels for safe and efficient targeted thrombolytic therapy in vivo are demonstrated. This is achieved by using magnetic beads elaborately grafted with heparinoid-polymer brushes (HPBs) upon the application of an alternating magnetic field B(t). Because of the dense surface charges bestowed by HPBs, the swarming nanorobots demonstrate reversible agglomeration-free reconfigurations, low hemolysis, anti-bioadhesion, and self-anticoagulation in high-ionic-strength blood environments. They are confirmed in vitro and in vivo to perform synergistic thrombolysis efficiently by "motile-targeting" drug delivery and mechanical destruction. Moreover, upon the completion of thrombolysis and removal of B(t), the nanorobots disassemble into dispersed particles in blood, allowing them to safely participate in circulation and be phagocytized by immune cells without apparent organ damage or inflammatory lesion. This work provides a rational multifaceted HPB biointerfacing design strategy for biomedical nanorobots and a general motile platform to deliver drugs for targeted therapies.

Antigen-loaded flagellate bacteria for enhanced adaptive immune response by intradermal injection

Since the skin limits the distribution of intradermal vaccines, a large number of dendritic cells in the skin cannot be fully utilized to elicit a more effective immune response. Here, we loaded the antigen to the surface of the flagellate bacteria that was modified by cationic polymer, thus creating antigen-loaded flagellate bacteria (denoted as 'FB-Ag') to overcome the skin barrier and perform the active delivery of antigen in the skin. The FB-Ag showed fast speed (∼0.2 μm s-1) and strong dendritic cell activation capabilities in the skin model in vitro. In vivo, the FB-Ag promoted the spread of antigen in the skin through active movement, increased the contact between Intradermal dendritic cells and antigen, and effectively activated the internal dendritic cells in the skin. In a mouse of pulmonary metastatic melanoma and in mice bearing subcutaneous melanoma tumor, the FB-Ag effectively increased antigen-specific therapeutic efficacy and produced long-lasting immune memory. More importantly, the FB-Ag also enhanced the level of COVID-19 specific antibodies in the serum and the number of memory B cells in the spleen of mice. The movement of antigen-loaded flagellate bacteria to overcome intradermal constraints may enhance the activation of intradermal dendritic cells, providing new ideas for developing intradermal vaccines.

Applications of microalga-powered microrobots in targeted drug delivery

Over the past decade, researchers have proposed a new class of drug delivery systems, bio-hybrid micro-robots, designed with a variety of living cell-driven micro-robots that utilize the unique mobility of natural organisms (bacteria, cells, exosomes, etc.) to transport effective drugs. Microalgae are considered potential drug delivery carriers. Recent studies have shown that microalga-based drug delivery systems exhibit excellent biocompatibility. In addition, microalgae have a large surfactant area, phototaxis, oxygen production, and other characteristics, so they are used as a carrier for the treatment of bacterial infections, cancer, etc. This review summarizes the modification of microalgae including click chemistry and electrostatic adsorption, and can improve the drug loading efficiency through dehydration and hydration strategies. The prepared microalgal drug delivery system can be targeted to different organs by different dosing methods or using external forces. Finally, it summarizes its antibacterial (gastritis, periodontitis, skin wound inflammation, etc.) and antitumor applications.

A drug co-delivery platform made of magnesium-based micromotors enhances combination therapy for hepatoma carcinoma cells

Combination therapy is an emerging strategy to overcome multidrug resistance (MDR) in hepatocellular carcinoma (HCC) chemotherapy treatment. However, the passive diffusion in traditional delivery systems greatly retards the approach and penetration of drugs into hepatocellular carcinoma cells and thus hinders the efficacy of combination therapy. Micro/nanomotors with autonomous locomotion in a tiny scale provide the possibility of tackling this issue. Herein, an active drug delivery micromotor platform delicately designed to load drugs with different physicochemical properties and enhance the drug permeability of cells is demonstrated for HCC chemotherapy treatment. The biocompatible micromotor platform Mg/PLGA/CHI comprised magnesium (Mg) coated with two polymer layers made of poly(lactic-co-glycolic acid) (PLGA) and chitosan (CHI), where the hydrophobic and hydrophilic drugs doxorubicin (Dox) and Curcumin (Cur) were loaded, respectively. The autonomous motion of the micromotors with velocity up to 45 μm s-1 greatly enhanced the diffusion of chemotherapeutic drugs and led to higher extracellular and intracellular drug distribution. Moreover, hydrogen produced during the motion eliminated the excess reactive oxygen species (ROS) in the human hepatocellular carcinoma (HepG2) cells. Compared with inert groups, the absorption of Dox and Cur from the active micromotors was about 2.9 and 1.5 times higher in human hepatocellular carcinoma (HepG2) cells. In addition, the anti-tumor activity also obviously improved at the micromotor concentration of 1 mg mL-1 (cell proliferation was reduced by almost 30%). Overall, this work proposes an approach based on loading different chemotherapy agents on an active delivery system to enhance drug permeability and overcome MDR and provides a potentially effective therapeutic strategy for the treatment of HCC.

An acoustically controlled helical microrobot

As a next-generation toolkit, microrobots can transform a wide range of fields, including micromanufacturing, electronics, microfluidics, tissue engineering, and medicine. While still in their infancy, acoustically actuated microrobots are becoming increasingly attractive. However, the interaction of acoustics with microstructure geometry is poorly understood, and its study is necessary for developing next-generation acoustically powered microrobots. We present an acoustically driven helical microrobot with a length of 350 μm and a diameter of 100 μm that is capable of locomotion using a fin-like double-helix microstructure. This microrobot responds to sound stimuli at ~12 to 19 kHz and mimics the spiral motion of natural microswimmers such as spirochetes. The asymmetric double helix interacts with the incident acoustic field, inducing a propulsion torque that causes the microrobot to rotate around its long axis. Moreover, our microrobot has the unique feature of its directionality being switchable by simply tuning the acoustic frequency. We demonstrate this locomotion in 2D and 3D artificial vasculatures using a single sound source.

A Review of Single-Cell Microrobots: Classification, Driving Methods and Applications

Single-cell microrobots are new microartificial devices that use a combination of single cells and artificial devices, with the advantages of small size, easy degradation and ease of manufacture. With externally driven strategies such as light fields, sound fields and magnetic fields, microrobots are able to carry out precise micromanipulations and movements in complex microenvironments. Therefore, single-cell microrobots have received more and more attention and have been greatly developed in recent years. In this paper, we review the main classifications, control methods and recent advances in the field of single-cell microrobot applications. First, different types of robots, such as cell-based microrobots, bacteria-based microrobots, algae-based microrobots, etc., and their design strategies and fabrication processes are discussed separately. Next, three types of external field-driven technologies, optical, acoustic and magnetic, are presented and operations realized in vivo and in vitro by applying these three technologies are described. Subsequently, the results achieved by these robots in the fields of precise delivery, minimally invasive therapy are analyzed. Finally, a short summary is given and current challenges and future work on microbial-based robotics are discussed.

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

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