Intelligent micro-/nanorobots as drug and cell carrier devices for biomedical therapeutic advancement: Promising development opportunities and translational challenges

Neurological insights into brain-targeted cancer therapy and bioinspired microrobots

Cancer, a multifaceted and pernicious disease, continuously challenges medicine, requiring innovative treatments. Brain cancers pose unique and daunting challenges due to the intricacies of the central nervous system and the blood-brain barrier. In this era of precision medicine, the convergence of neurology, oncology, and cutting-edge technology has given birth to a promising avenue - targeted cancer therapy. Furthermore, bioinspired microrobots have emerged as an ingenious approach to drug delivery, enabling precision and control in cancer treatment. This Keynote review explores the intricate web of neurological insights into brain-targeted cancer therapy and the paradigm-shifting world of bioinspired microrobots. It serves as a critical and comprehensive overview of these evolving fields, aiming to underscore their integration and potential for revolutionary cancer treatments.

Potential field mechanisms and distributed learning for enhancing the navigation of micro/nanorobot in biomedical environments

In complex systems, single micro/nanorobots encounter challenges related to limited loading capacity and navigation, hindering their effective utilization in targeted therapy and drug delivery. To solve these challenges, this paper explores potential field mechanisms as a means to simulate natural collective behavior. This approach aims to enhance the navigation and efficiency of micro/nanorobots in high-demand therapeutic areas. The mechanism enables micro/nanorobots to dynamically adapt to environmental gradients, minimizing off-target effects while maximizing therapeutic efficacy and enhancing robustness through redundancy. Additionally, this study introduces innovative distributed learning and cooperative control strategies. Each micro/nanorobot updates its navigation strategy through local interactions and influences with the dynamic environment. This allows micro/nanorobots to share information and improve their navigation toward therapeutic targets. The simulation results demonstrate that collective behavior and potential field mechanisms can enhance the precision and efficiency of targeted therapy and drug delivery in dynamically changing environments. In conclusion, the proposed approach can improve the limitations of single micro/nanobot, offering new possibilities for the development of advanced therapeutics and drug delivery systems.

A comprehensive review on the biomedical frontiers of nanowire applications

This comprehensive review examines the immense capacity of nanowires, nanostructures characterized by unbounded dimensions, to profoundly transform the field of biomedicine. Nanowires, which are created by combining several materials using techniques such as electrospinning and vapor deposition, possess distinct mechanical, optical, and electrical properties. As a result, they are well-suited for use in nanoscale electronic devices, drug delivery systems, chemical sensors, and other applications. The utilization of techniques such as the vapor-liquid-solid (VLS) approach and template-assisted approaches enables the achievement of precision in synthesis. This precision allows for the customization of characteristics, which in turn enables the capability of intracellular sensing and accurate drug administration. Nanowires exhibit potential in biomedical imaging, neural interfacing, and tissue engineering, despite obstacles related to biocompatibility and scalable manufacturing. They possess multifunctional capabilities that have the potential to greatly influence the intersection of nanotechnology and healthcare. Surmounting present obstacles has the potential to unleash the complete capabilities of nanowires, leading to significant improvements in diagnostics, biosensing, regenerative medicine, and next-generation point-of-care medicines.

Autonomous Nanorobots as Miniaturized Surgeons for Intracellular Applications

Artificial nanorobots have emerged as promising tools for a wide range of biomedical applications, including biosensing, detoxification, and drug delivery. Their unique ability to navigate confined spaces with precise control extends their operational scope to the cellular or subcellular level. By combining tailored surface functionality and propulsion mechanisms, nanorobots demonstrate rapid penetration of cell membranes and efficient internalization, enhancing intracellular delivery capabilities. Moreover, their robust motion within cells enables targeted interactions with intracellular components, such as proteins, molecules, and organelles, leading to superior performance in intracellular biosensing and organelle-targeted cargo delivery. Consequently, nanorobots hold significant potential as miniaturized surgeons capable of directly modulating cellular dynamics and combating metastasis, thereby maximizing therapeutic outcomes for precision therapy. In this review, we provide an overview of the propulsion modes of nanorobots and discuss essential factors to harness propulsive energy from the local environment or external power sources, including structure, material, and engine selection. We then discuss key advancements in nanorobot technology for various intracellular applications. Finally, we address important considerations for future nanorobot design to facilitate their translation into clinical practice and unlock their full potential in biomedical research and healthcare.

Precise Engineering of Growth Factor Presentation Using Extracellular Microenvironment-Mimicking Microfluidic Microparticles

One of the main challenges in tissue engineering is finding a way to deliver specific growth factors (GFs) with precise spatiotemporal control over their presentation. Here, we report a novel strategy for generating microscale carriers with enhanced affinity for high content loading suitable for the sustained and localized delivery of GFs. Our developed microparticles can be injected locally and sustainably release encapsulated growth factors for up to 28 days. Fine-tuning of particles' size, affinity, microstructures, and release kinetics is achieved using a microfluidic system along with bioconjugation techniques. We also describe an innovative 3D micromixer platform to control the formation of core-shell particles based on superaffinity using a polymer-peptide conjugate for further tuning of release kinetics and delayed degradation. Chitosan shells block the burst release of encapsulated GFs and enable their sustained delivery for up to 10 days. The matched release profiles and degradation provide the local tissues with biomimetic, developmental-biologic-compatible signals to maximize regenerative effects. The versatility of this approach is verified using three different therapeutic proteins, including human bone morphogenetic protein-2 (rhBMP-2), vascular endothelial growth factor (VEGF), and stromal cell-derived factor 1 (SDF-1α). As in vivo morphogenesis is typically driven by the combined action of several growth factors, the proposed technique can be developed to generate a library of GF-loaded particles with designated release profiles.

AI-enhanced biomedical micro/nanorobots in microfluidics

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

Magnetic nanoparticles for ferroptosis cancer therapy with diagnostic imaging

Ferroptosis offers a novel method for overcoming therapeutic resistance of cancers to conventional cancer treatment regimens. Its effective use as a cancer therapy requires a precisely targeted approach, which can be facilitated by using nanoparticles and nanomedicine, and their use to enhance ferroptosis is indeed a growing area of research. While a few review papers have been published on iron-dependent mechanism and inducers of ferroptosis cancer therapy that partly covers ferroptosis nanoparticles, there is a need for a comprehensive review focusing on the design of magnetic nanoparticles that can typically supply iron ions to promote ferroptosis and simultaneously enable targeted ferroptosis cancer nanomedicine. Furthermore, magnetic nanoparticles can locally induce ferroptosis and combinational ferroptosis with diagnostic magnetic resonance imaging (MRI). The use of remotely controllable magnetic nanocarriers can offer highly effective localized image-guided ferroptosis cancer nanomedicine. Here, recent developments in magnetically manipulable nanocarriers for ferroptosis cancer nanomedicine with medical imaging are summarized. This review also highlights the advantages of current state-of-the-art image-guided ferroptosis cancer nanomedicine. Finally, image guided combinational ferroptosis cancer therapy with conventional apoptosis-based therapy that enables synergistic tumor therapy is discussed for clinical translations.

Intelligent Navigation of a Magnetic Microrobot with Model-Free Deep Reinforcement Learning in a Real-World Environment

Microrobotics has opened new horizons for various applications, especially in medicine. However, it also witnessed challenges in achieving maximum optimal performance. One key challenge is the intelligent, autonomous, and precise navigation control of microrobots in fluid environments. The intelligence and autonomy in microrobot control, without the need for prior knowledge of the entire system, can offer significant opportunities in scenarios where their models are unavailable. In this study, two control systems based on model-free deep reinforcement learning were implemented to control the movement of a disk-shaped magnetic microrobot in a real-world environment. The training and results of an off-policy SAC algorithm and an on-policy TRPO algorithm revealed that the microrobot successfully learned the optimal path to reach random target positions. During training, the TRPO exhibited a higher sample efficiency and greater stability. The TRPO and SAC showed 100% and 97.5% success rates in reaching the targets in the evaluation phase, respectively. These findings offer basic insights into achieving intelligent and autonomous navigation control for microrobots to advance their capabilities for various applications.

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation. Metal-based degradable micromotor composed of magnesium (Mg), zinc (Zn), and iron (Fe) have promise due to their nontoxic fuel-free propulsion, favorable biocompatibility, and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media, efficient cargo delivery and favorable biocompatibility. A noteworthy number of degradable metal-based micromotors employ bubble propulsion, utilizing water as fuel to generate hydrogen bubbles. This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications. In addition, understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance. Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor. Here we review the design and recent advancements of metallic degradable micromotors. Furthermore, we describe the controlled degradation, efficient in vivo drug delivery, and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications. Moreover, we discuss micromotors' efficacy in detecting and destroying environmental pollutants. Finally, we address the limitations and future research directions of degradable metallic micromotors.

Cascade catalysis-coordinated nanorobots toward synergistic cancer chemoimmunotherapy

Cancer has always been the biggest threat to human health, but the effect of traditional treatments such as surgery, chemotherapy, and radiotherapy is not satisfactory. Currently, nanomedicine-based chemoimmunotherapy can improve clinical results through unique synergistic effects. However, it is mainly enriched at tumor sites based on EPR effects, without an active delivery strategy and relatively low tumor targeting distribution. Therefore, nanorobots (Cu@MPS-GOD) with magnetic responsiveness and enzyme-like activity were prepared, which can enrich and move to the tumor site under the action of a 3D magnetic field, and cause tumor cell immunogenic death by cascade catalytic Fenton reactions. Meanwhile, Cu@MPS-GOD can also activate immune cells or induce cancer cells to expose surface antigens, trigger systemic anti-cancer immunity, and have a good inhibitory effect on a breast tumor model in mice with an inhibition rate of 59.3%. This work provides an attractive strategy to expand the therapeutic effect of cancer when chemical dynamic therapy is combined with immunotherapy, which has a potential clinical application prospect.

Bladder microenvironment actuated proteomotors with ammonia amplification for enhanced cancer treatment

Enzyme-driven micro/nanomotors consuming in situ chemical fuels have attracted lots of attention for biomedical applications. However, motor systems composed by organism-derived organics that maximize the therapeutic efficacy of enzymatic products remain challenging. Herein, swimming proteomotors based on biocompatible urease and human serum albumin are constructed for enhanced antitumor therapy via active motion and ammonia amplification. By decomposing urea into carbon dioxide and ammonia, the designed proteomotors are endowed with self-propulsive capability, which leads to improved internalization and enhanced penetration in vitro. As a glutamine synthetase inhibitor, the loaded l-methionine sulfoximine further prevents the conversion of toxic ammonia into non-toxic glutamine in both tumor and stromal cells, resulting in local ammonia amplification. After intravesical instillation, the proteomotors achieve longer bladder retention and thus significantly inhibit the growth of orthotopic bladder tumor in vivo without adverse effects. We envision that the as-developed swimming proteomotors with amplification of the product toxicity may be a potential platform for active cancer treatment.

Intelligent nanomaterials for cancer therapy: recent progresses and future possibilities

Intelligent nanomedicine is currently one of the most active frontiers in cancer therapy development. Empowered by the recent progresses of nanobiotechnology, a new generation of multifunctional nanotherapeutics and imaging platforms has remarkably improved our capability to cope with the highly heterogeneous and complicated nature of cancer. With rationally designed multifunctionality and programmable assembly of functional subunits, the in vivo behaviors of intelligent nanosystems have become increasingly tunable, making them more efficient in performing sophisticated actions in physiological and pathological microenvironments. In recent years, intelligent nanomaterial-based theranostic platforms have showed great potential in tumor-targeted delivery, biological barrier circumvention, multi-responsive tumor sensing and drug release, as well as convergence with precise medication approaches such as personalized tumor vaccines. On the other hand, the increasing system complexity of anti-cancer nanomedicines also pose significant challenges in characterization, monitoring and clinical use, requesting a more comprehensive and dynamic understanding of nano-bio interactions. This review aims to briefly summarize the recent progresses achieved by intelligent nanomaterials in tumor-targeted drug delivery, tumor immunotherapy and temporospatially specific tumor imaging, as well as important advances of our knowledge on their interaction with biological systems. In the perspective of clinical translation, we have further discussed the major possibilities provided by disease-oriented development of anti-cancer nanomaterials, highlighting the critical importance clinically-oriented system design.

Advances of medical nanorobots for future cancer treatments

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

Biocompatible smart micro/nanorobots for active gastrointestinal tract drug delivery

INTRODUCTION

Oral delivery is the most commonly used route of drug administration owing to good patient compliance. However, the gastrointestinal (GI) tract contains multiple physiological barriers that limit the absorption efficiency of conventional passive delivery systems resulting in a low drug concentration reaching the diseased sites. Micro/nanorobots can convert energy to self-propulsive force, providing a novel platform to actively overcome GI tract barriers for noninvasive drug delivery and treatment.

AREAS COVERED

In this review, we first describe the microenvironments and barriers in the different compartments of the GI tract. Afterward, the applications of micro/nanorobots to overcome GI tract barriers for active drug delivery are highlighted and discussed. Finally, we summarize and discuss the challenges and future prospects of micro/nanorobots for further clinical applications.

EXPERT OPINION

Micro/nanorobots with the ability to autonomously propel themselves and to load, transport, and release payloads on demand are ideal carriers for active oral drug delivery. Although there are many challenges to be addressed, micro/nanorobots have great potential to introduce a new era of drug delivery for precision therapy.

Pressure-Gradient Counterwork of Dual-Fuel Driven Nanocarriers in Abnormal Interstitial Fluids for Enhancing Drug Delivery Efficiency

The abnormal pressure in tumor tissue is a significant limitation on the drug delivery efficiency of tumor therapy. This work reports a gradient-driven nanomotor as drug nanocarrier with the pressure-counterworking function. The dual-fuel nanomotors are formed by co-electrospinning of the photosensitive polymers with calcium peroxide (CaO₂ ) and catalase (CAT), followed by ultraviolet (UV) irradiation and bovine serum albumin (BSA) incubation. The UV-responsive cleavage nanomotors can effectively release O₂ molecules at the fractures as a driving force to increase the delivery speed and escape the phagocytosis of macrophage system in normal tissues. Furthermore, CAT catalyzes H₂ O₂ produced by CaO₂ and the tumor interstitial fluids to provide stronger power for the nanomotors. Additionally, according to the analysis of directional motions of the nanomotors, the functional relationship between the rotational diffusion coefficient (D_R ) and the physiological viscosity is constructed. The dual-fuel nanocarriers enable up to 13.25% of the injected dose (ID)/per gram tissue and significantly improve the penetration in deep tumor. It is of vital importance to design and obtain the adaptive pressure-gradient counterworking nanomotors, which can effectively improve the drug delivery efficiency in vitro and in vivo.

Efficient Preparation of a Magnetic Helical Carbon Nanomotor for Targeted Anticancer Drug Delivery

The applications of nanomotors in the biomedical field have been attracting extensive attention. However, it remains a challenge to fabricate nanomotors in a facile way and effectively load drugs for active targeted therapy. In this work, we combine the microwave heating method and chemical vapor deposition (CVD) to fabricate magnetic helical nanomotors efficiently. The microwave heating method can accelerate intermolecular movement, which converts kinetic energy into heat energy and shortens the preparation time of the catalyst used for carbon nanocoil (CNC) synthesis by 15 times. Fe₃O₄ nanoparticles are in situ nucleated on the CNC surface by the microwave heating method to fabricate magnetically driven CNC/Fe₃O₄ nanomotors. In addition, we achieved precise control of the magnetically driven CNC/Fe₃O₄ nanomotors through remote manipulation of magnetic fields. Anticancer drug doxorubicin (DOX) is then efficiently loaded onto the nanomotors via π-π stacking interactions. Finally, the drug-loaded CNC/Fe₃O₄@DOX nanomotor can accurately accomplish cell targeting under external magnetic field control. Under short-time irradiation of near-infrared light, DOX can be quickly released onto target cells to effectively kill the cells. More importantly, CNC/Fe₃O₄@DOX nanomotors allow for single-cell or cell-cluster-targeted anticancer drug delivery, providing a dexterous platform to potentially perform many medically relevant tasks in vivo. The efficient preparation method and application in drug delivery are beneficial for future industrial production and provide inspiration for advanced micro/nanorobotic systems using the CNC as a carrier for a wide range of biomedical applications.

Soft robot-enabled controlled release of oral drug formulations

The creation of highly effective oral drug delivery systems (ODDSs) has long been the main objective of pharmaceutical research. Multidisciplinary efforts involving materials, electronics, control, and pharmaceutical sciences encourage the development of robot-enabled ODDSs. Compared with conventional rigid robots, soft robots potentially offer better mechanical compliance and biocompatibility with biological tissues, more versatile shape control and maneuverability, and multifunctionality. In this paper, we first describe and highlight the importance of manipulating drug release kinetics, i.e. pharmaceutical kinetics. We then introduce an overview of state-of-the-art soft robot-based ODDSs comprising resident, shape-programming, locomotive, and integrated soft robots. Finally, the challenges and outlook regarding future soft robot-based ODDS development are discussed.

Advanced medical micro-robotics for early diagnosis and therapeutic interventions

Recent technological advances in micro-robotics have demonstrated their immense potential for biomedical applications. Emerging micro-robots have versatile sensing systems, flexible locomotion and dexterous manipulation capabilities that can significantly contribute to the healthcare system. Despite the appreciated and tangible benefits of medical micro-robotics, many challenges still remain. Here, we review the major challenges, current trends and significant achievements for developing versatile and intelligent micro-robotics with a focus on applications in early diagnosis and therapeutic interventions. We also consider some recent emerging micro-robotic technologies that employ synthetic biology to support a new generation of living micro-robots. We expect to inspire future development of micro-robots toward clinical translation by identifying the roadblocks that need to be overcome.

Promising Role of Polylactic Acid as an Ingenious Biomaterial in Scaffolds, Drug Delivery, Tissue Engineering, and Medical Implants: Research Developments, and Prospective Applications

In the present scenario, the research is now being focused on the naturally occurring polymers that can gradually replace the existing synthetic polymers for the development of bio composites having applications in medical surgeries and human implants. With promising mechanical properties and bio compatibility with human tissues, poly lactic acid (PLA) is now being viewed as a future bio material. In order to examine the applicability of PLA in human implants, the current article sheds light on the synthesis of PLA and its various copolymers used to alter its physical and mechanical properties. In the latter half, various processes used for the fabrication of biomaterials are discussed in detail. Finally, biomaterials that are currently in use in the field of biomedical (Scaffolding, drug delivery, tissue engineering, medical implants, derma, cosmetics, medical surgeries, and human implants) are represented with respective advantages in the sphere of biomaterials.

Applications and challenges of ultra-small particle size nanoparticles in tumor therapy

With the development of nanotechnology, nanomedicines are widely used in tumor therapy. However, biological barriers in the delivery of nanoparticles still limit their application in tumor therapy. As one of the most fundamental properties of nanoparticles, particle size plays a crucial role in the process of the nanoparticles delivery process. It is difficult for large size nanoparticles with fixed size to achieve satisfactory outcomes in every process. In order to overcome the poor penetration of larger size, nanoparticles with ultra-small particle size are proposed, which are more conducive to deep tumor penetration and uniform drug distribution. In this review, the latest progresses and advantages of ultra-small nanoparticles are systematically summarized, the perspectives and challenges of ultra-small nanoparticles strategy for cancer treatment are also discussed.

Imaging-Navigated Surgery

It is vitally important to guide or navigate therapeutic proceedings with a direct and visual approach in order to carefully undertake precision medical manipulations and efficiently evaluate the treatments. Imaging-navigated surgery is one of the common and prevailing technologies to realize this target, and more importantly it merges visualized medicine into next-generation theranostic paradigms in modern medicine. Endoscopes, surgical robots, and nanorobots are three major domains in terms of imaging-navigated surgery. The history of endoscopy has seen upgraded developments since the early 1800s. In contrast, surgical robots have been widely used and investigated in recent years, and they came into clinical uses only in the past decades. Nanorobots which closely depend on innovated and multifunctional biomaterials are still in their infancy. All these imaging-navigated technologies show similar and apparent advantages such as minimal invasiveness, minimized pain, positive prognosis, and relatively expected recovery, which have greatly improved surgery efficiency and patients' life quality. Therefore, the imaging-navigated surgery will be discussed in this chapter, and advanced clinical and preclinical medical applications will also be demonstrated for a diverse readers and comprehensive understanding.

Biomedical Nanosystems for In Vivo Detoxification: From Passive Delivery Systems to Functional Nanodevices and Nanorobots

The problem of low efficiency of nanotherapeutic drugs challenges the creation of new alternative biomedical nanosystems known as robotic nanodevices. In addition to encapsulating properties, nanodevices can perform different biomedical functions, such as precision surgery, in vivo detection and imaging, biosensing, targeted delivery, and, more recently, detoxification of endogenous and xenobiotic compounds. Nanodevices for detoxification are aimed at removing toxic molecules from biological tissues, using a chemical- and/or enzyme-containing nanocarrier for the toxicant to diffuse inside the nanobody. This strategy is opposite to drug delivery systems that focus on encapsulating drugs and releasing them under the influence of external factors. The review describes various kinds of nanodevices intended for detoxification that differ by the type of poisoning treatment they provide, as well as the type of materials and toxicants. The final part of the review is devoted to enzyme nanosystems, an emerging area of research that provides fast and effective neutralization of toxins in vivo.

Intelligent Micro-/Nanorobots for Cancer Theragnostic

Cancer is one of the most intractable diseases owing to its high mortality rate and lack of effective diagnostic and treatment tools. Advancements in micro-/nanorobot (MNR)-assisted sensing, imaging, and therapeutics offer unprecedented opportunities to develop MNR-based cancer theragnostic platforms. Unlike ordinary nanoparticles, which exhibit Brownian motion in biofluids, MNRs overcome viscous resistance in an ultralow Reynolds number (Re << 1) environment by effective self-propulsion. This unique locomotion property has motivated the advanced design and functionalization of MNRs as a basis for next-generation cancer-therapy platforms, which offer the potential for precise distribution and improved permeation of therapeutic agents. Enhanced barrier penetration, imaging-guided operation, and biosensing are additionally studied to enable the promising cancer-related applications of MNRs. Herein, the recent advances in MNR-based cancer therapy are comprehensively addresses, including actuation engines, diagnostics, medical imaging, and targeted drug delivery; promising research opportunities that can have a profound impact on cancer therapy over the next decade is highlighted.

"Motile-targeting" drug delivery platforms based on micro/nanorobots for tumor therapy

Traditional drug delivery systems opened the gate for tumor-targeted therapy, but they generally took advantage of enhanced permeability and retention or ligand-receptor mediated interaction, and thus suffered from limited recognition range (<0.5 nm) and low targeting efficiency (0.7%, median). Alternatively, micro/nanorobots (MNRs) may act as emerging "motile-targeting" drug delivery platforms to deliver therapeutic payloads, thereby making a giant step toward effective and safe cancer treatment due to their autonomous movement and navigation in biological media. This review focuses on the most recent developments of MNRs in "motile-targeting" drug delivery. After a brief introduction to traditional tumor-targeted drug delivery strategies and various MNRs, the representative applications of MNRs in "motile-targeting" drug delivery are systematically streamlined in terms of the propelling mechanisms. Following a discussion of the current challenges of each type of MNR in biomedical applications, as well as future prospects, several promising designs for MNRs that could benefit in "motile-targeting" drug delivery are proposed. This work is expected to attract and motivate researchers from different communities to advance the creation and practical application of the "motile-targeting" drug delivery platforms.

Extracellular matrix-mimicking nanofibrous chitosan microspheres as cell micro-ark for tissue engineering

In the present study, extracellular matrix (ECM)-mimicking nanofibrous chitosan microspheres (NCM) were developed via thermal induction of chitosan molecular chain from alkaline/urea aqueous solution. The regeneration of NCM from chitosan was proved to be physical process. The morphology of NCM could be precisely controlled by adjusting the initial solution concentration and the reaction temperature. The NCM possessed desirable in vitro/vivo biocompatibility and biodegradability. The excellent cell adhesion capability of NCM facilitated the formation of large-sized 3D geometric constructs in vitro. The NCM promoted in vitro osteogenic differentiation of rat bone marrow stem cells (rMSCs). Finally, pre-differentiated rMSCs-NCM constructs obviously enhanced in vivo bone healing of rat calvarial defects. This work opened up a new avenue for the construction of chitosan microspheres with ECM-like nanofibrous structure, indicated the great potential of the NCM as micro-Noah's Ark for stem cells to anchor, proliferate, and pre-differentiate for tissue engineering.

Stem Cell-Based Tissue Engineering for the Treatment of Burn Wounds: A Systematic Review of Preclinical Studies

Burn wounds are a devastating type of skin injury leading to severe impacts on both patients and the healthcare system. Current treatment methods are far from ideal, driving the need for tissue engineered solutions. Among various approaches, stem cell-based strategies are promising candidates for improving the treatment of burn wounds. A thorough search of the Embase, Medline, Scopus, and Web of Science databases was conducted to retrieve original research studies on stem cell-based tissue engineering treatments tested in preclinical models of burn wounds, published between January 2009 and June 2021. Of the 347 articles retrieved from the initial database search, 33 were eligible for inclusion in this review. The majority of studies used murine models with a xenogeneic graft, while a few used the porcine model. Thermal burn was the most commonly induced injury type, followed by surgical wound, and less commonly radiation burn. Most studies applied stem cell treatment immediately post-burn, with final endpoints ranging from 7 to 90 days. Mesenchymal stromal cells (MSCs) were the most common stem cell type used in the included studies. Stem cells from a variety of sources were used, most commonly from adipose tissue, bone marrow or umbilical cord, in conjunction with an extensive range of biomaterial scaffolds to treat the skin wounds. Overall, the studies showed favourable results of skin wound repair in animal models when stem cell-based tissue engineering treatments were applied, suggesting that such strategies hold promise as an improved therapy for burn wounds.

Immunomodulation and delivery of macrophages using nano-smooth drug-loaded magnetic microrobots for dual targeting cancer therapy

To realize the potential to use micro/nanorobots for targeted cancer therapy, it is important to improve their biocompatibility and targeting ability. Here, we report on drug-loaded magnetic microrobots capable of polarizing macrophages into the antitumor phenotype to target and inhibit cancer cells. In vitro tests demonstrated that the microrobots have good biocompatibility with normal cells and immune cells. Positively charged DOX was loaded onto the surface of microrobots via electrostatic interactions and exhibited pH-responsive release behavior. The nano-smooth surfaces of the microrobots activated M1 polarization of macrophages, thus activating their intrinsic targeting and antitumor abilities toward cancer cells. Through dual targeting from magnetic guidance and M1 macrophages, the microrobots were able to target and kill cancer cells in a 3D tumor spheroid culture assay. These findings demonstrate a way to improve the tumor-targeting and antitumor abilities of microrobots through the combined use of magnetic control, macrophages, and pH-responsive drug release.

Reproductive biology research down under: highlights from the Australian and New Zealand Annual Meeting of the Society for Reproductive Biology, 2021

Against the backdrop of a global pandemic, the Society for Reproductive Biology (SRB) 2021 meeting reunited the Australian and New Zealand reproductive research community for the first time since 2019 and was the first virtual SRB meeting. Despite the recent global research disruptions, the conference revealed significant advancements in reproductive research, the importance of which span human health, agriculture, and conservation. A core theme was novel technologies, including the use of medical microrobots for therapeutic and sperm delivery, diagnostic hyperspectral imaging, and hydrogel condoms with potential beyond contraception. The importance of challenging the contraceptive status quo was further highlighted with innovations in gene therapies, non-hormonal female contraceptives, epigenetic semen analysis, and in applying evolutionary theory to suppress pest population reproduction. How best to support pregnancies, particularly in the context of global trends of increasing maternal age, was also discussed, with several promising therapies for improved outcomes in assisted reproductive technology, pre-eclampsia, and pre-term birth prevention. The unique insights gained via non-model species was another key focus and presented research emphasised the importance of studying diverse systems to understand fundamental aspects of reproductive biology and evolution. Finally, the meeting highlighted how to effectively translate reproductive research into policy and industry practice.

Current approaches of nanomedicines in the market and various stage of clinical translation

Compared with traditional drug therapy, nanomedicines exhibit intriguing biological features to increase therapeutic efficiency, reduce toxicity and achieve targeting delivery. This review provides a snapshot of nanomedicines that have been currently launched or in the clinical trials, which manifests a diversified trend in carrier types, applied indications and mechanisms of action. From the perspective of indications, this article presents an overview of the applications of nanomedicines involving the prevention, diagnosis and treatment of various diseases, which include cancer, infections, blood disorders, cardiovascular diseases, immuno-associated diseases and nervous system diseases, etc. Moreover, the review provides some considerations and perspectives in the research and development of nanomedicines to facilitate their translations in clinic.

Magnetic-Powered Janus Cell Robots Loaded with Oncolytic Adenovirus for Active and Targeted Virotherapy of Bladder Cancer

A unique robotic medical platform is designed by utilizing cell robots as the active "Trojan horse" of oncolytic adenovirus (OA), capable of tumor-selective binding and killing. The OA-loaded cell robots are fabricated by entirely modifying OA-infected 293T cells with cyclic arginine-glycine-aspartic acid tripeptide (cRGD) to specifically bind with bladder cancer cells, followed by asymmetric immobilization of Fe₃ O₄ nanoparticles (NPs) on the cell surface. OA can replicate in host cells and induce cytolysis to release the virus progeny to the surrounding tumor sites for sustainable infection and oncolysis. The asymmetric coating of magnetic NPs bestows the cell robots with effective movement in various media and wireless manipulation with directional migration in a microfluidic device and bladder mold under magnetic control, further enabling steerable movement and prolonged retention of cell robots in the mouse bladder. The biorecognition of cRGD and robust, controllable propulsion of cell robots work synergistically to greatly enhance their tissue penetration and anticancer efficacy in the 3D cancer spheroid and orthotopic mouse bladder tumor model. Overall, this study integrates cell-based microrobots with virotherapy to generate an attractive robotic system with tumor specificity, expanding the operation scope of cell robots in biomedical community.

Recent Progress of Magnetically Actuated DNA Micro/Nanorobots

In the past few decades, the field of DNA origami-based micro/nanotechnology has developed dramatically and spawned attention increasingly, as its high integrality, rigid structure, and excellent resistance ability to enzyme digestion. Many two-dimensional and three-dimensional DNA nanostructures coordinated with optical, chemical, or magnetic triggers have been designed and assembled, extensively used as versatile templates for molecular robots, nanosensors, and intracellular drug delivery. The magnetic field has been widely regarded as an ideal driving and operating system for micro/nanomaterials, as it does not require high-intensity lasers like light control, nor does it need to change the chemical composition similar to chemical activation. Herein, we review the recent achievements in the induction and actuation of DNA origami-based nanodevices that respond to magnetic fields. These magnetic actuation-based DNA nanodevices were regularly combined with magnetic beads or gold nanoparticles and applied to generate single-stranded scaffolds, assemble various DNA nanostructures, and purify specific DNA nanostructures. Moreover, they also produced artificial magnetism or moved regularly driven by external magnetic fields to explain deeper scientific issues.

Micro/nanorobots for precise drug delivery via targeted transport and triggered release: a review

Micro/nanorobots that can effectively convert diverse energy sources into movement can revolutionize the field of pharmaceutical, particularly targeted drug delivery. By targeted transport and triggered release, drug can be delivered to targeted tissues or body sites. Targeted transport is discussed with different actuation energy sources including self-propelled (H₂O₂ and enzymes), external field-propelled (light, electrical, acoustics and magnetic field) and motile microorganism-propelled (bacterium, sperm, and contractile and immune cells) types. Triggered release systems including physiological environment, external fields and other mechanisms categories are also discussed here for the first time. With different transport and triggered release systems, micro/nanorobots achieved the goal of precise delivery of therapeutics. This review may provide a different perspective or referable guidance for the future development of more flexible targeted delivery systems.

A voyage from 3D to 4D printing in nanomedicine and healthcare: part I

The transition from 3D to 4D printing has revolutionized various domains of healthcare, pharmaceuticals, design and architecture, and coating processes. The evolution from 3D printing to 4D printing (4DP) has added a fourth dimension as a time-dependent response. This review discusses the significance, demands, various types of smart materials/biomaterials, as well as bioinks and printers used in 4DP technology. This review also provides insights into the limitations of the bioprinting process and bioinks used in various bioprinting technologies and the challenges that come with these limitations. A brief discussion on the future potential of the fundamentals and capabilities of 4D printing is also discussed.

One-Step Biosynthesis of Soft Magnetic Bacterial Cellulose Spheres with Localized Nanoparticle Functionalization

Actuated structures are becoming relevant in medical fields; however, they call for flexible/soft-base materials that comply with biological tissues and can be synthesized in simple fabrication steps. In this work, we extend the palette of techniques to afford soft, actuable spherical structures taking advantage of the biosynthesis process of bacterial cellulose. Bacterial cellulose spheres (BCS) with localized magnetic nanoparticles (NPs) have been biosynthesized using two different one-pot processes: in agitation and on hydrophobic surface-supported static culture, achieving core-shell or hollow spheres, respectively. Magnetic actuability is conferred by superparamagnetic iron oxide NPs (SPIONs), and their location within the structure was finely tuned with high precision. The size, structure, flexibility and magnetic response of the spheres have been characterized. In addition, the versatility of the methodology allows us to produce actuated spherical structures adding other NPs (Au and Pt) in specific locations, creating Janus structures. The combination of Pt NPs and SPIONs provides moving composite structures driven both by a magnetic field and a H₂O₂ oxidation reaction. Janus Pt/SPIONs increased by five times the directionality and movement of these structures in comparison to the controls.

Polymeric Micro/Nanocarriers and Motors for Cargo Transport and Phototriggered Delivery

Smart polymer-based micro/nanoassemblies have emerged as a promising alternative for transporting and delivering a myriad of cargo. Cargo encapsulation into (or linked to) polymeric micro/nanocarrier (PC) strategies may help to conserve cargo activity and functionality when interacting with its surroundings in its journey to the target. PCs for cargo phototriggering allow for excellent spatiotemporal control via irradiation as an external stimulus, thus regulating the delivery kinetics of cargo and potentially increasing its therapeutic effect. Micromotors based on PCs offer an accelerated cargo-medium interaction for biomedical, environmental, and many other applications. This review collects the recent achievements in PC development based on nanomicelles, nanospheres, and nanopolymersomes, among others, with enhanced properties to increase cargo protection and cargo release efficiency triggered by ultraviolet (UV) and near-infrared (NIR) irradiation, including light-stimulated polymeric micromotors for propulsion, cargo transport, biosensing, and photo-thermal therapy. We emphasize the challenges of positioning PCs as drug delivery systems, as well as the outstanding opportunities of light-stimulated polymeric micromotors for practical applications.

Micro and nanorobot-based drug delivery: an overview

Progress in the drug delivery system in the last few decades has led to many advancements for efficient drug delivery. Both micro and nanorobots, are regarded as superior drug delivery systems to deliver drugs efficiently by altering other forms of energy into propulsion and movements. Furthermore, it can be advantageous as it is directed to targeted sites beneath physiological environments and conditions. They have been validated to possess the capability to encapsulate, transport, and supply therapeutic contents directly to the disease sites, thus enhancing the therapeutic efficiency and decreasing systemic side effects of the toxic drugs. This review discusses about the microand nanorobots for the diagnostics and management of diseases, types of micro, and nanorobots, role of robots in drug delivery, and its biomedical applications.

Sequential Release of Paclitaxel and Imatinib from Core-Shell Microparticles Prepared by Coaxial Electrospray for Vaginal Therapy of Cervical Cancer

To optimize the anti-tumor efficacy of combination therapy with paclitaxel (PTX) and imatinib (IMN), we used coaxial electrospray to prepare sequential-release core–shell microparticles composed of a PTX-loaded sodium hyaluronate outer layer and an IMN-loaded PLGA core. The morphology, size distribution, drug loading, differential scanning calorimetry (DSC), Fourier transform infrared spectra (FTIR), in vitro release, PLGA degradation, cellular growth inhibition, in vivo vaginal retention, anti-tumor efficacy, and local irritation in a murine orthotopic cervicovaginal tumor model after vaginal administration were characterized. The results show that such core–shell microparticles were of spherical appearance, with an average size of 14.65 μm and a significant drug-loading ratio (2.36% for PTX, 19.5% for IMN, w/w), which might benefit cytotoxicity against cervical-cancer-related TC-1 cells. The DSC curves indicate changes in the phase state of PTX and IMN after encapsulation in microparticles. The FTIR spectra show that drug and excipients are compatible with each other. The release profiles show sequential characteristics in that PTX was almost completely released in 1 h and IMN was continuously released for 7 days. These core–shell microparticles showed synergistic inhibition in the growth of TC-1 cells. Such microparticles exhibited prolonged intravaginal residence, a >90% tumor inhibitory rate, and minimal mucosal irritation after intravaginal administration. All results suggest that such microparticles potentially provide a non-invasive local chemotherapeutic delivery system for the treatment of cervical cancer by the sequential release of PTX and IMN.

A Journey of Nanomotors for Targeted Cancer Therapy: Principles, Challenges, and a Critical Review of the State-of-the-Art

A nanomotor is a miniaturized device that converts energy stored in the environment into mechanical motion. The last two decades have witnessed a surge of research interests in the biomedical applications of nanomotors, but little clinical translation. To accelerate this process, targeted cancer therapy is used as an example to describe a "survive, locate, operate, and terminate" (SLOT) mission of a nanomotor, where it must 1) survive in the unfriendly in vivo environment, 2) locate its target as well as be located by human operators, 3) carry out specific operations, and 4) terminate after the mission is completed. Along this journey, the challenges presented to a nanomotor, including to power, navigate, steer, target, release, control, image, and communicate are discussed, and how state-of-the-art nanomotors meet or fall short of these requirements is critically reviewed. These discussions are then condensed into a table for easy reference. In particular, it is argued that chemically powered nanomotors are intrinsically ill-positioned for targeted cancer therapy, while nanomotors powered by magnetic fields or ultrasound show more promises. Following this argument, a tentative nanomotor design is then presented in the end to conform to the SLOT guideline, and to inspire practical, functional nanorobots that are yet to come.

Multifunctional biomolecule nanostructures for cancer therapy

Biomolecule-based nanostructures are inherently multifunctional and harbour diverse biological activities, which can be explored for cancer nanomedicine. The supramolecular properties of biomolecules can be precisely programmed for the design of smart drug delivery vehicles, enabling efficient transport in vivo, targeted drug delivery and combinatorial therapy within a single design. In this Review, we discuss biomolecule-based nanostructures, including polysaccharides, nucleic acids, peptides and proteins, and highlight their enormous design space for multifunctional nanomedicines. We identify key challenges in cancer nanomedicine that can be addressed by biomolecule-based nanostructures and survey the distinct biological activities, programmability and in vivo behaviour of biomolecule-based nanostructures. Finally, we discuss challenges in the rational design, characterization and fabrication of biomolecule-based nanostructures, and identify obstacles that need to be overcome to enable clinical translation.

Recent Advances in Microswimmers for Biomedical Applications

Microswimmers are a rapidly developing research area attracting enormous attention because of their many potential applications with high societal value. A particularly promising target for cleverly engineered microswimmers is the field of biomedical applications, where many interesting examples have already been reported for e.g., cargo transport and drug delivery, artificial insemination, sensing, indirect manipulation of cells and other microscopic objects, imaging, and microsurgery. Pioneered only two decades ago, research studies on the use of microswimmers in biomedical applications are currently progressing at an incredibly fast pace. Given the recent nature of the research, there are currently no clinically approved microswimmer uses, and it is likely that several years will yet pass before any clinical uses can become a reality. Nevertheless, current research is laying the foundation for clinical translation, as more and more studies explore various strategies for developing biocompatible and biodegradable microswimmers fueled by in vivo-friendly means. The aim of this review is to provide a summary of the reported biomedical applications of microswimmers, with focus on the most recent advances. Finally, the main considerations and challenges for clinical translation and commercialization are discussed.

Aptamer-Functionalized Natural Protein-Based Polymers as Innovative Biomaterials

Biomaterials science is one of the most rapidly evolving fields in biomedicine. However, although novel biomaterials have achieved well-defined goals, such as the production of devices with improved biocompatibility and mechanical properties, their development could be more ambitious. Indeed, the integration of active targeting strategies has been shown to allow spatiotemporal control of cell-material interactions, thus leading to more specific and better-performing devices. This manuscript reviews recent advances that have led to enhanced biomaterials resulting from the use of natural structural macromolecules. In this regard, several structural macromolecules have been adapted or modified using biohybrid approaches for use in both regenerative medicine and therapeutic delivery. The integration of structural and functional features and aptamer targeting, although still incipient, has already shown its ability and wide-reaching potential. In this review, we discuss aptamer-functionalized hybrid protein-based or polymeric biomaterials derived from structural macromolecules, with a focus on bioresponsive/bioactive systems.

Medical Micro/Nanorobots in Precision Medicine

Advances in medical robots promise to improve modern medicine and the quality of life. Miniaturization of these robotic platforms has led to numerous applications that leverages precision medicine. In this review, the current trends of medical micro and nanorobotics for therapy, surgery, diagnosis, and medical imaging are discussed. The use of micro and nanorobots in precision medicine still faces technical, regulatory, and market challenges for their widespread use in clinical settings. Nevertheless, recent translations from proof of concept to in vivo studies demonstrate their potential toward precision medicine.