Microfluidic Electrospray Niacin Metal-Organic Frameworks Encapsulated Microcapsules for Wound Healing

Programmable Logic in Metal-Organic Frameworks for Catalysis

Metal-organic frameworks (MOFs) have emerged as one of the most widely investigated materials in catalysis mainly due to their excellent component tunability, high surface area, adjustable pore size, and uniform active sites. However, the overwhelming number of MOF materials and complex structures has brought difficulties for researchers to select and construct suitable MOF-based catalysts. Herein, a programmable design strategy is presented based on metal ions/clusters, organic ligands, modifiers, functional materials, and post-treatment modules, which can be used to design the components, structures, and morphologies of MOF catalysts for different reactions. By establishing the corresponding relationship between these modules and functions, researchers can accurately and efficiently construct heterometallic MOFs, chiral MOFs, conductive MOFs, hierarchically porous MOFs, defective MOFs, MOF composites, and MOF-derivative catalysts. Further, this programmable design approach can also be used to regulate the physical/chemical microenvironments of pristine MOFs, MOF composites, and MOF-derivative materials for heterogeneous catalysis, electrocatalysis, and photocatalysis. Finally, the challenging issues and opportunities for the future research of MOF-based catalysts are discussed. Overall, the modular design concept of this review can be applied as a potent tool for exploring the structure-activity relationships and accelerating the on-demand design of multicomponent catalysts.

Chinese herb microneedle patch for wound healing

Traditional Chinese medicine and Chinese herbs have a demonstrated value for disease therapy and sub-health improvement. Attempts in this area tend to develop new forms to make their applications more convenient and wider. Here, we propose a novel Chinese herb microneedle (CHMN) patch by integrating the herbal extracts, Premna microphylla and Centella asiatica, with microstructure of microneedle for wound healing. Such path is composed of sap extracted from the herbal leaves via traditional kneading method and solidified by plant ash derived from the brine induced process of tofu in a well-designed mold. Because the leaves of the Premna microphylla are rich in pectin and various amino acids, the CHMN could be imparted with medicinal efficacy of heat clearing, detoxicating, detumescence and hemostatic. Besides, with the excellent pharmaceutical activity of Asiatic acid extracted from Centella asiatica, the CHMN is potential in promoting relevant growth factor genes expression in fibroblasts and showing excellent performance in anti-oxidant, anti-inflammatory and anti-bacterial activity. Taking advantages of these pure herbal compositions, we have demonstrated that the derived CHMN was with dramatical achievement in anti-bacteria, inhibiting inflammatory, collagen deposition, angiogenesis and tissue reconstruction during the wound closure. These results indicate that the integration of traditional Chinese herbs with progressive technologies will facilitate the development and promotion of traditional Chinese medicine in modern society.

Microfluidic encapsulated manganese organic frameworks as enzyme mimetics for inflammatory bowel disease treatment

Metal organic frameworks (MOFs) with physicochemical properties and adjustable structures have been proposed as very attractive materials. The studies on development of such functional materials tended to fabricate featured MOF objects with fascinating catalytic capabilities to utilize their biomedical values. In this paper, we present novel biocompatible manganese metal organic framework (Mn-MOF)-based catalase mimetics with microfluidic microcapsule encapsulation for intravital inflammatory bowel disease (IBD) treatment. Phosphoserine, a component of the cell membrane, served as an organic ligand to ensure biocompatibility of Mn-MOF. Owing to the core-shell structure of the microcapsule, the Mn-MOF exhibited a well-organized distribution and controlled release features, which could protect them from gastric juice and provide function in the intestine. Upon reaching the sites of the inflammatory bowel, Mn-MOF could effectively scavenge reactive oxygen species (ROS) over-produced by neutrophils and macrophages under various gastrointestinal pH environments, protecting intestinal epithelial cells from ROS damage. The Mn-MOF-encapsulated microcapsules exhibited high performances in treating spontaneous IBD in interleukin-10-deficient mice by relieving the oxidative stress, reducing the inflammation, and restoring the intestinal barrier. These results indicate that the functional Mn-MOF-encapsulated microcapsules have practical applications in the treatment of ROS-associated diseases.

Construction of a multifunctional 3D nanofiber aerogel loaded with ZnO for wound healing

Bacterial infection and severe wound inflammation are two primary harmful problems that bring harm to the human body and may cause death when a large-scale skin defect occurs. Thus, developing an effective and quick wound healing strategy for curing skin damage and trauma is vital. This study has developed a multifunctional PLA/gelatin/ZnO nanofiber aerogel with a three-dimensional structure through electrospinning and freeze-drying technology for wound healing. It has validated that the nanofiber aerogel has an excellent antibacterial property and biocompatibility. Meanwhile, benefiting from its three-dimensional nanofiber structure, the PLA/gelatin/ZnO nanofiber aerogel possesses good water absorption and air permeability. In vivo experiments have determined that the PLA/gel/ZnO nanofiber aerogel scaffolds effectively promote skin infection's wound healing and enhance angiogenesis that is practical with increasing ZnO concentration.

Hemostatic materials in wound care

Blood plays an essential role in the human body. Hemorrhage is a critical cause of both military and civilian casualties. The human body has its own hemostatic mechanism that involves complex processes and has limited capacity. However, in emergency situations such as battlefields and hospitals, when the hemostatic mechanism of the human body itself cannot stop bleeding effectively, hemostatic materials are needed for saving lives. In this review, the hemostatic mechanisms and performance of the most commonly used hemostatic materials, (including fibrin, collagen, zeolite, gelatin, alginate, chitosan, cellulose and cyanoacrylate) and the commercial wound dressings based on these materials, will be discussed. These materials may have limitations, such as poor tissue adhesion, risk of infection and exothermic reactions, that may lessen their hemostatic efficacy and cause secondary injuries. High-performance hemostatic materials, therefore, have been designed and developed to improve hemostatic efficiency in clinical use. In this review, hemostatic materials with advanced performances, such as antibacterial capacity, superhydrophobicity/superhydrophilicity, superelasticity, high porosity and/or biomimicry, will be introduced. Future prospects of hemostatic materials will also be discussed in this review.

Suction Cups-Inspired Adhesive Patch with Tailorable Patterns for Versatile Wound Healing

Medical patches play an important role in wound healing because of their tissue conformality, drug release capacity, and convenient operation. Great efforts have been devoted to developing new-generation patches with distinctive features promoting wound healing. Here, inspired by the structure of octopus suction cups and the component of natural tissue, a biocompatible wound patch with selective adhesiveness and individualized design using a combined strategy of template-replication and mask-guided lithography is presented. Such patches are based on Ecoflex film with suction-cup-mimicking microstructures to adhere to normal skin and with biocompatible gelatin methacryloyl (GelMA) hydrogel to contact wounded areas. An ultraviolet mask with a tailorable pattern is employed to shape the GelMA hydrogel into customized geometry replicating individual wound areas, and thus both adhesion and antiadhesion properties are integrated into the same patch. In addition, vascular endothelial growth factor is loaded to accelerate the healing process. Based on these advantages, the authors demonstrate that the present patches not only adhere to different skin surfaces, but also promote the treatment of a rat cutaneous wound model. Thus, it is believed that this versatile patch can break through the limitation of traditional patches and be ideal candidates for wound healing and related biomedical applications.

Microfluidics for Drug Development: From Synthesis to Evaluation

Drug development is a long process whose main content includes drug synthesis, drug delivery, and drug evaluation. Compared with conventional drug development procedures, microfluidics has emerged as a revolutionary technology in that it offers a miniaturized and highly controllable environment for bio(chemical) reactions to take place. It is also compatible with analytical strategies to implement integrated and high-throughput screening and evaluations. In this review, we provide a comprehensive summary of the entire microfluidics-based drug development system, from drug synthesis to drug evaluation. The challenges in the current status and the prospects for future development are also discussed. We believe that this review will promote communications throughout diversified scientific and engineering communities that will continue contributing to this burgeoning field.

MXene-Integrated Microneedle Patches with Innate Molecule Encapsulation for Wound Healing

Wound healing is a complex physiological process that involves coordinated phases such as inflammation and neovascularization. Attempts to promote the healing process tend to construct an effective delivery system based on different drugs and materials. In this paper, we propose novel MXene-integrated microneedle patches with adenosine encapsulation for wound healing. Owing to the dynamic covalent bonding capacity of boronate molecules with adenosine, 3-(acrylamido)phenylboronic acid- (PBA-) integrated polyethylene glycol diacrylate (PEGDA) hydrogel is utilized as the host material of microneedle patches. Benefitting from photothermal conversion capacity of MXene, the release of loaded adenosine could be accelerated under NIR irradiation for maintaining the activation signal around injury site. In vitro cell experiments proved the effect of MXene-integrated microneedle patches with adenosine encapsulation in enhancing angiogenesis. When applied for treating animal models, it is demonstrated that the microneedle patches efficiently promote angiogenesis, which is conductive to wound healing. These features make the proposed microneedle patch potential for finding applications in wound healing and other biomedical fields.

Bio-inspired intestinal scavenger from microfluidic electrospray for detoxifying lipopolysaccharide

Lipopolysaccharide (LPS) plays an important role in metabolic syndrome (MetS) and other gut-derived diseases, and detoxifying LPS is considered to be a fundamental approach to prevent and treat these diseases. Here, inspired by the feeding behaviour of scavenger, novel microfluidic microcapsules with alkaline phosphatase (ALP) encapsulation and the scavenger-like molecular sieve shell are presented for cleaning intestinal LPS. Benefiting from the precisely controlled of the pore size and microfluidic electrospray, the generated microcapsules were imparted with porous molecular-sieve shells and ALP encapsulated active cores. These microcapsules could continuously work as an intestinal scavenger after colonized in intestine. It has been demonstrated that the microcapsules could englobe LPS while inhibit the permeation of digestive enzyme, and this ability contributes to promising ALP's activity, protecting cells at the presence of LPS and reducing inflammation. In addition, this scavenger inspired microcapsule could effectively decrease the LPS in organs, reduce inflammation and regulating fat metabolism in vivo. These features make the ALP encapsulated microcapsules an ideal candidate for treating MetS and other LPS related diseases.

Zn-MOF Encapsulated Antibacterial and Degradable Microneedles Array for Promoting Wound Healing

An infected skin wound caused by external injury remains a serious challenge in clinical practice. Wound dressings with the properties of antibacterial activity and potent regeneration capacity are highly desirable for wound healing. In this paper, a degradable, ductile, and wound-friendly Zn-MOF encapsulated methacrylated hyaluronic acid (MeHA) microneedles (MNs) array is fabricated through the molding method for promoting wound healing. Due to the damage capability against the bacteria capsule and oxidative stress of the zinc ion released from the Zn-MOF, such MNs array presents excellent antibacterial activity, as well as considerable biocompatibility. Besides, the degradable MNs array composed of photo-crosslinked MeHA possesses the superior capabilities to continuously and steadily release the loaded active ingredients and avoid secondary damage to the wound. Moreover, the low molecular weight hyaluronic acid (HA) generated by hydrolysis of MeHA is also conducive to tissue regeneration. Benefiting from these features, it has been demonstrated that the Zn-MOF encapsulated degradable MNs array can dramatically accelerate epithelial regeneration and neovascularization. These results indicate that the combination of MOFs and degradable MNs array is of great value for promoting wound healing.

Boston Ivy-Inspired Disc-Like Adhesive Microparticles for Drug Delivery

Microparticles with strong adherence are expected as efficient drug delivery vehicles. Herein, we presented an ingenious hydrogel microparticle recapitulating the adhesion mechanism of Boston ivy tendrils adhesive discs (AD) for durable drug delivery. The particles were achieved by replicating a silica colloidal crystal aggregates assembled in a droplet template after rapid solvent extraction. Due to their unique shape, the nanostructure, and the sticky hydrogel component, such novel microparticles exhibited prominent adhesive property to the wet tissue environment. It was demonstrated that the bioinspired microcarriers loading with dexamethasone had a good therapeutic effect for ulcerative colitis due to the strong adhesion ability for prolonging the maintenance of drug availability. These virtues make the biomimetic microparticles potentially ideal for many practical clinical applications, such as drug delivery, bioimaging, and biodiagnostics.

A photothermally-induced HClO-releasing nanoplatform for imaging-guided tumor ablation and bacterial prevention

Photothermal therapy (PTT) is a cure that can inhibit tumor growth effectively and even remove tumor via photo-induced local hyperthermia. However, its shortcoming lies in the fact that excessive heat is most likely to lead to thermal injury at the epidermis of the tumor region and even the area of the surrounding tissue. As a consequence, the exposure of the thermally-induced wound would result in the increased risk of bacterial infection. To date, few PTT platforms have attached importance to the prevention of bacterial infection at the photothermally-induced wound. Herein, we reported a thermally-sensitive liposome nanosystem (Lipo-B-TCCA) containing aza-BODIPY and trichloroisocyanuric acid, which is conductive for the PTT of tumor and the prevention of bacteria. It is observed that the designed nanoplatform could exhibit remarkable stability, high photothermal conversion efficiency (31.4%), and efficient HClO-releasing ability in vitro and in vivo. Moreover, Lipo-B-TCCA is able to eliminate tumor efficiently via near infrared fluorescence and photothermal imaging guidance with low side effects. Most importantly, Lipo-B-TCCA could prevent the growth of S. aureus in the thermal wound during the process of PTT. The imaging-guided photothermally-induced HClO-releasing PTT nanoplatform for tumor ablation and bacterial prevention shows excellent performance and great potential for biomedical applications.

Protein-Based Hybrid Responsive Microparticles for Wound Healing

The in-depth development of biological materials, especially natural polymer materials, has injected strong vitality into clinical wound treatment. Here, a new type of controllable responsive microparticles composed of several natural polymer materials was presented for drug release and wound healing. These hybrid microparticles consisted of silk fibroin, gelatin, agarose, and black phosphorus quantum dots (BPQDs) and were loaded with growth factors and antibacterial peptides. Under near-infrared (NIR) irradiation, BPQDs could absorb the NIR light and increase the temperature of the microparticles to the melting point of gelatin. When the gelatin started to melt, the encapsulated drugs were gradually released because of the reversible phase transformation. Both in vitro and in vivo experiments have demonstrated that the BPQD-laden microparticles with a NIR-responsive feature could achieve the desired controllable release of growth factors to promote neovascularization formation. In addition, because antibacterial peptides were also mixed with the secondary hydrogel and encapsulated in the scaffolds, the microparticles are imparted with the antibacterial ability during storage and usage. These characteristics of BPQD-laden natural protein hybrid microparticles make them ideal for drug delivery and wound healing.

Propulsion Gait Analysis and Fluidic Trapping of Swinging Flexible Nanomotors

Micro- and nanomachines as feasible agents to exploit the microworld have attracted extensive research interest, particularly in the manipulation of soft nanorobots at small scales. Herein, we propose a model for regulating the motion of a swinging flexible nanomotor (SFN) driven by an oscillating magnetic field. Multisegments of an SFN are synthesized from nickel, gold, and porous silver. The coupling of magnetic actuation and the swinging pattern of SFNs are studied to reveal their mobility. Additionally, an optimal frequency occurs from the coupling of magnetic torque and structural deformation, rather than the simply considered step-out phenomenon. Meanwhile, a fluidic trapping region is formulated alongside the SFN. Such a trapping region is demonstrated by trapping a living neutrophil and accomplishing in vitro transportation using fluidic mediation. On-demand cargo delivery can be realized using a programmable magnetic field, and SFNs can be recycled with ease after manipulation owing to environmental concerns. In this study, we demonstrated the properties of SFNs that are useful bases for their customization and control. These flexible nanomotors may have the potential to promote drug delivery and biomedical operations in noncontact modes.

Metal-Organic Framework (MOF)-Based Biomaterials for Tissue Engineering and Regenerative Medicine

The synthesis of Metal-organic Frameworks (MOFs) and their evaluation for various applications is one of the largest research areas within materials sciences and chemistry. Here, the use of MOFs in biomaterials and implants is summarized as narrative review addressing primarely the Tissue Engineering and Regenerative Medicine (TERM) community. Focus is given on MOFs as bioactive component to aid tissue engineering and to augment clinically established or future therapies in regenerative medicine. A summary of synthesis methods suitable for TERM laboratories and key properties of MOFs relevant to biomaterials is provided. The use of MOFs is categorized according to their targeted organ (bone, cardio-vascular, skin and nervous tissue) and whether the MOFs are used as intrinsically bioactive material or as drug delivery vehicle. Further distinction between in vitro and in vivo studies provides a clear assessment of literature on the current progress of MOF based biomaterials. Although the present review is narrative in nature, systematic literature analysis has been performed, allowing a concise overview of this emerging research direction till the point of writing. While a number of excellent studies have been published, future studies will need to clearly highlight the safety and added value of MOFs compared to established materials for clinical TERM applications. The scope of the present review is clearly delimited from the general 'biomedical application' of MOFs that focuses mainly on drug delivery or diagnostic applications not involving aspects of tissue healing or better implant integration.

CCL4-mediated targeting of spleen tyrosine kinase (Syk) inhibitor using nanoparticles alleviates inflammatory bowel disease

Inflammatory bowel disease (IBD) has emerged a global disease and the ascending incidence and prevalence is accompanied by elevated morbidity, mortality, and substantial healthcare system costs. However, the current typical one-size-fits-all therapeutic approach is suboptimal for a substantial proportion of patients due to the variability in the course of IBD and a considerable number of patients do not have positive response to the clinically approved drugs, so there is still a great, unmet demand for novel alternative therapeutic approaches. Spleen tyrosine kinase (Syk), a cytoplasmic nonreceptor protein tyrosine kinase, plays crucial roles in signal transduction and there are emerging data implicating that Syk participates in pathogenesis of several gut disorders, such as IBD. In this study, we observed the Syk expression in IBD patients and explored the effects of therapeutic Syk inhibition using small-molecule Syk inhibitor piceatannol in bone marrow-derived macrophages (BMDMs). In addition, due to the poor bioavailability and pharmacokinetics of small-molecule tyrosine kinase inhibitors and superiority of targeting nanoparticles-based drug delivery system, we herein prepared piceatannol-encapsulated poly(lactic-co-glycolic acid) nanoparticles that conjugated with chemokine C-C motif ligand 4 (P-NPs-C) and studied its therapeutic effects in vitro in BMDMs and in vivo in experimental colitis model. Our results indicated that in addition to alleviating colitis, oral administration of P-NPs-C promoted the restoration of intestinal barrier function and improved intestinal microflora dysbiosis, which represents a promising treatment for IBD.

Multifunctional Composite Inverse Opal Film with Multiactives for Wound Healing

A film with an elaborate microstructure and multifunctions is urgently needed in wound healing. Here, we present a multiactive encapsulated inverse opal film with a monitorable delivery system for chronic wound healing. The inverse opal film is prepared by using poly(lactic-co-glycolic acid) to negatively replicate a colloidal crystal template, which presents a high specific surface area and interconnected nanopores. It could be imparted with a potent antibacterial effect and promote angiogenesis by loading the vascular endothelial growth factor into the nanopores and encapsulating by chitosan. In addition, it is demonstrated that the structure color change of the film could intuitively reflect the drug release progress from the nanopores, which made the film a real-time drug monitoring system. In the affected wound model, the properties of the multifunctional film in promoting wound healing are certified by the faster healing speed, more granulation tissue, less inflammation, and even a distribution of new blood vessels and collagen. These results indicate that the resultant multifunctional film has a practical application value in clinical wound care.

Trends in Micro-/Nanorobotics: Materials Development, Actuation, Localization, and System Integration for Biomedical Applications

Micro-/nanorobots (m-bots) have attracted significant interest due to their suitability for applications in biomedical engineering and environmental remediation. Particularly, their applications in in vivo diagnosis and intervention have been the focus of extensive research in recent years with various clinical imaging techniques being applied for localization and tracking. The successful integration of well-designed m-bots with surface functionalization, remote actuation systems, and imaging techniques becomes the crucial step toward biomedical applications, especially for the in vivo uses. This review thus addresses four different aspects of biomedical m-bots: design/fabrication, functionalization, actuation, and localization. The biomedical applications of the m-bots in diagnosis, sensing, microsurgery, targeted drug/cell delivery, thrombus ablation, and wound healing are reviewed from these viewpoints. The developed biomedical m-bot systems are comprehensively compared and evaluated based on their characteristics. The current challenges and the directions of future research in this field are summarized.

Hydrogels: The Next Generation Body Materials for Microfluidic Chips?

The integration of microfluidics with biomedical research is confronted with considerable limitations due to its body materials. With high content of water, hydrogels own superior biocompatibility and degradability. Can hydrogels become another material choice for the construction of microfluidic chips, particularly biofluidics? The present review aims to systematically establish the concept of hydrogel-based microfluidic chips (HMCs) and address three main concerns: i) why choosing hydrogels? ii) how to fabricate HMCs?, and iii) in which fields to apply HMCs? It is envisioned that hydrogels may be used increasingly as substitute for traditional materials and gradually act as the body material for microfluidic chips. The modifications of conventional process are highlighted to overcome issues arising from the incompatibility between the construction methods and hydrogel materials. Specifically targeting at the "soft and wet" hydrogels, an efficient flowchart of "i) high resolution template printing; ii) damage-free demolding; iii) twice-crosslinking bonding" is proposed. Accordingly, a broader microfluidic chip concept is proposed in terms of form and function. Potential biomedical applications of HMCs are discussed. This review also highlights the challenges arising from the material replacement, as well as the future directions of the proposed concept. Finally, the authors' viewpoints and perspectives for this emerging field are discussed.

Dual-Core Prebiotic Microcapsule Encapsulating Probiotics for Metabolic Syndrome

Designing strategies to utilize the synergistic effect of probiotics and prebiotics is a promising way in treating metabolic-related diseases. Here, inspired by the mutually promotable but mutually incompatible characteristics of Yin and Yang, dual-core microcapsules that encapsulate Lactobacillus and Bacillus subtilis into separate compartments were presented through electrostatically driven microfluidics. The microcapsules showed acid resistance and preserved probiotic activity. They also fostered the proliferation of probiotics while creating an anaerobic environment and promoted lactic acid fermentation without affecting each other. It has been demonstrated that the microcapsules could reduce inflammation, improve fat metabolism, and restore intestinal barrier functions, thus contributing to the treatment of metabolic syndrome in vivo. These features make the dual-core microcapsules an ideal candidate for treating metabolic syndrome and related diseases.

Surface Engineered Metal-Organic Frameworks (MOFs) Based Novel Hybrid Systems for Effective Wound Healing: A Review of Recent Developments

Wounds present serious medical complications and their healing requires strategies that promote angiogenesis, deposition of collagen as well as re-epithelialization of wounds. Currently used conventional wound healing strategies have become less effective due to various issues associated with them. Thus, novel strategies are needed to be developed for early and effective healing of wounds. Metal-organic frameworks (MOFs), formed by linking of metal ions through organic bridging ligands, are highly tunable hybrid materials and have attracted more considerable scientific attention due to their charming and prominent properties, such as abundant pore structures and multiple functionalities. Surface engineering of MOFs with unique ligands can overcome issues associated with conventional wound healing methods, thus resulting in early and effective wound healing. This review has been undertaken to elaborate wound healing, and the use of surface engineered MOFs for effective and rapid wound healing. The process of wound healing will be discussed followed by a detailed review of recent literature for summarizing applications of surface engineered MOFs for wound healing. MOFs wound healing will be discussed in terms of their use as antibacterial agents, therapeutic delivery vehicles, and dressing systems in wound healing.

Enhanced Light-Harvesting Efficiency and Adaptation: A Review on Visible-Light-Driven Micro/Nanomotors

As visible light accounts for a larger proportion of solar energy and is harmless to living organisms, it has the potential to be the energy source of micro/nanomotors, which transform visible-light energy into mechanical motion, for different applications, especially in environmental remediation. However, how to precisely control the motion of visible-light-driven micro/nanomotors (VLD-MNMs) and efficiently utilize the weak visible-light photon energy to acquire rapid motion are significant challenges. This review summarizes the most critical aspects, involving photoactive materials, propulsion mechanisms, control methods, and applications of VLD-MNMs, and discusses strategies to systematically enhance the energy-harvesting efficiency and adaptation. At first, the photoactive materials have been divided into inorganic and organic photoactive materials and comprehensively discussed. Then, different propulsion mechanisms of the current VLD-MNMs are presented to explain the improvement in the actuation force, speed, and environmental adaptability. In addition, considering the characteristics of easy control of VLD-MNMs, we summarized the direction, speed, and cluster control methods of VLD-MNMs for different application requirements. Subsequently, the potential applications of VLD-MNMs, e.g., in environmental remediation, micropumps, cargo delivery, and sensing in microscale, are presented. Finally, discussions and suggestions for future directions to enhance the energy-harvesting efficiency and adaptation of VLD-MNMs are provided.

Bio-inspired lubricant drug delivery particles for the treatment of osteoarthritis

Osteoarthritis is a chronic and irreversible degenerative disease that often occurs in middle-aged and elderly people. Although many clinical therapeutics like intra-articular drug injection have been widely used for treating osteoarthritis, there are still some shortcomings that need to be overcome such as frequent injection, inflammatory response, and potential overdose. Inspired by the natural biocompatible lubricant substances, hyaluronic acid (HA), a novel bio-inspired lubricant drug delivery microcarrier with pathological-state responsive switches, was developed for osteoarthritis treatment. In this system, a temperature-responsive hydrogel was used to form an inverse opal-structured microsphere scaffold to increase the drug loading efficiency, while HA was employed as a vehicle to encapsulate drugs. Due to the properties of the scaffold, the loaded lubricant and encapsulated drugs can be released when temperature rises in the joint cavity during exercise or osteoarthritis. In contrast, the delivery system will be locked and the drug release process will stop when the arthritis lessens or exercise is stopped. Thus, the designed microcarrier is endowed with the ability of intelligently releasing drugs and lubricants for curing osteoarthritis, demonstrating its great potential in biomedical applications.

Bio-inspired adhesive porous particles with human MSCs encapsulation for systemic lupus erythematosus treatment

Mesenchymal stem cells (MSCs) therapy is a promising treatment for Systemic lupus erythematosus (SLE) patients. However, this method is encumbered by suboptimal phenotype of MSCs used in clinical settings, and a short in vivo persistence time. Herein, inspired by the natural microstructure of the sand tower worm nest, we proposed novel adhesive porous particles with human MSCs encapsulation via microfluidic electrospray technology for SLE treatment. The porous microparticles were formed by immediate gelation reaction between sodium alginate (ALG) and poly-d-lysine (PDL), and then sacrificed polyethylene oxide (PEO) to form the pores. The resultant microparticles could protect MSCs from immune cells while maintain their immune modulating functions, and achieve rapid exchange of nutrients from the body. In addition, owing to the electrostatic adsorption and covalent bonding between PDL and tissues, the porous microparticles could adhere to the bowel surfaces tightly after intraperitoneal injection. Through in vivo imaging system (IVIS) methods and in vivo study, it was demonstrated that the MSCs-encapsulated porous adhesive microparticles could significantly increase the cellular half-life, turn activated inflammatory macrophages into an anti-inflammatory profile, and ameliorate disease progression in MRL/lpr mice. Thus, the MSCs-encapsulated porous microparticles showed distinctive functions in chronic SLE treatment, with additional potential to be used in a variety of biomedical applications.

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We proposed novel adhesive porous particles with MSCs encapsulation.

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MSCs could turn activated inflammatory macrophages into an anti-inflammatory profile.

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The porous microparticles could adhere to bowel surfaces tightly through electrostatic adsorption and covalent bonding.

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MSCs-encapsulated porous adhesive microparticles could significantly ameliorate disease progression in MRL/lpr mice.

Microfluidic Printing of Slippery Textiles for Medical Drainage around Wounds

Surface materials with specific wettability play significant roles in existing fields from environmental protection to biomedicine. Here, a 3D droplet transport microfiber textile with slippery liquid-infused porous surface is presented for medical drainage around wounds. The textile is fabricated by using a simple capillary microfluidic printing method to continuously spin polyurethane microfibers with liquid paraffin-infused porous surface and print them into a 3D-structure. Benefiting from the specific surface porous structure and oil encapsulation of the microfibers, aqueous droplets could be nondestructively and rapidly transported not only in simple single, double or multiple microfiber systems, but also in the microfibers composed stereoscopic textile through the microfluidic 3D printing. Based on this feature, it is demonstrated that the 3D slippery microfiber textile coupled with a vacuum sealing drainage therapy could significantly enhance the wound exudation drainage efficiency, reduce tissue injury, and prolong the effective service life in versatile wounds management. Thus, it is believed that the slippery microfiber textiles have potential for clinical applications.

Antibacterial and angiogenic chitosan microneedle array patch for promoting wound healing

A patch with the capability of avoiding wound infection and promoting tissue remolding is of great value for wound healing. In this paper, we develop a biomass chitosan microneedle array (CSMNA) patch integrated with smart responsive drug delivery for promoting wound healing. Chitosan possesses many outstanding features such as the natural antibacterial property and has been widely utilized for wound healing. Besides, the microstructure of microneedles enables the effective delivery of loaded drugs into the target area and avoids the excessive adhesion between the skin and the patch. Also, vascular endothelial growth factor (VEGF) is encapsulated in the micropores of CSMNA by temperature sensitive hydrogel. Therefore, the smart release of the drugs can be controllably realized via the temperature rising induced by the inflammation response at the site of wounds. It is demonstrated that the biomass CSMNA patch can promote inflammatory inhibition, collagen deposition, angiogenesis, and tissue regeneration during the wound closure. Thus, this versatile CSMNA patch is potentially valuable for wound healing in clinical applications.

Black Phosphorus-Loaded Separable Microneedles as Responsive Oxygen Delivery Carriers for Wound Healing

Oxygen carriers are attracting extensive interest in biomedical research and clinical applications such as wound healing, alternative blood transfusion, and acute trauma treatment. Great efforts have been devoted to the generation of oxygen carriers with special functions and properties to meet specific demands. Here, we present black phosphorus (BP)-loaded separable responsive microneedles (MNs) with oxygen carrying and controllable oxygen delivering ability for wound healing. Such MNs are composed of a polyvinyl acetate (PVA) backing layer and gelatin methacryloyl (GelMA) tips that are loaded with BP quantum dots (BP QDs) and hemoglobin (Hb). Taking advantage of the fast dissolvability of PVA, the backing layer soon disappears after the MNs are applied to skin and the noncytotoxic, biocompatible GelMA tips are left inside the skin. Due to the excellent photothermal effect of BP QDs and the reversible oxygen binding property of Hb, the local temperature of the skin will increase after near-infrared ray irradiation, resulting in the responsive oxygen release. Notably, the practical performance of such MNs has been demonstrated by treating the full-thickness cutaneous wounds of a type I diabetes rat model, indicating their potential value in wound healing and other related biomedical fields.

Spent mushroom substrate combined with alkaline amendment passivates cadmium and improves soil property

As an extremely toxic metal, cadmium (Cd) is readily taken up by most plants. In situ Cd passivation is of great importance to reduce Cd availability in soil. In this experiment, two alkaline amendments, lime (L) (at a dosage of 0.02%, 0.04%, or 0.08%) and biochar (B) (at a dosage of 0.5%, 1%, or 2%), were used to improve Cd passivation by spent mushroom substrate (SMS) in a simulating Cd-contaminated soil (0.6 mg kg^-1). Results showed that the application of SMS alone reduced Cd bioavailability by 44.80% and EC by 9.71% and increased soil pH by 0.61 units, CEC by 25.32%, and soil enzymes activities by 17.11% to 21.10% compared with non-amendment Cd-contaminated soil. Biochar combination enhanced the efficiency of SMS on Cd reduction by 48.32-66.58% and pH increased by 0.17 to 0.59 units and enzymes activities elevation by 5.74% to 47.29% in a dose-dependent manner. Lime also facilitated SMS to passivate Cd by decreasing bioavailable Cd by 63.10%-66.47% and increasing soil pH by 0.25-0.72 units and enzymes activities by 3.28% to 37.86% compared to those of SMS. Among six combined amendments, SMSB3 (0.5% SMS + 2% B) performed best in reducing bioavailable Cd (39.46% higher than SMS), increasing organic matter content (28.54% higher than SMS) and soil enzyme activities (25.82%, 47.29%, and 26.23% higher than that of SMS for catalase, urease, and invertase, respectively). Both biochar and lime can assist SMS to passivate Cd and improve soil property, and biochar is more efficient than lime in reducing cadmium content and increasing enzyme activity and organic matter.

The Construction and Application of Three-Dimensional Biomaterials

Biomaterials have been widely explored and applied in many areas, especially in the field of tissue engineering. The interface of biomaterials and cells has been deeply investigated. However, it has been demonstrated that conventional 2D biomaterials fail to maintain the 3D structures and phenotypes of cells, which is the result of their limited ability to mimic the latter's complex extracellular matrix. To overcome this challenge, cell cultivation dependent on 3D biomaterials has emerged as an alternative strategy to make the recovery of 3D structures and functions of cells possible. Thus, with the thriving development of 3D cell culture in tissue engineering, a holistic review of the construction and application of 3D biomaterials is desired. Here, recent developments in 3D biomaterials for tissue engineering are reviewed. An overview of various approaches to construct 3D biomaterials, such as electro-jetting/-spinning, micro-molding, microfluidics, and 3D bio-printing, is first presented. Their typical applications in constructing cell sheets, vascular structures, cell spheroids, and macroscopic cellular constructs are described as well. Following these two sections, the current status and challenges are analyzed, as well as the future outlook of 3D biomaterials for tissue engineering.

Living Bacterial Microneedles for Fungal Infection Treatment

Fungal infections are everlasting health challenges all over the world, bringing about great financial and medical burdens. Here, inspired by the natural competition law of beneficial bacteria against other microbes, we present novel living microneedles (LMNs) with functionalized bacteria encapsulation for efficient fungal infection treatment. The chosen beneficial bacterial components, Bacillus subtilis (B. subtilis), which are naturally found on the human skin and widely used for food processing, can get nutrients from the skin and escape from the immune system with the help of microneedles. Besides, the encapsulated B. subtilis can continuously produce and secrete various potential antifungal agents which can directly bind to fungal cell surface-associated proteins and destruct the cell membranes, thus avoiding drug resistance. After immobilization in the LMNs, the bacteria can stay within the LMNs without invasion and the encapsulated bacteria together with microneedles can be removed after application. Thus, the side effects, especially the risk for subsequent bacterial infections, are controlled to a minimum to ensure security. In addition, strong penetrability of the microneedles enhances penetration of antifungal agents, and their heights can be adjusted according to the infected depth to acquire better therapeutic effects. These features make the LMNs potentially valuable for clinical applications.

Bioinspired Adhesive and Antibacterial Microneedles for Versatile Transdermal Drug Delivery

Microneedles have attracted increasing interest among various medical fields due to their painless, noninvasive, and efficient way of drug delivery. However, practical applications of these microneedles in different epidermal locations and environments are still restricted by their low adhesion and poor antimicrobial activity. Here, inspired by the antibacterial strategy of Paenibacillus polymyxa and adhesion mechanisms of mussel byssi and octopus tentacles, we develop hierarchical microneedles with multifunctional adhesive and antibacterial abilities. With polydopamine hydrogel as the microneedle base and a loop of suction-cup-structured concave chambers encircling each microneedle, the generated microneedles can fit the skin well; keep strong adhesion in dry, moist, and wet environments; and realize self-repair after being split into two parts. Besides, as polymyxin is loaded into both the hydrogel tips and the polydopamine base, the microneedles are endowed with excellent ability to resist common bacteria during storage and usage. We have demonstrated that these microneedles not only showed excellent adhesion when applied to knuckles and ideal antibacterial activity but also performed well in drug-sustained release and treatment for the osteoarthritis rat model. These results indicate that bioinspired multifunctional microneedles will break through the limitation of traditional methods and be ideal candidates for versatile transdermal drug delivery systems.

Migration-Prevention Strategy to Fabricate Single-Atom Fe Implanted N-Doped Porous Carbons for Efficient Oxygen Reduction

It is highly desired but challenging to achieve highly active single-atom Fe sites from iron-based metal-organic frameworks (MOFs) for efficient oxygen reduction reaction (ORR) due to the easy aggregation of iron species and formation of the inactive Fe-based particles during pyrolysis. Herein, a facile migration-prevention strategy is developed involving the incorporation of polyaniline (PANI) into the pores of iron porphyrinic-based MOF PCN-224(Fe) and followed by pyrolysis to obtain the single-atom Fe implanted N-doped porous carbons material PANI@PCN-224(Fe)-900. The introduced PANI inside the pores of PCN-224(Fe) not only served as protective fences to prevent the aggregation of the iron species during thermal annealing, but also acted as nitrogen sources to increase the nitrogen content and form Fe-Nx-C active sites. Compared with the pristine PCN-224(Fe) derived carbonization sample containing Fe-based particles, the carbonaceous material PANI@PCN-224(Fe)-900 without inactive Fe-based particles exhibited superb ORR electrocatalytic activity with a more positive half-wave potential, significantly improved stability in both alkaline media, and more challenging acidic condition. The migration-prevention strategy provides a new way to fabricate atomically dispersed metal active sites via pyrolysis approach for promoting catalysis.