Dissolvable Microneedles Coupled with Nanofiber Dressings Eradicate Biofilms via Effectively Delivering a Database-Designed Antimicrobial Peptide

Nanozyme-Incorporated Microneedles for the Treatment of Chronic Wounds

Acute wounds are converted to chronic wounds due to advanced age and diabetic complications. Nanozymes catalyze ROS production to kill bacteria without causing drug resistance, while microneedles (MNs) can break through the skin barrier to deliver drugs effectively. Nanozymes can be intergrateded into MNs delivery systems to improve painless drug delivery. It can also reduce the effective dose of drug sterilization while increasing delivery efficiency and effectively killing wounded bacteria while preventing drug resistance. This paper describes various types of metal nanozymes from previous studies and compares their mutual enhancement with nanozymes. The pooled results show that the MNs, through material innovation, are able to both penetrate the scab and deliver nanozymes and exert additional anti-inflammatory and bactericidal effects. The catalytic effect of some of the nanozymes can also accelerate the lysis of the MNs or create a cascade reaction against inflammation and infection. However, the issue of increased toxicity associated with skin penetration and clinical translation remains a challenge. This study reviews the latest published results and corresponding challenges associated with the use of MNs combined with nanozymes for the treatment of wounds, providing further information for future research.

Design Strategy of Microneedle Systems for Skin Wound Healing: Based on the Structure of Tips and Therapeutic Methodologies

The skin, being the largest organ of the human body, is susceptible to damage resulting in wounds that are vulnerable to pathogenic attacks and fail to provide effective protection for internal tissues. Therefore, it is crucial to expedite wound healing. In recent years, microneedles have garnered significant attention as an innovative drug delivery system owing to their noninvasive and painless administration, simplified application process, precise control over drug release, and versatile loading capabilities. Consequently, they hold immense potential for the treatment of skin wound. This review presents a comprehensive design strategy for the microneedle system in promoting skin wound healing. First, the process of skin wound healing and the characteristics of specific wounds are elucidated. The design strategies for microneedles are subsequently presented and classified based on their structural and therapeutic methodologies. Finally, a succinct recapitulation of the previously discussed points and a prospective analysis are provided.

Numerical modeling of ultrasound-triggered microneedle-mediated delivery of drug particles into bacterial biofilms

Ultrasonic microneedle patches, a class of ultrasound-driven transdermal drug delivery systems, are promising in addressing bacterial biofilms. This device has been proven to be more effective in treating Staphylococcus aureus biofilms than drug in free solution. However, there exists a notable gap in understanding how various excitation conditions and material parameters affect drug delivery efficiency. This study aims to fill this void by conducting an comprehensive multi-physics numerical analysis of ultrasonic microneedle patches, with the ultimate goal of enhancing drug delivery. First, we investigate the impact of various ultrasound frequencies on drug penetration depths. The findings reveal that local resonance can accelerate drug release within a shorter time window (first 1.5 h), whereas non-resonant frequencies enable more profound and prolonged diffusion. This information is crucial for medical professionals in selecting the most effective frequency for optimal drug administration. Furthermore, our investigation extends to the effects of applied voltage on temperature distribution, a critical aspect for ensuring medical safety during the application of these patches. Additionally, we examine how particles of different sizes respond to acoustic pressure and streaming fields, providing valuable insights for tailoring drug delivery strategies to specific therapeutic needs. Overall, our findings offer comprehensive guidelines for the effective use of ultrasonic microneedle patches, potentially shifting the paradigm in patient care and enhancing the overall quality of life.

Ultrasound-Responsive Aligned Piezoelectric Nanofibers Derived Hydrogel Conduits for Peripheral Nerve Regeneration

Nerve guidance conduits (NGCs) are considered as promising treatment strategy and frontier trend for peripheral nerve regeneration, while their therapeutic outcomes are limited by the lack of controllable drug delivery and available physicochemical cues. Herein, novel aligned piezoelectric nanofibers derived hydrogel NGCs with ultrasound (US)-triggered electrical stimulation (ES) and controllable drug release for repairing peripheral nerve injury are proposed. The inner layer of the NGCs is the barium titanate piezoelectric nanoparticles (BTNPs)-doped polyvinylidene fluoride-trifluoroethylene [BTNPs/P(VDF-TrFE)] electrospinning nanofibers with improved piezoelectricity and aligned orientation. The outer side of the NGCs is the thermoresponsive poly(N-isopropylacrylamide) hybrid hydrogel with bioactive drug encapsulation. Such NGCs can not only induce neuronal-oriented extension and promote neurite outgrowth with US-triggered wireless ES, but also realize the controllable nerve growth factor release with the hydrogel shrinkage under US-triggered heating. Thus, the NGC can positively accelerate the functional recovery and nerve axonal regeneration of rat models with long sciatic nerve defects. It is believed that the proposed US-responsive aligned piezoelectric nanofibers derived hydrogel NGCs will find important applications in clinic neural tissue engineering.

Advancements in Aerogel Technology for Antimicrobial Therapy: A Review

This paper explores the latest advancements in aerogel technology for antimicrobial therapy, revealing their interesting capacity that could improve the current medical approaches for antimicrobial treatments. Aerogels are attractive matrices because they can have an antimicrobial effect on their own, but they can also provide efficient delivery of antimicrobial compounds. Their interesting properties, such as high porosity, ultra-lightweight, and large surface area, make them suitable for such applications. The fundamentals of aerogels and mechanisms of action are discussed. The paper also highlights aerogels' importance in addressing current pressing challenges related to infection management, like the limited drug delivery alternatives and growing resistance to antimicrobial agents. It also covers the potential applications of aerogels in antimicrobial therapy and their possible limitations.

Physiological Microenvironment Dependent Self-Cross-Linking of Multifunctional Nanohybrid for Prolonged Antibacterial Therapy via Synergistic Chemodynamic-Photothermal-Biological Processes

Herein, a multifunctional nanohybrid (PL@HPFTM nanoparticles) was fabricated to perform the integration of chemodynamic therapy, photothermal therapy, and biological therapy over the long term at a designed location for continuous antibacterial applications. The PL@HPFTM nanoparticles consisted of a polydopamine/hemoglobin/Fe2+ nanocomplex with comodification of tetrazole/alkene groups on the surface as well as coloading of antimicrobial peptides and luminol in the core. During therapy, the PL@HPFTM nanoparticles would selectively cross-link to surrounding bacteria via tetrazole/alkene cycloaddition under chemiluminescence produced by the reaction between luminol and overexpressed H2O2 at the infected area. The resulting PL@HPFTM network not only significantly damaged bacteria by Fe2+-catalyzed ROS production, effective photothermal conversion, and sustained release of antimicrobial peptides but dramatically enhanced the retention time of these therapeutic agents for prolonged antibacterial therapy. Both in vitro and in vivo results have shown that our PL@HPFTM nanoparticles have much higher bactericidal efficiency and remarkably longer periods of validity than free antibacterial nanoparticles.

Exosomes-carried curcumin based on polysaccharide hydrogel promote flap survival

Flap grafting is a common technique used to repair skin defects in orthopedics and plastic and reconstructive surgeries. However, oxidative stress injury caused by ischemia and ischemia-reperfusion injury at the distal end of the skin flap can cause flap necrosis. Curcumin is a natural compound with anti-inflammatory and antioxidant properties that tackle oxidative stress. However, its applicability is limited by its poor water solubility. Exosomes are membranous vesicles that can be loaded with hydrophobic drugs. They are widely studied in drug delivery applications and can be investigated to augment curcumin efficiency. In this study, a self-healing oxidized pullulan polysaccharide-carboxymethylated chitosan composite hydrogel was used as a curcumin-loaded exosome delivery system to evaluate its impact on the viability of skin flaps. The hydrogel exhibited good self-healing properties that allowed the continuous and stable release of drugs. It had anti-inflammatory and antioxidant properties that could reduce oxidative stress damage due to early ischemia and hypoxia of the skin flap in vitro. Moreover, this composite hydrogel attenuated inflammatory responses, promoted angiogenesis, and reduced the distal necrosis of the flap in vivo. Therefore, our hydrogel provides a novel strategy for skin flap graft protection with reduced necrosis and the potential for broad clinical applications.

It Takes Two to Tangle: Microneedle Patches Co-delivering Monoclonal Antibodies and Engineered Antimicrobial Peptides Effectively Eradicate Wound Biofilms

Wound biofilms pose a great clinical challenge. Herein, this work reports a dissolvable microneedle patch for dual delivery of monoclonal antibodies anti-PBP2a and engineers antimicrobial peptides W379. In vitro antibacterial efficacy testing with microneedle patches containing a combination of 250 ng mL-1 W379 and 250 ng mL-1 anti-BPB2a decreases the bacterial count from ≈3.31 × 107 CFU mL-1 to 1.28 × 102 CFU mL-1 within 2 h without eliciting evident cytotoxicity. Ex vivo testing indicates W379 and anti-PBP2a co-loaded microneedle patch displayed a remarkable reduction of bacterial load by ≈7.18 log CFU after administered only once within 48 h. The bacterial count is significantly diminished compared to the treatment by either W379 or anti-PBP2a-loaded alone microneedle patches. When administered twice within 48 h, no bacteria are identified. Further in vivo study also reveals that after two treatments of W379 and anti-PBP2a co-loaded PVP microneedle patches within 48 h, the bacterial colonies are undetectable in a type II diabetic mouse wound biofilm model. Taken together, W379 and anti-PBP2a co-loaded PVP microneedle patches hold great promise in treating wound biofilms.

Functional biomacromolecules-based microneedle patch for the treatment of diabetic wound

Diabetic wounds are a common complication of diabetes. The prolonged exposure to high glucose and oxidative stress in the wound environment increases the risk of bacterial infection and abnormal angiogenesis, leading to amputation. Microneedle patches have shown promise in promoting the healing of diabetic wounds through transdermal drug delivery. These patches target the four main aspects of diabetic wound treatment: hypoglycemia, antibacterial action, inflammatory regulation, and tissue regeneration. By overcoming the limitations of traditional administration methods, microneedle patches enable targeted therapy for deteriorated tissues. The design of these patches extends beyond the selection of needle tip material and biomacromolecule encapsulated drugs; it can also incorporate near-infrared rays to facilitate cascade reactions and treat diabetic wounds. In this review, we comprehensively summarize the advantages of microneedle patches compared to traditional treatment methods. We focus on the design and mechanism of these patches based on existing experimental articles in the field and discuss the potential for future research on microneedle patches.

Dissolving microneedle system containing Ag nanoparticle-decorated silk fibroin microspheres and antibiotics for synergistic therapy of bacterial biofilm infection

Most cases of delayed wound healing are associated with bacterial biofilm infections due to high antibiotic resistance. To improve patient compliance and recovery rates, it is critical to develop minimally invasive and efficient methods to eliminate bacterial biofilms as an alternative to clinical debridement techniques. Herein, we develop a dissolving microneedle system containing Ag nanoparticles (AgNPs)-decorated silk fibroin microspheres (SFM-AgNPs) and antibiotics for synergistic treatment of bacterial biofilm infection. Silk fibroin microspheres (SFM) are controllably prepared in an incompatible system formed by a mixture of protein and carbohydrate solutions by using a mild all-aqueous phase method and serve as biological templates for the synthesis of AgNPs. The SFM-AgNPs exert dose- and time-dependent broad-spectrum antibacterial effects by inducing bacterial adhesion. The combination of SFM-AgNPs with antibiotics breaks the limitation of the antibacterial spectrum and achieves better efficacy with reduced antibiotic dosage. Using hyaluronic acid (HA) as the soluble matrix, the microneedle system containing SFM-AgNPs and anti-Gram-positive coccus drug (Mupirocin) inserts into the bacterial biofilms with sufficient strength, thereby effectively delivering the antibacterial agents and realizing good antibiofilm effect on Staphylococcus aureus-infected wounds. This work demonstrates the great potential for the development of novel therapeutic systems for eradicating bacterial biofilm infections.

A Comprehensive Review of Recent Research into the Effects of Antimicrobial Peptides on Biofilms-January 2020 to September 2023

Microbial biofilm formation creates a persistent and resistant environment in which microorganisms can survive, contributing to antibiotic resistance and chronic inflammatory diseases. Increasingly, biofilms are caused by multi-drug resistant microorganisms, which, coupled with a diminishing supply of effective antibiotics, is driving the search for new antibiotic therapies. In this respect, antimicrobial peptides (AMPs) are short, hydrophobic, and amphipathic peptides that show activity against multidrug-resistant bacteria and biofilm formation. They also possess broad-spectrum activity and diverse mechanisms of action. In this comprehensive review, 150 publications (from January 2020 to September 2023) were collected and categorized using the search terms 'polypeptide antibiotic agent', 'antimicrobial peptide', and 'biofilm'. During this period, a wide range of natural and synthetic AMPs were studied, of which LL-37, polymyxin B, GH12, and Nisin were the most frequently cited. Furthermore, although many microbes were studied, Staphylococcus aureus and Pseudomonas aeruginosa were the most popular. Publications also considered AMP combinations and the potential role of AMP delivery systems in increasing the efficacy of AMPs, including nanoparticle delivery. Relatively few publications focused on AMP resistance. This comprehensive review informs and guides researchers about the latest developments in AMP research, presenting promising evidence of the role of AMPs as effective antimicrobial agents.

Recent progress of polymeric microneedle-assisted long-acting transdermal drug delivery

Microneedle (MN)-assisted drug delivery technology has gained increasing attention over the past two decades. Its advantages of self-management and being minimally invasive could allow this technology to be an alternative to hypodermic needles. MNs can penetrate the stratum corneum and deliver active ingredients to the body through the dermal tissue in a controlled and sustained release. Long-acting polymeric MNs can reduce administration frequency to improve patient compliance and therapeutic outcomes, especially in the management of chronic diseases. In addition, long-acting MNs could avoid gastrointestinal reactions and reduce side effects, which has potential value for clinical application. In this paper, advances in design strategies and applications of long-acting polymeric MNs are reviewed. We also discuss the challenges in scale manufacture and regulations of polymeric MN systems. These two aspects will accelerate the effective clinical translation of MN products.

Innovative freeze-drying technique in the fabrication of dissolving microneedle patch: Enhancing transdermal drug delivery efficiency

Microneedle patch (MNP) has become a hot research topic in the field of transdermal drug delivery due to its ability to overcome the stratum corneum barrier. Among the various types of microneedles, dissolving microneedles represent one of the most promising transdermal delivery methods. However, the most used method for preparing dissolving microneedles, namely microfabrication, suffers from issues such as long drying time, susceptibility to humidity, and large batch-to-batch variability, which limit the development of dissolving microneedles. In this study, we report for the first time a method for preparing dissolving microneedles using freeze-drying technology. We screened substrates suitable for freeze-dried microneedle patch (FD-MNP) and used coating technology to enhance the mechanical strength of FD-MNP, allowing them to meet the requirements for skin penetration. We successfully prepared FD-MNP using hyaluronic acid as the substrate and insulin as the model drug. Scanning electron microscopy revealed that the microneedles had a porous structure. After coating, the mechanical strength of the microneedles was 0.61 N/Needle, and skin penetration rate was 97%, with a penetration depth of 215 μm. The tips of the FD-MNP dissolved completely within approximately 60 s after skin penetration, which is much faster than conventional MNP (180 s). In vitro transdermal experiments showed that the FD-MNP shortened the lag time for transdermal delivery of rhodamine 123 and insulin compared to conventional MNP, indicating a faster transdermal delivery rate. Pharmacological experiments showed that the FD-MNP lowered mouse blood glucose levels more effectively than conventional MNP, with a relative pharmacological availability of 96.59 ± 2.84%, higher than that of conventional MNP (84.34 ± 3.87%), P = 0.0095. After storage under 40℃ for two months, the insulin content within the FD-MNP remained high at 95.27 ± 4.46%, which was much higher than that of conventional MNP (58.73 ± 3.71%), P < 0.0001. In conclusion, freeze-drying technology is a highly valuable method for preparing dissolving microneedles with potential applications in transdermal drug delivery.

A Bacterial Responsive Microneedle Dressing with Hydrogel Backing Layer for Chronic Wound Treatment

The treatment of chronic wounds still presents great challenges due to being infected by biofilms and the damaged healing process. The current treatments do not address the needs of chronic wounds. In this study, a highly effective dressing (Dox-DFO@MN Hy) for the treatment of chronic wounds is described. This dressing combines the advantages of microneedles (MNs) and hydrogels in the treatment of chronic wounds. MNs is employed to debride the biofilms and break down the wound barrier, providing rapid access to therapeutic drugs from hydrogel backing layer. Importantly, to kill the pathogenic bacteria in the biofilms specifically, Doxycycline hydrochloride (Dox) is wrapped into the polycaprolactone (PCL) microspheres that have lipase-responsive properties and loaded into the tips of MNs. At the same time, hydrogel backing layer is used to seal the wound and accelerate wound healing. Benefiting from the combination of two advantages of MNs and hydrogel, the dressing significantly reduces the bacteria in the biofilms and effectively promotes angiogenesis and cell migration in vitro. Overall, Dox-DFO@MN Hy can effectively treat chronic wounds infected with biofilms, providing a new idea for the treatment of chronic wounds.

Enhancing diabetic wound healing: advances in electrospun scaffolds from pathogenesis to therapeutic applications

Diabetic wounds are a significant subset of chronic wounds characterized by elevated levels of inflammatory cytokines, matrix metalloproteinases (MMPs), and reactive oxygen species (ROS). They are also associated with impaired angiogenesis, persistent infection, and a high likelihood of hospitalization, leading to a substantial economic burden for patients. In severe cases, amputation or even mortality may occur. Diabetic foot ulcers (DFUs) are a common complication of diabetes, with up to 25% of diabetic patients being at risk of developing foot ulcers over their lifetime, and more than 70% ultimately requiring amputation. Electrospun scaffolds exhibit a structural similarity to the extracellular matrix (ECM), promoting the adhesion, growth, and migration of fibroblasts, thereby facilitating the formation of new skin tissue at the wound site. The composition and size of electrospun scaffolds can be easily adjusted, enabling controlled drug release through fiber structure modifications. The porous nature of these scaffolds facilitates gas exchange and the absorption of wound exudate. Furthermore, the fiber surface can be readily modified to impart specific functionalities, making electrospinning nanofiber scaffolds highly promising for the treatment of diabetic wounds. This article provides a concise overview of the healing process in normal wounds and the pathological mechanisms underlying diabetic wounds, including complications such as diabetic foot ulcers. It also explores the advantages of electrospinning nanofiber scaffolds in diabetic wound treatment. Additionally, it summarizes findings from various studies on the use of different types of nanofiber scaffolds for diabetic wounds and reviews methods of drug loading onto nanofiber scaffolds. These advancements broaden the horizon for effectively treating diabetic wounds.

Integration of polysaccharide electrospun nanofibers with microneedle arrays promotes wound regeneration: A review

Utilizing electrospun nanofibers and microneedle arrays in wound regeneration has been practiced for several years. Researchers have recently asserted that using multiple methods concurrently might enhance efficiency, despite the inherent strengths and weaknesses of each individual approach. The combination of microneedle arrays with electrospun nanofibers has the potential to create a drug delivery system and wound healing method that offer improved efficiency and accuracy in targeting. The use of microneedles with nanofibers allows for precise administration of pharmaceuticals due to the microneedles' capacity to pierce the skin and the nanofibers' role as a drug reservoir, resulting in a progressive release of drugs over a certain period of time. Electrospun nanofibers have the ability to imitate the extracellular matrix and provide a framework for cellular growth and tissue rejuvenation, while microneedle arrays show potential for enhancing tissue regeneration and enhancing the efficacy of wound healing. The integration of electrospun nanofibers with microneedle arrays may be customized to effectively tackle particular obstacles in the fields of wound healing and drug delivery. However, some issues must be addressed before this paradigm may be fully integrated into clinical settings, including but not limited to ensuring the safety and sterilization of these products for transdermal use, optimizing manufacturing methods and characterization of developed products, larger-scale production, optimizing storage conditions, and evaluating the inclusion of multiple therapeutic and antimicrobial agents to increase the synergistic effects in the wound healing process. This research examines the combination of microneedle arrays with electrospun nanofibers to enhance the delivery of drugs and promote wound healing. It explores various kinds of microneedle arrays, the materials and processes used, and current developments in their integration with electrospun nanofibers.

Multifunctional MXene-doped photothermal microneedles for drug-resistant bacteria-infected wound healing

Skin injuries and drug-resistant bacterial infections pose serious challenges to human health. It is essential to establish a novel multifunctional platform with good anti-infection and wound-healing abilities. In this study, a new MXene-doped composite microneedle (MN) patch with excellent mechanical strength and photothermal antibacterial and ROS removal properties has been developed for infected wound healing. When the MN tips carrying the MXene nanosheets are inserted into the cuticle of the skin, they will quickly dissolve and subsequently release the nanomaterials into the subcutaneous infection area. Under 808 nm NIR irradiation, the MXene, as a "nano-thermal knife", sterilizes and inhibits bacterial growth through synergistic effects of sharp edges and photothermal antibacterial activity. Furthermore, ROS caused by injury and infection can be cleared by MXene-doped MNs to avoid excessive inflammatory responses. Based on the synergistic antibacterial and antioxidant strategy, the MXene-doped MNs have demonstrated excellent wound-healing properties in an MRSA-infected wound model, such as promoting re-epithelialization, collagen deposition, and angiogenesis and inhibiting the expression of pro-inflammatory factors. Therefore, the multifunctional MXene-doped MN patches provide an excellent alternative for clinical drug-resistant bacteria-infected wound management.

Novel microneedle platforms for the treatment of wounds by drug delivery: A review

The management and treatment of wounds are complex and pose a substantial financial burden to the patient. However, the complex environment of wounds leads to inadequate drug absorption to achieve the desired therapeutic effect. As a novel technological platform, microneedles are widely used in drug delivery because of their multiple drug loading, multistage drug release, and multiple designs of topology. This study systematically summarizes and analyzes the manufacturing methods and limitations of different microneedles, as well as the latest research advances in pain management, drug delivery, and healing promotion, and presents the challenges and opportunities for clinical applications. On this basis, the development of microneedles in external wound repair and management is envisioned, and it is hoped that this study can provide guidelines for the design of microneedle systems in different application contexts, including the selection of materials, preparation methods, and structural design, to achieve better healing and regeneration results.

An Integrated Therapeutic and Preventive Nanozyme-Based Microneedle for Biofilm-Infected Diabetic Wound Healing

The healing of biofilm-infected diabetic wounds characterized by a deteriorative tissue microenvironment represents a substantial clinical challenge. Current treatments remain unsatisfactory due to the limited antibiofilm efficacy caused by weak tissue and biofilm permeability of drugs and the risk of reinfection during the healing process. To address these issues, an integrated therapeutic and preventive nanozyme-based microneedle (denoted as Fe2 C/GOx@MNs) is engineered. The dissolvable tips with enough mechanical strength can deliver and rapidly release Fe2 C nanoparticles (NPs)/glucose oxidase (GOx) in the biofilm active regions, enhancing tissue and biofilm permeability of Fe2 C NPs/GOx, ultimately achieving highly efficient biofilm elimination. Meanwhile, the chitosan backing layer can not only act as an excellent physical barrier between the wound bed and the external environment, but also prevent the bacterial reinvasion during wound healing with its superior antibacterial property. Significantly, the biofilm elimination and reinfection prevention abilities of Fe2 C/GOx@MNs on wound healing are proved on methicillin-resistant Staphylococcus aureus-biofilm-infected diabetic mouse model with full-thickness wound. Together, these results demonstrate the promising clinical application of Fe2 C/GOx@MNs in biofilm-infected wound healing.

Highly active nisin coated polycaprolactone electrospun fibers against both Staphylococcus aureus and Pseudomonas aeruginosa

In this study, a wound dressing of electrospun polycaprolactone (PCL) fibers incorporating the antimicrobial peptide (AMP) nisin was fabricated. Nisin was physically adsorbed to the PCL fibers and tested for antibacterial activity against both Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). The PCL fibers had an average diameter of 1.16 μm ± 0.42 μm and no significant change in diameter occurred after nisin adsorption. X-ray photoelectron spectroscopy (XPS) analysis of the fibers detected nitrogen indicative of adsorbed nisin and the signal was used to quantify the levels of coverage on the fiber surfaces. In vitro nisin release studies showed a burst release profile with 80 % of the nisin being released from the fibers within 30 min. Air plasma pre-treatment of the PCL fibers to render them hydrophilic improved nisin loading and release. Antibacterial testing was performed using minimum inhibitory concentration (MIC) and surface attachment assays. The released nisin remained active against both Gram positive S. aureus and Gram negative P. aeruginosa, which has previously been difficult to achieve with single polymer fiber systems. Mammalian cell culture of the nisin coated fibers with L-929 mouse fibroblasts and human epidermal keratinocytes (HEKa) showed that the nisin did not have a significant effect on the biocompatibility of the PCL fibers. The results presented here demonstrate that the physical adsorption, which is a post-treatment, overcomes the potential limitations of harsh chemicals and fabrication conditions of electrospinning from organic solvents and provides a drug loading system having effective antibacterial properties in wound dressings.

Cerium oxide nanoparticles in diabetic foot ulcer management: Advances, limitations, and future directions

Diabetic foot ulcer (DFU) is one of the most serious complications of diabetes, potentially resulting in wound infection and amputation under severe circumstances. Oxidative stress and dysbiosis are the primary factors that delay wound healing, posing challenges to effective treatment. Unfortunately, conventional approaches in these aspects have proven satisfactory in achieving curative outcomes. Recent research has increasingly focused on using nanoparticles, leveraging their potential in wound dressing and medication delivery. Their unique physical properties further enhance their therapeutic effectiveness. Among these nanoparticles, cerium oxide nanoparticles (CONPs) have garnered attention due to their notable beneficial effects on oxidative stress and microbial abundance, thus representing a promising therapeutic avenue for DFU. This review comprehensively assesses recent studies on CONPs in treating DFU. Furthermore, we elaborate on the wound healing process, ceria synthesis, and incorporating CONPs with other materials. Crucially, a thorough evaluation of CONPs' toxicity as a novel metallic nanomaterial for therapeutic use must precede their formal clinical application. Additionally, we identify the current challenges CONPs encounter and propose future directions for their development.

Magnesium/gallic acid bioMOFs laden carbonized mushroom aerogel effectively heals biofilm-infected skin wounds

Biofilm-infected acute skin wounds are still one of the significant challenges that need to be solved urgently in wound healing. Herein, we reported a magnesium/gallic acid bio-MOFs laden carbonized mushroom aerogel (QMOFs-PCMA) combined with photothermal therapy for eradicating biofilms in skin wounds. The design of bioMOFs is mainly responsible for regulating immunity. In vitro, it exhibited ROS clearance and antioxidant ability. In vivo, it could regulate local immune responses from pro-inflammatory status to pro-regenerative status, resulting in decreased inflammatory cytokines expression and increased anti-inflammatory cytokines expression. The carbonized mushroom aerogel is mainly responsible for photothermal therapy (PTT), and the polydopamine and bioMOFs could enhance the photothermal conversion efficiency and stability of carbonized aerogels. The carbonized aerogel in combination with PTT could eradicate S. aureus biofilm in both in vitro and in vivo studies and clear E. coli biofilms in vitro studies. The biofilm clearance and improved inflammatory responses laid a good foundation for wound healing, resulting in the granulation tissue formation, re-epithelialization, and angiogenesis significantly enhanced in the QMOFs-PCMA + NIR group. Our results indicate that the QMOFs-PCMA combined with photothermal therapy may provide a promising treatment for biofilm-infected skin wounds.

Functional Microneedle Patch for Wound Healing and Biological Diagnosis and Treatment

Wound healing, especially chronic wounds, has been one of the major challenges in the field of biomedicine. Drug therapy alone is not effective, so a variety of functional wound healing dressings have been developed. Microneedles have attracted more and more attentions in the field of wound healing dressings due to their penetration and high drug delivery efficiency. In this review, all the studies on the application of microneedles in wound healing in recent years are summarized, classify different microneedles according to their functions in the process of wound healing, discuss the current challenges in the transformation of microneedle technology toward clinical applications, and finally look forward to the future design and development directions of microneedles in this field.

Antibacterial micro/nanomotors: advancing biofilm research to support medical applications

Multi-drug resistant (MDR) bacterial infections are gradually increasing in the global scope, causing a serious burden to patients and society. The formation of bacterial biofilms, which is one of the key reasons for antibiotic resistance, blocks antibiotic penetration by forming a physical barrier. Nano/micro motors (MNMs) are micro-/nanoscale devices capable of performing complex tasks in the bacterial microenvironment by transforming various energy sources (including chemical fuels or external physical fields) into mechanical motion or actuation. This autonomous movement provides significant advantages in breaking through biological barriers and accelerating drug diffusion. In recent years, MNMs with high penetrating power have been used as carriers of antibiotics to overcome bacterial biofilms, enabling efficient drug delivery and improving the therapeutic effectiveness of MDR bacterial infections. Additionally, non-antibiotic antibacterial strategies based on nanomaterials, such as photothermal therapy and photodynamic therapy, are continuously being developed due to their non-invasive nature, high effectiveness, and non-induction of resistance. Therefore, multifunctional MNMs have broad prospects in the treatment of MDR bacterial infections. This review discusses the performance of MNMs in the breakthrough and elimination of bacterial biofilms, as well as their application in the field of anti-infection. Finally, the challenges and future development directions of antibacterial MNMs are introduced.

The Progress in the Application of Dissolving Microneedles in Biomedicine

In recent years, microneedle technology has been widely used for the transdermal delivery of substances, showing improvements in drug delivery effects with the advantages of minimally invasive, painless, and convenient operation. With the development of nano- and electrochemical technology, different types of microneedles are increasingly being used in other biomedical fields. Recent research progress shows that dissolving microneedles have achieved remarkable results in the fields of dermatological treatment, disease diagnosis and monitoring, and vaccine delivery, and they have a wide range of application prospects in various biomedical fields, showing their great potential as a form of clinical treatment. This review mainly focuses on dissolving microneedles, summarizing the latest research progress in various biomedical fields, providing inspiration for the subsequent intelligent and commercial development of dissolving microneedles, and providing better solutions for clinical treatment.

Microneedle-based cell delivery and cell sampling for biomedical applications

Cell-based therapeutics are novel therapeutic strategies that can potentially treat many presently incurable diseases through novel mechanisms of action. Cell therapies may benefit from the ease, safety, and efficacy of administering therapeutic cells. Despite considerable recent technological and biological advances, several barriers remain to the clinical translation and commercialization of cell-based therapies, including low patient compliance, personal handling inconvenience, poor biosafety, and limited biocompatibility. Microneedles (MNs) are emerging as a promising biomedical device option for improved cell delivery with little invasion, pain-free administration, and simplicity of disposal. MNs have shown considerable promise in treating a wide range of diseases and present the potential to improve cell-based therapies. In this review, we first summarized the latest advances in the various types of MNs developed for cell delivery and cell sampling. Emphasis was given to the design and fabrication of various types of MNs based on their structures and materials. Then we focus on the recent biomedical applications status of MNs-mediated cell delivery and sampling, including tissue repair (wound healing, heart repair, and endothelial repair), cancer treatment, diabetes therapy, cell sampling, and other applications. Finally, the current status of clinical application, potential perspectives, and the challenges for clinical translation are also highlighted.

Reactive Oxygen Species-Scavenging Nanosystems in the Treatment of Diabetic Wounds

Diabetic wounds are characterized by drug-resistant bacterial infections, biofilm formation, impaired angiogenesis and perfusion, and oxidative damage to the microenvironment. Given their complex nature, diabetic wounds remain a major challenge in clinical practice. Reactive oxygen species (ROS), which have been shown to trigger hyperinflammation and excessive cellular apoptosis, play a pivotal role in the pathogenesis of diabetic wounds. ROS-scavenging nanosystems have recently emerged as smart and multifunctional nanomedicines with broad synergistic applicability. The documented anti-inflammatory and pro-angiogenic ability of ROS-scavenging treatments predestines these nanosystems as promising options for the treatment of diabetic wounds. Yet, in this context, the therapeutic applicability and efficacy of ROS-scavenging nanosystems remain to be elucidated. Herein, the role of ROS in diabetic wounds is deciphered, and the properties and strengths of nanosystems with ROS-scavenging capacity for the treatment of diabetic wounds are summarized. In addition, the current challenges of such nanosystems and their potential future directions are discussed through a clinical-translational lens.

Cell-free fat extract-loaded microneedles attenuate inflammation-induced apoptosis and mitochondrial damage in tendinopathy

Existing clinical treatments for tendinopathy mainly focus on reducing pain, whereas inhibiting or reversing disease progression remains challenging. Local therapeutic drugs, such as glucocorticoids, cause adverse effects on the metabolism of tendon tissues and injection-related complications. Therefore, new administration modalities for tendinopathy need to be developed. In this study, we designed a hydrogel-based microneedle (MN) system for the long-term transdermal delivery of our novel biological cell-free fat extract (CEFFE) to treat tendinopathies. We found that CEFFE-loaded MNs (CEFFE-MNs) had good biosafety and inhibited lipopolysaccharide (LPS)-induced apoptosis and matrix degradation in Achilles tendon cells of rats. The Achilles tendons of rats returned to their maximum mechanical strength after applying CEFFE-MNs. The administration of CEFFE-MNs had better anti-apoptosis and tendon repair-promoting effects than CEFEF injections in vivo. Transcriptome sequencing indicated that the anti-apoptosis effect of CEFFE-MNs was highly related to tumor necrosis factor (TNF) signaling. CEFFE-MNs inhibited the expression of TNF, TNF receptor 1, and downstream nuclear factor-kappa B signaling. Additionally, CEFFE-MNs rescued LPS-induced mitochondrial dynamics in tendon cells via the TNF-Drp1 axis. Our study reports a novel CEFFE-MN system that exhibits long-term anti-inflammatory and anti-apoptotic effects, suggesting it as a new treatment route for tendinopathy with broad clinical translation prospects.

Applications of Degradable Hydrogels in Novel Approaches to Disease Treatment and New Modes of Drug Delivery

Hydrogels are particularly suitable materials for loading drug delivery agents; their high water content provides a biocompatible environment for most biomolecules, and their cross-linked nature protects the loaded agents from damage. During delivery, the delivered substance usually needs to be released gradually over time, which can be achieved by degradable cross-linked chains. In recent years, biodegradable hydrogels have become a promising technology in new methods of disease treatment and drug delivery methods due to their many advantageous properties. This review briefly discusses the degradation mechanisms of different types of biodegradable hydrogel systems and introduces the specific applications of degradable hydrogels in several new methods of disease treatment and drug delivery methods.

A Cu@ZIF-8 encapsulated antibacterial and angiogenic microneedle array for promoting wound healing

Skin wounds caused by external injuries remain a serious challenge in clinical practice. Wound dressings that are antibacterial, pro-angiogenic, and have potent regeneration capacities are highly desirable for wound healing. In this study, a minimally invasive and wound-friendly Cu@ZIF-8 encapsulated PEGDA/CMCS microneedle (MN) array was fabricated using the molding method to promote wound healing. The MNs had good biocompatibility, excellent mechanical strength, as well as strong antibacterial properties and pro-angiogenic effects. When incubated with H2O2, Cu@ZIF-8 nanoparticles generated reactive oxygen species, which contributed to their antibacterial properties. Due to the oxidative stress of the cupric ions released from Cu@ZIF-8 and the anti-bacterial capability of the PEGDA/CMCS hydrogel scaffold, such an MN array presents excellent antibacterial activity. Moreover, with the continuous release of Cu ions from the scaffold, such MNs are effective in terms of promoting angiogenesis. With considerable biocompatibility and a minimally invasive approach, the degradable MN array composed of PEGDA/CMCS possessed superior capabilities to continuously and steadily release the loaded ingredients and avoid secondary damage to the wound. Benefiting from these features, the Cu@ZIF-8 encapsulated degradable MN array can dramatically accelerate epithelial regeneration and neovascularization. These results indicated that the combination of Cu@ZIF-8 and degradable MN arrays is valuable in promoting wound healing, which opened a new window for treatment of skin defection.

Recent Advances in Functional Wound Dressings

Significance: Nowadays, the wound dressing is no longer limited to its primary wound protection ability. Hydrogel, sponge-like material, three dimensional-printed mesh, and nanofiber-based dressings with incorporation of functional components, such as nanomaterials, growth factors, enzymes, antimicrobial agents, and electronics, are able to not only prevent/treat infection but also accelerate the wound healing and monitor the wound-healing status. Recent Advances: The advances in nanotechnologies and materials science have paved the way to incorporate various functional components into the dressings, which can facilitate wound healing and monitor different biological parameters in the wound area. In this review, we mainly focus on the discussion of recently developed functional wound dressings. Critical Issues: Understanding the structure and composition of wound dressings is important to correlate their functions with the outcome of wound management. Future Directions: "All-in-one" dressings that integrate multiple functions (e.g., monitoring, antimicrobial, pain relief, immune modulation, and regeneration) could be effective for wound repair and regeneration.

Scarless wound healing programmed by core-shell microneedles

Effective reprogramming of chronic wound healing remains challenging due to the limited drug delivery efficacy hindered by physiological barriers, as well as the inappropriate dosing timing in distinct healing stages. Herein, a core-shell structured microneedle array patch with programmed functions (PF-MNs) is designed to dynamically modulate the wound immune microenvironment according to the varied healing phases. Specifically, PF-MNs combat multidrug-resistant bacterial biofilm at the early stage via generating reactive oxygen species (ROS) under laser irradiation. Subsequently, the ROS-sensitive MN shell gradually degrades to expose the MN core component, which neutralizes various inflammatory factors and promotes the phase transition from inflammation to proliferation. In addition, the released verteporfin inhibits scar formation by blocking Engrailed-1 (En1) activation in fibroblasts. Our experiments demonstrate that PF-MNs promote scarless wound repair in mouse models of both acute and chronic wounds, and inhibit the formation of hypertrophic scar in rabbit ear models.

Combating Bacterial Biofilms: Current and Emerging Antibiofilm Strategies for Treating Persistent Infections

Biofilms are intricate multicellular structures created by microorganisms on living (biotic) or nonliving (abiotic) surfaces. Medically, biofilms often lead to persistent infections, increased antibiotic resistance, and recurrence of infections. In this review, we highlighted the clinical problem associated with biofilm infections and focused on current and emerging antibiofilm strategies. These strategies are often directed at disrupting quorum sensing, which is crucial for biofilm formation, preventing bacterial adhesion to surfaces, impeding bacterial aggregation in viscous mucus layers, degrading the extracellular polymeric matrix, and developing nanoparticle-based antimicrobial drug complexes which target persistent cells within the biofilm core. It is important to acknowledge, however, that the use of antibiofilm agents faces obstacles, such as limited effectiveness in vivo, potential cytotoxicity to host cells, and propensity to elicit resistance in targeted biofilm-forming microbes. Emerging next generation antibiofilm strategies, which rely on multipronged approaches, were highlighted, and these benefit from current advances in nanotechnology, synthetic biology, and antimicrobial drug discovery. The assessment of current antibiofilm mitigation approaches, as presented here, could guide future initiatives toward innovative antibiofilm therapeutic strategies. Enhancing the efficacy and specificity of some emerging antibiofilm strategies via careful investigations, under conditions that closely mimic biofilm characteristics within the human body, could bridge the gap between laboratory research and practical application.

Janus porous polylactic acid membranes with versatile metal-phenolic interface for biomimetic periodontal bone regeneration

Conventional treatment to periodontal and many other bone defects requires the use of barrier membranes to guided tissue regeneration (GTR) and guided bone regeneration (GBR). However, current barrier membranes normally lack of the ability to actively regulate the bone repairing process. Herein, we proposed a biomimetic bone tissue engineering strategy enabled by a new type of Janus porous polylactic acid membrane (PLAM), which was fabricated by combining unidirectional evaporation-induced pore formation with subsequent self-assembly of a bioactive metal-phenolic network (MPN) nanointerface. The prepared PLAM-MPN simultaneously possesses barrier function on the dense side and bone-forming function on the porous side. In vitro, the presence of MPN nanointerface potently alleviated the proinflammatory polarization of mice bone marrow-derived macrophages (BMDMs), induced angiogenesis of human umbilical vein endothelial cells (HUVECs), and enhanced the attachment, migration and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs). The implantation of PLAM-MPN into rat periodontal bone defects remarkably enhanced bone regeneration. This bioactive MPN nanointerface within a Janus porous membrane possesses versatile capacities to regulate cell physiology favoring bone regeneration, demonstrating great potential as GTR and GBR membranes for clinical applications.

Nanomotors-loaded microneedle patches for the treatment of bacterial biofilm-related infections of wound

The biofilms formed by bacteria at the wound site can effectively protect the bacteria, which greatly weakens the effect of antibiotics. Herein, a microneedle patch for wound treatment is designed, which can effectively penetrate the biofilms in a physical way because of the penetration ability of the microneedles and the motion behavior of the nanomotors, and deliver bacterial quorum sensing inhibitor luteolin (Le) and nanomotors with multiple antibacterial properties within biofilms. Firstly, the nanomotors-loaded microneedle patches are prepared and characterized. The results of in vitro and in vivo experiments show that the microneedle patches have good biosafety and antibacterial properties. Among them, Le can inhibit the growth of biofilms. Further, under near-infrared (NIR) irradiation, the nanomotors loaded with photosensitizer ICG and nitric oxide (NO) donor L-arginine (L-Arg) can move in the biofilms under the double driving effect of photothermal and NO, and can give full play to the multiple anti-biological infection effects of photothermal therapy (PTT), photodynamic therapy (PDT) and NO, and finally realize the effective removal of biofilms and promote wound healing. The intervention of nanomotor technology has brought about a new therapeutic strategy for bacterial biofilm-related infection of wound.

Mechanically Robust Dissolving Microneedles Made of Supramolecular Photosensitizers for Effective Photodynamic Bacterial Biofilm Elimination

Bacterial biofilms pose severe threats to public health worldwide and are intractable by conventional antibiotic treatment. Antimicrobial photodynamic therapy (PDT) is emerging as a promising strategy for eradicating biofilms by virtue of low invasiveness, broad-spectrum antibacterial activity, and nondrug resistance. However, its practical efficacy is impeded by the low water solubility, severe aggregation, and poor penetration of photosensitizers (PSs) into the dense extracellular polymeric substances (EPS) of biofilms. Herein, we develop a dissolving microneedle (DMN) patch composed of a sulfobutylether-β-cyclodextrin (SCD)/tetra(4-pyridyl)-porphine (TPyP) supramolecular PS for enhanced biofilm penetration and eradication. The inclusion of TPyP into the SCD cavity can drastically inhibit the aggregation of TPyP, thereby allowing for nearly tenfold reactive oxygen species production and high photodynamic antibacterial efficacy. Moreover, the TPyP/SCD-based DMN (TSMN) possesses excellent mechanical performance that can easily pierce the EPS of biofilm with a penetration depth of ∼350 μm, enabling sufficient contact of TPyP with bacteria and optimal photodynamic elimination of bacterial biofilms. Furthermore, TSMN could efficiently eradicate Staphylococcus aureus biofilm infection in vivo with good biosafety. This study offers a promising platform for supramolecular DMN for efficient biofilm elimination and other PDTs.

Engineering of clarithromycin loaded stimulus responsive dissolving microneedle patches for the treatment of biofilms

This study aimed to fabricate clarithromycin laden Eudragit S-100-based microfibers (MF), microfibers coated film (MB), clarithromycin loaded polyvinyl pyrollidone, hyaluronic acid and sorbitol-based dissolving microneedle patches (CP) and microfibers coated microneedle patches (MP). Morphological and phase analysis of formulations were carried out by scanning electron microscopy and differential scanning calorimetry, X-ray diffraction, respectively. Substrate liquefaction test, in vitro drug release, antimicrobial assay and in vivo antibiofilm studies were performed. MF exhibited a uniform surface and interconnected network. Morphological analysis of CP revealed sharp-tipped and uniform-surfaced microstructures. Clarithromycin was incorporated within MF and CP as amorphous solid. Liquefaction test indicated hyaluronate lyase enzyme responsiveness of hyaluronic acid. Fibers-based formulations (MF, MB and MP) provided an alkaline pH (7.4) responsive drug release; ∼79 %, ∼78 % and ∼81 %, respectively within 2 hours. CP showed a drug release of ∼82 % within 2 hours. MP showed ∼13 % larger inhibitory zone against Staphylococcus aureus (S. aureus) as compared to MB and CP. A relatively rapid eradication of S. aureus in infected wounds and subsequent skin regeneration was observed following MP application as compared to MB and CP indicating its usefulness for the management of microbial biofilms.

Bee Sting-Inspired Inflammation-Responsive Microneedles for Periodontal Disease Treatment

Periodontal lesions are common and frustrating diseases that impact life quality. Efforts in this aspect aim at developing local drug delivery systems with better efficacy and less toxicity. Herein, inspired by the sting separation behavior of bees, we conduct novel reactive oxygen species (ROS)-responsive detachable microneedles (MNs) that carry antibiotic metronidazole (Met) for controllable periodontal drug delivery and periodontitis treatment. Benefiting from the needle-base separation ability, such MNs can penetrate through the healthy gingival to reach the gingival sulcus's bottom while offering minimal impact to oral function. Besides, as the drug-encapsulated cores were protected by poly (lactic-co-glycolic acid) (PLGA) shells in MNs, the surrounding normal gingival tissue is not affected by Met, resulting in excellent local biosafety. Additionally, with the ROS-responsive PLGA-thioketal-polyethylene glycol MN tips, they can be unlocked to release Met directly around the pathogen under the high ROS in the periodontitis sulcus, bringing about improved therapeutic effects. Based on these characteristics, the proposed bioinspired MNs show good therapeutic results in treating a rat model with periodontitis, implying their potential in periodontal disease.

Recent progress of antibacterial hydrogels in wound dressings

Hydrogels are essential biomaterials due to their favorable biocompatibility, mechanical properties similar to human soft tissue extracellular matrix, and tissue repair properties. In skin wound repair, hydrogels with antibacterial functions are especially suitable for dressing applications, so novel antibacterial hydrogel wound dressings have attracted widespread attention, including the design of components, optimization of preparation methods, strategies to reduce bacterial resistance, etc. In this review, we discuss the fabrication of antibacterial hydrogel wound dressings and the challenges associated with the crosslinking methods and chemistry of the materials. We have investigated the advantages and limitations (antibacterial effects and antibacterial mechanisms) of different antibacterial components in the hydrogels to achieve good antibacterial properties, and the response of hydrogels to stimuli such as light, sound, and electricity to reduce bacterial resistance. Conclusively, we provide a systematic summary of antibacterial hydrogel wound dressings findings (crosslinking methods, antibacterial components, antibacterial methods) and an outlook on long-lasting antibacterial effects, a broader antibacterial spectrum, diversified hydrogel forms, and the future development prospects of the field.

Triggered release of antimicrobial peptide from microneedle patches for treatment of wound biofilms

Biofilms pose a great challenge for wound management. Herein, this study describes a near-infrared (NIR) light-responsive microneedle patch for on-demand release of antimicrobial peptide for treatment of wound biofilms. IR780 iodide as a photothermal conversion agent and molecularly engineered peptide W379 as an antimicrobial agent are loaded in dissolvable poly(vinylpyrrolidone) (PVP) microneedle patches followed by coating with a phase change material 1-tetradecanol (TD). After placing in an aqueous solution or biofilm containing wounds ex vivo and in vivo, upon exposure to NIR light, the incorporated IR780 induces light-to-heat conversion, causing the melting of TD. This leads to the dissolution of PVP microneedles, enabling the release of loaded W379 peptide from the microneedles into surrounding regions (e.g., solution, biofilm, wound bed). Compared with traditional microneedle patches, NIR light responsive microneedle patches can program the release of antimicrobial peptide and show high antibacterial efficacy in vitro. Meanwhile, this work indicates that NIR light responsive TD-coated, W379-loaded PVP microneedle patches show excellent antibiofilm activities ex vivo and in vivo. Additionally, this microneedle system could be a promising platform for delivering other antimicrobial agents.

Microneedles for in situ tissue regeneration

Tissue injury is a common clinical problem, which may cause great burden on patients' life. It is important to develop functional scaffolds to promote tissue repair and regeneration. Due to their unique composition and structure, microneedles have attracted extensive attention in various tissues regeneration, including skin wound, corneal injury, myocardial infarction, endometrial injury, and spinal cord injury et al. Microneedles with micro-needle structure can effectively penetrate the barriers of necrotic tissue or biofilm, therefore improving the bioavailability of drugs. The use of microneedles to deliver bioactive molecules, mesenchymal stem cells, and growth factors in situ allows for targeted tissue and better spatial distribution. At the same time, microneedles can also provide mechanical support or directional traction for tissue, thus accelerating tissue repair. This review summarized the research progress of microneedles for in situ tissue regeneration over the past decade. At the same time, the shortcomings of existing researches, future research direction and clinical application prospect were also discussed.

Dissolvable sodium alginate-based antibacterial wound dressing patches: Design, characterization, and in vitro biological studies

The treatment of infected wounds in patients with highly sensitive skin is challenging. Some of the available wound dressings cause further skin tear and bleeding upon removal thereby hindering the healing process. In this study, dissolvable antibacterial wound dressing patches loaded with cephalexin monohydrate were prepared from different amounts of sodium alginate (SA) and carboxymethyl cellulose (CMC) by the solvent casting evaporation technique. The patches displayed good tensile strength (3.83-13.83 MPa), appropriate thickness (0.09 to 0.31 mm) and good flexibility (74-98 %) suitable for the skin. The patches displayed good biodegradability and low moisture uptake suitable to prevent microbial invasion on the wound dressings upon storage. The release profile of the drug from the patches was sustained in the range of 47-80 % for 48 h, revealing their capability to inhibit bacterial infection. The biological assay showed that the patches did not induce cytotoxic effects on HaCaT cells, revealing good biocompatibility. The antimicrobial effect of the patches on the different strains of bacteria used in the study was significant. The cell migration (66.7-74.3 %) to the scratched gap was promising revealing the patches' capability to promote wound closure. The results obtained show that the wound dressings are potential materials for the treatment of infected wounds.

Antibacterial, wet adhesive, and healing-promoting nanosheets for the treatment of oral ulcers

The severe pain caused by oral ulcers seriously affects food intake and speech, bringing great inconvenience in daily life. Drug-loaded patches are mostly used to treat oral mucosal diseases such as oral ulcers and oral lichen planus, but their effects are limited because of the influences of saliva and muscle movement. To enhance the adhesion of drug-loaded patches used in the oral cavity, we designed antimicrobial peptides (AMPs)-modified polycaprolactone (PCL)-collagen nanosheets (APCNs). The internal layer is a bioactive and antibacterial collagen layer modified with antimicrobial peptides. The backing layer is a hydrophobic PCL layer with good mechanical strength that can reduce external influences. We have characterized and tested the APCNs. First, the APCNs exhibited continuous and strong adhesion to irregular buccal mucosa surfaces under wet conditions and external force action. Antibacterial experiments showed that the APCNs had high antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria. Moreover, the APCNs showed good biocompatibility and promoted the adhesion of fibroblasts in vitro. Furthermore, APCNs treatment accelerated ulcer healing in a Sprague Dawley rat oral ulcer model. Our study developed antibacterial, wet-adhesive, and healing-promoting PCL-collagen nanosheets and demonstrated that these nanosheets could be promising adhesive therapeutic agents for the treatment of oral mucosal ulcers.

Smart microneedle patches for wound healing and management

The number of patients with non-healing wounds is generally increasing globally, placing a huge social and economic burden on every country. The complexity of the wound-healing process remains a major health challenge despite the numerous studies that have been reported on conventional wound dressings. Therefore, a therapeutic system that combines diagnostic and therapeutic modalities is essential to monitor wound-related biomarkers and facilitate wound healing in real time. Microneedles, as a multifunctional platform, are promising for transdermal diagnostics and drug delivery. Their advantages are mainly reflected in painless transdermal drug delivery, good biocompatibility, and ease of self-administration. In this work, we review recent advances in the use of microneedle patches for wound healing and monitoring. The paper first provides a brief overview of the skin structure and the wound healing process, and then discusses the current state of research and prospects for the development of wound-related biomarkers and their real-time monitoring based on microneedle sensors. It summarizes the current state of research based on the unique design of microneedle patches, including biomimetic, conductive, and environmentally responsive, to achieve wound healing. It further summarizes the prospects for the application of different microneedle-based drug delivery modalities and drug delivery substances for wound healing, due to their superior transdermal drug delivery advantages. It concludes with challenges and expectations for the use of smart microneedle patches for wound healing and management.

Nitric oxide-releasing poly(ionic liquid)-based microneedle for subcutaneous fungal infection treatment

Poor permeation of therapeutic agents and similar eukaryotic cell metabolic and physiological properties of fungi and human cells are two major challenges that lead to the failure of current therapy for fungi-induced skin and soft tissue infections. Herein, a nitric oxide (NO)-releasing poly(ionic liquid)-based microneedle (PILMN-NO) with the capacity of deep persistent NO toward subcutaneous fungal bed is presented as a synergistic antifungal treatment strategy to treat subcutaneous fungal infection. Upon the insertion of PILMN-NO into skin, the contact fungicidal activities induced by electrostatic and hydrophobic effects of poly(ionic liquid) and the released NO sterilization resulting from the peroxidation and nitrification effect of NO achieved enhanced antifungal efficacy against fungi (Candida albicans) both in vitro and in vivo. Simultaneously, PILMN-NO showed biofilm ablation ability and efficiently eliminated mature biofilms. In vivo fungal-induced subcutaneous abscess studies revealed that PILMN-NO could effectively sterilize fungi while suppressing the inflammatory reaction, facilitating collagen deposition and angiogenesis, and promoting wound healing. This work provides a new strategy to overcome the difficulties in deep skin fungal infection treatment and has potential for further exploitation of NO-releasing microbicidal therapy.

A review on the synthesis and development of alginate hydrogels for wound therapy

Convenient and low-cost dressings can reduce the difficulty of wound treatment. Alginate gel dressings have the advantages of low cost and safe usage, and they have obvious potential for development in biomedical materials. Alginate gel dressings are currently a research area of great interest owing to their versatility, intelligent, and their application attempts in treating complex wounds. We present a detailed summary of the preparation of alginate hydrogels and a study of their performance improvement. Herein, we summarize the various applications of alginate hydrogels. The research focuses in this area mainly include designing multifunctional dressings for the treatment of various wounds and fabricating specialized dressings to assist physicians in the treatment of complex wounds (TOC). This review gives an outlook for future directions in the field of alginate hydrogel dressings. We hope to attract more research interest and studies in alginate hydrogel dressings, thus contributing to the creation of low-cost and highly effective wound treatment materials.

Peripheral Microneedle Patch for First-Aid Hemostasis

Despite the minimized puncture sizes and high efficiency, microneedle (MN) patches have not been used to inject hemostatic drugs into bleeding wounds because they easily destroy capillaries when a tissue is pierced. In this study, a shelf-stable dissolving MN patch is developed to prevent rebleeding during an emergency treatment. A minimally and site-selectively invasive hemostatic drug delivery system is established by using a peripheral MN (p-MN) patch that does not directly intrude the wound site but enables topical drug absorption in the damaged capillaries. The invasiveness of MNs is histologically examined by using a bleeding liver of a Sprague-Dawley (SD) rat as an extreme wound model in vivo. The skin penetration force is quantified to demonstrate that the administration of the p-MN patch is milder than that of the conventional MN patch. Hemostatic performance is systematically studied by analyzing bleeding weight and time and comparing them with that of conventional hemostasis methods. The superior performance of a p-MN for the heparin-pretreated SD rat model is demonstrated by intravenous injection in vivo.

A Highly Efficacious Electrical Biofilm Treatment System for Combating Chronic Wound Bacterial Infections

Biofilm infection has a high prevalence in chronic wounds and can delay wound healing. Current treatment using debridement and antibiotic administration imposes a significant burden on patients and healthcare systems. To address their limitations, a highly efficacious electrical antibiofilm treatment system is described in this paper. This system uses high-intensity current (75 mA cm-2 ) to completely debride biofilm above the wound surface and enhance antibiotic delivery into biofilm-infected wounds simultaneously. Combining these two effects, this system uses short treatments (≤2 h) to reduce bacterial count of methicillin-resistant S. aureus (MRSA) biofilm-infected ex vivo skin wounds from 1010 to 105.2 colony-forming units (CFU) g-1 . Taking advantage of the hydrogel ionic circuit design, this system enhances the in vivo safety of high-intensity current application compared to conventional devices. The in vivo antibiofilm efficacy of the system is tested using a diabetic mouse-based wound infection model. MRSA biofilm bacterial count decreases from 109.0 to 104.6 CFU g-1 at 1 day post-treatment and to 103.3 CFU g-1 at 7 days post-treatment, both of which are below the clinical threshold for infection. Overall, this novel technology provides a quick, safe, yet highly efficacious treatment to chronic wound biofilm infections.

Glucose metabolism-inspired catalytic patches for NIR-II phototherapy of diabetic wound infection

Medical patches hold great prospects for diabetic wound administration, while their practical effects in diabetic wound management remain mired by the complexity of wound microenvironments. Here, inspired by the biological processes of glucose metabolism, we present a catalytic microneedle patch that encapsulates near-infrared-II responsive and dual-nanozyme active Au-Cu₂MoS₄ nanosheets (Au-CMS NSs) for treating diabetic wound infection. Since microneedle patches have great tissue penetration ability, the Au-CMS NSs can be delivered to deep tissues and fully interact with wound environments. Benefitting from the dual nanozyme activities (glucose oxidase and catalase) and near-infrared-II photothermal performances of Au-CMS NSs, the composited catalytic patch realizes in situ glucose consumption, oxygen generation, and bacterial elimination. Notably, their repeatability of near-infrared-II responsive antibacterial capability has been proved both in vitro and in diabetic mice against methicillin-resistant Staphylococcus aureus. The catalytic patch can find wide catalytic applications in wound care and infection prevention. STATEMENT OF SIGNIFICANCE: Effective treatment of diabetic wound infection remains still challenging in the clinic owing to the complex wound microenvironments. Herein, inspired by the biological processes of glucose metabolism in lives, we propose a novel strategy to treat wound infections by modulating the diabetic wound microenvironments. A near-infrared-II (NIR-II) responsive biocatalytic microneedle patch with both glucose oxidase- and catalase-like activities capable of killing bacteria, reducing glucose level, and supplying O₂ is developed. The patch not only achieves efficient antibacterial outcomes in vitro, but also is a valuable wound patch for efficient treatment of MRSA-infected wounds in diabetic mice. We anticipate that this therapeutic strategy will provide the applications in chronic inflammation and infections.

Antimicrobial peptide-grafted PLGA-PEG nanoparticles to fight bacterial wound infections

Wound infection treatment with antimicrobial peptides (AMPs) is still not a reality, due to the loss of activity in vivo. Unlike the conventional strategy of encapsulating AMPs on nanoparticles (NPs) leaving activity dependent on the release profile, this work explores AMP grafting to poly(D,L-lactide-co-glycolide)-polyethylene glycol NPs (PLGA-PEG NPs), whereby AMP exposition, infection targeting and immediate action are promoted. NPs are functionalized with MSI-78(4-20), an equipotent and more selective derivative of MSI-78, grafted through a thiol-maleimide (Mal) Michael addition. NPs with different ratios of PLGA-PEG/PLGA-PEG-Mal are produced and characterized, with 40%PLGA-PEG-Mal presenting the best colloidal properties and higher amounts of AMP grafted as shown by surface charge (+8.6 ± 1.8 mV) and AMP quantification (326 μg mL^-1, corresponding to 16.3 μg of AMP per mg of polymer). NPs maintain the activity of the free AMP with a minimal inhibitory concentration (MIC) of 8-16 μg mL^-1 against Pseudomonas aeruginosa, and 16-32 μg mL^-1 against Staphylococcus aureus. Moreover, AMP grafting accelerates killing kinetics, from 1-2 h to 15 min for P. aeruginosa and from 6-8 h to 0.5-1 h for S. aureus. NP activity in a simulated wound fluid is maintained for S. aureus and decreases slightly for P. aeruginosa. Furthermore, NPs do not demonstrate signs of cytotoxicity at MIC concentrations. Overall, this promising formulation helps unleash the full potential of AMPs for the management of wound infections.