Flexible Microneedle Array Patch for Chronic Wound Oxygenation and Biofilm Eradication

Theory of nanostructured sensors integrated in/on microneedles for diagnostics and therapy

Efficient real-time diagnostics and on-demand drug delivery are essential components in modern healthcare, especially for managing chronic diseases. The lack of a rapid and effective sensing and therapeutic system can result in analyte level deviations, leading to severe complications. Minimally invasive microneedle (MN)-based patches integrating nanostructures (NSs) in their volume or on their surface have emerged as a biocompatible technology for delay-free analyte sensing and therapy. However, a quantitative relationship for the signal response in NS-assisted reactions remains elusive. Existing generalized formalisms are derived for in-vitro applications, raising questions about their direct applicability to in-situ wearable sensors. In this study, we apply the reaction-diffusion theory to establish a generalized physics-guided framework for NS-in-MN platforms in wearable applications. The model relates the signal response to analyte concentration, incorporating geometric, physical, and catalytic platform properties. Approximating the model under NS (binding or catalytic) and environmental (mass transport) limitations, we validate it against numerical simulations and various experimental results from diverse conditions - analyte sensing (glucose, lactic acid, pyocyanin, miRNA, etc.) in artificial and in-vivo environments (humans, mice, pigs, plants, etc.) through electrochemical and optical/colorimetric, enzymatic and non-enzymatic platforms. The results plotted in the scaled response show that (a) NS-limited platforms exhibit a linear dependence, (b) Mass transport-limited platforms saturate to 1, (c) a one-to-one mapping against traditional sensitivity plots unifies the scattered data points reported in literature. The universality of the model provides insightful perspectives for the design and optimization of MN-based sensing technologies, with potential extensions to dissolvable MNs as part of analyte-responsive closed-loop therapeutic applications.

Nanomaterials-incorporated polymeric microneedles for wound healing applications

There is a growing and urgent need for developing novel biomaterials and therapeutic approaches for efficient wound healing. Microneedles (MNs), which can penetrate necrotic tissues and biofilm barriers at the wound and deliver active ingredients to the deeper layers in a minimally invasive and painless manner, have stimulated the interests of many researchers in the wound-healing filed. Among various materials, polymeric MNs have received widespread attention due to their abundant material sources, simple and inexpensive manufacturing methods, excellent biocompatibility and adjustable mechanical strength. Meanwhile, due to the unique properties of nanomaterials, the incorporation of nanomaterials can further extend the application range of polymeric MNs to facilitate on-demand drug release and activate specific therapeutic effects in combination with other therapies. In this review, we firstly introduce the current status and challenges of wound healing, and then outline the advantages and classification of MNs. Next, we focus on the manufacturing methods of polymeric MNs and the different raw materials used for their production. Furthermore, we give a summary of polymeric MNs incorporated with several common nanomaterials for chronic wounds healing. Finally, we discuss the several challenges and future prospects of transdermal drug delivery systems using nanomaterials-based polymeric MNs in wound treatment application.

Targeting Diverse Wounds and Scars: Recent Innovative Bio-design of Microneedle Patch for Comprehensive Management

Wounds and the subsequent formation of scars constitute a unified and complex phased process. Effective treatment is crucial; however, the diverse therapeutic approaches for different wounds and scars, as well as varying treatment needs at different stages, present significant challenges in selecting appropriate interventions. Microneedle patch (MNP), as a novel minimally invasive transdermal drug delivery system, has the potential for integrated and programmed treatment of various diseases and has shown promising applications in different types of wounds and scars. In this comprehensive review, the latest applications and biotechnological innovations of MNPs in these fields are thoroughly explored, summarizing their powerful abilities to accelerate healing, inhibit scar formation, and manage related symptoms. Moreover, potential applications in various scenarios are discussed. Additionally, the side effects, manufacturing processes, and material selection to explore the clinical translational potential are investigated. This groundwork can provide a theoretical basis and serve as a catalyst for future innovations in the pursuit of favorable therapeutic options for skin tissue regeneration.

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.

Simvastatin nanocrystals-based dissolving microneedles for wound healing

Currently, one of the main problems encountered in wound healing therapy is related to inefficient drug delivery. However, dissolving microneedles (DMNs) can be administered percutaneously to effectively deliver a drug to a deep wound area. Simvastatin (SIM) can promote wound healing, albeit its insolubility in water limits its application. Here, we designed a DMNs (SIM-NC@DMNs) drug delivery system loaded with SIM nanocrystals (SIM-NC) and evaluated its efficacy in wound healing. Based on our observations, the dissolution performance of insoluble SIM is significantly improved after the preparation of SIM-NC. For example, the saturation solubility of SIM-NC in deionized water and PBS increased by 150.57 times and 320.14 times, respectively. After the SIM-NC@DMNs are deeply inserted into the wound, the needle portion, which is composed of hyaluronic acid (HA), dissolves rapidly, and the SIM-NC loaded on the needle portion is efficiently released into the deep wound area for optimal therapeutic efficacy. The combination of NC and DMNs makes this system further effective for wound healing. Our cumulative work suggests that the newly developed SIM-NC@DMNs possess great potential in accelerating wound healing. By day 12 after treatment, the residual wound area in the Control group was 21.34 %, while the residual wound area in the SIM-NC@DMNs group was only 2.36 %. This result as well as provides certain evidence of its efficacy for wound healing therapy. The SIM-NC@DMNs drug delivery system may become an efficient treatment modality that promotes wound healing, with a promising potential in the field of wound healing research.

Biofilm microenvironment triggered self-enhancing photodynamic immunomodulatory microneedle for diabetic wound therapy

The treatment of diabetic wounds faces enormous challenges due to complex wound environments, such as infected biofilms, excessive inflammation, and impaired angiogenesis. The critical role of the microenvironment in the chronic diabetic wounds has not been addressed for therapeutic development. Herein, we develop a microneedle (MN) bandage functionalized with dopamine-coated hybrid nanoparticles containing selenium and chlorin e6 (SeC@PA), which is capable of the dual-directional regulation of reactive species (RS) generation, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), in response to the wound microenvironment. The SeC@PA MN bandage can disrupt barriers in wound coverings for efficient SeC@PA delivery. SeC@PA not only depletes endogenous glutathione (GSH) to enhance the anti-biofilm effect of RS, but also degrades GSH in biofilms through cascade reactions to generate more lethal RS for biofilm eradication. SeC@PA acts as an RS scavenger in wound beds with low GSH levels, exerting an anti-inflammatory effect. SeC@PA also promotes the M2-phenotype polarization of macrophages, accelerating wound healing. This self-enhanced, catabolic and dynamic therapy, activated by the wound microenvironment, provides an approach for treating chronic wounds.

Microalgae Microneedle Supplies Oxygen for Antiphotoaging Treatment

UV exposure often triggers photoaging of the skin. Pharmacological treatment suffers from severe side effects as well as poor efficacy because of insufficient skin penetration. Dissolved oxygen has been previously shown to reverse photoaged skin; however, the treatment is often limited by the availability of equipment (e.g., high-pressure oxygen). Poor oxygen diffusion into the skin has also limited its therapeutic efficacy. Herein, we developed a microneedle patch to deliver living microalgae to the deeper layers of the skin for efficient oxygenation and reversal of photoaging. The continuous release of oxygen from microalgae in the skin through photosynthesis reversed the inflammatory microenvironment and reduced reactive oxygen species levels in the photodamaged skin, leading to collagen regeneration and reduced wrinkles. This study provides not only a means for highly efficient skin oxygenation and reversal of photoaging but also an important theoretical basis for the clinical treatment of photoaging.

Non-destructive processing of silver containing glass ceramic antibacterial coating on polymeric surgical mesh surfaces

Surgical meshes composed of bioinert polymers such as polypropylene are widely used in millions of hernia repair procedures to prevent the recurrence of organ protrusion from the damaged abdominal wall. However, post-operative mesh infection remains a significant complication, elevating hernia recurrence risks from 3.6% to 10%, depending on the procedure type. While attempts have been made to mitigate these infection-related complications by using antibiotic coatings, the rise in antibiotic-resistant bacterial strains threatens their effectiveness. Bioactive glass-ceramics featuring noble metals, notably silver nanoparticles (AgNPs), have recently gained traction for their wide antibacterial properties and biocompatibility. Yet, conventional methods of synthesizing and coating of such materials often require high temperatures, thus making them impractical to be implemented on temperature-sensitive polymeric substrates. To circumvent this challenge, a unique approach has been explored to deposit these functional compounds onto temperature-sensitive polypropylene mesh (PP-M) surfaces. This approach is based on the recent advancements in cold atmospheric plasma (CAP) assisted deposition of SiO2 thin films and laser surface treatment (LST), enabling the selective heating and formation of functional glass-ceramic compounds under atmospheric conditions. A systematic study was conducted to identify optimal LST conditions that resulted in the effective formation of a bioactive glass-ceramic structure without significantly altering the chemical and mechanical properties of the underlying PP-M (less than 1% change compared to the original properties). The developed coating with optimized processing conditions demonstrated high biocompatibility and persistent antibacterial properties (>7 days) against both Gram-positive and Gram-negative bacteria. The developed process is expected to provide a new stepping stone towards depositing a wide range of functional bioceramic coatings onto different implant surfaces, thereby decreasing their risk of infection and associated complications.

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.

Biocompatibility and Safety Assessment of Combined Topical Ozone and Antibiotics for Treatment of Infected Wounds

Wound infections with antibiotic-resistant bacteria, particularly the Gram-negative strains, pose a substantial health risk for patients with limited treatment options. Recently topical administration of gaseous ozone and its combination with antibiotics through portable systems has been demonstrated to be a promising approach to eradicate commonly found Gram-negative strains of bacteria in wound infections. However, despite the significant impact of ozone in treating the growing number of antibiotic-resistant infections, uncontrolled and high concentrations of ozone can cause damage to the surrounding tissue. Hence, before such treatments could advance into clinical usage, it is paramount to identify appropriate levels of topical ozone that are effective in treating bacterial infections and safe for use in topical administration. To address this concern, we have conducted a series of in vivo studies to evaluate the efficacy and safety of a portable and wearable adjunct ozone and antibiotic wound therapy system. The concurrent ozone and antibiotics are applied through a wound interfaced gas permeable dressing coated with water-soluble nanofibers containing vancomycin and linezolid (traditionally used to treat Gram-positive infections) and connected to a portable ozone delivery system. The bactericidal properties of the combination therapy were evaluated on an ex vivo wound model infected with Pseudomonas aeruginosa, a common Gram-negative strain of bacteria found in many skin infections with high resistance to a wide range of currently available antibiotics. The results indicated that the optimized combination delivery of ozone (4 mg h^-1) and topical antibiotic (200 μg cm^-2) provided complete bacteria eradication after 6 h of treatment while having minimum cytotoxicity to human fibroblast cells. Furthermore, in vivo local and systemic toxicity studies (e.g., skin monitoring, skin histopathology, and blood analysis) on pig models showed no signs of adverse effects of ozone and antibiotic combination therapy even after 5 days of continuous administration. The confirmed efficacy and biosafety profile of the adjunct ozone and antibiotic therapy places it as a strong candidate for treating wound infection with antimicrobial-resistant bacteria and further pursuing human clinical trials.

Flexible Monitoring, Diagnosis, and Therapy by Microneedles with Versatile Materials and Devices toward Multifunction Scope

Microneedles (MNs) have drawn rising attention owing to their merits of convenience, noninvasiveness, flexible applicability, painless microchannels with boosted metabolism, and precisely tailored multifunction control. MNs can be modified to serve as novel transdermal drug delivery, which conventionally confront with the penetration barrier caused by skin stratum corneum. The micrometer-sized needles create channels through stratum corneum, enabling efficient drug delivery to the dermis for gratifying efficacy. Then, incorporating photosensitizer or photothermal agents into MNs can conduct photodynamic or photothermal therapy, respectively. Besides, health monitoring and medical detection by MN sensors can extract information from skin interstitial fluid and other biochemical/electronic signals. Here, this review discloses a novel monitoring, diagnostic, and therapeutic pattern by MNs, with elaborate discussion about the classified formation of MNs together with various applications and inherent mechanism. Hereby, multifunction development and outlook from biomedical/nanotechnology/photoelectric/devices/informatics to multidisciplinary applications are provided. Programmable intelligent MNs enable logic encoding of diverse monitoring and treatment pathways to extract signals, optimize the therapy efficacy, real-time monitoring, remote control, and drug screening, and take instant treatment.

Transdermal drug delivery via microneedles to mediate wound microenvironment

Cutaneous wound healing is a complex process, while modulating the wound microenvironment has become an essential therapeutic goal. In clinics, advanced dressings or dermal templates can promote wound healing but their ability in mediating wound microenvironment is limited. In the last decade, microneedle (MN) array patches have emerged as a new class of wound dressings. These dressings enable non-invasive transdermal and precise medication delivery. Combined with smart materials, MN additionally allows real-time monitoring of wound site markers such as inflammatory factors, oxygen levels, vascularization, pH and temperature, etc., while releasing therapeutic molecules responsively to the wound site. In this review, the MN-based strategies were reviewed for modulating wound microenvironment via introducing the main characteristics of the wound microenvironment and various types of MN-based delivery systems. Additionally, the progress and future trends in the application of MNs in mediating wound microenvironments are also discussed.

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.

Design and Evaluation of Dissolvable Microneedles for Treating Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused predominantly by immune dysregulation. The global impact of AD continues to increase, making it not only a significant public health issue but also a risk factor for progression into other allergic phenotype disorders. Treatment of moderate-to-severe symptomatic AD involves general skin care, restoration of the skin barrier function, and local anti-inflammatory drug combinations, and may also require systemic therapy, which is often associated with severe adverse effects and is occasionally unsuitable for long-term use. The main objective of this study was to develop a new delivery system for AD treatment based on dissolvable microneedles containing dexamethasone incorporated in a dissolvable polyvinyl alcohol/polyvinylpyrrolidone matrix. SEM imaging of the microneedles showed well-structured arrays comprising pyramidal needles, fast drug release in vitro in Franz diffusion cells, an appropriate mechanical strength recorded with a texture analyzer, and low cytotoxicity. Significant clinical improvements, including in the dermatitis score, spleen weights, and clinical scores, were observed in an AD in vivo model using BALB/c nude mice. Taken together, our results support the hypothesis that microneedle devices loaded with dexamethasone have great potential as a treatment for AD and possibly for other skin conditions as well.

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.

Organ-on-a-Chip Platform with an Integrated Screen-Printed Electrode Array for Real-Time Monitoring Trans-Epithelial Barrier and Bubble Formation

Cellular tight junctions play a key role in establishing a barrier between different compartments of the body by regulating the selective passage of different solutes across epithelial and endothelial tissues. Over the past decade, significant efforts have been conducted to develop more clinically relevant "organ-on-a-chip" models with integrated trans-epithelial electrical resistance (TEER) monitoring systems to help better understand the fundamental underpinnings of epithelial tissue physiology upon exposure to different substances. However, most of these platforms require the use of high-cost and time-consuming photolithography processes, which limits their scalability and practical implementation in clinical research. To address this need, we have developed a low-cost microfluidic platform with an integrated electrode array that allows continuous real-time monitoring of TEER and the risk of bubble formation in the microfluidic system by using scalable manufacturing technologies such as screen printing and laser processing. The integrated printed electrode array exhibited excellent stability (with less than ∼0.02 Ω change in resistance) even after long-term exposure to a complex culture medium. As a proof of concept, the fully integrated platform was tested with HMT3522 S1 epithelial cells to evaluate the tight barrier junction formation through TEER measurement and validated with standard immunostaining procedures for Zonula occludens-1 protein. This platform could be regarded as a stepping stone for the fabrication of disposable and low-cost organ and tissue-on-a-chip models with integrated sensors to facilitate studying the dynamic response of epithelial tissues to different substances in more physiologically relevant conditions.

Enhanced skin drug delivery using dissolving microneedles: a potential approach for the management of skin disorders

INTRODUCTION

For decades, finding effective long-term or disease-modifying treatments for skin disorders has been a major focus of scientists. The conventional drug delivery systems showed poor efficacy with high doses and are associated with side effects, which lead to challenges in adherence to therapy. Therefore, to overcome the limitations of conventional drug delivery systems, drug delivery research has focused on topical, transdermal, and intradermal drug delivery systems. Among all, the dissolving microneedles have gained attention with a new range of advantages of drug delivery in skin disorders such as breaching skin barriers with minimal discomfort and its simplicity of application to the skin, which allows patients to administer it themselves.

AREAS COVERED

This review highlighted the insights into dissolving microneedles for different skin disorders in detail. Additionally, it also provides evidence for its effective utilization in the treatment of various skin disorders. The clinical trial status and patents for dissolving microneedles for the management of skin disorders are also covered.

EXPERT OPINION

The current review on dissolving microneedles for skin drug delivery is accentuating the breakthroughs achieved so far in the management of skin disorders. The output of the discussed case studies anticipated that dissolving microneedles can be a novel drug delivery strategy for the long-term treatment of skin disorders.

Microneedle arrays integrated with microfluidic systems: Emerging applications and fluid flow modeling

Microneedle arrays are patches of needles at micro- and nano-scale, which are competent and versatile technologies that have been merged with microfluidic systems to construct more capable devices for biomedical applications, such as drug delivery, wound healing, biosensing, and sampling body fluids. In this paper, several designs and applications are reviewed. In addition, modeling approaches used in microneedle designs for fluid flow and mass transfer are discussed, and the challenges are highlighted.

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.

An antibacterial and proangiogenic double-layer drug-loaded microneedle patch for accelerating diabetic wound healing

Diabetic wounds are difficult to heal because of bacterial infections and insufficient angiogenesis. Herein, we report a double-layer drug-loaded microneedle patch with antibacterial and angiogenesis-promoting properties for diabetic wound healing. The double-layer microneedle comprises the hyaluronic acid (HA)-loaded antibacterial drug tetracycline hydrochloride (TCH) as the tip and a mixture of chitosan and silk fibroin containing the angiogenic drug deferoxamine (DFO) as the substrate. In the double-layer drug-loaded microneedle system (DMN@TCH/DFO), rapid dissolution of HA at the tip releases TCH to promote early antibacterial activity. The substrate exhibits excellent swelling properties, facilitating the absorption of tissue fluid from the wound to promote wound contraction. Simultaneously, DFO is released to promote angiogenesis. Therefore, DMN@TCH/DFO exhibited adequate mechanical properties, excellent swelling and biocompatibility, antibacterial properties, and angiogenesis-promoting capabilities. In a wound model of diabetic rats, DMN@TCH/DFO reduced inflammatory responses, promoted angiogenesis, and facilitated collagen deposition, thereby accelerating diabetic wound healing. Overall, DMN@TCH/DFO can accelerate the healing of diabetic wounds and has clinical application prospects.

Intradermal delivery of an angiotensin II receptor blocker using a personalized microneedle patch for treatment of hypertrophic scars

High-quality postoperative rehabilitation is the focus of most patients currently, and hypertrophic scar (HS) greatly reduces the patient's quality of life due to the symptom of severe itching. Traditional HS therapies are associated with limitations, such as poor drug delivery efficiency for topical administration and severe pain for intralesional injection. In this study, we developed a personalized microneedle patch system for minimally invasive and effective treatment of HSs. The microneedle patches were personalized designed and fabricated with 3D printing in order to adapt to individual HS. The optimized microneedle patches were composed of dissolving gelatin and starch and loaded with losartan. Losartan, as a drug class of angiotensin II receptor blockers (ARBs), can effectively inhibit the proliferation and migration of hypertrophic scar fibroblasts (HSFs) and downregulate the gene expression related to scar formation in HSFs. The dissolving microneedle patches exhibited strong mechanical strength, effectively penetrated the stratum corneum of HSs and increased the losartan delivery into HSs upon dissolution of gelatin and starch. Together, the losartan-loaded microneedle patches effectively inhibited the formation of HSs in rabbit ears with reduced scar elevation index (SEI), and decreased fibrosis and collagen deposition in HSs. This personalized microneedle patch system increases the drug delivery efficiency into HSs with minimal invasion, and opens a new window for personalized management and treatment of skin diseases.

Role of wound microbiome, strategies of microbiota delivery system and clinical management

Delayed wound healing is one of the most global public health threats affecting nearly 100 million people each year, particularly the chronic wounds. Many confounding factors such as aging, diabetic disease, medication, peripheral neuropathy, immunocompromises or arterial and venous insufficiency hyperglycaemia are considered to inhibit wound healing. Therapeutic approaches for slow wound healing include anti-infection, debridement and the use of various wound dressings. However, the current clinical outcomes are still unsatisfied. In this review, we discuss the role of skin and wound commensal microbiota in the different healing stages, including inflammation, cell proliferation, re-epithelialization and remodelling phase, followed by multiple immune cell responses to commensal microbiota. Current clinical management in treating surgical wounds and chronic wounds was also reviewed together with potential controlled delivery systems which may be utilized in the future for the topical administration of probiotics and microbiomes. This review aims to introduce advances, novel strategies, and pioneer ideas in regulating the wound microbiome and the design of controlled delivery systems.

Smart capsule for targeted proximal colon microbiome sampling

The gastrointestinal (GI) tract, particularly the colon region, holds a highly diverse microbial community that plays an important role in the metabolism, physiology, nutrition, and immune function of the host body. Accumulating evidence has revealed that alteration in these microbial communities is the pivotal step in developing various metabolic diseases, including obesity, inflammatory bowel disease (IBD), and colorectal cancer. However, there is still a lack of clear understanding of the interrelationship between microbiota and diet as well as the effectiveness of chemoprevention strategies, including pre and probiotic agents in modifying the colonic microbiota and preventing digestive diseases. Existing methods for assessing these microbiota-diet interactions are often based on samples collected from the feces or endoscopy techniques which are incapable of providing information on spatial variations of the gut microbiota or are considered invasive procedures. To address this need, here we have developed an electronic-free smart capsule that enables site-specific sampling of the gut microbiome within the proximal colon region of the GI tract. The 3D printed device houses a superabsorbent hydrogel bonded onto a flexible polydimethylsiloxane (PDMS) disk that serves as a milieu to collect the fluid in the gut lumen and its microbiome by rapid swelling and providing the necessary mechanical actuation to close the capsule after the sampling is completed. The targeted colonic sampling is achieved by coating the sampling aperture on the capsule with a double-layer pH-sensitive enteric coating, which delays fluid in the lumen from entering the capsule until it reaches the proximal colon of the GI tract. To identify the appropriate pH-responsive double-layer coating and processing condition, a series of systematic dissolution characterizations in different pH conditions that mimicked the GI tract was conducted. The effective targeted microbial sampling performance and preservation of the smart capsule with the optimized design were validated using both realistic in vitro GI tract models with mixed bacteria cultures and in vivo with pigs as an animal model. The results from 16s rRNA and WideSeq analysis in both in vitro and in vivo studies showed that the bacterial population sampled within the retrieved capsule closely matched the bacterial population within the targeted sampling region (proximal colon). Herein, it is envisioned that such smart sampling capsule technology will provide new avenues for gastroenterological research and clinical applications, including diet-host-microbiome relationships, focused on human GI function and health. STATEMENT OF SIGNIFICANCE: The colonic microbiota plays a major role in the etiology of numerous diseases. Extensive efforts have been conducted to monitor the gut microbiome using sequencing technologies based on samples collected from feces or mucosal biopsies that are typically obtained by colonoscopy. Despite the simplicity of fecal sampling procedures, they are incapable of preserving spatial and temporal information about the bacteria through the gastrointestinal (GI) tract. In contrast, colonoscopy is an invasive and impractical approach to frequently assess the effect of dietary and therapeutic intake on the microbiome and their impact on the health of the patient. Here, we developed a non-invasive capsule that enables targeted sampling from the ascending colon, thereby providing crucial information for disease prediction and monitoring.

Printed graphene-based electrochemical sensor with integrated paper microfluidics for rapid lidocaine detection in blood

Topical lidocaine patches are commonly used to relieve pain and suffering in various clinical and household settings. Despite its extensive use, excessive skin absorption during numbing or pain reduction procedures can cause systemic toxicity, which can lead to life-threatening conditions. Rapid and reliable monitoring of escalating levels of lidocaine in the blood could help management/prevention of lidocaine overdose and its associated complications. To address this need, here we have developed a disposable point-of-care (POC) diagnostic platform composed of an integrated graphene-based electrochemical sensor with paper-based microfluidics for rapid detection of lidocaine levels in serum and blood samples. The fabrication process takes advantage of advanced, scalable manufacturing techniques, including printing, laser processing, and nondestructive near infrared (NIR) drying. The sensitivity tests of the platform revealed a sensitivity of ∼0.2 μA μM^-1 towards lidocaine concentrations in the clinically relevant range (1-100 μM) in both complex matrix fluids of serum and blood with high cross specificity in the presence of the interfering analytes. This proof-of-concept platform could be regarded as the first step toward the development of low-cost and translational POC devices that could help in better pain management and reduce potential side effects or misuse of analgesics.

Biofilms: Formation, Research Models, Potential Targets, and Methods for Prevention and Treatment

Due to the continuous rise in biofilm-related infections, biofilms seriously threaten human health. The formation of biofilms makes conventional antibiotics ineffective and dampens immune clearance. Therefore, it is important to understand the mechanisms of biofilm formation and develop novel strategies to treat biofilms more effectively. This review article begins with an introduction to biofilm formation in various clinical scenarios and their corresponding therapy. Established biofilm models used in research are then summarized. The potential targets which may assist in the development of new strategies for combating biofilms are further discussed. The novel technologies developed recently for the prevention and treatment of biofilms including antimicrobial surface coatings, physical removal of biofilms, development of new antimicrobial molecules, and delivery of antimicrobial agents are subsequently presented. Finally, directions for future studies are pointed out.

Antibiofilm Efficacy of the Pseudomonas aeruginosa Pbunavirus vB_PaeM-SMS29 Loaded onto Dissolving Polyvinyl Alcohol Microneedles

Resistant bacteria prevail in most chronic skin wounds and other biofilm-related topical skin infections. Bacteriophages (phages) have proven their antimicrobial effectiveness for treating different antibiotic-resistant and multidrug-resistant bacterial infections, but not all phages are effective against biofilms. Phages possessing depolymerases can reach different biofilm layers; however, those that do not have depolymerase activity struggle to penetrate and navigate in the intricate 3D biofilm structure and mainly infect bacteria lodged in the outer biofilm layers. To address this, Pseudomonas aeruginosa phage vB_PaeM-SMS29, a phage with poor antibiofilm properties, was incorporated into polyvinyl alcohol (PVA, Mowiol 4:88) supplemented with 0.1% (v/v) of glycerol, and cast onto two different microneedle arrays varying in geometry. The dissolving microneedles were thoroughly characterized by microscopy, force-displacement, swelling, phage release and stability. Furthermore, 48 h-old biofilms were formed using the colony biofilm procedure (absence of broth), and the antibiofilm efficacy of the phage-loaded microneedles was evaluated by viable cell counts and microscopy and compared to free phages. The phages in microneedles were fairly stable for six months when stored at 4 °C, with minor decreases in phage titers observed. The geometry of the microneedles influenced the penetration and force-displacement characteristics but not the antimicrobial efficacy against biofilms. The two PVA microneedles loaded with phages reduced P. aeruginosa PAO1 biofilms by 2.44 to 2.76 log₁₀ CFU·cm^-2 at 24 h. These values are significantly higher than the result obtained after the treatment with the free phage (1.09 log₁₀ CFU·cm^-2). Overall, this study shows that the distribution of phages caused by the mechanical disruption of biofilms using dissolving microneedles can be an effective delivery method against topical biofilm-related skin infections.

Printed Low-Cost PEDOT:PSS/PVA Polymer Composite for Radiation Sterilization Monitoring

During the γ-radiation sterilization process, the levels of radiation exposure to a medical device must be carefully monitored to achieve the required sterilization without causing deleterious effects on its intended physical and chemical properties. To address this issue, here we have demonstrated the development of an all-printed disposable low-cost sensor that exploits the change in electrical impedance of a semi-interpenetrating polymer network (SIPN) composed of poly(vinyl alcohol) (PVA) and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) as a functional polymer composite for radiation sterilization monitoring applications. Specifically, the PEDOT:PSS acts as the electrically conductive medium, while the PVA provides the ductility and stability of the printed sensors. During irradiation exposure, chain scission and cross-linking events occur concurrently in the PEDOT:PSS and PVA polymer chains, respectively. The concurrent scissoring of the PEDOT polymer and cross-linking of the PVA polymer network leads to the formation of a stable SIPN with reduced electrical conductivity, which was verified through FTIR, Raman, and TGA analysis. Systematic studies of different ratios of PEDOT:PSS and PVA mixtures were tested to identify the optimal ratio that provided the highest radiation sensitivity and stability performance. The results showed that PEDOT:PSS/PVA composites with 10 wt % PVA produced sensors with relative impedance changes of 30% after 25 kGy and up to 370% after 53 kGy (which are two of the most commonly used radiation exposure levels for sterilization applications). This composition showed high electrical impedance stability with less than ±5% change over 18 days after irradiation exposure. These findings demonstrate the feasibility of utilizing a printing technology for scalable manufacturing of low-cost, flexible radiation sensors for more effective monitoring of radiation sterilization processes.

Laser-Assisted Nanotexturing and Silver Immobilization on Titanium Implant Surfaces to Enhance Bone Cell Mineralization and Antimicrobial Properties

Despite the great advancement and wide use of titanium (Ti) and Ti-based alloys in different orthopedic implants, device-related infections remain the major complication in modern orthopedic and trauma surgery. Most of these infections are often caused by both poor antibacterial and osteoinductive properties of the implant surface. Here, we have demonstrated a facile two-step laser nanotexturing and immobilization of silver onto the titanium implants to improve both cellular integration and antibacterial properties of Ti surfaces. The required threshold laser processing power for effective nanotexturing and osseointegration was systematically determined by the level of osteoblast cells mineralized on the laser nanotextured Ti (LN-Ti) surfaces using a neodymium-doped yttrium aluminum garnet laser (Nd:YAG, wavelength of 1.06 μm). Laser processing powers above 24 W resulted in the formation of hierarchical nanoporous structures (average pore 190 nm) on the Ti surface with a 2.5-fold increase in osseointegration as compared to the pristine Ti surface. Immobilization of silver nanoparticles onto the LN-Ti surface was conducted by dip coating in an aqueous silver ionic solution and subsequently converted to silver nanoparticles (AgNPs) by using a low power laser-assisted photocatalytic reduction process. Structural and surface morphology analysis via XRD and SEM revealed a uniform distribution of Ag and the formation of an AgTi-alloy interface on the Ti surface. The antibacterial efficacy of the LN-Ti with laser immobilized silver (LN-Ti/LI-Ag) was tested against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The LN-Ti/LI-Ag surface was observed to have efficient and stable antimicrobial properties for over 6 days. In addition, it was found that the LN-Ti/LI-Ag maintained a cytocompatibility and bone cell mineralization property similar to the LN-Ti surface. The differential toxicity of the LN-Ti/LI-Ag between bacterial and cellular species qualifies this approach as a promising candidate for novel rapid surface modification of biomedical metal implants.

Advances in the Sensing and Treatment of Wound Biofilms

Wound biofilms represent a particularly challenging problem in modern medicine. They are increasingly antibiotic resistant and can prevent the healing of chronic wounds. However, current treatment and diagnostic options are hampered by the complexity of the biofilm environment. In this review, we present new chemical avenues in biofilm sensors and new materials to treat wound biofilms, offering promise for better detection, chemical specificity, and biocompatibility. We briefly discuss existing methods for biofilm detection and focus on novel, sensor-based approaches that show promise for early, accurate detection of biofilm formation on wound sites and that can be translated to point-of-care settings. We then discuss technologies inspired by new materials for efficient biofilm eradication. We focus on ultrasound-induced microbubbles and nanomaterials that can both penetrate the biofilm and simultaneously carry active antimicrobials and discuss the benefits of those approaches in comparison to conventional methods.

Mapping the Mechanical and Immunological Profiles of Polymeric Microneedles to Enable Vaccine and Immunotherapy Applications

Biomaterials hold great promise for vaccines and immunotherapy. One emerging biomaterials technology is microneedle (MNs) delivery. MNs are arrays of micrometer-sized needles that are painless and efficiently deliver cargo to the specialized immunological niche of the skin. MNs typically do not require cold storage and eliminate medical sharps. Nearly all materials exhibit intrinsic properties that can bias immune responses toward either pro-immune or inhibitory effects. Thus, because MNs are fabricated from degradable polymers to enable cargo loading and release, understanding the immunological profiles of these matrices is essential to enable new MN vaccines and immunotherapies. Additionally, understanding the mechanical properties is important because MNs must penetrate the skin and conform to a variety of skin or tissue geometries. Here we fabricated MNs from important polymer classes – including extracellular matrix biopolymers, naturally-derived polymers, and synthetic polymers – with both high- and low-molecular-weights (MW). We then characterized the mechanical properties and intrinsic immunological properties of these designs. The library of polymer MNs exhibited diverse mechanical properties, while causing only modest changes in innate signaling and antigen-specific T cell proliferation. These data help inform the selection of MN substrates based on the mechanical and immunological requirements needed for a specific vaccine or immunotherapy application.

Microneedle-Based Natural Polysaccharide for Drug Delivery Systems (DDS): Progress and Challenges

In this focused progress review, the most widely accepted methods of transdermal drug delivery are hypodermic needles, transdermal patches and topical creams. However, microneedles (MNs) (or microneedle arrays) are low-invasive 3D biomedical constructs that bypass the skin barrier and produce systemic and localized pharmacological effects. In the past, biomaterials such as carbohydrates, due to their physicochemical properties, have been extensively used to manufacture microneedles (MNs). Due to their wide range of functional groups, carbohydrates enable the design and development of tunable properties and functionalities. In recent years, numerous microneedle products have emerged on the market, although much research needs to be undertaken to overcome the various challenges before the successful introduction of microneedles into the market. As a result, carbohydrate-based microarrays have a high potential to achieve a future step in sensing, drug delivery, and biologics restitution. In this review, a comprehensive overview of carbohydrates such as hyaluronic acid, chitin, chitosan, chondroitin sulfate, cellulose and starch is discussed systematically. It also discusses the various drug delivery strategies and mechanical properties of biomaterial-based MNs, the progress made so far in the clinical translation of carbohydrate-based MNs, and the promotional opportunities for their commercialization. In conclusion, the article summarizes the future perspectives of carbohydrate-based MNs, which are considered as the new class of topical drug delivery systems.

Oxygenation therapies for improved wound healing: Current trends and technologies

Degree of oxygenation is one of the important parameters governing various processes, including cell proliferation, angiogenesis, extracellular matrix production, and even combating the microbial burden at the wound site, all...

Small intestinal sampling capsule for inflammatory bowel disease type detection and management

Although serum and fecal biomarkers (e.g., lactoferrin, and calprotectin) have been used in management and distinction between inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), none are proven to be a differential diagnostic tool between Crohn's disease (CD) and ulcerative colitis (UC). The main challenge with laboratory-based biomarkers in the stool test is the inability to indicate the location of the disease/inflammation in the gastrointestinal (GI) tract due to the homogenous nature of the collected fecal sample. For the first time, we have designed and developed a battery-free smart capsule that will allow targeted sampling of inflammatory biomarkers inside the gut lumen of the small intestine. The capsule is designed to provide a simple and non-invasive complementary tool to fecal biomarker analysis to differentiate the type of IBD by pinpointing the site of inflammatory biomarkers secretion (e.g., small or large bowel) throughout the GI tract. The capsule takes advantage of the rapid change from an acidic environment in the stomach to higher pH levels in the small intestine to dissolve a pH-sensitive polymeric coating as a means to activate the sampling process of the capsule within the small intestine. A swelling polyacrylamide hydrogel is placed inside the capsule as a milieu to collect the sampled GI fluid while also providing the required mechanical actuation to close the capsule once the sampling is completed. The hydrogel component along with the collected GI fluid can be easily obtained from the capsule through the screw-cap design for further extraction and analysis. As a proof of concept, the capsule's performance in sampling and extraction of bovine serum albumin (BSA) and calprotectin - a key biomarker of inflammation - was assessed within the physiologically relevant ranges. The ratio of extracted biomarkers relative to that in the initial sampling environment remained constant (∼3%) and independent of the sampling matrix in both in vitro and ex vivo studies. It is believed that the demonstrated technology will provide immediate impact in more effective IBD type differential diagnostic and treatment strategies by providing a non-invasive assessment of inflammation biomarkers profile throughout the digestive tract.

Advances in the Sensing and Treatment of Wound Biofilms

Wound biofilms represent a particularly challenging problem in modern medicine. They are increasingly antibiotic resistant and can prevent the healing of chronic wounds. However, current treatment and diagnostic options are hampered by the complexity of the biofilm environment. In this review, we present new chemical avenues in biofilm sensors and new materials to treat wound biofilms, offering promise for better detection, chemical specificity, and biocompatibility. We briefly discuss existing methods for biofilm detection and focus on novel, sensor‐based approaches that show promise for early, accurate detection of biofilm formation on wound sites and that can be translated to point‐of‐care settings. We then discuss technologies inspired by new materials for efficient biofilm eradication. We focus on ultrasound‐induced microbubbles and nanomaterials that can both penetrate the biofilm and simultaneously carry active antimicrobials and discuss the benefits of those approaches in comparison to conventional methods.