Advances in the Sensing and Treatment of Wound Biofilms

A self-supplied hydrogen peroxide and nitric oxide-generating nanoplatform enhances the efficacy of chemodynamic therapy for biofilm eradication

Bacterial biofilms present a profound challenge to global public health, often resulting in persistent and recurrent infections that resist treatment. Chemodynamic therapy (CDT), leveraging the conversion of hydrogen peroxide (H2O2) to highly reactive hydroxyl radicals (•OH), has shown potential as an antibacterial approach. Nonetheless, CDT struggles to eliminate biofilms due to limited endogenous H2O2 and the protective extracellular polymeric substances (EPS) within biofilms. This study introduces a multifunctional nanoplatform designed to self-supply H2O2 and generate nitric oxide (NO) to overcome these hurdles. The nanoplatform comprises calcium peroxide (CaO2) for sustained H2O2 production, a copper-based metal-organic framework (HKUST-1) encapsulating CaO2, and l-arginine (l-Arg) as a natural NO donor. When exposed to the acidic microenvironment within biofilms, the HKUST-1 layer decomposes, releasing Cu2+ ions and l-Arg, and exposing the CaO2 core to initiate a cascade of reactions producing reactive species such as H2O2, •OH, and superoxide anions (•O2-). Subsequently, H2O2 catalyzes l-Arg to produce NO, which disperses the biofilm and reacts with •O2- to form peroxynitrite, synergistically eradicating bacteria with •OH. In vitro assays demonstrated the nanoplatform's remarkable antibiofilm efficacy against both Gram-positive Methicillin-resistant Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, significantly reducing bacterial viability and EPS content. In vivo mouse model experiments validated the nanoplatform's effectiveness in eliminating biofilms and promoting infected wound healing without adverse effects. This study represents a breakthrough in overcoming traditional CDT limitations by integrating self-supplied H2O2 with NO's biofilm-disrupting capabilities, offering a promising therapeutic strategy for biofilm-associated infection.

H2O2-Activatable Liposomal Nanobomb Capable of Generating Hypoxia-Irrelevant Alkyl Radicals by Photo-Triggered Cascade Reaction for High-Performance Elimination of Biofilm Bacteria

High H2O2 levels are widely present at the infection sites or in the biofilm microenvironment. Herein, hemin with peroxidase-like catalytic activity and its substrate, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), are simultaneously introduced into a liposomal nanoparticle containing thermosensitive 2,2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIBI)-loaded bovine serum albumin (BAG), rationally constructing an H2O2-activatable liposomal nanobomb (Lipo@BHA) for combating biofilm-associated bacterial infections with high performance. In the presence of H2O2, hemin can catalyze the conversion of ABTS into its oxidized form (ABTS·+) with strong near-infrared (NIR) absorption, which produces photonic hyperpyrexia to cause the decomposition of AIBI into oxygen-independent alkyl radicals (·R) and nitrogen (N2) microbubbles. The former not only directly damage bacterial cells but also significantly accelerates the oxidization of ABTS to ABTS·+ for augmenting photothermal-triggered generation of ·R. Interestingly, the released N2 can induce transient cavitation to rupture lysosomal nanoparticle and improve the biofilm permeability, thereby enhancing the antibiofilm effect of Lipo@BHA. The proposed Lipo@BHA exhibits satisfactory multi-mode combination antibacterial properties. Through endogenous H2O2-activated cascade reaction, Lipo@BHA achieves remarkable hypoxia-irrelevant ·R therapy of biofilm-associated wound infections with low cytotoxicity and good in vivo biosafety. Therefore, this work presents a versatile H2O2-activatable cascade ·R generation strategy for biofilm-specific therapeutic applications.

Accelerated healing of intractable biofilm-infected diabetic wounds by trypsin-loaded quaternized chitosan hydrogels that disrupt extracellular polymeric substances and eradicate bacteria

Complex and stubborn bacterial biofilm infections significantly hinder diabetic wound healing and threaten public health. Therefore, a dressing material that effectively clears biofilms and promotes wound healing is urgently required. Herein, we introduce a novel strategy for simultaneously dispersing extracellular polymeric substances and eradicating drug-resistant bacteria. We prepared an ultrabroad-spectrum and injectable quaternized chitosan (QCS) hydrogel loaded with trypsin, which degrades biofilm extracellular proteins. Increased temperature initiated QCS gelation to form the hydrogel, enabling the sustained release of trypsin and effective adherence of the hydrogel to irregularly shaped wounds. To reproduce clinical scenarios, biofilms formed by a mixture of Staphylococcus aureus (S. aureus), Methicillin-resistant S. aureus, and Pseudomonas aeruginosa were administered to the wounds of rats with streptozotocin-induced diabetes. Under these severe infection conditions, the hydrogel efficiently suppressed inflammation, promoted angiogenesis, and enhanced collagen deposition, resulting in accelerated healing of diabetic wounds. Notably, the hydrogel demonstrates excellent biocompatibility without cytotoxicity. In summary, we present a trypsin-loaded QCS hydrogel with tremendous clinical applications potential for the treatment of chronic infected wounds.

Repetitive combined doses of bacteriophages and gentamicin protect against Staphylococcus aureus implant-related infections in Galleria mellonella

Aims

Bacteriophages infect, replicate inside bacteria, and are released from the host through lysis. Here, we evaluate the effects of repetitive doses of the Staphylococcus aureus phage 191219 and gentamicin against haematogenous and early-stage biofilm implant-related infections in Galleria mellonella.

Methods

For the haematogenous infection, G. mellonella larvae were implanted with a Kirschner wire (K-wire), infected with S. aureus, and subsequently phages and/or gentamicin were administered. For the early-stage biofilm implant infection, the K-wires were pre-incubated with S. aureus suspension before implantation. After 24 hours, the larvae received phages and/or gentamicin. In both models, the larvae also received daily doses of phages and/or gentamicin for up to five days. The effect was determined by survival analysis for five days and quantitative culture of bacteria after two days of repetitive doses.

Results

In the haematogenous infection, a single combined dose of phages and gentamicin, and repetitive injections with gentamicin or in combination with phages, resulted in significantly improved survival rates. In the early-stage biofilm infection, only repetitive combined administration of phages and gentamicin led to a significantly increased survival. Additionally, a significant reduction in number of bacteria was observed in the larvae after receiving repetitive doses of phages and/or gentamicin in both infection models.

Conclusion

Based on our results, a single dose of the combination of phages and gentamicin is sufficient to prevent a haematogenous S. aureus implant-related infection, whereas gentamicin needs to be administered daily for the same effect. To treat early-stage S. aureus implant-related infection, repetitive doses of the combination of phages and gentamicin are required.

Chitosan-Based Hydrogels as Antibacterial/Antioxidant/Anti-Inflammation Multifunctional Dressings for Chronic Wound Healing

Due to repeated microbial infection, persistent inflammation, excessive oxidative stress, and cell dysfunction, chronic wounds are difficult to heal, posing a serious threat to public health. Therefore, developing multifunctional wound dressings that can regulate the complex microenvironment of chronic wounds and enhance cellular function holds great significance. Recently, chitosan has emerged as a promising biopolymer for wound healing due to its excellent biocompatibility, biodegradability, and versatile bioactivity. The aim of this review is to provide a comprehensive understanding of the mechanisms of delayed chronic wound healing and discuss the healing-promoting properties of chitosan and its derivatives, such as good biocompatibility, antibacterial activity, hemostatic capacity, and the ability to promote tissue regeneration. On this basis, the potential applications of chitosan-based hydrogels are summarized in chronic wound healing, including providing a suitable microenvironment, eliminating bacterial infections, promoting hemostasis, inhibiting chronic inflammation, alleviating oxidative stress, and promoting tissue regeneration. In addition, the concerns and perspectives for the clinical application of chitosan-based hydrogels are also discussed.

Unlocking Wearable Microbial Fuel Cells for Advanced Wound Infection Treatment

Better infection control will accelerate wound healing and alleviate associated healthcare burdens. Traditional antibacterial dressings often inadequately control infections, inadvertently promoting antibacterial resistance. Our research unveils a novel, dual-functional living dressing that autonomously generates antibacterial agents and delivers electrical stimulation, harnessing the power of spore-forming Bacillus subtilis. This dressing is built on an innovative wearable microbial fuel cell (MFC) framework, using B. subtilis endospores as a powerful, dormant biocatalyst. The endospores are resilient, reactivating in nutrient-rich wound exudate to produce electricity and antibacterial compounds. The combination allows B. subtilis to outcompete pathogens for food and other resources, thus fighting infections. The strategy is enhanced by the extracellular synthesis of tin oxide and copper oxide nanoparticles on the endospore surface, boosting antibacterial action, and electrical stimulation. Moreover, the MFC framework introduces a pioneering dressing design featuring a conductive hydrogel embedded within a paper-based substrate. The arrangement ensures cell stability and sustains a healing-friendly moist environment. Our approach has proven very effective against three key pathogens in biofilms: Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus demonstrating exceptional capabilities in both in vitro and ex vivo models. Our innovation marks a significant leap forward in wearable MFC-based wound care, offering a potent solution for treating infected wounds.

A one-two punch strategy for diabetic wound management based on an antibiotic-hybrid biomineralized iron sulfide nanoparticle

Bacterial infection and immune imbalance are the primary culprits behind chronic wounds in individuals with diabetes, impeding the progression of damaged tissues towards normal healing. To achieve a harmonious balance between pro- and anti-inflammation within these infected areas, herein, we propose a one-two punch strategy for on-demand therapy of diabetes-infected wounds, utilizing an azithromycin (AZM)-hybrid nanocomposite termed GOx@FexSy/AZM. During the infective stage, the nanocomposite facilitates the production of ROS, coupled with the burst release of AZM and H2S gas, effectively dismantling biofilms and achieving rapid sterilization. Subsequently, the hyperinflammatory response induced by antibiosis is significantly mitigated through the synergistic action of tissue H2S and the prolonged half-life of AZM. These components inhibit the activity of pro-inflammatory transcription factors (AP-1 and NF-κB) within macrophages, thereby promoting the polarization of macrophages towards a reparative M2 phenotype and facilitating tissue remodeling. By catering to the diverse requirements of wound healing at different stages, this nanocomposite accelerates a sensible transition from inflammation to the reparative phase. In summary, this one-two punch strategy gives an instructive instance for procedural treatment of diabetes wound infection. STATEMENT OF SIGNIFICANCE: The treatment of diabetic wound infection presents two major challenges: the diminished antibacterial efficacy arising from biofilm formation and bacterial resistance, as well as the inadequate transition of the wound microenvironment from pro-inflammatory to anti-inflammatory states after bacterial clearance. In this work, a biomineralized iron sulfide nanocomposite was prepared to mediate cascade catalytic (ROS storm) / antibiotic (AZM) / gas (H2S) triple-synergetic antibacterial therapy during the initial stage of bacterial infection, achieving the goal of rapid bactericidal effect; Subsequently, the residual H2S and long half-life AZM would inhibit the key pro-inflammatory transcription factors and promote the macrophages polarization to reparative M2, which effectively mediated tissue repair after hyperinflammatory reactions, leading to orderly treatment of hyperglycemic infected wounds.

Ceramic Dressings-A New Non-Pharmacological Therapeutic Option in the Management of Chronic Wounds?

A new ceramic dressing, free from active antimicrobial or pharmaceutical agents, uses physical binding mechanisms for its absorption capacities and bacterial-binding properties. The purpose of this study was to evaluate wound healing, bacterial-related retention, and diagnostic properties of ceramic dressings in patients with stagnated chronic wounds.

METHODS

In this monocentric, intra-individually controlled, prospective study, patients with conservatively treated refractory chronic wounds were enrolled. One week before the start of the application with ceramic dressing, it was ensured during a screening phase that chronic wounds showed less than a 10% reduction in wound size. During the 4-week ceramic dressing treatment wound size measurements, wound scoring, measurement of wound exudate amount, wound swabs, and ceramic dressing sonication (low-intensity ultrasound) were carried out. The sonication fluid of the removed ceramic dressing was used for analysis of bacterial retention and compared to wound swabs.

RESULTS

A total of 20 patients with a mean age of 64.6 years (±26.2) and 21 chronic wounds were included in this study. After a 4-week treatment, a significant reduction of median wound size from 1178 mm2 (range 104-6300) to 751.5 mm2 (range 16-4819) and better total wound scores were observed (p < 0.001). The sensitivity of bacteria detection was 90.7% in the sonication fluid from the ceramic dressings, while only 76.9% in the conventional wound swabs.

CONCLUSION

The new ceramic dressing seems to have a positive impact on wound healing in chronic wounds. Bacteria-binding characteristics of the investigated ceramic dressing, in combination with its debridement, absorption, and detoxification properties, could contribute to its healing abilities. Based on those results, the investigated ceramic dressing seems to be a promising new treatment option for chronic wounds without the use of any active antimicrobial or pharmacological agents. Moreover, ceramic dressings can also be considered for microbiological diagnostic purposes.

Improving outcomes for patients with hard-to-heal wounds following adoption of the Wound Hygiene Protocol: real-world evidence

OBJECTIVE

To evaluate the impact of a four-step biofilm-based wound care strategy, Wound Hygiene Protocol (WHP: cleanse, debride, refashion, and dress), on hard-to-heal wounds.

METHOD

This was a prospective, real-world analysis of hard-to-heal wounds managed with the WHP that incorporated Aquacel Ag+ (Convatec Ltd., UK) dressings. Data were captured electronically between April 2021 and December 2022. The primary endpoint was change in wound volume from baseline to final assessment.

RESULTS

A total of 693 wounds in 669 patients (median patient age: 74 years) were included in the analysis with a median treatment time of 31 days. Most health professionals were general nurses (50%) or nurse practitioners (38%). Patient homes (27%) and community clinics (27%) were the most common clinical settings. Venous leg ulcers (26%) and pressure ulcers/injuries (17%) were the most common wound type. Duration was >12 months in 21% of wounds. At baseline, the mean wound volume was 57.8cm3. At the final assessment, mean wound volume was 17.2cm3, corresponding to an 80% reduction from baseline; p<0.001). At baseline, 66% of wounds were static or deteriorating. At final assessment, this had decreased to 5%, and 94% had improved or healed. Exudate levels were moderate or high in 69% of wounds at baseline which decreased to 25% at final assessment (p<0.001). Suspected biofilm and local wound infection decreased from 79% and 43%, respectively, at baseline, to 18% and 3%, respectively, at final assessment (p<0.001 for both).

CONCLUSION

The WHP is a new proposed standard of care that successfully treated hard-to-heal wounds by addressing the key local barriers to wound healing.

Effect of Ducrosia anethifolia methanol extract against methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa biofilms on excision wound in diabetic mice

Background

Ducrosia anethifolia is an aromatic desert plant used in Saudi folk medicine to treat skin infections. It is widely found in Middle Eastern countries.

Methods

A methanolic extract of the plant was prepared, and its phytoconstituents were determined using LC-MS. In-vitro and in-vivo antibacterial and antibiofilm activities of the methanolic extract were evaluated against multidrug-resistant bacteria. The cytotoxic effect was assessed using HaCaT cell lines in-vitro. Diabetic mice were used to study the in-vivo antibiofilm and wound healing activity using the excision wound method.

Results

More than 50 phytoconstituents were found in the extract after LC-MS analysis. The extract exhibited antibacterial activity against both the tested pathogens. The extract was free of irritant effects on mice skin, and no cytotoxicity was observed on HaCaT cells with an IC50 value of 1381 µg/ml. The ointment formulation of the extract increased the healing of diabetic wounds. The microbial load of both pathogens in the wounded tissue was also reduced after the treatment. The extract was more effective against methicillin-resistant Staphylococcus aureus (MRSA) than MDR-P. aeruginosa in both in vitro and in vivo experiments. Further, skin regeneration was also observed in histological studies.

Conclusions

The results showed that D. anethifolia methanol extract supports wound healing in infected wounds in diabetic mice through antibacterial, antibiofilm, and wound healing activities.

Comparative analysis of electrochemical and optical sensors for detection of chronic wounds biomarkers: A review

Chronic wounds (CW) present a significant healthcare challenge due to their prolonged healing time and associated complications. To effectively treat these wounds and prevent further deterioration, monitoring their healing progress is crucial. Traditional wound assessment methods relying on visual inspection and subjective evaluation are prone to inter-observer variability. Biomarkers play a critical role in objectively evaluating wound status and predicting healing outcomes, providing quantitative measures of wound healing progress, inflammation, infection, and tissue regeneration. Recent attention has been devoted to identifying and validating CW biomarkers. Various studies have investigated potential biomarkers, including growth factors, cytokines, proteases, and extracellular matrix components, shedding light on the complex molecular and cellular processes within CW. This knowledge enables a more targeted and personalized approach to wound management. Accurate and sensitive techniques are necessary for detecting CW biomarkers. Thus, this review compares and discusses the use of electrochemical and optical sensors for biomarker determination. The advantages and disadvantages of these sensors are highlighted. Differences in detection capabilities and characteristics such as non-invasiveness, portability, high sensitivity, specificity, simplicity, cost-effectiveness, compatibility with point-of-care applications, and real-time monitoring of wound biomarkers will be pointed out and compared. In summary, this work provides an overview of CW, explores the emerging field of CW biomarkers, and discusses methods for detecting these biomarkers, with a specific focus on optical and electrochemical sensors. The potential of further research and development in this field for advancing wound care and improving patient outcomes will also be noted.

Antibacterial Activity of Various Morphologies of Films Based on Guanidine Derivatives of Pillar[5]arene: Influence of the Nature of One Substitute on Self-assembly

The progress of the pillar[5]arene chemistry allowed us to set out a new concept on application of the supramolecular assemblies to create antimicrobial films with variable surface morphologies and biological activities. Antibacterial films were derived from the substituted pillar[5]arenes containing nine pharmacophoric guanidine fragments and one thioalkyl substituent. Changing the only thioalkyl fragment in the macrocycle structure made it possible to control the biological activity of the resulting antibacterial coating. Pretreatment of the surface with aqueous solution of the amphiphilic pillar[5]arenes reduced the biofilm thickness by 56 ± 10% of Gram-positive Staphylococcus aureus in the case of the pillar[5]arene containing a thiooctyl fragment and by 52 ± 7% for the biofilm of Gram-negative Klebsiella pneumoniae in the case of pillar[5]arene containing a thiooctadecyl fragment. Meanwhile, the cytotoxicity of the synthesized macrocycles was examined at a concentration of 50 μg/mL, which was significantly lower than that of bis-guanidine-based antimicrobial preparations.

Phage therapy as a glimmer of hope in the fight against the recurrence or emergence of surgical site bacterial infections

PURPOSE

Over the last decade, surgery rates have risen alarmingly, and surgical-site infections are expanding these concerns. In spite of advances in infection control practices, surgical infections continue to be a significant cause of death, prolonged hospitalization, and morbidity. As well as the presence of bacterial infections and their antibiotic resistance, biofilm formation is one of the challenges in the treatment of surgical wounds.

METHODS

This review article was based on published studies on inpatients and laboratory animals receiving phage therapy for surgical wounds, phage therapy for tissue and bone infections treated with surgery to prevent recurrence, antibiotic-resistant wound infections treated with phage therapy, and biofilm-involved surgical wounds treated with phage therapy which were searched without date restrictions.

RESULTS

It has been shown in this review article that phage therapy can be used to treat surgical-site infections in patients and animals, eliminate biofilms at the surgical site, prevent infection recurrence in wounds that have been operated on, and eradicate antibiotic-resistant infections in surgical wounds, including multi-drug resistance (MDR), extensively drug resistance (XDR), and pan-drug resistance (PDR). A cocktail of phages and antibiotics can also reduce surgical-site infections more effectively than phages alone.

CONCLUSION

In light of these encouraging results, clinical trials and research with phages will continue in the near future to treat surgical-site infections, biofilm removal, and antibiotic-resistant wounds, all of which could be used to prescribe phages as an alternative to antibiotics.

Harnessing antimicrobial peptide-coupled photosensitizer to combat drug-resistant biofilm infections through enhanced photodynamic therapy

Bacterial biofilm-associated infection was one of the most serious threats to human health. However, effective drugs for drug-resistance bacteria or biofilms remain rarely reported. Here, we propose an innovative strategy to develop a multifunctional antimicrobial agent with broad-spectrum antibacterial activity by coupling photosensitizers (PSs) with antimicrobial peptides (AMPs). This strategy capitalizes on the ability of PSs to generate reactive oxygen species (ROS) and the membrane-targeting property of AMPs (KRWWKWIRW, a peptide screened by an artificial neural network), synergistically enhancing the antimicrobial activity. In addition, unlike conventional aggregation-caused quenching (ACQ) photosensitizers, aggregation-induced emission (AIE) PSs show stronger fluorescence emission in the aggregated state to help visualize the antibacterial mechanism. In vitro antibacterial experiments demonstrated the excellent killing effects of the developed agent against both Gram-positive (G+) and Gram-negative (G-) bacteria. The bacterial-aggregations induced ability enhanced the photoactivatable antibacterial activity against G- bacteria. Notably, it exhibited a significant effect on destroying MRSA biofilms. Moreover, it also showed remarkable efficacy in treating wound infections in mice in vivo. This multifunctional antimicrobial agent holds significant potential in addressing the challenges posed by bacterial biofilm-associated infections and drug-resistant bacteria.

Bi-functional quercetin/copper nanoparticles integrating bactericidal and anti-quorum sensing properties for preventing the formation of biofilms

Biofilms formed by pathogenic bacteria present a persistent risk to human health. While the eradication of matured biofilms remains a formidable challenge, delaying or preventing their formation, which is coordinately regulated by quorum sensing (QS), presents a simpler and more advantageous strategy. Quercetin, a naturally occurring compound with anti-QS properties, has the potential to act as an antibiofilm agent. However, it is plagued by certain inherent drawbacks, including poor water solubility and limited bioavailability. Furthermore, solely blocking QS is not enough to prevent biofilm formation because it lacks bactericidal properties. To address these difficulties, we fabricated bi-functional nanoparticles through the co-assembly of quercetin and copper ions in a facile manner. The resulting quercetin/copper nanoparticles (QC NPs) demonstrated minimal cytotoxicity and hemolysis in vitro. In response to the low pH of microenvironments that were populated by bacterial colonies, the QC NPs underwent disassembly to release copper ions and quercetin. The former exterminated bacteria by disrupting the integrity of the cell membrane, while the latter disrupted the processes involved in QS that are responsible for the biofilm by downregulating the expression of specific genes, effectively preventing the formation of biofilms by both Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. In addition, the QC NPs were integrated into a bacterial cellulose membrane. The composite membrane proved to be highly effective at inhibiting biofilm formation in vitro and demonstrated the ability to reduce inflammatory responses and accelerate the healing of bacteria-infected wounds in vivo. Overall, the bi-functional QC NPs hold great potential for use in addressing the challenges associated with the management of bacterial biofilms.

Antibiofilm activity of polyethylene glycol-quercetin nanoparticles-loaded gelatin-N,O-carboxymethyl chitosan composite nanogels against Staphylococcus epidermidis

BACKGROUND

Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection.

OBJECTIVES

Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation.

METHODS

The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied.

RESULTS

Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production.

CONCLUSIONS

This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

Herbal Medicine-Inspired Carbon Quantum Dots with Antibiosis and Hemostasis Effects for Promoting Wound Healing

Bleeding and bacterial infections are crucial factors affecting wound healing. The usage of herbal medicine-derived materials holds great potential for promoting wound healing. However, the uncertain intrinsic effective ingredients and unclear mechanism of action remain great concerns. Herein, inspired by the herbal medicine Ligusticum wallichii, we reported the synthesis of tetramethylpyrazine-derived carbon quantum dots (TMP-CQDs) for promoting wound healing. Of note, the use of TMP as the precursor instead of L. wallichii ensured the repeatability and homogeneity of the obtained products. Furthermore, TMP-CQDs exhibited high antibacterial activity. Mechanically, TMP-CQDs inhibited the DNA repair, biosynthesis, and quorum sensing of the bacteria and induced intracellular reactive oxygen species (ROS). Moreover, TMP-CQDs could accelerate blood coagulation through activating factor VIII and promoting platelet aggregation. Effective wound healing was achieved by using TMP-CQDs in the Staphylococcus aureus-infected mouse skin wound model. This study sheds light on the development of herbal medicine-inspired materials as effective therapeutic drugs.

A Novel Comprehensive Therapeutic Approach to the Challenges of Chronic Wounds: A Brief Review and Clinical Experience Report

Following the clinical perspective and concept that a healthy body will not develop chronic wounds, the central approach for the treatment described here is based on an understanding of how the body transforms the wound microenvironment from a non-healing to a healing state. As part of a comprehensive treatment regimen that includes OCM™ (complete matrix), wound preparation, and skin protectant formulations, the OCM contains components for complete wound healing by attending to the individual needs required to promote the closure of each unique chronic wound. During application of the comprehensive treatment regimen in independent investigator-led trials, the total wound percentage average reduction over the first 4 weeks of treatment was 60% across multiple wound types; median time to total wound closure was 6.9 weeks. Safety testing of the OCM formulation shows no potential allergenicity, no potential sensitization, and no known product-related adverse events. Clinical trials evaluating the OCM formulation as part of the comprehensive treatment regimen of multiple wound types are underway. Results of clinical trials and real-world experiences will expand current knowledge of the wound-healing potential of this novel product.

Urchin-like Fe3O4@Bi2S3 Nanospheres Enable the Destruction of Biofilm and Efficiently Antibacterial Activities

Biofilm-associated infections (BAIs) have been considered a major threat to public health, which induce persistent infections and serious complications. The poor penetration of antibacterial agents in biofilm significantly limits the efficiency of combating BAIs. Magnetic urchin-like core-shell nanospheres of Fe3O4@Bi2S3 were developed for physically destructing biofilm and inducing bacterial eradication via reactive oxygen species (ROS) generation and innate immunity regulation. The urchin-like magnetic nanospheres with sharp edges of Fe3O4@Bi2S3 exhibited propeller-like rotation to physically destroy biofilm under a rotating magnetic field (RMF). The mild magnetic hyperthermia improved the generation of ROS and enhanced bacterial eradication. Significantly, the urchin-like nanostructure and generated ROS could stimulate macrophage polarization toward the M1 phenotype, which could eradicate the persistent bacteria with a metabolic inactivity state through phagocytosis, thereby promoting the recovery of implant infection and inhibiting recurrence. Thus, the design of magnetic-driven sharp-shaped nanostructures of Fe3O4@Bi2S3 provided enormous potential in combating biofilm infections.

Biofilm Microenvironment-Sensitive Piezoelectric Nanomotors for Enhanced Penetration and ROS/NO Synergistic Bacterial Elimination

Sonodynamic therapy offers a highly accurate treatment for bacterial infections; however, its antibacterial efficacy is hindered by bacterial biofilms that limit the penetration of sonosensitizers. Herein, a nitric oxide (NO)-driven mushroom-like Janus nanomotor (BT@PDA-La) based on the unilateral coating of polydopamine (PDA) on piezoelectric tetragonal barium titanate (BT) and further modified with l-arginine (l-Arg) on the PDA side is fabricated. In the infected microenvironment with high levels of H2O2, NO is produced unilaterally from BT@PDA-La, thus leading to its self-propelled movement and facilitating its permeability in the biofilm. Under ultrasonic vibrations, the piezoelectric effect of BT@PDA-La is triggered by the exogenous mechanical wave, and toxic reactive oxygen species (ROS) are efficiently generated via an in situ catalytic reaction. The synergistic treatment with ROS/NO achieved the destruction of biofilms and embedded drug-resistant bacteria in vitro. Importantly, BT@PDA-La exhibits excellent biofilm penetration capacity, effectively eliminating biofilm infection while accelerating the healing of infected muscles by alleviating oxidative stress, regulating inflammatory factors, and accelerating angiogenesis. Collectively, this study provides a promising strategy for enhancing the penetration of pathological environment-driven nanomaterials through biofilms and advances the application of nanomotors for the therapy of bacterial infections in clinical medicine.

A Novel Potential Treatment for Diabetic Foot Ulcers and Non-Healing Ulcers - Case Series

Introduction: Appropriate care and treatment of a wound is the need of the hour whether it is an infected or a non-infected wound. If wound healing is delayed for some reason, it leads to serious complications and further increases the hospital stay and cost of treatment. Herein, we describe a novel antimicrobial wound dressing formulation (VG111), with an objective to generate the preliminary data showing the distinct advantages in various types of wounds.

Method: This case series involved the treatment of acute cases of wounds or chronic wounds that did not respond well to conventional wound healing treatments with VG111 in patients with different etiologies. Thirteen cases of patients that included patients with diabetes, pressure ulcers, burns, trauma, and others treated with VG111 showed rapid wound healing in all the cases, even obviating the need for a graft when complete skin regeneration occurred.

Result: This was illustrated by clearing of the wound infections, reduction/disappearance of the exudate, appearance of intense granulation, epithelialization, and anti-biofilm activity followed by complete wound closure. This VG111 precludes the need for systemic antimicrobial agents in localized infections and therefore, this single agent is an attempt to address the limitations and the drawbacks of the available products.

Conclusion: Despite patients belonging to the old age group and having comorbidities like diabetes, still VG111 showed effective rapid wound healing, and that too without any scar formation in hardto- heal, infected, and non-infected wounds.

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Point-of-care detection devices for wound care and monitoring

Healthcare resources are heavily burdened by infections that impede the wound-healing process. A wide range of advanced technologies have been developed for detecting and quantifying infection biomarkers. Finding a timely, accurate, non-invasive diagnostic alternative that does not require a high level of training is a critical step toward arresting common clinical patterns of wound health decline. There is growing interest in the development of innovative diagnostics utilizing a variety of emerging technologies, and new biomarkers have been investigated as potential indicators of wound infection. In this review, we summarize diagnostics available for wound infection, including those used in clinics and still under development.

An Immunomodulatory Biomimetic Single-Atomic Nanozyme for Biofilm Wound Healing Management

Nanozyme-driven catalytic antibacterial therapy has become a promising modality for bacterial biofilm infections. However, current catalytic therapy of biofilm wounds is severely limited by insufficient catalytic efficiency, excessive inflammation, and deep tissue infection. Drawing from the homing mechanism of natural macrophages, herein, a hollow mesoporous biomimetic single-atomic nanozyme (SAN) is fabricated to actively target inflamed parts, suppress inflammatory factors, and eliminate deeply organized bacteria for enhance biofilm eradication. In the formulation, this biomimetic nanozyme (Co@SAHSs@IL-4@RCM) consists of IL-4-loaded cobalt SANs-embedded hollow sphere encapsulate by RAW 264.7 cell membrane (RCM). Upon accumulation at the infected sites through the specific receptors of RCM, Co@SAHS catalyze the conversion of hydrogen peroxide into hydroxyl radicals and are further amplify by NIR-II photothermal effect and glutathione depletion to permeate and destroy biofilm structure. This behavior subsequently causes the dissociation of RCM shell and the ensuing release of IL-4 that can reprogram macrophages, enabling suppression of oxidative injury and tissue inflammation. The work paves the way to engineer alternative "all-in-one" SANs with an immunomodulatory ability and offers novel insights into the design of bioinspired materials.

Antibiotic failure: Beyond antimicrobial resistance

Despite significant progress in antibiotic discovery, millions of lives are lost annually to infections. Surprisingly, the failure of antimicrobial treatments to effectively eliminate pathogens frequently cannot be attributed to genetically-encoded antibiotic resistance. This review aims to shed light on the fundamental mechanisms contributing to clinical scenarios where antimicrobial therapies are ineffective (i.e., antibiotic failure), emphasizing critical factors impacting this under-recognized issue. Explored aspects include biofilm formation and sepsis, as well as the underlying microbiome. Therapeutic strategies beyond antibiotics, are examined to address the dimensions and resolution of antibiotic failure, actively contributing to this persistent but escalating crisis. We discuss the clinical relevance of antibiotic failure beyond resistance, limited availability of therapies, potential of new antibiotics to be ineffective, and the urgent need for novel anti-infectives or host-directed therapies directly addressing antibiotic failure. Particularly noteworthy is multidrug adaptive resistance in biofilms that represent 65 % of infections, due to the lack of approved therapies. Sepsis, responsible for 19.7 % of all deaths (as well as severe COVID-19 deaths), is a further manifestation of this issue, since antibiotics are the primary frontline therapy, and yet 23 % of patients succumb to this condition.

Research frontiers and hotspots in bacterial biofilm wound therapy: bibliometric and visual analysis for 2012-2022

Background

Bacterial biofilms, which can protect bacteria from host immune response and drug attack, are an important factor in the difficult healing of chronic wound infection, which has become a major problem in medical development. This paper aimed to analyze literature related to bacterial biofilm wound treatment published between 2012 and 2022 using bibliometric and visual analysis.

Methods

Publications related to bacterial biofilm wound treatment from 2012 to 2022 were selected from the Web of Science Core Collection. Microsoft Excel 2021, bibliometrics, CiteSpace6.1, and VOSviewer1.6.18 were used to extract and analyze data.

Results

A total of 940 articles were published between 2012 and 2022, with the United States being the leading country (with 302 papers, 32.13%) and the University of Copenhagen in Denmark being the leading institution (with 26 published articles) in the field. Steven L Percival, a British academic, published the most articles (14). In the field of bacterial biofilm wound treatment, keywords suggested that the research gradually transitioned from lower limb venous ulcer, negative pressure-assisted healing to chronic wound, in-vitro bacterial biological model research, and then to the development of more microscopic and more advanced technologies such as antibacterial activity and nanomaterials. "Nanoparticles", "inhibition/antibacterial", "delivery", "gold nanoparticles", "hydrogel", "wound healing", etc., may become new research hotspots in this field.

Conclusion

There is a lack of specific and effective treatment methods for diagnosing and treating bacterial biofilms in wounds. Through the development of multidisciplinary cooperation, early diagnosis and treatment of bacterial biofilms in wounds can be achieved. These data may provide a useful reference for scholars studying more effective bacterial biofilm wound treatment.

A Label-Free and Ultrasensitive Prussian Blue-Based Dipstick Sensor for Bacterial and Biofilm Detection

Water and food contamination has become the major contributor to infections and deaths. However, rapid and sensitive bacterial detection still remains an unmet demand that has attracted widespread attention. Often water and food samples are sent out for laboratory testing to detect the presence of contamination, which is time-consuming and laborious. Herein, we have developed a highly sensitive, tenable, affordable, and robust (STAR) paper-based colorimetric dipstick sensor based on the principle of Prussian blue (PB) synthesis as an indicator of bacterial contamination. In the presence of bacteria, it leads to the formation of PB, a dye that acts as a colorimetric indicator. The intensity of the PB is the direct measure of the degree of contamination. The fabrication of the STAR dipstick sensor involves a simple and cost-effective process. The STAR dipstick sensor is ultrasensitive and can detect up to 101 CFU/mL of bacteria within minutes of contact with the test sample. The STAR dipstick sensor is fabricated using biodegradable components, which is speculated to facilitate quick and environmentally friendly degradation after each use. The sensor has been validated for its properties and capabilities at different pH to detect both Gram-positive and Gram-negative bacterial strains in real-time samples. The stability and degradation were also monitored. Comprehensively, the proposed STAR dipstick sensor can serve as a point-of-care device to detect bacterial contamination in a swift and sensitive manner.

A Rapidly Responsive Sensor for Wireless Detection of Early and Mature Microbial Biofilms

Biofilm-associated infections, which are able to resist antibiotics, pose a significant challenge in clinical treatments. Such infections have been linked to various medical conditions, including chronic wounds and implant-associated infections, making them a major public-health concern. Early-detection of biofilm formation offers significant advantages in mitigating adverse effects caused by biofilms. In this work, we aim to explore the feasibility of employing a novel wireless sensor for tracking both early-stage and matured-biofilms formed by the medically relevant bacteria Staphylococcus aureus and Pseudomonas aeruginosa. The sensor utilizes electrochemical reduction of an AgCl layer bridging two silver legs made by inkjet-printing, forming a part of near-field-communication tag antenna. The antenna is interfaced with a carbon cloth designed to promote the growth of microorganisms, thereby serving as an electron source for reduction of the resistive AgCl into a highly-conductive Ag bridge. The AgCl-Ag transformation significantly alters the impedance of the antenna, facilitating wireless identification of an endpoint caused by microbial growth. To the best of our knowledge, this study for the first time presents the evidence showcasing that electrons released through the actions of bacteria can be harnessed to convert AgCl to Ag, thus enabling the wireless, battery-less, and chip-less early-detection of biofilm formation.

Antimicrobial polymer-loaded hydrogels for the topical treatment of multidrug-resistant wound biofilm infections

Integration of antimicrobial polymeric nanoparticles into hydrogel materials presents a promising strategy to address multidrug-resistant biofilm infections. Here we report an injectable hydrogel loaded with engineered cationic antimicrobial polymeric nanoparticles (PNPs) for the effective topical treatment of severe wound biofilm infections. The PNPs demonstrated biofilm penetration and disruption, resulting in the eradication of resistant and persister cells that reside within the biofilm. Significantly, PNPs did not elicit resistance development even after multiple exposures to sub-therapeutic doses. In vitro studies showed PNPs significantly reduced prolonged inflammation due to infection and promoted fibroblast migration. These PNPs were then incorporated into Poloxamer 407 (P407) hydrogels and utilized as an inert carrier for PNPs to provide a controlled and sustained topical release of the antimicrobial nanoparticles at the wound area. In vivo studies using a mature (4-day) wound biofilm infection in a murine model mimicking severe human wound infections demonstrated provided 99% bacterial biofilm clearance and significantly enhanced wound healing. Overall, this work demonstrated the efficacy and selectivity of the antimicrobial polymer-loaded hydrogel platform as a topical treatment for difficult-to-treat wound biofilm infections.

Rational multivalency construction enables bactericidal effect amplification and dynamic biomaterial design

The multivalency of bioligands in living systems brings inspiration for not only the discovery of biological mechanisms but also the design of extracellular matrix (ECM)-mimicking biomaterials. However, designing controllable multivalency construction strategies is still challenging. Herein, we synthesized a series of well-defined multivalent antimicrobial peptide polymers (mAMPs) by clicking ligand molecules onto polymers prepared by reversible addition-fragmentation chain transfer polymerization. The multiple cationic ligands in the mAMPs could enhance the local disturbance of the anionic phospholipid layer of the bacterial membrane through multivalent binding, leading to amplification of the bactericidal effect. In addition to multivalency-enhanced antibacterial activity, mAMPs also enable multivalency-assisted hydrogel fabrication with an ECM-like dynamic structure. The resultant hydrogel with self-healing and injectable properties could be successfully employed as an antibacterial biomaterial scaffold to treat infected skin wounds. The multivalency construction strategy presented in this work provides new ideas for the biomimetic design of highly active and dynamic biomaterials for tissue repair and regeneration.

Current status and progress in research on dressing management for diabetic foot ulcer

Diabetic foot ulcer (DFU) is a major complication of diabetes and is associated with a high risk of lower limb amputation and mortality. During their lifetime, 19%-34% of patients with diabetes can develop DFU. It is estimated that 61% of DFU become infected and 15% of those with DFU require amputation. Furthermore, developing a DFU increases the risk of mortality by 50%-68% at 5 years, higher than some cancers. Current standard management of DFU includes surgical debridement, the use of topical dressings and wound decompression, vascular assessment, and glycemic control. Among these methods, local treatment with dressings builds a protective physical barrier, maintains a moist environment, and drains the exudate from DFU wounds. This review summarizes the development, pathophysiology, and healing mechanisms of DFU. The latest research progress and the main application of dressings in laboratory and clinical stage are also summarized. The dressings discussed in this review include traditional dressings (gauze, oil yarn, traditional Chinese medicine, and others), basic dressings (hydrogel, hydrocolloid, sponge, foam, film agents, and others), bacteriostatic dressings, composite dressings (collagen, nanomaterials, chitosan dressings, and others), bioactive dressings (scaffold dressings with stem cells, decellularized wound matrix, autologous platelet enrichment plasma, and others), and dressings that use modern technology (3D bioprinting, photothermal effects, bioelectric dressings, microneedle dressings, smart bandages, orthopedic prosthetics and regenerative medicine). The dressing management challenges and limitations are also summarized. The purpose of this review is to help readers understand the pathogenesis and healing mechanism of DFU, help physicians select dressings correctly, provide an updated overview of the potential of biomaterials and devices and their application in DFU management, and provide ideas for further exploration and development of dressings. Proper use of dressings can promote DFU healing, reduce the cost of treating DFU, and reduce patient pain.

Emerging Bioprinting for Wound Healing

Bioprinting has attracted much attention due to its suitability for fabricating biomedical devices. In particular, bioprinting has become one of the growing centers in the field of wound healing, with various types of bioprinted devices being developed, including 3D scaffolds, microneedle patches, and flexible electronics. Bioprinted devices can be designed with specific biostructures and biofunctions that closely match the shape of wound sites and accelerate the regeneration of skin through various approaches. Herein, a comprehensive review of the bioprinting of smart wound dressings is presented, emphasizing the crucial effect of bioprinting in determining biostructures and biofunctions. The review begins with an overview of bioprinting techniques and bioprinted devices, followed with an in-depth discussion of polymer-based inks, modification strategies, additive ingredients, properties, and applications. The strategies for the modification of bioprinted devices are divided into seven categories, including chemical synthesis of novel inks, physical blending, coaxial bioprinting, multimaterial bioprinting, physical absorption, chemical immobilization, and hybridization with living cells, and examples are presented. Thereafter, the frontiers of bioprinting and wound healing, including 4D bioprinting, artificial intelligence-assisted bioprinting, and in situ bioprinting, are discussed from a perspective of interdisciplinary sciences. Finally, the current challenges and future prospects in this field are highlighted.

A Sustained-Release Nanosystem with MRSA Biofilm-Dispersing and -Eradicating Abilities Accelerates Diabetic Ulcer Healing

Introduction

Drug-resistant bacterial infections and biofilm formation play important roles in the pathogenesis of diabetic refractory wounds. Tea tree oil (TTO) exhibits antimicrobial, antimycotic, and antiviral activities, especially against common clinically resistant strains, such as methicillin-resistant Staphylococcus aureus (MRSA), making it a potential natural antimicrobial for the treatment of acute and chronic wounds. However, TTO is insoluble in water, volatile, light-sensitive, and cytotoxic. While previous macroscopic studies have focused on sterilization with TTO, none have sought to alter its structure or combine it with other materials to achieve sustained release.

Methods

Electrospun TTO nanoliposomes (TTO-NLs), arranged linearly via high-pressure homogenization, could stabilize the structure and performance of TTO to achieve slow drug release. Herein, we established a composite nano-sustained release system, TTO-NL/polyvinyl alcohol/chitosan (TTO-NL@PCS), using high-voltage electrospinning.

Results

Compared with the control, TTO-NL@PCS exhibits higher concentrations of the active TTO drug components, terpinen-4-ol and 1,8-cineole. Owing to its increased stability and slow release, early exposure to TTO-NL@PCS increases the abundance of reactive oxygen species in vitro, ultimately causing the biofilm to disperse and completely killing MRSA without inducing cytotoxic effects to the host. Moreover, in BKS-Leprem2Cd479/Gpt mice with a whole-layer skin infection, untargeted metabolomics analysis of wound exudates reveals upregulated PGF2α/FP receptor signaling and interleukin (IL)-1β and IL-6 expression following application of the composite system. The composite also ameliorates the chemotaxis disorder in early treatment and attenuates the wound inflammatory response during the repair stage of diabetic inflammatory wounds, and upregulates VEGF expression in the wound bed.

Conclusion

TTO-NL@PCS demonstrates the remarkable potential for accelerating diabetic and MRSA-infected wound healing.

Detection and imaging of bacterial biofilms with glutathione-stabilized gold nanoclusters

Bacterial biofilms colonize chronic wounds and surfaces of medical devices, thus making the development of reliable methods for imaging and detection of biofilms crucial. Although fluorescent identification of bacteria is sensitive and non-destructive, the lack of biofilm-specific fluorescent dyes limits the application of this technique to biofilm detection. Here, we demonstrate, for the first time, that fluorescent glutathione-stabilized gold nanoclusters (GSH-AuNCs) without targeting ligands can specifically interact with extracellular matrix components of Gram-negative and Gram-positive bacterial biofilms resulting in fluorescent staining of bacterial biofilms. By contrast, fluorescent bovine serum albumin-stabilized gold nanoclusters and 11-mercaptoundecanoic acid - stabilized gold nanoclusters do not stain the extracellular matrix of biofilms. According to molecular docking studies, GSH-AuNCs show affinity to several targets in extracellular matrix, including amyloid-anchoring proteins, matrix proteins and polysaccharides. Some experimental evidence was obtained for the interaction of GSH-AuNCs with the lipopolysaccharide (LPS) that was isolated from the matrix of Azospirillum baldaniorum biofilms. Based on GSH-AuNCs properties, we propose a new fluorescent method for the measurement of biofilm biomass with a limit of detection 1.7 × 10⁵ CFU/mL. The sensitivity of the method is 10-fold higher than the standard biofilm quantification with the crystal violet assay. There is a good linear relationship between the fluorescence intensity from the biofilms and the number of CFU from the biofilms in the range from 2.6 × 10⁵ to 6.7 × 10⁷ CFU/mL. The developed nanocluster-mediated method of biofilm staining was successfully applied for quantitative detection of biofilm formation on urinary catheter surface. The presented data suggest that fluorescent GSH-AuNCs can be used to diagnose medical device-associated infections.

Sustainable emerging high-intensity sonication processing to enhance the protein bioactivity and bioavailability: An updated review

High-intensity ultrasound (HIU) is considered one of the promising non-chemical eco-friendly techniques used in food processing. Recently (HIU) is known to enhance food quality, extraction of bioactive compounds and formulation of emulsions. Various foods are treated with ultrasound, including fats, bioactive compounds, and proteins. Regarding proteins, HIU induces acoustic cavitation and bubble formation, causing the unfolding and exposure of hydrophobic regions, resulting in functional, bioactive, and structural enhancement. This review briefly portrays the impact of HIU on the bioavailability and bioactive properties of proteins; the effect of HIU on protein allergenicity and anti-nutritional factors has also been discussed. HIU can enhance bioavailability and bioactive attributes in plants and animal-based proteins, such as antioxidant activity, antimicrobial activity, and peptide release. Moreover, numerous studies revealed that HIU treatment could enhance functional properties, increase the release of short-chain peptides, and decrease allergenicity. HIU could replace the chemical and heat treatments used to enhance protein bioactivity and digestibility; however, its applications are still on research and small scale, and its usage in industries is yet to be implemented.

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.

Advances in Antimicrobial Peptide Discovery via Machine Learning and Delivery via Nanotechnology

Antimicrobial peptides (AMPs) have been investigated for their potential use as an alternative to antibiotics due to the increased demand for new antimicrobial agents. AMPs, widely found in nature and obtained from microorganisms, have a broad range of antimicrobial protection, allowing them to be applied in the treatment of infections caused by various pathogenic microorganisms. Since these peptides are primarily cationic, they prefer anionic bacterial membranes due to electrostatic interactions. However, the applications of AMPs are currently limited owing to their hemolytic activity, poor bioavailability, degradation from proteolytic enzymes, and high-cost production. To overcome these limitations, nanotechnology has been used to improve AMP bioavailability, permeation across barriers, and/or protection against degradation. In addition, machine learning has been investigated due to its time-saving and cost-effective algorithms to predict AMPs. There are numerous databases available to train machine learning models. In this review, we focus on nanotechnology approaches for AMP delivery and advances in AMP design via machine learning. The AMP sources, classification, structures, antimicrobial mechanisms, their role in diseases, peptide engineering technologies, currently available databases, and machine learning techniques used to predict AMPs with minimal toxicity are discussed in detail.

A dual-modal ROS generator based on multifunctional PDA-MnO2@Ce6 nanozymes for synergistic chemo-photodynamic antibacterial therapy

The rapid emergence of drug-resistant bacteria has attracted great attention to exploring advanced antibacterial methods. However, single-modal antibacterial therapy cannot easily eliminate drug-resistant bacteria completely due to its low efficacy. Therefore, it is essential to achieve multi-modal antibacterial therapy effectively. Herein, a dual-modal ROS generator was designed based on photosensitive PDA-MnO₂@Ce6/liposome (PMCL) nanozymes for synergistic chemo-photodynamic therapy. PMCL nanozymes adhere to bacteria through liposome-membrane fusion. Meanwhile, PMCL catalyzes endogenous hydrogen peroxide (H₂O₂) to generate hydroxyl radicals (˙OH) and singlet oxygen (¹O₂) under laser irradiation. Furthermore, the photothermal effect can accelerate the generation of ROS. Based on dual-enzyme activities (mimicking peroxidase and catalase) and photodynamic properties, PMCL achieves powerful antibacterial efficacy and mature bacterial biofilm eradication. With the synergistic chemo-photodynamic effects, bacterial populations decrease by >99.76% against Gram-positive S. aureus and Gram-negative E. coli. Notably, the synergistic antibacterial properties of PMCL nanozymes are further explored using a mouse wound model of S. aureus infection. This work fabricated an efficient dual-modal ROS generator to kill bacteria, further providing a new strategy for treating wound infection.

From Antibacterial to Antibiofilm Targeting: An Emerging Paradigm Shift in the Development of Quaternary Ammonium Compounds (QACs)

In a previous development stage, mostly individual antibacterial activity was a target in the optimization of biologically active compounds and antiseptic agents. Although this targeting is still valuable, a new trend has appeared since the discovery of superhigh resistance of bacterial cells upon their aggregation into groups. Indeed, it is now well established that the great majority of pathogenic germs are found in the environment as surface-associated microbial communities called biofilms. The protective properties of biofilms and microbial resistance, even to high concentrations of biocides, cause many chronic infections in medical settings and lead to serious economic losses in various areas. A paradigm shift from individual bacterial targeting to also affecting more complex cellular frameworks is taking place and involves multiple strategies for combating biofilms with compounds that are effective at different stages of microbiome formation. Quaternary ammonium compounds (QACs) play a key role in many of these treatments and prophylactic techniques on the basis of both the use of individual antibacterial agents and combination technologies. In this review, we summarize the literature data on the effectiveness of using commercially available and newly synthesized QACs, as well as synergistic treatment techniques based on them. As an important focus, techniques for developing and applying antimicrobial coatings that prevent the formation of biofilms on various surfaces over time are discussed. The information analyzed in this review will be useful to researchers and engineers working in many fields, including the development of a new generation of applied materials; understanding biofilm surface growth; and conducting research in medical, pharmaceutical, and materials sciences. Although regular studies of antibacterial activity are still widely conducted, a promising new trend is also to evaluate antibiofilm activity in a comprehensive study in order to meet the current requirements for the development of highly needed practical applications.

Tailored anti-biofilm activity - Liposomal delivery for mimic of small antimicrobial peptide

The eradication of bacteria embedded in biofilms is among the most challenging obstacles in the management of chronic wounds. These biofilms are found in most chronic wounds; moreover, the biofilm-embedded bacteria are considerably less susceptible to conventional antimicrobial treatment than the planktonic bacteria. Antimicrobial peptides and their mimics are considered attractive candidates in the pursuit of novel therapeutic options for the treatment of chronic wounds and general bacterial eradication. However, some limitations linked to these membrane-active antimicrobials are making their clinical use challenging. Novel innovative delivery systems addressing these limitations represent a smart solution. We hypothesized that incorporation of a novel synthetic mimic of an antimicrobial peptide in liposomes could improve its anti-biofilm effect as well as the anti-inflammatory activity. The small synthetic mimic of an antimicrobial peptide, 7e-SMAMP, was incorporated into liposomes (~280 nm) tailored for skin wounds and evaluated for its potential activity against both biofilm formation and eradication of pre-formed biofilms. The 7e-SMAMP-liposomes significantly lowered inflammatory response in murine macrophages (~30 % reduction) without affecting the viability of macrophages or keratinocytes. Importantly, the 7e-SMAMP-liposomes completely eradicated biofilms produced by Staphylococcus aureus and Escherichia coli above concentrations of 6.25 μg/mL, whereas in Pseudomonas aeruginosa the eradication reached 75 % at the same concentration. Incorporation of 7e-SMAMP in liposomes improved both the inhibition of biofilm formation as well as biofilm eradication in vitro, as compared to non-formulated antimicrobial, therefore confirming its potential as a novel therapeutic option for bacteria-infected chronic wounds.

Biofilms in wound healing: A bibliometric and visualised study

Bibliometric analyses are often used as a means of visualising the knowledge base and associated trends and patterns in a target scientific field based on a quantitative review of the corresponding literature. In this study, we explore the current status of research pertaining to biofilms in wound healing and elucidate trends in this research space. Through this process, we gain insight into findings from papers indexed in the Web of Science Core Collection. These references were then analysed and plotted using Microsoft Excel 2019, VOSviewer, and CiteSpace V. The results provide a fresh perspective regarding global trends and hotspots in biofilm-related wound healing research. These findings also offer a foundation that researchers can use to identify active hotspots of scientific interest to guide further research endeavours.

Biofilms in Chronic Wound Infections: Innovative Antimicrobial Approaches Using the In Vitro Lubbock Chronic Wound Biofilm Model

Chronic wounds have harmful effects on both patients and healthcare systems. Wound chronicity is attributed to an impaired healing process due to several host and local factors that affect healing pathways. The resulting ulcers contain a wide variety of microorganisms that are mostly resistant to antimicrobials and possess the ability to form mono/poly-microbial biofilms. The search for new, effective and safe compounds to handle chronic wounds has come a long way throughout the history of medicine, which has included several studies and trials of conventional treatments. Treatments focus on fighting the microbial colonization that develops in the wound by multidrug resistant pathogens. The development of molecular medicine, especially in antibacterial agents, needs an in vitro model similar to the in vivo chronic wound environment to evaluate the efficacy of antimicrobial agents. The Lubbock chronic wound biofilm (LCWB) model is an in vitro model developed to mimic the pathogen colonization and the biofilm formation of a real chronic wound, and it is suitable to screen the antibacterial activity of innovative compounds. In this review, we focused on the characteristics of chronic wound biofilms and the contribution of the LCWB model both to the study of wound poly-microbial biofilms and as a model for novel treatment strategies.

Chitosan enhanced the stability and antibiofilm activity of self-propelled Prussian blue micromotor

The emergence, spread and difficult removal of bacteria biofilm, represent an ever-increasing persistent infections and medical complications challenge worldwide. Herein, a self-propelled system Prussian blue micromotor (PB MMs) were constructed by gas-shearing technology for efficient degradation of biofilms by combining chemodynamic therapy (CDT) and photothermal therapy (PTT). With the interpenetrating network crosslinked by alginate, chitosan (CS) and metal ions as the substrate, PB was generated and embedded in the micromotor at the same time of crosslinking. The micromotors are more stable and could capture bacteria with the addition of CS. The micromotors show excellent performance, containing photothermal conversion, reactive oxygen species (ROS) generation and bubble produced by catalyzing Fenton reaction for motion, which served as therapeutic agent could chemically kill bacteria and physically destroy biofilm. This research work opens a new path of an innovative strategy to efficiently remove biofilm.

Antibacterial smart hydrogels: New hope for infectious wound management

Millions of people die annually due to uncured wound infections. Healthcare systems incur high costs to treat wound infections. Tt is predicted to become more challenging due to the rise of multidrug-resistant conditions. During the last decades, smart antibacterial hydrogels could attract attention as a promising solution, especially for skin wound infections. These antibacterial hydrogels are termed 'smart' due to their response to specific physical and chemical environmental stimuli. To deliver different drugs to particular sites in a controlled manner, various types of crosslinking strategies are used in the manufacturing process. Smart hydrogels are designed to provide antimicrobial agents to the infected sites or are built from polymers with inherent disinfectant properties. This paper aims to critically review recent pre-clinical and clinical advances in using smart hydrogels against skin wound infections and propose the next best thing for future trends. For this purpose, an introduction to skin wound healing and disease is presented and intelligent hydrogels responding to different stimuli are introduced. Finally, the most promising investigations are discussed in their related sections. These studies can pave the way for producing new biomaterials with clinical applications.

Stimuli-responsive therapeutic systems for the treatment of diabetic infected wounds

Diabetic wound infection is a common disease that has significantly reduced people's quality of life. Although tremendous achievements have been made in clinical treatment, the crucial challenge in diabetic infected wound management stems from the detrimental diabetic wound environment and the emergence of bacterial resistance after long-term medication, which result in a reduced efficacy, an increased dosage of medication, and severe side effects. To tackle these issues, it is of great significance to develop an innovative treatment strategy for diabetic wound infection therapy. Currently, the exploitation of nanobiomaterial-based therapeutic systems for diabetic infected wounds is booming, and therapeutic systems with a stimuli-responsive performance have received extensive attention. These therapeutic systems are able to accelerate diabetic infected wound healing due to the on-demand release of therapeutic agents in diabetic infected wounds in response to stimulating factors. Based on the characteristics of diabetic infected wounds, many endogenous stimuli-responsive (e.g., glucose, enzyme, hypoxia, and acidity) therapeutic systems have been employed for the targeted treatment of infected wounds in diabetic patients. Additionally, exogenous stimulants, including light, magnetism, and temperature, are also capable of achieving on-demand drug release and activation. In this review, the characteristics of diabetic infected wounds are presented, and then exogenous/endogenous stimuli therapeutic systems for the treatment of diabetic infected wounds are summarized. Finally, the current challenges and future outlook of stimuli-responsive therapeutic systems are also discussed.

Biofilm Microenvironment-Mediated MoS2 Nanoplatform with Its Photothermal/Photodynamic Synergistic Antibacterial Molecular Mechanism and Wound Healing Study

Drug-resistant bacterial infections pose a serious threat to human public health. Biofilm formation is one of the main factors contributing to the development of bacterial resistance, characterized by a hypoxic and microacidic microenvironment. Traditional antibiotic treatments have been ineffective against multidrug-resistant (MDR) bacteria. Novel monotherapies have had little success. On the basis of the photothermal effect, molybdenum disulfide (MoS₂) nanoparticles were used to link quaternized polyethylenimine (QPEI), dihydroporphyrin e6 (Ce6), and Panax notoginseng saponins (PNS) in a zeolitic imidazolate framework-8 (ZIF-8). A multifunctional nanoplatform (MQCP@ZIF-8) was constructed with dual response to pH and near-infrared light (NIR), which resulted in synergistic photothermal and photodynamic antibacterial effects. The nanoplatform exhibited a photothermal conversion efficiency of 56%. It inhibited MDR Escherichia coli (E. coli) and MDR Staphylococcus aureus (S. aureus) by more than 95% and effectively promoted wound healing in mice infected with MDR S. aureus. The nanoplatform induced the death of MDR bacteria by promoting biofilm ablation, disrupting bacterial cell membranes and intracellular DNA, and interfering with intracellular material and energy metabolism. In this study, a multifunctional nanoplatform with good antibacterial effect was developed. The molecular mechanisms of MDR bacteria were also elucidated for possible clinical application.

Three lines of defense: A multifunctional coating with anti-adhesion, bacteria-killing and anti-quorum sensing properties for preventing biofilm formation of Pseudomonas aeruginosa

Surfaces of synthetic materials are highly susceptible to pathogenic bacteria colonization and further biofilm formation, leading to device failure in both biomedical and industrial applications. Complete elimination of the mature biofilms formed on the surfaces, however, remains a great challenge due to the complexity of chemical composition and physical structure. Therefore, prevention of biofilm formation becomes a preferred strategy for solving the biofilm-associated problems. Herein, a multifunctional coating showing three lines of defense to prevent biofilm formation of Pseudomonas aeruginosa is fabricated by a simple and versatile method. This coating is composed of multilayers of quaternized chitosan with bactericidal property and acylase with anti-quorum sensing property and a topmost layer of hyaluronic acid with anti-adhesion property. The substrate deposited with this coating could suppress initial adhesion of a majority of bacteria, and then kill the attached bacteria and interfere with their quorum sensing systems related to biofilm formation. The results of short-term antibacterial experiments show that our coating reduced 98 ± 2% of attached live bacteria. In long-term antibiofilm experiments, this "three lines of defense" design endows the coating with enhanced antibiofilm property against the biofilm formation for at least 3 days by reducing 98 ± 1% of bacterial proliferation and 71 ± 2% of biomass production. Benefiting from the natural building blocks with good biocompatibility and the versatile and environmentally friendly preparation method, this coating shows negligible cytotoxicity and broad applicability, providing great potential for a variety of biomedical applications. STATEMENT OF SIGNIFICANCE: Pathogenic biofilms formed on the surfaces of medical devices and materials pose an urgent problem, and it remains challenging to treat and eradicate the established biofilms. Herein, we developed an antibiofilm coating showing three lines of defense to prevent biofilm formation, which could be deposited on diverse substrates via a simple and versatile method. This coating was based on three natural materials with anti-adhesive, bactericidal, and anti-quorum sensing properties and showed different function in a self-adaptive way to target the sequential stages of biofilm formation by preventing initial bacterial adhesion, killing attached bacteria and interfering with their quorum sensing system to inhibit bacterial proliferation and biofilm maturation. This coating with improved antibiofilm performance might provide a simple and reliable solution to the problems associated with biofilm on surfaces.

A biofilm microenvironment-responsive one-for-all bactericidal nanoplatform for photothermal-augmented multimodal synergistic therapy of pathogenic bacterial biofilm infection

We rationally construct a biofilm microenvironment-responsive bactericidal nanoplatform (ZnPMp) consisting of ZnO core, a Fe3+-doped polydopamine coating and methylene blue (MB) payload for combined CT/CDT/PTT/PDT multi-mode antibacterial therapy.