Multifunctional wound dressing for rapid hemostasis, bacterial infection monitoring and photodynamic antibacterial therapy

Dopamine-alginate-zinc ion dressings employing synergistic active and passive antimicrobial strategies for enhanced burn wound infection management and accelerated healing

Burn wounds are particularly challenging to manage due to high infection rates, excessive exudate, and impaired healing. We developed an innovative burn Polydopamine-Alginate-Zinc ion (Zn2+) dressing (APBM) using a synergistic approach combining passive bacterial inhibition and active sterilization mechanisms. APBM was synthesized through a facile two-step process, integrating an effective bacterial adhesion-blocking mechanism with active sterilization via Zn2+. In vitro studies demonstrated that APBM achieved over 99 % antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and exhibited notable activity against Candida albicans (C. albicans). The antibacterial effect persisted for 11 days against S. aureus and 9 days against E. coli. APBM exhibited an exudate absorption rate twice that of conventional polyurethane (PU) sponges. In a rat burn model, APBM enhanced micro angiogenesis, collagen deposition and reduced inflammation, resulting in a 27.5 % faster wound healing rate compared to the blank group. This performance was superior to dressings employing only a single antimicrobial strategy and conventional sponges. Overall, APBM showed significant potential as a composite functional dressing addressing infection prevention, exudate management, and healing promotion, presenting a promising solution to the major challenges faced in burn wound care.

Synergistic photothermal and photodynamic therapy to promote bacteria-infected wound healing using ZnO@PDA/Ag-integrated waterborne polyurethane films

Light-induced antibacterial effects aim to overcome the limitations of antibiotic-resistant bacteria and provide an effective solution for wound healing applications. This research focuses on developing a multifunctional wound dressing based on waterborne polyurethane (WPU) adorned with a hybrid photo nano-sensitizer (ZnO@PDA/Ag) that demonstrates near-infrared (NIR)-triggered synergistic photothermal and photodynamic effects. Through a facile synthesis process, zinc oxide (ZnO) nanoparticles were coated with polydopamine (PDA) to enhance biocompatibility, photothermic effect, and charge transfer efficiency due to a surface sensitization and passivation strategy. The synthesis was followed by the in situ reduction and decoration of plasmon silver nanoparticles (Ag NPs) to augment photodynamic activity. The structure, chemical composition, and morphology of the ZnO@PDA/Ag nano-sensitizer were examined and the results confirmed the successful synthesis. Furthermore, based on photo-thermal and fluorescence signal measurements under near-infrared (NIR) irradiation, the ZnO@PDA/Ag nanoparticles in aqueous dispersions exhibit effective light-to-heat conversion, as well as a strong ability for NIR-induced singlet oxygen generation. The WPU films incorporating the ZnO@PDA/Ag nano-sensitizer exhibit complete phototherapy inhibition of both Gram-negative E. coli and Gram-positive S. aureus bacteria. In addition, the films exhibited an appropriate biocompatibility in contact with L929 fibroblast cells. Moreover, in vivo studies in a rat wound model demonstrated accelerated wound healing and tissue regeneration with the application of ZnO@PDA/Ag in WPU nanocomposite film, particularly under NIR light irradiation. Histological analysis confirmed the formation of mature epithelial layers and minimal inflammatory response, indicating the potential of this film for clinical wound management.

Protoporphyrin IX-modified chitosan/sodium alginate based cryogels for rapid hemostasis and antibacterial photodynamic therapy of infected wound healing

Due to the porous and interconnected structure, cryogels significantly facilitate blood exudate absorption and support rapid hemostasis as novel wound dressings. However, cryogels suffer from insufficient inherent antibacterial properties, which seriously limits their clinical applications. Herein, we developed a chitosan (CHI) and sodium alginate (SA) composite-based antibacterial photodynamic therapy (aPDT) cryogel for rapid hemostasis and infected wound healing. In this cryogel, the photosensitizer protoporphyrin IX (PpIX) was chemically immobilized onto CHI (CHI-PpIX), while the phenylboronic acid (PBA) molecules were coupled onto SA (SA-PBA). The resulting CHI-PpIX/SA-PBA (CPSP) hydrogel was created by mixing CHI-PpIX and SA-PBA, followed by freeze-drying to form the CPSP cryogel. Through forming dynamic boronic ester bonds between PBA and diol groups on bacterial cell walls, CPSP was endowed with bacterial capturing capacity and enhanced aPDT. In vitro antibacterial experiments revealed its enhanced aPDT efficiency owing to PBA-mediated bacterial targeting. In addition, in vivo assays demonstrated its effective hemostatic, antibacterial and wound healing-promoting capacities. By effectively integrating aPDT with bacterial capturing capabilities and addressing the limitations of existing wound dressings, the CPSP cryogel offers a promising solution for rapid hemostasis and the treatment of infected wounds.

A Dry Patch with In Situ Solid-to-Gel Transformation for All-in-One Skin Wound Care

Hydrogel-based dressing materials offer significant potential in expediting skin wound healing. Nevertheless, they face several challenges: poor adhesion to wound tissues, difficulties in preservation under ambient conditions, and limited multifunctionality to support all wound healing stages. In this work, a dry patch is designed to address these persistent issues by featuring an in situ solid-to-gel transformation and Janus wet tissue adhesiveness. The HGP patch integrates a wet adhesive layer combining dopamine-conjugated hyaluronic acid (HD) and poly(acrylic acid) (PAA), a drug-loading layer comprising gelatin (Gel), and a nonadhesive gelation layer of poly(vinyl alcohol) (PVA) and sodium alginate (SA). This hierarchical structural design confers exceptional wound adhesion, hemostatic capabilities, and antibacterial and antioxidant activities, as well as immune regulatory properties. These attributes collectively support accelerated skin wound healing, particularly in cases complicated by bacterial infections. This research charts an approach to engineer hydrogel-based wound dressings through on-site hydrogel formation, thus advancing the treatment of wounds afflicted with complex infections.

High strength "breathable" glycosilicone/Aloe vera polysaccharide-based gel dressing for efficient wound repair

Medical wound dressings are effective in protecting wounds, maintaining moisture, creating an optimal healing environment and accelerating wound healing. However, their deficiencies in mechanical properties, adhesion and prevention of adhesion to the wound bed have been identified as limiting factors for their therapeutic efficacy in wound healing. To address these issues, we prepared glycosilicone gel dressings consisting of hydrophobic polysiloxanes and highly hydrophilic polysaccharides via ester exchange and silicone hydrogen addition reactions. Silicone gel dressings exhibit skin-like "respiratory" properties, with good permeability to O2 and CO2. Additionally, elongation and other important parameters are similar to those of the skin, which provides a foundation for the application of silicone gels in the field of wound dressings. The introduction of Aloe vera polysaccharide (AP) results in the glycosilicone gel exhibiting certain mechanical properties, including a tensile strength of 0.35 MPa and an adhesion force of 10 N/m. Furthermore, a mouse model of total skin defect demonstrated that the wound healing rate of the mice on the 12th day was 98 %, which effectively promotes wound healing. Consequently, the glycosilicone gel is anticipated to be an optimal wound dressing.

Chitosan/agarose hydrogel dressing: pH response real-time monitoring and chemo-/photodynamic therapy synergistic treatment of infected wounds

The early diagnosis and real-time monitoring of bacterial infections are of great significance for the establishment of integrated diagnosis and treatment systems. In this study, a pH-responsive smart hydrogel patch system, named CABP, was developed to monitor and treat wound infections. CABP has a sandwich structure, with non-woven fabric/chitosan (NF/CS) as the intermediate skeleton layer, Agarose/chitosan/Bromothymol Blue (AG/CS/BTB) hydrogel as the detection layer, and Agarose/chitosan/phthalocyanine (AG/CS/Pc) hydrogel as the treatment layer. When Staphylococcus aureus (S. aureus) infection occurs, the pH of the environment decreases, which triggers the CABP to change from its original blue color to yellow, achieving an intuitive visual transformation. Moreover, the hydrogel patch showed a significant inhibition rate of up to 99.99971 % against S. aureus under 660 nm light radiation, showing a good photodynamic therapy (PDT)/ chemotherapy (CT) synergistic effect. In addition, CABP showed excellent antibacterial and wound healing effects on S. aureus infection in a full-layer skin defect experiment. In short, the patch system is simple to prepare and easy to use, and can provide important research value for the integrated diagnosis and treatment system in biomedical applications.

Spray-assisted layer-by-layer deposition of quaternized chitosan/tannic acid for the construction of multifunctional bio-based nonwoven dressings

Gauze wound dressings have received considerable attention due to their cost-effectiveness, excellent mechanical properties, and widespread applications. However, their inability to actively combat microorganisms and effectively scavenge free radicals results in suboptimal wound management. In this study, a novel nonwoven-based gauze dressing coated with quaternized chitosan/tannic acid (QCS/TA), based on electrostatic interaction and hydrogen bonding, was successfully prepared using a spray-assisted layer-by-layer assembly method. The bio-based nonwoven dressing, assembled with multiple interlacing bilayers, demonstrated outstanding antimicrobial properties, eliminating 99.99 % of Staphylococcus aureus (S. aureus) and 85 % of Escherichia coli (E. coli). Compared to the pristine nonwoven dressing, the QCS/TA-coated nonwoven dressing scavenged >85 % of the surrounding radicals within 2 h. Additionally, the nonwoven dressing exhibits excellent coagulation properties. Notably, the facile spraying procedure preserved most of the softness and breathability of the nonwoven substrate. After the deposition of seven bilayers, the bending stiffness and drape coefficient increased by only 37.63 % and 3.85 %, respectively, while the air permeability and moisture permeability reached 1712 mm/s and 3683.58 g/m2/d, respectively. This bio-based nonwoven dressing, derived from safe and non-toxic ingredients, holds promise as the next generation of multifunctional gauze dressings.

Advancements of Porphyrin-Derived Nanomaterials for Antibacterial Photodynamic Therapy and Biofilm Eradication

The threat posed by antibiotic-resistant bacteria and the challenge of biofilm formation has highlighted the inadequacies of conventional antibacterial therapies, leading to increased interest in antibacterial photodynamic therapy (aPDT) in recent years. This approach offers advantages such as minimal invasiveness, low systemic toxicity, and notable effectiveness against drug-resistant bacterial strains. Porphyrins and their derivatives, known for their high molar extinction coefficients and singlet oxygen quantum yields, have emerged as crucial photosensitizers in aPDT. However, their practical application is hindered by challenges such as poor water solubility and aggregation-induced quenching. To address these limitations, extensive research has focused on the development of porphyrin-based nanomaterials for aPDT, enhancing the efficacy of photodynamic sterilization and broadening the range of antimicrobial activity. This review provides an overview of various porphyrin-based nanomaterials utilized in aPDT and biofilm eradication in recent years, including porphyrin-loaded inorganic nanoparticles, porphyrin-based polymer assemblies, supramolecular assemblies, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). Additionally, insights into the prospects of aPDT is offered, highlighting its potential for practical implementation.

Smart Dressings and Their Applications in Chronic Wound Management

During chronic wound healing, the inflammatory phase can endure for extended periods, heavily impeding or halting the process. Regular inspections and dressing changes are crucial. Modern dressings like hydrogels, hydrocolloids, and foam provide protection and an optimal healing environment. However, they have limitations in offering real-time wound bed status and healing rate. Evaluation relies heavily on direct observation, and passive dressings fail to identify subtle healing differences, preventing adaptive adjustments in biological factors and drug concentrations. In recent years, the clinical field recognizes the value of integrating intelligent diagnostic tools into wound dressings. By monitoring biomarkers linked to chronic wounds' inflammatory state, real-time data can be captured, reducing medical interventions and enabling more effective treatment plans. This fosters innovation in chronic wound care. Researchers have developed smart dressings with sensing, active drug delivery, and self-adjustment capabilities. These dressings detect inflammatory markers like temperature, pH, and oxygen content, enhancing drug bioavailability on the wound surface. As wound healing technology evolves, these smart dressings hold immense potential in chronic wound care and treatment. This comprehensive review updates our understanding on the role and mechanism of action of the smart dressings in chronic refractory wounds by summarizing and discussing the latest research progresses, including the intelligent monitoring of wound oxygen content, temperature, humidity, pH, infection, and enzyme kinetics; intelligent drug delivery triggered by temperature, pH, near-infrared, and electricity; as well as the intelligent self-adjustment of pressure and shape. The review also delves into the constraints and future perspectives of smart dressings in clinical settings, thereby advancing the development of smart wound dressings for chronic wound healing and their practical application in clinical practice.

Dual cross-linked self-healing hydrogel enhanced by dopamine nanoparticles and raffinose for wound healing

A series of intricate and dynamic physiological healing processes are involved in the healing of skin wounds. Herein, a multifunctional hydrogel is firstly designed and constructed by L-arginine-grafted O-carboxymethyl chitosan (CMCA), catechol-modified oxidized hyaluronic acid (DOHA), and dopamine nanoparticles (pDA-NPs). pDA-NPs were loaded in hydrogel for inherently powerful antimicrobial properties and could be as a cross-linking agent to construct hydrogels. Raffinose (Raf) was further incorporated to obtain CMCA-DOHA-pDA2@Raf hydrogel for its function of modulating epidermal differentiation. The hydrogel has good physicochemical properties and could promote cell proliferation and migration, which shows superior hemostatic capabilities in animal models of hemorrhage. The hydrogel significantly promoted wound healing on rat skin defect models by upregulating VEGF and CD31 and decreasing IL-6 and TNF-α, stimulating neovascularization and collagen deposition in epithelial structures. This multifunctional hydrogel implies the potential to be a dynamic wound dressing.

Anti-adhesion multifunctional poly(lactic-co-glycolic acid)/polydimethylsiloxane wound dressing for bacterial infection monitoring and photodynamic antimicrobial therapy

Wound infection and adhesion are important factors affecting wound healing. Early detection of pathogen infection and reduction of wound-to-dressing adhesion are critical for improving wound healing. Herein, Ester-J, which can rapidly respond to lipase secreted by bacteria, was designed and synthesized. Then, Ester-J was co-spun with poly(lactic-co-glycolic acid) (PLGA) and polydimethylsiloxane (PDMS) to prepare a PP-EsJ hydrophobic anti-adhesion dressing with a contact angle of 140.7°. When the PP-EsJ membrane came into contact with the bacteria, the loaded Ester-J was hydrolyzed to Tph-TSF-OH, releasing bright cyan-blue fluorescence, thus providing a fluorescence switch for an early warning of infection. The detection limits of PP-EsJ for Pseudomonas aeruginosa and Staphylococcus aureus were 1.0 × 105 and 1.0 × 106 CFU/mL, respectively. Subsequently, Tph-TSF-OH released 1O2 through light irradiation, which rapidly killed P. aeruginosa and S. aureus, and accelerated wound healing. Compared with the control group, enhanced wound closure (up to 99.80 ± 1.10 %) was observed in mice treated with the PP-EsJ membrane. The PP-EsJ membrane not only effectively reduced the risk of external infection but also reduced adhesions to the skin during dressing changes. These characteristics make PP-EsJ membranes potentially useful for clinical treatment.

Intelligent wound dressing for simultaneous in situ detection and elimination of pathogenic bacteria

Wound infections hinder the healing process and potentially result in life-threatening complications, which urgently require rapid and timely detection and treatment pathogens during the early stages of infection. Here, an intelligent wound dressing was developed to enable in situ detection and elimination of pathogenic bacteria through a combination of point-of-care testing and antibacterial photodynamic therapy technology. The dressing is an injectable hydrogel composed of carboxymethyl chitosan and oxidized sodium alginate, with addition of 4-methylumphulone beta-D-glucoside (MUG) and up-converted nanoparticles coated with titanium dioxide (UCNPs@TiO2). The presence of bacteria can be visually detected by monitoring the blue fluorescence of 4-methylumbellione, generated through the reaction between MUG and the pathogen-associated enzyme. The UCNPs@TiO2 photosensitizers were synthesized and demonstrated high antibacterial activity through the generation of reactive oxygen species when exposed to near-infrared irradiation. Meanwhile, a smartphone-based portable detection system equipped with a self-developed Android app was constructed for in situ detection of pathogens in mere seconds, detecting as few as 103 colony-forming unit. Additionally, the dressing was tested in a rat infected wound model and showed good antibacterial activity and pro-healing ability. These results suggest that the proposed intelligent wound dressing has potential for use in the diagnosis and management of wound infections. STATEMENT OF SIGNIFICANCE: An intelligent wound dressing has been prepared for simultaneous in situ detection and elimination of pathogenic bacteria. The presence of bacteria can be visually detected by tracking the blue fluorescence of the dressing. Moreover, a smartphone-based detection system was constructed to detect and diagnose pathogenic bacteria before reaching the infection limit. Meanwhile, the dressing was able to effectively eliminate key pathogenic bacteria on demand through antibacterial photodynamic therapy under NIR irradiation. The proposed intelligent wound dressing enables timely detection and treatment of infectious pathogens at an early stage, which is beneficial for wound management.

Electrospun fibers based anisotropic silk fibroin film with photodynamic antibacterial therapy for S. aureus infected wound healing

Bacterial infection has been regarded as a life-threatening problem in clinic. In addition to screening of new antibiotics, it is important to develop highly effective antibacterial materials against antibiotic resistance with capacities on modulating chronic inflammation. Herein, aligned Chlorin e6 (Ce6) conjugated silk fibroin electrospun fibers were successfully fabricated on silk fibroin based film via electrospining to achieve effective photodynamic antibacterial activities under near infrared (NIR) irradiation. The aligned electrospun fiber based film composite (SFCF@Film) exhibited good mechanical properties and desirable hemocompatibility. SFCF@Film provided a promising guidance cue for directing cell orientation and promoting cell growth. Significantly, SFCF@Film effectively generated ROS under NIR irradiation to kill S. aureus for treating wound infections within 10 min and promoted M2 polarization of macrophages for wound healing at later stage. Therefore, we believed that this engineered bioscaffold can be a powerful strategy for handling wound infection.

Preparation and Activity of Hemostatic and Antibacterial Dressings with Greige Cotton/Zeolite Formularies Having Silver and Ascorbic Acid Finishes

The need for prehospital hemostatic dressings that exert an antibacterial effect is of interest for prolonged field care. Here, we consider a series of antibacterial and zeolite formulary treatment approaches applied to a cotton-based dressing. The design of the fabric formulations was based on the hemostatic dressing TACGauze with zeolite Y incorporated as a procoagulant with calcium and pectin to facilitate fiber adherence utilizing silver nanoparticles, and cellulose-crosslinked ascorbic acid to confer antibacterial activity. Infra-red spectra were employed to characterize the chemical modifications on the dressings. Contact angle measurements were employed to document the surface hydrophobicity of the cotton fabric which plays a role in the contact activation of the coagulation cascade. Ammonium Y zeolite-treated dressings initiated fibrin equal to the accepted standard hemorrhage control dressing and showed similar improvement with antibacterial finishes. The antibacterial activity of cotton-based technology utilizing both citrate-linked ascorbate-cellulose conjugate analogs and silver nanoparticle-embedded cotton fibers was observed against Staphylococcus aureus and Klebsiella pneumoniae at a level of 99.99 percent in the AATCC 100 assay. The hydrogen peroxide levels of the ascorbic acid-based fabrics, measured over a time period from zero up to forty-eight hours, were in line with the antibacterial activities.

Exploring the Impact of Alginate-PVA Ratio and the Addition of Bioactive Substances on the Performance of Hybrid Hydrogel Membranes as Potential Wound Dressings

Healthcare professionals face an ongoing challenge in managing both acute and chronic wounds, given the potential impact on patients' quality of life and the limited availability of expensive treatment options. Hydrogel wound dressings offer a promising solution for effective wound care due to their affordability, ease of use, and ability to incorporate bioactive substances that enhance the wound healing process. Our study aimed to develop and evaluate hybrid hydrogel membranes enriched with bioactive components such as collagen and hyaluronic acid. We utilized both natural and synthetic polymers and employed a scalable, non-toxic, and environmentally friendly production process. We conducted extensive testing, including an in vitro assessment of moisture content, moisture uptake, swelling rate, gel fraction, biodegradation, water vapor transmission rate, protein denaturation, and protein adsorption. We evaluated the biocompatibility of the hydrogel membranes through cellular assays and performed instrumental tests using scanning electron microscopy and rheological analysis. Our findings demonstrate that the biohybrid hydrogel membranes exhibit cumulative properties with a favorable swelling ratio, optimal permeation properties, and good biocompatibility, all achieved with minimal concentrations of bioactive agents.

Multi-functional carboxymethyl chitosan/sericin protein/halloysite composite sponge with efficient antibacterial and hemostatic properties for accelerating wound healing

The development of wound dressings with hemostatic and antibacterial properties has attracted great attention. In this study, we prepared a multi-functional natural substance sponge (CMC/Ser-Ag/HNT) composed of carboxymethyl chitosan (CMC), sericin-silver nanoparticle (Ser-Ag), and halloysite (HNT). CMC/Ser-Ag/HNT sponge was demonstrated to bear desired hygroscopicity, porosity, compressive strength and compressive stability, cytocompatibility, and hemocompatibility. The mechanical properties (compressive strength of 100 kPa) and hemostatic capacity (hemostasis time of 15 ± 3 s in the liver injury model and 12 ± 3 s in the caudal injury model) were enhanced by introducing HNT into the CMC sponge. Ser-Ag was synthesized in situ via the redox nature of tyrosine residues in sericin in a "one-step, green" way to enhance the antibacterial activity of the hybrid sponge against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In addition, the rat full-thickness skin defect model experiments demonstrated that the CMC/Ser-Ag/HNT4 sponge significantly promoted epithelialization and collagen formation. Immunofluorescence staining assays revealed that the composite sponge reduced inflammation by downregulating the expression of IL-6 and enhanced angiogenesis by upregulating VEGF expression. All the findings demonstrated the great potential of CMC/Ser-Ag/HNT sponge as versatile clinical wound dressing, especially for hemorrhagic and infected wounds.

Rational design of porous structure-based sodium alginate/chitosan sponges loaded with green synthesized hybrid antibacterial agents for infected wound healing

An ideal wound dressing should have excellent antimicrobial properties and provide a suitable microenvironment for regenerating damaged skin tissue. In this study, we utilized sericin to biosynthesize silver nanoparticles in situ and introduced curcumin to obtain Sericin-AgNPs/Curcumin (Se-Ag/Cur) antimicrobial agent. The hybrid antimicrobial agent was then encapsulated in a physically double cross-linking 3D structure network (Sodium alginate-Chitosan, SC) to obtain the SC/Se-Ag/Cur composite sponge. The 3D structural networks were constructed through electrostatic interactions between sodium alginate and chitosan and ionic interactions between sodium alginate and calcium ions. The prepared composite sponges have excellent hygroscopicity (contact angle 51.3° ± 5.6°), moisture retention ability, porosity (67.32 % ± 3.37 %), and mechanical properties (>0.7 MPa) and exhibit good antibacterial ability against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). In addition, in vivo experiments have shown that the composite sponge promotes epithelial regeneration and collagen deposition in wounds infected with S. aureus or P. aeruginosa. Tissue immunofluorescence staining analysis confirmed that the SC/Se-Ag/Cur complex sponge stimulated upregulated expression of CD31 to promote angiogenesis while downregulating TNF-α expression to reduce inflammation. These advantages make it an ideal candidate for infectious wound repair materials, providing an effective repair strategy for clinical skin trauma infections.

Recent advances in engineered polymeric materials for efficient photodynamic inactivation of bacterial pathogens

Nowadays, infectious diseases persist as a global crisis by causing significant destruction to public health and the economic stability of countries worldwide. Especially bacterial infections remain a most severe concern due to the prevalence and emergence of multi-drug resistance (MDR) and limitations with existing therapeutic options. Antibacterial photodynamic therapy (APDT) is a potential therapeutic modality that involves the systematic administration of photosensitizers (PSs), light, and molecular oxygen (O₂) for coping with bacterial infections. Although the existing porphyrin and non-porphyrin PSs were effective in APDT, the poor solubility, limited efficacy against Gram-negative bacteria, and non-specific distribution hinder their clinical applications. Accordingly, to promote the efficiency of conventional PSs, various polymer-driven modification and functionalization strategies have been adopted to engineer multifunctional hybrid phototherapeutics. This review assesses recent advancements and state-of-the-art research in polymer-PSs hybrid materials developed for APDT applications. Further, the key research findings of the following aspects are considered in-depth with constructive discussions: i) PSs-integrated/functionalized polymeric composites through various molecular interactions; ii) PSs-deposited coatings on different substrates and devices to eliminate healthcare-associated infections; and iii) PSs-embedded films, scaffolds, and hydrogels for regenerative medicine applications.

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Synthetic strategies of engineered polymer-based hybrid materials integrated with photosensitizers for APDT.

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Utilization of photosensitizer-incorporated polymeric materials in health care applications.

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Challenges and opportunities in the future development of polymeric biomaterials with improved photo-bactericidal properties.

Applications of polydopaminic nanomaterials in mucosal drug delivery

Polydopamine (PDA) is a biopolymer with unique physicochemical properties, including free-radical scavenging, high photothermal conversion efficiency, biocompatibility, biodegradability, excellent fluorescent and theranostic capacity due to their abundant surface chemistry. Thus, PDA is used for a myriad of applications including drug delivery, biosensing, imaging and cancer therapy. Recent reports present a new functionality of PDA as a coating nanomaterial, with major implications in mucosal drug delivery applications, particularly muco-adhesion and muco-penetration. However, this application has received minimal traction in the literature. In this review, we present the physicochemical and functional properties of PDA and highlight its key biomedical applications, especially in cancer therapy. A detailed presentation of the role of PDA as a promising coating material for nanoparticulate carriers intended for mucosal delivery forms the core aspect of the review. Finally, a reflection on key considerations and challenges in the utilizing PDA for mucosal drug delivery, along with the possibilities of translation to clinical studies is expounded.

Preparation and in Vitro Property Research of Cholic Acid Nanoparticles with Dual-functions of Hemostasis and Antibacterial

Background

Hemorrhage control and anti-infection play a crucial role in promoting wound healing in trauma-related injuries.

Objectives

This study aimed to prepare nanoparticles with dual functions of hemostasis and antibacterial properties.

Methods

The dual-functional nanoparticles (CDCA-PLL NPs) were developed using a self-assembly method based on the electrostatic forces between poly-L-lysine (PLL) and Chenodeoxycholic acid (CDCA). The physicochemical properties, hemostatic properties, and antibacterial activities were investigated.

Results

The prepared nanoparticles displayed a spherical structure, exhibiting a high drug loading capacity, encapsulation efficiency, and good stability. The CDCA-PLL NPs could reduce the hemolysis caused by PLL and promote the proliferation of human fibroblasts, indicating excellent biosafety. Moreover, CDCA-PLL NPs demonstrated a shorter in vivo hemostasis time and reduced blood loss in mouse tail vein hemorrhage, femoral vein hemorrhage, femoral artery hemorrhage, and liver hemorrhage models. Also, CDCA-PLL NPs showed excellent antibacterial efficacy against E. coli and S. aureus.

Conclusions

CDCA-PLL NPs have great potential to be extensively applied as a hemostatic and antibacterial agent in various clinical conditions.

Fabrication of chitosan-gelatin films incorporated with thymol-loaded alginate microparticles for controlled drug delivery, antibacterial activity and wound healing: In-vitro and in-vivo studies

Previously, studies have demonstrated the unique characteristics of chitosan-gelatin films as wound dressings applications. However, their application has been limited due to their inadequacy of antimicrobial and anti-inflammatory characteristics. To improve the intended multifunctional characteristics of chitosan-gelatin film, in this study, we designed a novel composite film with the capability of controlled and prolonged release of thymol as a natural antioxidant and antimicrobial drug. Here, thymol-loaded ALG MPs (Thymol-ALG MPs) were prepared by electrospraying method and incorporated into the chitosan-gelatin film. The composite wound dressings of Thymol-ALG MPs incorporated in chitosan-gelatin film (CS-GEL/Thymol-ALG MPs) were characterized by in vitro and in vivo evaluations. The Thymol-ALG MPs demonstrated spherical and uniform morphology, with high encapsulation efficiency (88.9 ± 1.1 %). The CS-GEL/Thymol-ALG MPs exhibited high antibacterial activity against both Gram-positive and Gram-negative bacteria and no cytotoxicity for the L929 fibroblast cells. The release trend of thymol from CS-GEL/Thymol-ALG MPs and Thymol-ALG MPs followed a pseudo-Fickian diffusion mechanism. This wound dressing effectively accelerates the wound healing process at rats' full-thickness skin excisions. Also, the histological analysis demonstrated that the CS-GEL/Thymol-ALG MPs could significantly enhance epithelialization, collagen deposition, and induce skin regeneration. The present antibacterial composite film has promising characteristics for wound dressings applications.

Peptide hydrogel based sponge patch for wound infection treatment

Dressing with the function of anti-wound infection and promoting skin repair plays an important role in medicine, beauty industry, etc. In terms of anti-wound infection, traditional dressings, such as gauze, have problems such as excessive bleeding in the process of contact or removal, and slow wound healing due to poor biological compatibility. The development of new functional and biocompatible dressings has essential application value in biomedical fields. In this study, a new type of dressing based on polypeptide functional sponge patch was constructed. The porous sponge patch is made of antimicrobial peptide and medical agarose through gel and freeze-drying technology. In vitro antibacterial experiments and small animal skin wound infection model experiments show that the porous sponge has excellent antibacterial and anti-skin infection activities, as well as the function of promoting wound healing.

Peptide–Polymer Conjugates: A Promising Therapeutic Solution for Drug-Resistant Bacteria

By 2050, it is estimated that 10 million people will die of drug-resistant bacterial infection caused by antibiotic abuse. Antimicrobial peptide (AMP) is widely used to prevent such circumstances, for the positively charged AMPs can kill drug-resistant bacteria by destroying negatively charged bacterial cell membrane, and has excellent antibacterial efficiency and low drug resistance. However, due to the defects in low in vivo stability, easy degradation, and certain cytotoxicity, its practical clinical application is limited. The emergence of peptide–polymer conjugates (PPC) helps AMPs overcome these shortcomings. By combining with functional polymers, the positive charge of AMPs is partially shielded, and its stability and water solubility are improved, so as to prolong the in vivo circulation time of AMPs and reduce its cytotoxicity. At the same time, the self-assembly ability of PPC enables it to assemble into different nanostructures to undertake specific antibacterial tasks. At present, PPC is mainly used in wound dressing, bone tissue repair, antibacterial coating of medical devices, nerve repair, tumor treatment, and oral health maintenance. In this study, we summarize the structure, synthesis methods, and the clinical applications of PPC, so as to present the current challenges and discuss the future prospects of antibacterial therapeutic materials.

Centella asiatica extract in carboxymethyl cellulose at its optimal concentration improved wound healing in mice model

Centella asiatica (C. asiatica) has reported to be one of the traditional herbal remedies, whereas poor water solubility leads to lower bioavailability thereby affecting it remedial efficacy. Therefore, we aimed to evaluate its efficacy through increased bioavailability by using high viscosity Carboxymethyl Cellulose (CMC) as solvent on methanol-based extract on wound healing, in vivo. The preparation was applied as 0.0% (control, CMC alone), 0.25. 0.5 and 1% concentrations of extract of C. asiatica. We evaluated the efficiency of preparations on wound healing progression as progression of wound contraction, tissue proliferation and cells deposition, and relative level of gene expression for genes associated with wound healing. The results showed that 0.5% extract in CMC had significantly higher (P < 0.05) wound contraction than control and other concentrations. The level tissue deposition and the infiltration of polymorphonuclear cells in groups treated with 0.5 % concentration preparation were higher than that other treatments and control. Similarly, the relative level of gene expression in 0.5% concentration treated group were statistically significantly higher (P < 0.05) than that of control. It is believed that the lower concentration of the extract would have lessor effect on wound healing, whereas higher concertation would be interfering the optimal inflammatory tissue deposition; and there by negatively affecting wound healing. The results indicated that C. asiatica can be optimally used at 0.5 % of extract in CMC for wound healing as indicated by speeding the progression of wound closure and by increasing the expression of collagen II and III together with reducing the expression of TGFβ1. However, higher concentrations of the crude extract of C. asiatica could paradoxically resulting in undesired effects. It is recommended that further evaluation should be performed on wider scale and the economic feasibility evaluation should be performed.

Comparison of physical, mechanical and biological effects of leucocyte-PRF and advanced-PRF on polyacrylamide nanofiber wound dressings: In vitro and in vivo evaluations

Platelet-rich fibrin (PRF) is extracted from the blood without biochemical interference and, also, with the ability of a long-term release of growth factors that can stimulate tissue repair and regerenation. Here, leucocyte- and platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin (A-PRF) were extracted and utilized for the creation of nanofibers containing polyacrylamide (PAAm), PAAm / L-PRF and PAAm / A-PRP through electrospinning processing technique. The effect of the type of PRF on the physical, mechanical and biological properties of the resultant nanofiberous wound dressings are thoroughly evaluated. The results presented in the current study reveals that the fiber diameter is grealtly reduced through the utilization of L-PRF. In addition, mechanical property is also positively affected by L-PRF and the degradation rate is found to be higher compared to A-PRF group. The L929 cells proliferation and adhesion, angiogenesis potential and wound healing ability was significantly higher in PAAm/A-PRF nanofibers compared to pure PAAm and PAAm/L-PRF nanofibers owed to the release of vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF). Overall, the utilization of L-PRF or A-PRF can improve the physical, mechanical and biological behavior of nanofiber making them an ideal candidate for wound dressings, with the emphasis on the skin tissue repair and regeneration applications.

Bacitracin-Engineered BSA/ICG Nanocomplex with Enhanced Photothermal and Photodynamic Antibacterial Activity

To reduce the drug resistance of bacteria and enhance the antibacterial ability in bacterial infection therapy, we designed a new antibacterial nanoagent. In this system, a photosensitizer (indocyanine green, ICG) was loaded in bovine serum albumin (BSA) through hydrophobic-interaction-induced self-assembly to form stable BSA@ICG nanoparticles. Furthermore, a positively charged antibacterial peptide bacitracin (Bac) was physically immobilized onto the surface of BSA@ICG to generate a bacterial-targeted nanomedicine BSA@ICG@Bac through electrostatic interactions. Afterward, its photodynamic and photothermal activities were intensely evaluated. Moreover, its bactericidal efficiency was assessed via in vitro antibacterial assays and bacterial biofilm destruction tests. First, the obtained BSA@ICG@Bac showed both good singlet oxygen generation property and high photothermal conversion efficiency. In addition, it showed enhanced photodynamic and photothermal antibacterial capacities and biofilm-removing ability in vitro due to Bac modification. To sum up, our research provided an economic and less-time-consuming approach to preparing antibacterial nanomedicines with excellent antibacterial ability. Therefore, the prepared antibacterial nanomedicines have great potential to be utilized in clinical trials in the future.

Enhanced photocatalytic and antibacterial activity of acridinium-grafted g-C3N4 with broad-spectrum light absorption for antimicrobial photocatalytic therapy

As a metal-free polymeric photocatalyst, graphitic carbon nitride (g-C₃N₄) has attracted great attention owing to its high stability and low toxicity. However, g-C₃N₄ suffers from low light harvesting ability which limits its applications in antimicrobial photocatalytic therapy (APCT). Herein, acridinium (ADN)-grafted g-C₃N₄ (ADN@g-C₃N₄) nanosheets are prepared via covalent grafting of ADN to g-C₃N₄. The obtained ADN@g-C₃N₄ exhibits a narrow optical band gap (2.12 eV) and a wide optical absorption spectrum (intensity a.u. > 0.30) ranging from ultraviolet to near-infrared region. Moreover, ADN@g-C₃N₄ would produce reactive oxygen species (ROS) under light irradiation to exert effective sterilization and biofilm elimination activities against both gram-negative and gram-positive bacteria. Molecular dynamics simulation reveals that the ADN@g-C₃N₄ may move toward, tile and insert the bacterial lipid bilayer membrane through strong van der Waals and electrostatic interaction, decreasing the order parameter of the lipid while increasing the conducive of ROS migration, inducing ADN@g-C₃N₄ with improved antimicrobial and antibiofilm performance. Moreover, ADN@g-C₃N₄ could efficiently eradicate oral biofilm on artificial teeth surfaces. This work may provide a broad-spectrum light-induced photocatalytic therapy for preventing and treating dental plaque diseases and artificial teeth-related infections, showing potential applications for intractable biofilm treatment applications. An acridinium-grafted g-C₃N₄ (ADN@g-C₃N₄) with a narrow band gap and broad-spectrum light absorption was synthesized. The narrow optical band gap and improved electrostatic interaction with bacterial lipid bilayer membrane of ADN@g-C₃N₄ strengthened the ROS generation and facilitated the diffusion of ROS to bacteria surface, leading to enhanced photocatalytic and antibacterial activity against bacteria and corresponding biofilm under light irradiation. STATEMENT OF SIGNIFICANCE: An acridinium-grafted g-C₃N₄ (ADN@g-C₃N₄) with a narrow band gap and broad-spectrum light absorption was developed as an antimicrobial photocatalytic therapy agent. The ADN@g-C₃N₄ exhibited enhanced photocatalytic and antibacterial activity against bacteria and corresponding biofilm under light irradiation, showing potential applications for intractable biofilm treatment.

Potential of plant secondary metabolite-based polymers to enhance wound healing

There is a global epidemic of non-healing wounds. Chronic inflammation, overexpression of pro-inflammatory cytokines, oxidative stress and bacterial infection are implicated in delayed wound healing. Natural extracts are a rich source of bioactive molecules called plant secondary metabolites (PSMs) that include terpenes and phenols. These molecules may facilitate wound healing through their antioxidant, anti-inflammatory, and antibacterial activity. After briefly outlining the process of wound healing and how it is compromised in chronic wounds, this review focuses on investigating how PSMs-based polymers may improve wound healing. Best methods for incorporating PSMs into wound dressings are reviewed and critically compared. The exiting body of literature strongly suggests that PSMs-based polymers incorporated into wound dressings could have clinical value in aiding wound healing. STATEMENT OF SIGNIFICANCE: Chronic wounds develop by the persistence of inflammation, oxidative stress and infection. Chronic wounds affect the worldwide population, by reducing quality of life of patients with significant cost to healthcare systems. To help chronic wounds to heal and overcome this burden, materials with anti-inflammatory, antioxidant and antibacterial properties are required. Plant secondary metabolites (PSMs) are volatile materials that have all these properties. PSMs-based polymers can be fabricated by polymerization techniques. The present review provides an overview of the state-of-the-art of the wound healing mechanisms of PSMs. Current developments in the field of PSMs-based polymers are reviewed and their potential use as wound dressings is also covered.

Persistent Luminescence-Based Theranostics for Real-Time Monitoring and Simultaneously Launching Photodynamic Therapy of Bacterial Infections

External light irradiation is usually required in bacterial infection theranostics; however, it is always accompanied by limited light penetration, imaging interference, and incomplete bacterial destruction. Herein, a feasible "image-launching therapy" strategy is developed to integrate real-time optical imaging and simultaneous photodynamic therapy (PDT) of bacterial infections into persistent luminescence (PL) nanoparticles (NPs). Mesoporous silica NPs are used as a substrate for in situ deposition of PL nanodots of ZnGa₂ O₄ :Cr³⁺ to obtain mPL NPs, followed by surface grafting with silicon phthalocyanine (Si-Pc) and electrostatic assembly of cyanine 7 (Cy7) to fabricate mPL@Pc-Cy NPs. The PL emission of light-activated mPL@Pc-Cy NPs is quenched by Cy7 assembly at physiological conditions through the fluorescence resonance energy transfer effect, but is rapidly restored after disassembly of Cy7 in response to bacterial infections. The self-illuminating capabilities of NPs avoid tissue autofluorescence under external light irradiation and achieve real-time colorimetric imaging of bacterial infections. In addition, the afterglow of mPL NPs can persistently excite Si-Pc photosensitizers to promote PDT efficacy for bacterial elimination and accelerate wound full recovery with normal histologic features. Thus, this study expands the theranostic strategy for precise imaging and simultaneous non-antibiotic treatment of bacterial infections without causing side effects to normal tissues.

Bio-inspired hydrogels with fibrous structure: A review on design and biomedical applications

Numerous tissues in the human body have fibrous structures, including the extracellular matrix, muscles, and heart, which perform critical biological functions and have exceptional mechanical strength. Due to their high-water content, softness, biocompatibility and elastic nature, hydrogels resemble biological tissues. Traditional hydrogels, on the other hand, have weak mechanical properties and lack tissue-like fibrous structures, limiting their potential applications. Thus, bio-inspired hydrogels with fibrous architectures have piqued the curiosity of biomedical researchers. Here, we review fabrication strategies for fibrous hydrogels and their recent progress in the biomedical fields of wound dressings, drug delivery, tissue engineering scaffolds and bioadhesives. Challenges and future perspectives are also discussed.

Regulating the bacterial oxygen microenvironment via a perfluorocarbon-conjugated bacteriochlorin for enhanced photodynamic antibacterial efficacy

Photodynamic therapy (PDT) has attracted considerable attention, since it could effectively kill bacteria and prevent the development of multi-drug resistance. However, PDT currently suffers from oxygen limitation and hypoxia is a prominent feature of pathological states encountered in inflammation, wounds, and bacterial infections. Herein, an oxygen-tunable nanoplatform based on perfluorocarbon-conjugated tetrafluorophenyl bacteriochlorin (FBC-F) was designed for effective antimicrobial therapy. The introduction of fluorine atoms can not only increase the reactive oxygen species (ROS) production capacity of FBC-F by facilitating the intersystem crossing (ISC) process of FBC photosensitizers, but also make FBC-F deliver more oxygen into the treatment sites benefiting from the outstanding oxygen-dissolving capability of perfluorocarbon. As a consequence, the FBC-F nanoplatform was able to efficiently generate singlet oxygens for type II PDT, as well as superoxide anions and hydroxyl radicals for type I PDT, and significantly improve antibacterial efficacy in vitro. In vivo experiments further proved that the FBC-F with a powerful antibacterial capability could well promote wound healing and destroy biofilm. Thus, this FBC-F nanoplatform may open a new path in photodynamic antibacterial therapy. STATEMENT OF SIGNIFICANCE: Photodynamic therapy is a promising antibacterial treatment, but its efficacy is severely compromised by hypoxia. To overcome such a limitation, we constructed an oxygen-regulated nanoplatform (FBC-F) by attaching perfluorocarbons (PFC) to the NIR photosensitizer (FBC). As an analogue of bacteriochlorin, FBC could generate ¹O₂ through energy transfer , as well as O₂^-· and ·OH through electron transfer for synergistic type I and type II photodynamic antibacterial therapy. Benefiting from the oxygen-dissolving capability of PFC, FBC-F could efficiently deliver more oxygen into the treatment site and alleviate the hypoxic environment. As a consequence, FBC-F could effectively generate large amounts of reactive oxygen species to achieve improved antibacterial efficacy and provide a promising approach for eliminating biofilms.

Advances and Potentials of Polydopamine Nanosystem in Photothermal-Based Antibacterial Infection Therapies

Bacterial infection remains one of the most dangerous threats to human health due to the increasing cases of bacterial resistance, which is caused by the extensive use of current antibiotics. Photothermal therapy (PTT) is similar to photodynamic therapy (PDT), but PTT can generate heat energy under the excitation of light of specific wavelength, resulting in overheating and damage to target cells or sites. Polydopamine (PDA) has been proved to show plenty of advantages, such as simple preparation, good photothermal conversion effects, high biocompatibility, and easy functionalization and adhesion. Taking these advantages, dopamine is widely used to synthesize the PDA nanosystem with excellent photothermal effects, good biocompatibility, and high drug loading ability, which therefore play more and more important roles for anticancer and antibacterial treatment. PDA nanosystem-mediated PTT has been reported to induce significant tumor inhibition, as well as bacterial killings due to PTT-induced hyperthermia. Moreover, combined with other cancer or bacterial inhibition strategies, PDA nanosystem-mediated PTT can achieve more effective tumor and bacterial inhibitions. In this review, we summarized the progress of preparation methods for the PDA nanosystem, followed by advances of their biological functions and mechanisms for PTT uses, especially in the field of antibacterial treatments. We also provided advances on how to combine PDA nanosystem-mediated PTT with other antibacterial methods for synergistic bacterial killings. Moreover, we further provide some prospects of PDA nanosystem-mediated PTT against intracellular bacteria, which might be helpful to facilitate their future research progress for antibacterial therapy.