Bio-inspired crosslinking and matrix-drug interactions for advanced wound dressings with long-term antimicrobial activity

The ASB@HNTs-PVA nanofiber membrane, possessing both anti-inflammatory and hemostatic activities, promotes the healing of T2D skin wounds

The healing of diabetic wounds has long been a significant challenge in the field of medicine. The elevated sugar levels surrounding diabetic wounds create a conducive environment for harmful bacterial growth, resulting in purulent infections that impede the healing process. Thus, the development of a biomaterial that can enhance the healing of diabetic wounds holds great importance. This study developed electrospun dressings for wound healing by combining traditional Chinese medicine and clay. The study utilized electrospinning technology to prepare polyvinyl alcohol (PVA) nanofiber membranes containing ASB and HNTs. These ASB@HNTs-PVA nanofiber membranes demonstrated rapid hemostasis, along with antibacterial and anti-inflammatory properties, facilitating the recovery of type 2 diabetic (T2D) wounds. Various analyses were conducted to assess the performance of the composite nanofiber membrane, including investigations into its biocompatibility and hemostatic abilities through antibacterial experiments, cell experiments, and mouse liver tail bleeding experiments. Western blot analysis confirmed that the composite nanofiber membrane could decrease the levels of inflammatory factors IL-1β and TNF-α. A type 2 diabetic mouse model was utilized, with wounds artificially induced on the backs of mice. Application of the nanofiber membrane to the wounds further confirmed its anti-inflammatory effects and ability to enhance wound healing in vivo.

High-flexible chitosan-based composite membrane with multi-layer biopolymer coatings for anti-bacterial drug delivery and wound healing

Flexible chitosan-based membranes were prepared by casting/solvent evaporation method using chitosan flocks as raw material. To improve mechanical and biological properties, chitosan microspheres (CMs) were prepared and integrated to form the composite membranes. Two different anti-bacterial drugs, e.g., tetracycline hydrochloride (TH) and silver sulfadiazine (AgSD), were loaded into the CMs and composite membranes to enhance their anti-bacterial properties. Furthermore, composite membranes were alternately coated by multi-layers of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS) via the layer-by-layer self-assembly and Schiff-base cross-linking. Our results demonstrated that the microspheres and multi-layer coatings could improve the swelling, water vapor transmission and hydrophilicity of the composite membranes. The chitosan microspheres and multi-layer coatings increased the tensile strength and decreased the elongation at the break of the membranes. Our composite membrane had better mechanical properties, slow drug release, anti-bacterial properties, which could promote cell proliferation. This composite membrane has great application potential in inhibiting bacterial infection and promoting wound regeneration.

Telodendrimer functionalized hydrogel platform for sustained antibiotics release in infection control

Wound infection commonly causes delayed healing, especially in the setting of chronic wounds. Local release of antibiotics is considered a viable approach to treat chronic wounds. We have developed a versatile telodendrimer (TD) platform for efficient loading of charged antibiotic molecules via a combination of multivalent and synergistic charge and hydrophobic interactions. The conjugation of TD in biocompatible hydrogel allows for topical application to provide sustained antibiotic release. Notably, a drug loading capacity as high as 20 % of the drug-to-resin dry weight ratio can be achieved. The payload content (PC) and release profile of the various antibiotics can be optimized by fine-tuning TD density and valency in hydrogel based on the charge and hydrophobic features of the drug, e.g., polymyxin B (PMB), gentamycin (GM), and daptomycin (Dap), for effective infection control. We have shown that hydrogel with moderately reduced TD density demonstrates a more favorable release profile than hydrogel with higher TD density. Antibiotics loaded in TD hydrogel have comparable antimicrobial potency and reduced cytotoxicity compared to the free antibiotics due to a prolonged, controlled drug release profile. In a mouse model of skin and soft tissue infection, the subcutaneous administration of PMB-loaded TD hydrogel effectively eliminated the bacterial burden. Overall, these results suggest that engineerable TD hydrogels have great potential as a topical treatment to control infection for wound healing. STATEMENT OF SIGNIFICANCE: Wound infection causes a significant delay in the wound healing process, which results in a significant financial and resource burden to the healthcare system. PEGA-telodendrimer (TD) resin hydrogel is an innovative and versatile platform that can be fine-tuned to efficiently encapsulate different antibiotics by altering charged and hydrophobic structural moieties. Additionally, this platform is advantageous as the TD density in the resin can also be fine-tuned to provide the desired antibiotic payload release profile. Sustained antibiotics release through optimization of TD density provides a prolonged therapeutic window and reduces burst release-induced cytotoxicity compared to conventional antibiotics application. Studies in a preclinical mouse model of bacteria-induced skin and soft tissue infection demonstrated promising therapeutic efficacy as evidenced by effective infection control and prolonged antibacterial efficacy of antibiotics-loaded PEGA-TD resin. In conclusion, the PEGA-TD resin platform provides a highly customizable approach for effective antibiotics release with significant potential for topical application to treat various bacterial wound infections to promote wound healing.

Catecholamines polymerization crosslinking for alginate-based burn wound dressings developed with ciprofloxacin and zinc oxide interactions

There is an increasing demand for stable and durable wound dressings to treat burn injuries and infections. Bioactive electrospun nanofibrous mats with antibacterial properties are promising for wound dressing usage. Electrospinning of biopolymers for wound dressing applications needs post-spinning crosslinking to prevent mat dissolution in moist wound environments. Here, we prepared durable wound dressing by using the Dopamine (DA) polymerization crosslinking in Alginate (ALG)/Polyvinyl alcohol (PVA) nanofibrous mats, which are developed by Ciprofloxacin (CIP) and Zinc oxide (ZO). The nanofibrous mats were investigated by FESEM, FTIR, mechanical strength, water contact angle, degradation, degree of swelling, and WVTR tests. The analyses demonstrate the nanofibrous mats with uniform and unbranched fibers, with a hydrophilic nature, which was porous, durable, and stable. Also, it showed the CIP and ZO addition enhanced their durability by crosslinking reinforcement. In addition, the drug release and antibacterial assays demonstrated the pH-sensitive release with more drug release at higher pH (bacterial invasion) and impressive antibacterial activity (up to 99 %). In the burn wound model in rats, the ALG/PVA/DA/CIP/ZO nanofibrous mats displayed excellent wound healing ability in wound closure and tissue regeneration. Also, complete re-epithelization and remodeling and highest collagen synthesis in histological assessment.

Natural Extracts for Antibacterial Applications

Bacteria-induced epidemics and infectious diseases are seriously threatening the health of people around the world. In addition, antibiotic therapy has been inducing increasingly more serious bacterial resistance, which makes it urgent to develop new treatment strategies to combat bacteria, including multidrug-resistant bacteria. Natural extracts displaying antibacterial activity and good biocompatibility have attracted much attention due to greater concerns about the safety of synthetic chemicals and emerging drug resistance. These antibacterial components can be isolated and utilized as antimicrobials, as well as transformed, combined, or wrapped with other substances by using modern assistive technologies to fight bacteria synergistically. This review summarizes recent advances in natural extracts from three kinds of sources-plants, animals, and microorganisms-for antibacterial applications. This work discusses the corresponding antibacterial mechanisms and the future development of natural extracts in antibacterial fields.

Smart Nanofibrous Hydrogel Wound Dressings for Dynamic Infection Diagnosis and Control: Soft but Functionally Rigid

Chronic wounds, such as burns and diabetic foot ulcers, pose significant challenges to global healthcare systems due to prolonged hospitalization and increased costs attributed to susceptibility to bacterial infections. The conventional use of antibiotic-loaded and metal-impregnated dressings exacerbates concerns related to multidrug resistance and skin argyrosis. In response to these challenges, our research introduces a unique approach utilizing antibiotic-free smart hydrogel wound dressings with integrated infection eradication and diagnostic capabilities. Electrospinning stands out as a method capable of producing hydrogel nanofibrous materials possessing favorable characteristics for treating wounds and detecting infections under conditions utilizing sustainable materials. In this study, innovative dressings are fabricated through electrospinning polycaprolactone (PCL)/gelatin (GEL) hybrid hydrogel nanofibers, incorporating pDA as a cross-linker, εPL as a broad-spectrum antimicrobial agent, and anthocyanin as a pH-responsive probe. The developed dressings demonstrate exceptional antioxidant (>90% radical scavenging) and antimicrobial properties (95-100% killing). The inclusion of polyphenols/flavonoids and εPL leads to absolute bacterial eradication, and in vitro assessments using HaCaT cells indicate increased cell proliferation, decreased reactive oxygen species (ROS) production, and enhanced cell viability (100% Cell viability). The dressings display notable alterations in color that correspond to different wound conditions. Specifically, they exhibit a red/violet hue under healthy wound conditions (pH 4-6.5) and a green/blue color under unhealthy wound conditions (pH > 6.5). These distinctive color changes provide valuable insights into the versatile applications of the dressings in the care and management of wounds. Our findings suggest that these antibiotic-free smart hydrogel wound dressings hold promise as an effective and sustainable solution for chronic wounds, providing simultaneous infection control and diagnostic monitoring. This research contributes to advancing the field of wound care, offering a potential paradigm shift in the development of next-generation wound dressings.

An Erythrocyte-Templated Iron Single-Atom Nanozyme for Wound Healing

Iron single-atom nanozymes represent a promising artificial enzyme with superior activity owing to uniform active sites that can precisely mimic active center of nature enzymes. However, current synthetic strategies are hard to guarantee each active site at single-atom state. In this work, an erythrocyte-templated strategy by utilizing intrinsic hemin active center of hemoglobin as sing-atom source for nanozyme formation is developed. By combining cell fixation, porous salinization, and high-temperature carbonization, erythrocytes are successfully served as uniform templates to synthesize nanozymes with fully single-atom FeN4 active sites which derived from hemin of hemoglobin, resulting in an enhanced peroxidase (POD)-like activity. Interestingly, the catalytic activity of erythrocyte-templated nanozyme (ETN) shows dependence on animal species, among which murine ETN performed superior catalytic efficiency. In addition, the as-prepared ETNs display a honeycomb-like network structure, serving as a sponge to accelerate hemostasis based on the interactions with prothrombin and fibrinogen. These features enable ETN to effectively kill methicillin-resistant Staphylococcus aureus (MRSA) by combining POD-like catalysis with near-infrared (NIR) induced photothermal effect, and subsequently suitable to promote wound healing. This study provides a proof-of-concept for facile fabrication of multifunctional nanozymes with uniform single-atom active sites by utilizing intrinsic iron structure characteristics of biogenic source like erythrocytes.

Copper-Zinc-Doped Bilayer Bioactive Glasses Loaded Hydrogel with Spatiotemporal Immunomodulation Supports MRSA-Infected Wound Healing

Developing biomaterials with antimicrobial and wound-healing activities for the treatment of wound infections remains challenging. Macrophages play non-negligible roles in healing infection-related wounds. In this study, a new sequential immunomodulatory approach is proposed to promote effective and rapid wound healing using a novel hybrid hydrogel dressing based on the immune characteristics of bacteria-associated wounds. The hydrogel dressing substrate is derived from a porcine dermal extracellular matrix (PADM) and loaded with a new class of bioactive glass nanoparticles (BGns) doped with copper (Cu) and zinc (Zn) ions (Cu-Zn BGns). This hybrid hydrogel demonstrates a controlled release of Cu2+ and Zn2+ and sequentially regulates the phenotypic transition of macrophages from M1 to M2 by alternately activating nucleotide-binding oligomerization domain (NOD) and inhibiting mitogen-activated protein kinases (MAPK) signaling pathways. Additionally, its dual-temporal bidirectional immunomodulatory function facilitates enhanced antibacterial activity and wound healing. Hence, this novel hydrogel is capable of safely and efficiently accelerating wound healing during infections. As such, the design strategy provides a new direction for exploring novel immunomodulatory biomaterials to address current clinical challenges related to the treatment of wound infections.

An antibacterial nanoclay- and chitosan-based quad composite with controlled drug release for infected skin wound healing

Microbial infections of surgical sites and other wounds represent a major impediment for patients. Multifunctional low-cost dressings promoting tissue reparation while preventing infections are of great interest to medical professionals. Here, clay-based laponite nanodiscs (LAP) were loaded with the antibacterial drug kanamycin (KANA) before being embedded into a poly(lactic-co-glycolic acid) (PLGA) membrane and coated with the biopolymer chitosan (CS). Results indicated that these biocompatible materials combined the excellent capacity of LAP for controlled drug release with the mechanical robustness of PLGA and the antibacterial properties of CS as well as its hydrophilicity to form a composite highly suitable as an infection-preventing wound dressing. In vitro, PLGA/LAP/KANA/CS released drugs in a sustainable manner over 30 d, completely inhibited the growth of infectious bacteria, prompted the adhesion fibroblasts, and accelerated their proliferation 1.3 times. In vivo, the composite enabled the fast healing of infected full-thickness skin wounds with a 96.19 % contraction after 14 d. During the healing process, PLGA/LAP/KANA/CS stimulated re-epithelization, reduced inflammation, and promoted both angiogenesis and the formation of dense collagen fibers with an excellent final collagen volume ratio of 89.27 %. Thus, multifunctional PLGA/LAP/KANA/CS made of low-cost components demonstrated its potential for the treatment of infected skin wounds.

Essential Oils Infused Poly-ε-Caprolactone/Gelatin Electrospun Nanofibrous Mats: Biocompatibility and Antibacterial Study

Infections caused by antibiotic-resistant pathogens result in a delayed wound-healing process. As an approach to prevent infections, alternatives in the form of natural antimicrobial products have become public interest. Essential oils derived from plants are used as antimicrobials owing to their broad-spectrum activity against pathogenic organisms. In this study, essential oil from seeds of watermelon, jackfruit, and papaya was incorporated into poly-ε-caprolactone/gelatin nanofibers using an electrospinning technique. The synthesized nanofibers were smooth, continuous, and bead-free. The nanofibers were found to be mechanically competent as confirmed by the universal tensile tester. The antibacterial activity of the various essential oil-loaded nanofibrous mats was determined by disc diffusion assay. Furthermore, they were found to be non-toxic and biocompatible by MTT and CMFDA assays on fibroblast cells. The obtained results have demonstrated that essential oil-loaded nanofiber mats are promising alternatives to conventional antibacterial wound dressings.

An Observational Study of Knowledge of First Aid for Burns among Parents in Indonesia

Burns represent a large portion of injuries attending emergency departments each year, with children accounting for the biggest proportion. Appropriate first aid has been shown to help improve the outcome of burns and decrease the need for surgical intervention. Several studies outside of Indonesia demonstrate inadequate parental knowledge of burns first aid, but few evaluated interventions to improve knowledge. A period of data gathering from June to September 2022 was included the parents who have offspring aged between 18 and 12. This questionnaire was developed to achieve the objectives of this study and was based on others of a similar nature. A total of 102 participants were included in this study. In total, 102 parents (79.4% female [n = 81], 20.6% male [n = 21]) were questioned. Baseline knowledge was found to be poor overall; it was found that nearly 91% of parents did not know the first-aid procedures for treating pediatric burns. However, educational initiatives were effective in advancing this knowledge. When a child got burned, nearly 68% of parents knew to use cold running water, and about 70% knew to get help from a doctor. Cold running water being applied is an extremely positive sign, which can have the most beneficial effect on the healing of the injury. No other variables analyzed were shown to be statistically significant predictors of pre- or post-test scores (all P > 0.05). This study concluded that educational knowledge was effective to improve the parents' ability in performing first aid for burn care.

Alumina Ceramic Nanofibers: An Overview of the Spinning Gel Preparation, Manufacturing Process, and Application

As an important inorganic material, alumina ceramic nanofibers have attracted more and more attention because of their excellent thermal stability, high melting point, low thermal conductivity, and good chemical stability. In this paper, the preparation conditions for alumina spinning gel, such as the experimental raw materials, spin finish aid, aging time, and so on, are briefly introduced. Then, various methods for preparing the alumina ceramic nanofibers are described, such as electrospinning, solution blow spinning, centrifugal spinning, and some other preparation processes. In addition, the application of alumina ceramic nanofibers in thermal insulation, high-temperature filtration, catalysis, energy storage, water restoration, sound absorption, bioengineering, and other fields are described. The wide application prospect of alumina ceramic nanofibers highlights its potential as an advanced functional material with various applications. This paper aims to provide readers with valuable insights into the design of alumina ceramic nanofibers and to explore their potential applications, contributing to the advancement of various technologies in the fields of energy, environment, and materials science.

Emerging Polymer-Based Nanosystem Strategies in the Delivery of Antifungal Drugs

Nanosystems-based antifungal agents have emerged as an effective strategy to address issues related to drug resistance, drug release, and toxicity. Among the diverse materials employed for antifungal drug delivery, polymers, including polysaccharides, proteins, and polyesters, have gained significant attention due to their versatility. Considering the complex nature of fungal infections and their varying sites, it is crucial for researchers to carefully select appropriate polymers based on specific scenarios when designing antifungal agent delivery nanosystems. This review provides an overview of the various types of nanoparticles used in antifungal drug delivery systems, with a particular emphasis on the types of polymers used. The review focuses on the application of drug delivery systems and the release behavior of these systems. Furthermore, the review summarizes the critical physical properties and relevant information utilized in antifungal polymer nanomedicine delivery systems and briefly discusses the application prospects of these systems.

Ultrasound-triggered piezocatalytic composite hydrogels for promoting bacterial-infected wound healing

Wound healing has become one of the basic issues faced by the medical community because of the susceptibility of skin wounds to bacterial infection. As such, it is highly desired to design a nanocomposite hydrogel with excellent antibacterial activity to achieve high wound closure effectiveness. Here, based on ultrasound-triggered piezocatalytic therapy, a multifunctional hydrogel is designed to promote bacteria-infected wound healing. Under ultrasonic vibration, the surface of barium titanate (BaTiO3, BT) nanoparticles embedded in the hydrogel rapidly generate reactive oxygen species (ROS) owing to the established strong built-in electric field, endowing the hydrogel with superior antibacterial efficacy. This modality shows intriguing advantages over conventional photodynamic therapy, such as prominent soft tissue penetration ability and the avoidance of serious skin phototoxicity after systemic administration of photosensitizers. Moreover, the hydrogel based on N-[tris(hydroxymethyl)methyl]acrylamide (THM), N-(3-aminopropyl)methacrylamide hydrochloride (APMH) and oxidized hyaluronic acid (OHA) exhibits outstanding self-healing and bioadhesive properties able to accelerate full-thickness skin wound healing. Notably, compared with the widely reported mussel-inspired adhesive hydrogels, OHA/THM-APMH hydrogel due to the multiple hydrogen bonds from unique tri-hydroxyl structure overcomes the shortage that catechol groups are easily oxidized, giving it long-term and repeatable adhesion performance. Importantly, this hybrid hydrogel confines BT nanoparticles to wound area and locally induced piezoelectric catalysis under ultrasound to eradicate bacteria, markedly improving the therapeutic biosafety and exhibits great potential for harmless treatment of bacteria-infected tissues.

Wound healing promotion by flaxseed extract-loaded polyvinyl alcohol/chitosan nanofibrous scaffolds

Impaired wound healing is a severe complication of sufferers, related to prolonged wound closure, a high infection rate, and eventually disabilities of organs. To aid resolve this issue, we developed the electrospun polyvinyl alcohol and chitosan (PVA/CS) nanofibrous scaffold-loaded flaxseed extract. The scaffold containing 10 wt% of the extract indicated a three-dimensional cross-network with a nano-scale diameter (257 ± 37 nm) and smooth surface. Also, the relevant analyses confirmed high water absorption, porosity, and wettability of the scaffold. Fourier-transform infrared (FTIR), degradation, and mechanical studies revealed the intact presence and loading of the extract into the scaffold, the complete degradation over 48 h, and a high tensile elastic modulus. Besides, the advanced scaffold displayed remarkable anti-oxidant and could inhibit the growth of both Gram-positive and negative bacteria compared to the free PVA/CS scaffold. Desired fibroblast viability and blood compatibility of flaxseed-loaded scaffold endorsed the biocompatibility for wound zones. The in vitro studies showed that the flaxseed-loaded scaffold resulted in an accelerated wound healing process and 100 % closure of the scratched area within 48 h. The results obtained reveal that the flaxseed-loaded PVA/CS electrospun scaffold could be effectively applied for wound healing promotion.

Electrospun Conducting Polymers: Approaches and Applications

Inherently conductive polymers (CPs) can generally be switched between two or more stable oxidation states, giving rise to changes in properties including conductivity, color, and volume. The ability to prepare CP nanofibers could lead to applications including water purification, sensors, separations, nerve regeneration, wound healing, wearable electronic devices, and flexible energy storage. Electrospinning is a relatively inexpensive, simple process that is used to produce polymer nanofibers from solution. The nanofibers have many desirable qualities including high surface area per unit mass, high porosity, and low weight. Unfortunately, the low molecular weight and rigid rod nature of most CPs cannot yield enough chain entanglement for electrospinning, instead yielding polymer nanoparticles via an electrospraying process. Common workarounds include co-extruding with an insulating carrier polymer, coaxial electrospinning, and coating insulating electrospun polymer nanofibers with CPs. This review explores the benefits and drawbacks of these methods, as well as the use of these materials in sensing, biomedical, electronic, separation, purification, and energy conversion and storage applications.

In Situ Transformation of Electrospun Nanofibers into Nanofiber-Reinforced Hydrogels

Nanofiber-reinforced hydrogels have recently gained attention in biomedical engineering. Such three-dimensional scaffolds show the mechanical strength and toughness of fibers while benefiting from the cooling and absorbing properties of hydrogels as well as a large pore size, potentially aiding cell migration. While many of such systems are prepared by complicated processes where fibers are produced separately to later be embedded in a hydrogel, we here provide proof of concept for a one-step solution. In more detail, we produced core-shell nanofibers from the natural proteins zein and gelatin by coaxial electrospinning. Upon hydration, the nanofibers were capable of directly transforming into a nanofiber-reinforced hydrogel, where the nanofibrous structure was retained by the zein core, while the gelatin-based shell turned into a hydrogel matrix. Our nanofiber-hydrogel composite showed swelling to ~800% of its original volume and water uptake of up to ~2500% in weight. The physical integrity of the nanofiber-reinforced hydrogel was found to be significantly improved in comparison to a hydrogel system without nanofibers. Additionally, tetracycline hydrochloride was incorporated into the fibers as an antimicrobial agent, and antimicrobial activity against Staphylococcus aureus and Escherichia coli was confirmed.

Recent Progress on Bioinspired Antibacterial Surfaces for Biomedical Application

Surface bacterial fouling has become an urgent global challenge that calls for resilient solutions. Despite the effectiveness in combating bacterial invasion, antibiotics are susceptible to causing microbial antibiotic resistance that threatens human health and compromises the medication efficacy. In nature, many organisms have evolved a myriad of surfaces with specific physicochemical properties to combat bacteria in diverse environments, providing important inspirations for implementing bioinspired approaches. This review highlights representative natural antibacterial surfaces and discusses their corresponding mechanisms, including repelling adherent bacteria through tailoring surface wettability and mechanically killing bacteria via engineering surface textures. Following this, we present the recent progress in bioinspired active and passive antibacterial strategies. Finally, the biomedical applications and the prospects of these antibacterial surfaces are discussed.

Biopaper Based on Ultralong Hydroxyapatite Nanowires and Cellulose Fibers Promotes Skin Wound Healing by Inducing Angiogenesis

Skin injury that is difficult to heal caused by various factors remains a major clinical challenge. Hydroxyapatite (HAP) has high potential for wound healing owing to its high biocompatibility and adequate angiogenic ability, while traditional HAP materials are not suitable for wound dressing due to their high brittleness and poor mechanical properties. To address this challenge, we developed a novel wound dressing made of flexible ultralong HAP nanowire-based biopaper. This biopaper is flexible and superhydrophilic, with suitable tensile strength (2.57 MPa), high porosity (77%), and adequate specific surface area (36.84 m2·g−1) and can continuously release Ca2+ ions to promote the healing of skin wounds. Experiments in vitro and in vivo show that the ultralong HAP nanowire-based biopaper can effectively induce human umbilical vein endothelial cells (HUVECs) treated with hypoxia and rat skin tissue to produce more angiogenic factors. The as-prepared biopaper can also enhance the proliferation, migration, and in vitro angiogenesis of HUVECs. In addition, the biopaper can promote the rat skin to achieve thicker skin re-epithelialization and the formation of new blood vessels, and thus promote the healing of the wound. Therefore, the ultralong HAP nanowire-based biopaper has the potential to be a safe and effective wound dressing and has significant clinical application prospects.

A review on Biopolymer-derived Electrospun Nanofibers for Biomedical and Antiviral Applications

Unique aspects of polymer-derived nanofibers provide significant potential in the area of biomedical and health care applications. Much research has demonstrated several plausible nanofibers to overcome the modern-day challenges in...

Polymeric Nanomaterials for Efficient Delivery of Antimicrobial Agents

Bacterial infections have threatened the lives of human beings for thousands of years either as major diseases or complications. The elimination of bacterial infections has always occupied a pivotal position in our history. For a long period of time, people were devoted to finding natural antimicrobial agents such as antimicrobial peptides (AMPs), antibiotics and silver ions or synthetic active antimicrobial substances including antimicrobial peptoids, metal oxides and polymers to combat bacterial infections. However, with the emergence of multidrug resistance (MDR), bacterial infection has become one of the most urgent problems worldwide. The efficient delivery of antimicrobial agents to the site of infection precisely is a promising strategy for reducing bacterial resistance. Polymeric nanomaterials have been widely studied as carriers for constructing antimicrobial agent delivery systems and have shown advantages including high biocompatibility, sustained release, targeting and improved bioavailability. In this review, we will highlight recent advances in highly efficient delivery of antimicrobial agents by polymeric nanomaterials such as micelles, vesicles, dendrimers, nanogels, nanofibers and so forth. The biomedical applications of polymeric nanomaterial-based delivery systems in combating MDR bacteria, anti-biofilms, wound healing, tissue engineering and anticancer are demonstrated. Moreover, conclusions and future perspectives are also proposed.

Polydopamine Nanosheets Doped Injectable Hydrogel with Nitric Oxide Release and Photothermal Effects for Bacterial Ablation and Wound Healing

The development of wound dressings with combined antibacterial activities and pro-healing functions has always been an intractable medical task for treating bacterial wound infection. Herein, a novel injectable hybrid hydrogel dressing is developed, which is doped with nitric oxide (NO) donor (N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine, BNN6) loaded two-dimensional polydopamine nanosheets (PDA NS). The hydrogel matrix is in situ formed through dynamic Schiff base crosslinking between hydrazide-modified γ-polyglutamic acid (γ-PGA-ADH) and aldehyde-terminated Pluronic F127 (F127-CHO). Under 808 nm irradiation, the embedded PDA NS exhibits outstanding photothermal transform properties (56.1%) and on-demand NO release. The combination of photothermal and NO gas therapy with a synergistic antibacterial effect works on both Escherichia coli and Staphylococcus aureus in vitro. Furthermore, a full-thickness skin defect model also demonstrates that the hybrid hydrogel shows outstanding antibacterial properties and effectively accelerates the wound healing process. Overall, this study provides a facile and promising method for the fabrication of PDA NS based multifunctional hydrogel dressing for the application of infectious skin wound healing.

Tailoring the proliferation of fibroblast cells by multiresponsive and thermosensitive stem cells composite F127 hydrogel containing folic acid.MgO:ZnO/chitosan hybrid microparticles for skin regeneration

In this study, biodegradable and thermosensitive F127 hydrogel containing folic acid.MgO:ZnO/chitosan hybrid particles (FMZC) was fabricated as a 3D mesenchymal stem cells (MSCs) delivery vehicle for regenerative medicine and wound healing purposes, in such a way to be responsive to lysozyme and UVA irradiation. The results showed that F127 hydrogel containing FMZC is a suitable and nontoxic construct for encapsulation of MSCs in the presence of lysozyme and UVA irradiation, bearing high stem cell viability and proliferation. The final hydrogel, MSC&FMZC, in response to lysozyme induced a higher proliferation rate and migration in human foreskin fibroblast cells (HFF). These phenomena were attributed to the released F.MgO:ZnO nanocomposites from chitosan microparticles and paracrine factors from MSCs within the hydrogel, resulting in synergistic biological effects. Moreover, lysozyme-treated MSC&FMZC hydrogel showed higher antibacterial and anti-biofilm activity against both Gram-positive and Gram-negative bacteria than bare hydrogel. However, a significant increase in the antibacterial activity of MSC&FMZC was observed as the treated bacteria were subjected to UVA irradiation owing to the photocatalytic activity of F.MgO:ZnO nanocomposites. Regarding the antibacterial activity and stimulating skin cell behavior of MSC&FMZC hydrogel that can promote the regenerative activities of skin, it could be considered as a promising scaffold for bacteria-accompanied wound healing.

Biocompatible, antibacterial and anti-inflammatory zinc ion cross-linked quaternized cellulose‑sodium alginate composite sponges for accelerated wound healing

Bacterial infection has become one of the most challenges for wound healing, which causes serious inflammatory response and delays the healing process. Herein, a novel sponge with excellent biocompatible, antibacterial and anti-inflammatory properties based on quaternized cellulose (QC), sodium alginate (SA) and Zn²⁺ was reported. The existence of physical interactions, such as electrostatic interaction, chelation and hydrogen bonding endowed the sponges with enhanced mechanical property. The composite sponges exhibited outstanding biocompatibility and hemostatic efficiency due to the compatible nature of the component and physical cross-linking, as well as superior antibacterial property benefited from the synergistic effects of steady Zn²⁺ release and quaternary ammonium group. In vivo investigation validated that the enhanced antibacterial and anti-inflammatory effect of the sponges, which significantly promoted wound closure and the reconstruction of skin tissue through epithelial regeneration, collagen deposition and mitigating inflammatory cell infiltration. Overall, the novel sponge demonstrated great potentials in bacteria-associated wound management.

Challenges and solutions in polymer drug delivery for bacterial biofilm treatment: A tissue-by-tissue account

To tackle the emerging antibiotic resistance crisis, novel antimicrobial approaches are urgently needed. Bacterial communities (biofilms) are a particular concern in this context. Biofilms are responsible for most human infections and are inherently less susceptible to antibiotic treatments. Biofilms have been linked with several challenging chronic diseases, including implant-associated osteomyelitis and chronic wounds. The specific local environments present in the infected tissues further contribute to the rise in antibiotic resistance by limiting the efficacy of systemic antibiotic therapies and reducing drug concentrations at the infection site, which can lead to reoccurring infections. To overcome the shortcomings of systemic drug delivery, encapsulation within polymeric carriers has been shown to enhance antimicrobial efficacy, permeation and retention at the infection site. In this Review, we present an overview of current strategies for antimicrobial encapsulation within polymeric carriers, comparing challenges and solutions on a tissue-by-tissue basis. We compare challenges and proposed drug delivery solutions from the perspective of the local environments for biofilms found in oral, wound, gastric, urinary tract, bone, pulmonary, vaginal, ocular and middle/inner ear tissues. We will also discuss future challenges and barriers to clinical translation for these therapeutics. The following Review demonstrates there is a significant imbalance between the research focus being placed on different tissue types, with some targets (oral and wound biofims) being extensively more studied than others (vaginal and otitis media biofilms and endocarditis). Furthermore, the importance of the local tissue environment when selecting target therapies is demonstrated, with some materials being optimal choices for certain sites of bacterial infection, while having limited applicability in others.

Gelatin hydrogel/contact lens composites as rutin delivery systems for promoting corneal wound healing

Corneal wound healing is a highly regulated biological process that is of importance for reducing the risk of blinding corneal infections and inflammations. Traditional eye drop was the main approach for promoting corneal wound healing. However, its low bioavailability required a high therapeutic concentration, which can lead to ocular or even systemic side effects. To develop a safe and effective method for treating corneal injury, we fabricated rutin-encapsulated gelatin hydrogel/contact lens composites by dual crosslinking reactions including in situ free radical polymerization and carboxymethyl cellulose/N-hydroxysulfosuccinimide crosslinking. In vitro drug release results evidenced that rutin in the composites could be sustainedly released for up to 14 days. In addition, biocompatibility assay indicated nontoxicity of the composites. Finally, the effect of rutin-encapsulated composites on the healing of the corneal injury in rabbits was investigated. The injury was basically cured in corneas using rutin-encapsulated composites (healing rate, 98.3% ± 0.7%) at 48 h post-operation, while the damage was still present in corneas using the composite (healing rate, 87.0% ± 4.5%). Further proteomics analysis revealed that corneal wound healing may be promoted by the ERK/MAPK and PI3K/AKT signal pathways. These results inform a potential intervention strategy to facilitate corneal wound healing in humans.

Advances in multifunctional chitosan-based self-healing hydrogels for biomedical applications

Multifunctional self-healing hydrogels have recently attracted considerable interest in biomedical applications owing to their diverse properties, including self-healing, adhesion, conduction, antibacterial, and stimulus-response, which can meet various application requirements, ranging from wound dressings and delivery vehicles to the production of scaffolds for tissue repair and regeneration. As a natural polycationic polysaccharide with good biocompatibility, chitosan is widely used in hydrogel formation as there are many amino and hydroxyl groups along the chains that can actively participate in various physical effects and chemical reactions, which enable it to construct self-healing hydrogels and fulfill multiple functions. In this review, the formation of chitosan-based self-healing hydrogels and the related self-healing mechanism are summarized, including Schiff base, metal coordination, ionic and hydrogen bonds, hydrophobic and host-guest interactions, with a focus on the strategies for their multi-functionalization. In the last section, the applications of the chitosan-based self-healing hydrogels in the fields of wound dressings, delivery vehicles, scaffolds, and biological sensors are discussed. Overall, it is highly expected that this review could provide an insight into the prospective development of multifunctional self-healing hydrogels for biomedical applications.

Performance of Polydopamine Complex and Mechanisms in Wound Healing

Polydopamine (PDA) has been gradually applied in wound healing of various types in the last three years. Due to its rich phenol groups and unique structure, it can be combined with a variety of materials to form wound dressings that can be used for chronic infection, tissue repair in vivo and serious wound healing. PDA complex has excellent mechanical properties and self-healing properties, and it is a stable material that can be used for a long period of time. Unlike other dressings, PDA complexes can achieve both photothermal therapy and electro activity. In this paper, wound healing is divided into four stages: antibacterial, anti-inflammatory, cell adhesion and proliferation, and re-epithelialization. Photothermal therapy can improve the bacteriostatic rate and remove reactive oxygen species to inhibit inflammation. Electrical signals can stimulate cell proliferation and directional migration. With low reactive oxygen species (ROS) levels, inflammatory factors are down-regulated and growth factors are up-regulated, forming regular collagen fibers and accelerating wound healing. Finally, five potential development directions are proposed, including increasing drug loading capacity, optimization of drug delivery platforms, improvement of photothermal conversion efficiency, intelligent electroactive materials and combined 3D printing.

Recent advances in nanotherapeutics for the treatment of burn wounds

Moderate or severe burns are potentially devastating injuries that can even cause death, and many of them occur every year. Infection prevention, anti-inflammation, pain management and administration of growth factors play key roles in the treatment of burn wounds. Novel therapeutic strategies under development, such as nanotherapeutics, are promising prospects for burn wound treatment. Nanotherapeutics, including metallic and polymeric nanoformulations, have been extensively developed to manage various types of burns. Both human and animal studies have demonstrated that nanotherapeutics are biocompatible and effective in this application. Herein, we provide comprehensive knowledge of and an update on the progress of various nanoformulations for the treatment of burn wounds.

Cationic Lignin-Based Hyperbranched Polymers to Circumvent Drug Resistance in Pseudomonas Keratitis

The rise of antimicrobial-resistant bacteria strains has been a global public health concern due to their ability to cause increased patient morbidity and a greater burden on the healthcare system. As one of the potential solutions to overcome such bacterial infections, hyperbranched copolymers with cationic charges were developed. These copolymers were assessed for their antimicrobial efficacy and their bactericidal mechanisms. They were found to be potent against mobile colistin-resistant 1 strains, which was significant as colistin is known to be the last-resort antibiotic against Gram-negative bacteria. Furthermore, there was no sign of mutational resistance developed by E. Coli ATCC 25922 and MCR 1+ E. Coli against the copolymer even up to 20 passages. The ability to evade inducing resistance would provide invaluable insights for future antibiotic development. Our studies suggest that the bactericidal efficacy comes from the ability to target the outer membrane efficaciously. In vivo study using a Pseudomonas keratitis model showed that the copolymer was compatible with the eye and further supported that the copolymer treatment was effective for complete bacteria elimination.

Poly(amino acid) based fibrous membranes with tuneable in vivo biodegradation

In this work two types of biodegradable polysuccinimide-based, electrospun fibrous membranes are presented. One contains disulfide bonds exhibiting a shorter (3 days) in vivo biodegradation time, while the other one has alkyl crosslinks and a longer biodegradation time (more than 7 days). According to the mechanical measurements, the tensile strength of the membranes is comparable to those of soft the connective tissues and visceral tissues. Furthermore, the suture retention test suggests, that the membranes would withstand surgical handling and in vivo fixation. The in vivo biocompatibility study demonstrates how membranes undergo in vivo hydrolysis and by the 3rd day they become poly(aspartic acid) fibrous membranes, which can be then enzymatically degraded. After one week, the disulfide crosslinked membranes almost completely degrade, while the alkyl-chain crosslinked ones mildly lose their integrity as the surrounding tissue invades them. Histopathology revealed mild acute inflammation, which diminished to a minimal level after seven days.

Advancements in release-active antimicrobial biomaterials: A journey from release to relief

Escalating medical expenses due to infectious diseases are causing huge socioeconomic pressure on mankind globally. The emergence of antibiotic resistance has further aggravated this problem. Drug-resistant pathogens are also capable of forming thick biofilms on biotic and abiotic surfaces to thrive in a harsh environment. To address these clinical problems, various strategies including antibacterial agent delivering matrices and bactericidal coatings strategies have been developed. In this review, we have discussed various types of polymeric vehicles such as hydrogels, sponges/cryogels, microgels, nanogels, and meshes, which are commonly used to deliver antibiotics, metal nanoparticles, and biocides. Compositions of these polymeric matrices have been elaborately depicted by elucidating their chemical interactions and potential activity have been discussed. On the other hand, various implant/device-surface coating strategies which exploit the release-active mechanism of bacterial killing are discussed in elaboration. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Efficacy of Water-Soluble Pearl Powder Components Extracted by a CO2 Supercritical Extraction System in Promoting Wound Healing

Pearl powder is a biologically active substance that is widely used in traditional medicine, skin repair and maintenance. The traditional industrial extraction processes of pearl powder are mainly based on water, acid or enzyme extraction methods, all of which have their own drawbacks. In this study, we propose a new extraction process for these active ingredients, specifically, water-soluble components of pearl powder extracted by a CO2 supercritical extraction system (SFE), followed by the extraction efficiency evaluation. A wound-healing activity was evaluated in vitro and in vivo. This demonstrated that the supercritical extraction technique showed high efficiency as measured by the total protein percentage. The extracts exhibited cell proliferation and migration-promoting activity, in addition to improving collagen formation and healing efficiency in vivo. In brief, this study proposes a novel extraction process for pearl powder, and the extracts were also explored for wound-healing bioactivity, demonstrating the potential in wound healing.

Nanoparticle mediated RNA delivery for wound healing

Wound healing is a complicated physiological process that comprises various steps, including hemostasis, inflammation, proliferation, and remodeling. The wound healing process is significantly affected by coexisting disease states such as diabetes, immunosuppression, or vascular disease. It can also be impacted by age, repeated injury, or hypertrophic scarring. These comorbidities can affect the rate of wound closure, the quality of wound closure, and tissues' function at the affected sites. There are limited options to improve the rate or quality of wound healing, creating a significant unmet need. Advances in nucleic acid research and the human genome project have developed potential novel approaches to address these outstanding requirements. In particular, the use of microRNA, short hairpin RNA, and silencing RNA is unique in their abilities as key regulators within the physiologic machinery of the cell. Although this innovative therapeutic approach using ribonucleic acid (RNA) is an attractive approach, the application as a therapeutic remains a challenge due to site-specific delivery, off-target effects, and RNA degradation obstacles. An ideal delivery system is essential for successful gene delivery. An ideal delivery system should result in high bioactivity, inhibit rapid dilution, controlled release, allow specific activation timings facilitating physiological stability, and minimize multiple dosages. Currently, these goals can be achieved by inorganic nanoparticle (NP) (e.g., cerium oxide, gold, silica, etc.) based delivery systems. This review focuses on providing insight into the preeminent research carried out on various RNAs and their delivery through NPs for effective wound healing. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Antioxidant and multi-sensitive PNIPAAm/keratin double network gels for self-stripping wound dressing application

Hydrogel is a potential wound dressing material due to its ability to maintain a humid environment, the strong absorptive capacity of exuded tissue fluid, and gas exchange function. Herein, poly(N-isopropyl acrylamide)/keratin double network (PNIPAAm/keratin DN) gels were fabricated through covalent and ionic double cross-linking strategy. The effects of PNIPAAm/keratin ratios on the morphology and swelling rate of gels were characterized. The DN gels could swell up from 2600% to 4600% in proportion to the keratin content, demonstrating their great ability to absorb tissue fluid. The gels possessed thermo-sensitiveness, imparting self-stripping property. Moreover, the antibacterial chlorhexidine acetate (CHX) was loaded into gels with a post-fabrication drug-loading strategy. The release behavior showed that CHX-loaded DN gels exhibited multiple responsive characteristics (temperature, pH, and ROS). Furthermore, the drug-loaded gels showed greater antibacterial activity than free CHX due to the sustained drug release effect. Meanwhile, the antioxidant efficiency of PNIPAAm/keratin DN gels was ca. 33.1%, while the PNIPAAm gel was just ca. 18.2%, indicating the strong oxidation resistance of DN gels. In the Sprague Dawley (SD) rat skin defect model, the hydrogel had better tissue regeneration ability than the commercial film. Taken together, the multifunctional PNIPAAm/keratin DN gels are potential candidates for clinical wound treatment.

NIR-triggered photocatalytic and photothermal performance for sterilization based on copper sulfide nanoparticles anchored on Ti3C2Tx MXene

Harmful bacterial flourish with the increase in environmental pollution and pose a great threat to human health. Thus, developing new and efficient antibacterial materials is imperative to reduce the pollution caused by traditional sterilization materials and improve sterilization efficiency. In this study, a new photocatalytic antibacterial material was developed to achieve an efficient antibacterial effect. Ti₃C₂T_x@CuS composites were synthesized by simple hydrothermal method, by which copper sulfide (CuS) nanoparticles were anchored on the surface of Ti₃C₂T_x to sharply improve the photocatalytic its antibacterial ability. Ti₃C₂T_x@CuS exhibits excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with bactericidal rates of 99.6% and 99.1%, respectively. Photoluminescence spectroscopy (PL), decay time PL, photocurrent test, electrochemical impedance spectroscopy and finite element method showed that the formation of Ti₃C₂T_x@CuS heterojunction promoted the separation of electrons and holes, improved the electron transport efficiency, and elevated the generation of reactive oxygen species. Moreover, Ti₃C₂T_x@CuS has a stronger photothermal effect and causes more heat release than CuS to improve antibacterial performance. The Ti₃C₂T_x@CuS heterojunction has a broad application prospect in the disinfection and antibacterial fields.

Non-Toxic Crosslinking of Electrospun Gelatin Nanofibers for Tissue Engineering and Biomedicine-A Review

Electrospinning can be used to prepare nanofiber mats from diverse polymers, polymer blends, or polymers doped with other materials. Amongst this broad range of usable materials, biopolymers play an important role in biotechnological, biomedical, and other applications. However, several of them are water-soluble, necessitating a crosslinking step after electrospinning. While crosslinking with glutaraldehyde or other toxic chemicals is regularly reported in the literature, here, we concentrate on methods applying non-toxic or low-toxic chemicals, and enzymatic as well as physical methods. Making gelatin nanofibers non-water soluble by electrospinning them from a blend with non-water soluble polymers is another method described here. These possibilities are described together with the resulting physical properties, such as swelling behavior, mechanical strength, nanofiber morphology, or cell growth and proliferation on the crosslinked nanofiber mats. For most of these non-toxic crosslinking methods, the degree of crosslinking was found to be lower than for crosslinking with glutaraldehyde and other common toxic chemicals.

Core-Shell Structured Antimicrobial Nanofiber Dressings Containing Herbal Extract and Antibiotics Combination for the Prevention of Biofilms and Promotion of Cutaneous Wound Healing

Burn wounds are susceptible to microbial invasion from both resident and exogenous bacteria, which becomes a critical public health issue and causes substantial economic burden. There is a perceived demand to produce new antimicrobial wound dressings that hinder bacterial colonization while accelerating the healing process and hence would provide an improved standard of care for patients. Since ancient times, herbal extracts from medicinally important plants have extensively been used for treating burn injuries. This work reports the utility of electrospun nanofibers containing plant extracts and antibiotics combination as a multifunctional scaffold for treating second-degree burns. First, we determined the various components of plant extracts from Gymnema sylvestre by two different processing methods and their synergism with minocycline antibiotics. Then, we prepared core-shell nanofibrous dressings with poly-ε-caprolactone/gelatin laden with minocycline hydrochloride as a shell and gelatin infused with G. sylvestre extracts (ultrasound-assisted extracts and cold macerated extracts) as the core using coaxial electrospinning. The electrospun nanofibers displayed a smooth, continuous, and bead-free morphology with adequate wettability. The presence of extract components in the core-shell nanofibers resulted in enhanced mechanical properties when compared to pristine mats. The core-shell structures resulted in sustained release of the bioactive components when compared to nanofiber blends. Core-shell nanofiber mats containing plant extracts and antibiotic combinations displayed potent antimicrobial and antibiofilm properties while promoting the spread and proliferation of skin cells when compared to pristine mats. In a porcine model of cutaneous second-degree burns, we showed that wounds treated with the antimicrobial dressing improved re-epithelialization and collagen organization in comparison to untreated wounds.

Pearl Powder-An Emerging Material for Biomedical Applications: A Review

Pearl powder is a well-known traditional Chinese medicine for a variety of indications from beauty care to healthcare. While used for over a thousand years, there has yet to be an in-depth understanding and review in this area. The use of pearl powder is particularly growing in the biomedical area with various benefits reported due to the active ingredients within the pearl matrix itself. In this review, we focus on the emerging biomedical applications of pearl powder, touching on applications of pearl powder in wound healing, bone repairing, treatment of skin conditions, and other health indications.

Antimicrobial core-shell electrospun nanofibers containing Ajwain essential oil for accelerating infected wound healing

Treatment of skin injuries is still facing major challenges, such as chronicity and infections, particularly those caused by multi-drug resistance pathogens. An effective treatment of such wounds should accelerate the wound healing process while preventing bacterial contamination. Here, a novel core-shell nanofiber mat was fabricated comprising gelatin/polyvinyl alcohol (as a core) and aloe vera/arabinose/polyvinylpyrrolidone (as a shell) for accelerating the healing process of bacteria-infected wounds. Trachyspermum Ammi (Ajwain) essential oil (EO), as a potent and natural antimicrobial agent against microorganisms, was incorporated into the core of nanofiber mats using coaxial electrospinning. The microscopy images demonstrated the successful fabrication of the core-shell structure with a uniform fiber size of 564 ± 106.35 nm. Moreover, Ajwain EO-loaded nanofiber mat (core-shell/EO) provided excellent antimicrobial activity and antioxidant ability. The in vitro and ex vivo release of Ajwain EO from the fabricated nanofiber mat corroborated a prolonged release profile. Furthermore, in vivo antibacterial activity, wound closure, and histomorphological examinations showed the high efficacy of the core-shell/EO mat in the treatment of Staphylococcus aureus-infected full-thickness rat wounds compared to standard control treatment with a gauze. Overall, these results represent the core-shell/EO mat's potential as a newly developed wound dressing for bacteria-infected full-thickness skin injuries.

Drug-Eluting Medical Textiles: From Fiber Production and Textile Fabrication to Drug Loading and Delivery

Drug-eluting medical textiles have recently gained great attention to be used in different applications due to their cost effectiveness and unique physical and chemical properties. Using various fiber production and textile fabrication technologies, fibrous constructs with the required properties for the target drug delivery systems can be designed and fabricated. This review summarizes the current advances in the fabrication of drug-eluting medical textiles. Different fiber production methods such as melt-, wet-, and electro-spinning, and textile fabrication techniques such as knitting and weaving are explained. Moreover, various loading processes of bioactive agents to obtain drug-loaded fibrous structures with required physicochemical and morphological properties, drug delivery mechanisms, and drug release kinetics are discussed. Finally, the current applications of drug-eluting fibrous systems in wound care, tissue engineering, and transdermal drug delivery are highlighted.

A New Potent Antimicrobial Metalloporphyrin

A series of bis-acryl functionalized porphyrins and their corresponding metalloporphyrins (M=Co, Mn) were synthesized and investigated for their antimicrobial properties through MIC screening and bacteria time-kill kinetic studies. The Mn(III) 4-(bis)methylphenyl-substituted-porphyrins showed superior batericidal activities even in the dark with low hemotoxicity and good cytotoxicity profile.

Electrospun nanofibers promote wound healing: theories, techniques, and perspectives

At present, the clinical strategies for treating chronic wounds are limited, especially when it comes to pain relief and rapid wound healing. Therefore, there is an urgent need to develop alternative treatment methods. This paper provides a systematic review on recent researches on how electrospun nanofiber scaffolds promote wound healing and how the electrospinning technology has been used for fabricating multi-dimensional, multi-pore and multi-functional nanofiber scaffolds that have greatly promoted the development of wound healing dressings. First, we provide a review on the four stages of wound healing, which is followed by a discussion on the evolvement of the electrospinning technology, what is involved in electrospinning devices, and factors affecting the electrospinning process. Finally, we present the possible mechanisms of electrospun nanofibers to promote wound healing, the classification of electrospun polymers, cell infiltration favoring fiber scaffolds, antibacterial fiber scaffolds, and future multi-functional scaffolds. Although nanofiber scaffolds have made great progress as a type of multi-functional biomaterial, major challenges still remain for commercializing them in a way that fully meets the needs of patients.

Therapy of infected wounds: overcoming clinical challenges by advanced drug delivery systems

In recent years, the incidence of infected wounds is steadily increasing, and so is the clinical as well as economic interest in effective therapies. These combine reduction of pathogen load in the wound with general wound management to facilitate the healing process. The success of current therapies is challenged by harsh conditions in the wound microenvironment, chronicity, and biofilm formation, thus impeding adequate concentrations of active antimicrobials at the site of infection. Inadequate dosing accuracy of systemically and topically applied antibiotics is prone to promote development of antibiotic resistance, while in the case of antiseptics, cytotoxicity is a major problem. Advanced drug delivery systems have the potential to enable the tailor-made application of antimicrobials to the side of action, resulting in an effective treatment with negligible side effects. This review provides a comprehensive overview of the current state of treatment options for the therapy of infected wounds. In this context, a special focus is set on delivery systems for antimicrobials ranging from semi-solid and liquid formulations over wound dressings to more advanced carriers such as nano-sized particulate systems, vesicular systems, electrospun fibers, and microneedles, which are discussed regarding their potential for effective therapy of wound infections. Further, established and novel models and analytical techniques for preclinical testing are introduced and a future perspective is provided.

A simple, green chemistry technology for fabrication of tissue-engineered scaffolds based on mussel-inspired 3D centrifugal spun

The fabrication of 3D fibrous scaffolds with highly interconnected pores has been crucial in the development of tissue regeneration techniques. The present study describes the fabrication of 3D fibrous scaffolds by freeze-drying of polydopamine (PDA) coated centrifugal spun gelatin fibers. We wanted to combine the mussel-inspired chemistry, Maillard reaction, and the 3D microstructural advantages of centrifugal spun fibers to develop the green fibrous scaffolds at low cost, high speed, and desired mold shape. The resultant PDA-gelatin fibers exhibited a smooth 3D microstructure with a uniform formation of PDA thin ad-layer that enhanced the mechanical properties and stability of the scaffolds, and thereby decreased the degradation rate. All scaffolds showed promising properties including good dimensional and mechanical stability under wet state, optimal porosity over 94%, and high water uptake of approximately 1500%. The results of cell culture studies, further confirmed that all scaffolds exhibited appropriate biocompatibility, cell proliferation, migration, and infiltration. Particularly, the PDA-coated scaffolds showed a significant enhancement in proliferation, migration, and infiltration of HDF-GFP⁺ cells. These results show that a 3D porous fibrous scaffold with simplifying tunable density and desirable shape on a large scale can be readily prepared for different fields of tissue engineering applications.

Nanocellulose from Cotton Waste and Its Glycidyl Methacrylate Grafting and Allylation: Synthesis, Characterization and Adsorption Properties

Nanocellulose (NC) is getting ahead as a renewable, biodegradable and biocompatible biomaterial. The NCs for this study were recovered from industrial cotton waste (CFT) by acid hydrolysis (HNC) and by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation (ONC). They were functionalized by radical based glycidyl methacrylate (GMA) grafting providing crystalline HNC-GMA and ONC-GMA, and by allylation (ALL) providing amorphous HNC-ALL and ONC-ALL. HNC, ONC and their derivatives were chemically and morphologically characterized. Crystalline NCs were found capable to adsorb, from diluted water solution (2 × 10^-3 M), the antibiotics vancomycin (VC), ciprofloxacin (CP), amoxicillin (AM) and the disinfectant chlorhexidine (CHX), while amorphous NCs did not show any significant adsorption properties. Adsorption capability was quantified by measuring the concentration change in function of the contact time. The adsorption kinetics follow the pseudo-second order model and show complex adsorption mechanisms investigated by an intraparticle diffusion model and interpreted by structure-property relationships. ONC and ONC-GMA loaded with VC, and HNC and HNC-GMA loaded with CP were not colonized by Staphylococcus aureus and by Klebsiella pneumonia and suggested long lasting release capability. Our results can envisage developing CFT derived NCs for environmental applications (water remediation) and for biomedical applications (antibacterial NC). Among the future developments, it could also be of interest to take advantage of acidic, glycidyl and allyl groups' reactivity to provide other NCs from the NC object of this study.

Prevention of pulmonary air leaks using a biodegradable tissue-adhesive fiber sheet based on Alaska pollock gelatin modified with decanyl groups

Tissue adhesives have been widely used in surgery to treat pulmonary air leaks. However, conventional adhesives have poor interfacial strength under wet conditions. To overcome this clinical problem, we modified Alaska pollock-derived gelatin to include decanyl (C10) groups (C10-ApGltn) and used electrospinning to create a tissue-adhesive fiber sheet (AdFS). C10-AdFS showed higher burst strength when adhering to porcine pleura compared with a sheet of original ApGltn (Org-ApGltn). Hematoxylin-eosin-stained sections after burst experiments reveal that a dense C10-AdFS layer remained on the surface of the porcine pleura. The effect of the degree of C10 modification of ApGltn on the burst strength was evaluated. ApGltn with a C10 modification ratio of 13 mol% amino groups (13C10-AdFS) exhibited the highest burst strength. Furthermore, from ex vivo experiments with extracted rat lung, 13C10-AdFS exhibited a higher burst strength (41 cm H₂O) than Org-AdFS. The decanyl groups in 13C10-AdFS interacted with the hydrophobic proteins and the lipid bilayers of the cells, resulting in the high interfacial strength between 13C10-AdFS and the pleura. Moreover, 13C10-AdFS samples implanted subcutaneously in the backs of rats were completely degraded within 21 days without any severe inflammation. These results show that 13C10-AdFS is a promising adhesive material for the treatment of pulmonary air leaks.