Nonwoven Releasing Propolis as a Potential New Wound Healing Method—A Review

Wound healing poses a serious therapeutic problem. Methods which accelerate tissue regeneration and minimize or eliminate complications are constantly being sought. This paper is aimed at evaluation of the potential use of biodegradable polymer nonwovens releasing propolis as wound healing dressings, based on the literature data. Propolis is honeybee product with antioxidant, antibacterial, antifungal, anticancer, anti-inflammatory, analgesic, and regenerative properties. Controlled release of this substance throughout the healing should promote healing process, reduce the risk of wound infection, and improve aesthetic effect. The use of biodegradable aliphatic polyesters and polyester carbonates as a propolis carrier eliminates the problem of local drug administration and dressing changes. Well-known degradation processes and kinetics of the active substance release allows the selection of the material composition appropriate to the therapy. The electrospinning method allows the production of nonwovens that protect the wound against mechanical damage. Moreover, this processing technique enables adjusting product properties by modifying the production parameters. It can be concluded that biodegradable polymer dressings, releasing a propolis, may find potential application in the treatment of complicated wounds, as they may increase the effectiveness of treatment, as well as improve the patient’s life quality.     

Heterogeneous surface properties on wallstents

Wallstent has been successfully used to open up clogged peripheral arteries. Co? Cr alloy is the preferred metal for the construction of wallstent. Unfortunately, major complications such as in‐stent intimal hyperplasia,stent obstruction, and stent stricture are often reported, and these complications could be related to the metallic properties of the wallstent. In this study, the electrochemical properties of Co? Cr wires from wallstent were investigated using cyclic polarization, open‐circuit potential, potentiostatic condition, and electrochemical impedance spectroscopy. Scanning electron microscopy and X‐ray mapping were also employed to investigate the surface morphology and elemental distribution after electrochemical measurement. Results of this study showed the heterogeneous electrochemical properties of Co? Cr alloy wires that could result in severe galvanic corrosion of wallstent after implantation. Severe corrosion process could cause fracture of wallstent, resulting in localized inflammation, allergy, and thicker neointima. Copyright © 2009 John Wiley & Sons, Ltd.     

Biodegradable Sodium Alginate/Carrageenan/Cellulose Composite Hydrogel Wound Dressings Containing Herbal Extracts for Promoting Blood Coagulation and Wound Healing

Accelerating the coagulation process and preventing wound infection are major challenges in the wound care process. Therefore, new multifunctional wound dressings with procoagulant, antibacterial, and antioxidant properties have enormous potential for clinical application. In this work, biodegradable hydrogels containing herbal extracts are prepared for wound dressings. First, the active ingredients are extracted from Amaranthus spinosus (A. spinosus) and Rubia cordifolia (R. cordifolia) and added to the hydrogels prepared from microcrystalline cellulose (MCC), carrageenan, and sodium alginate. Then the composite hydrogels are air-dried to obtain the wound dressings. The wound dressings prepared in this work have good biocompatibility and moisture retention. The mechanical properties of the wound dressings are further improved with the addition of MCC. Besides, the wound dressings have excellent procoagulant, antibacterial, and antioxidant properties due to the presence of R. cordifolia extract. Overall, the most effective group of wound dressings with different ingredient formulations reduces clotting time by 75% and largely inhibits bacterial growth. The wound dressings perform well in the animal wound models to promote wound healing. These results indicate that the hydrogel wound dressings prepared in this work have great potential for medical applications.     

A self-expandable C-shaped 3D printing tracheal stent for combinatorial controlled paclitaxel release and tracheal support

Current tracheal stents palliatively relieve malignant tracheal stenosis but cannot treat the tumor, resulting in the occurrence of restenosis due to tumor progressive over-growth. Moreover, the stents block the entire tracheal mucosa contact with them and thus prevent mucus/sputum discharge, causing an airway blockage. In order to overcome those shortcomings, we study a novel self-expandable C-shaped tracheal stent loaded with paclitaxel (PTX), which consists of an inner poly (ε-caprolactone) layer, a middle Fe₃O₄ magnetic nanoparticles loaded poly (ε-caprolactone) layer and an outer PTX-loaded ethylene-vinyl acetate copolymer layer containing phase-change 1-hexadecanol. The C-shaped tracheal stents are easily fabricated on a roller by using a self-made specific three-dimensional printer. It is found that the stents present unidirectional PTX release, good self-expanding and appropriate trachea supporting properties, and generate heat to raise temperature under an alternating magnetic field, which facilitates temperature-responsive PTX release and permeation in tracheal tissue. The stents have good biosafety in rabbits and keep airway patency for the investigated period (1 month) without the occurrence of mucus/sputum blockage after implantation in rabbit trachea. This study provides a scientific basis for the development of novel self-expandable C-shaped tracheal stents with combinatorial tracheal support and local chemotherapy.     

Chitosan-Based Hydrogels for Infected Wound Treatment

Wound infections slow down the healing process and lead to complications such as septicemia, osteomyelitis, and even death. Although traditional methods relying on antibiotics are effective in controlling infection, they have led to the emergence of antibiotic-resistant bacteria. Hydrogels with antimicrobial function become a viable option for reducing bacterial colonization and infection while also accelerating healing processes. Chitosan is extensively developed as antibacterial wound dressings due to its unique biochemical properties and inherent antibacterial activity. In this review, the recent research progress of chitosan-based hydrogels for infected wound treatment, including the fabrication methods, antibacterial mechanisms, antibacterial performance, wound healing efficacy, etc., is summarized. A concise assessment of current limitations and future trends is presented.     

Preparation and antimicrobial properties of LL‐37 peptide immobilized lignin/caprolactone polymer film

The use of biopolymers has gained priority in tissue engineering and biotechnology, both as dressing material and for enhancing treatment efficiency. There is a demand for new biopolymers designed with protease inhibitors and antimicrobials. LL‐37 is an important antimicrobial peptide in human skin and exhibits a broad spectrum of antimicrobial activity against bacteria, fungi, and viral pathogens. Using lignin which is an abundant carbohydrate polymer in nature and a polyacrylic acid, we prepared a lignin/caprolactone biodegradable film by plastifying caprolactone and polyacyrlic acid. Lignin/caprolactone biodegradable film was activated with CDI and then immobilized LL‐37 peptide. The structure was elucidated in terms of its functional groups by attenuated total reflectance‐fourier transform infrared spectroscopy (ATR‐FTIR), and the morphology of the lignin/caprolactone biodegradable film was characterized by scanning electron microscopy (SEM) before and after the immobilization process. The amount of LL‐37 immobilized was determined by ELISA method. It was found that 97% of LL‐37 peptide was successfully immobilized onto the lignin/caprolactone biodegradable film. Antimicrobial activity was determined in the lignin/caprolactone biodegradable film samples by quantitative antimicrobial activity method. According to the results, LL‐37 immobilized lignin/caprolactone biodegradable film samples were effective on test organisms; Gram‐positive Staphylococcus aureus and Gram‐negative Escherichia coli. In bio‐compatibility assays, the ability to support tissue cell integration was detected by using 3 T3 mouse fibroblasts. Samples were examined under transverse microscope, non‐immobilized sample showed a huge cellular death, whereas LL‐37 immobilized lignin/caprolactone biodegradable film had identical cellular growth with the control group. This dual functional lignin/caprolactone biodegradable film with enhanced antibacterial properties and increased tissue cell compatibility may be used to design new materials for various types of biological applications.     

Dual‐Functional Dextran‐PEG Hydrogel as an Antimicrobial Biomedical Material

Microbial infections continually present a major worldwide public healthcare threat, particularly in instances of impaired wound healing and biomedical implant fouling. The development of new materials with the desired antimicrobial property to avoid and treat wound infection is urgently needed in wound care management. This study reports a novel dual‐functional biodegradable dextran‐poly(ethylene glycol) (PEG) hydrogel covalently conjugated with antibacterial Polymyxin B and Vancomycin (Vanco). The hydrogel is designed as a specialized wound dressing that eradicates existing bacteria and inhibits further bacteria growth, while, ameliorating the side effects of antibiotics and accelerating tissue repair and regeneration. The hydrogel exhibits potent antibacterial activities against both gram‐negative bacteria Escherichia coli (E. coli) and gram‐positive bacteria Staphylococcus aureus (S. aureus) with no observable toxicity to mouse fibroblast cell line NIH 3T3. These results demonstrate the immense potential of dextran‐PEG hydrogel as a wound dressing healthcare material in efficiently controlling bacteria growth in complex biological systems.     

Advances in coatings on Mg alloys and their anti-microbial activity for implant applications

Magnesium matrix composites reinforced by calcium phosphate could not show the desired effect on the magnesium breakdown rate. Rapid disintegration rate limited the magnesium alloys used as biodegradable implant material. The rate of degradation can be minimized and biological activity can be improved in the magnesium alloy by Hydroxyapatite (HA) coating with the improvement of bone induction and conduction abilities. Various alkali post-treatment and conversion coating methods are applied to deposit HA coatings and biocompatible dicalcium phosphate dihydrate (DCPD) on magnesium alloy so that corrosion resistance and surface biocompatibility can be improved to be used in bone tissue engineering applications. Magnesium's corrosion resistance will weaken its antibacterial properties, which are linked to and proportional to the alkaline pH at the time of breakdown. The goal of this study is to bring together and compare contemporary research on different coatings on magnesium and related alloys in relation to antibacterial functionalized activities. A though review has been performed on in vivo and in vitro cytocompatibility, material property, corrosion resistance, and antibacterial properties of the coatings. Increased degradation behavior, biocompatibility, and bioactivity have been achieved following multiple procedures such as alkali treatment with HA electrochemical deposition on magnesium alloy. Multifunctional coatings can make safe and bioactive magnesium alloy surfaces for biodegradable implant applications.     

Citronellol-Based Long-Lasting Antibacterial Cotton Fabrics without Bacterial Resistance

Antibacterial cotton helps prevent the growth and spread of harmful microorganisms, reduces the risk of infection, and has a prolonged service life by reducing bacterial degradation. However, most antibacterial agents used are toxic to humans and the environment. Citronellol-poly(N,N-dimethyl ethyl methacrylate) (CD), a highly effective antibacterial polymer, is synthesized from natural herbal essential oils (EOs). CD exhibited efficient, rapid bactericidal activity against Gram-positive, Gram-negative, and drug-resistant bacteria. Citronellol's environmental benignity makes CDs less hemolytic. Notably, negligible drug resistance developed after 15 bacterial subcultures. The CD-treated cotton fabric displayed better antibacterial performance than AAA-grade antibacterial fabric, even after repeated washing. This study extends the practical application of EOs to antibacterial surfaces and fabrics, which is promising for use in personal care products and medical settings.     

Construction of Antibacterial N‐Halamine Polymer Nanomaterials Capable of Bacterial Membrane Disruption for Efficient Anti‐Infective Wound Therapy

The increasing occurrence of bacterial infection at the wound sites is a serious global problem, demanding the rapid development of new antibacterial materials for wound dressing to avoid the abuse of antibiotics and thereby antibiotic resistance. In this work, the authors first report on antibacterial N‐halamine polymer nanomaterials based on a strategic copolymerization of 3‐allyl‐5,5‐dimethylhydantoin (ADMH) and methyl methacrylate (MMA), which exhibits in vitro and in vivo antimicrobial efficacy against pathogenic bacteria including Staphylococcus aureus and Escherichia coli. Particularly, when a biological evaluation is run for wound therapy, the N‐halamine polymer nanomaterials exhibit a powerful antibacterial efficiency and wound healing ability after a series of histological examination of mouse wound. After the evaluation of biological and chemical surroundings, the proposed four‐stage mechanism suggests that, with unique antibacterial N? Cl bonds, the N‐halamine polymer nanomaterials can disrupt the bacterial membrane, as a result causing intracellular content leaked out and thereby cell death. Based on the synergistic action of antibacterial and wound therapy, the N‐halamine polymer nanomaterials are expected to be promising as wound dressing materials in medical healing and biomaterials.     

Synthesis and investigation of binding interactions of 1,4-benzoxazine derivatives on topoisomerase IV in Acinetobacter baumannii$

Abstract

Acinetobacter baumannii has emerged as an important pathogen for nosocomial infections having high morbidity and mortality. This pathogen is notorious for antimicrobial resistance to many common antimicrobial agents including fluoroquinolones, which have both intrinsic and acquired resistance mechanisms. Fluoroquinolones targeting the bacterial topoisomerase II (DNA gyrase and Topo IV) show potent broad-spectrum antibacterial activity by the stabilization of the covalent enzyme–DNA complex. However, their efficacy is now being threatened by an increasing prevalence of resistance. Fluoroquinolones cause stepwise mutations in DNA gyrase and Topo IV, having alterations of their binding sites. Furthermore, the water–Mg⁺² bridge, which provides enzyme–fluoroquinolone interactions, has a significant role in resistance. In this study, 13 compounds were synthesized as 1,4-benzoxazine derivatives which act as bacterial topoisomerase II inhibitors and their antibacterial activities were determined against multi-drug resistant Acinetobacter strains which have ciprofloxacin (CIP) resistant and GyrA mutation. Afterwards we performed docking studies with Topo IV (pdb:2XKK) of these compounds to comprehend their binding properties in Discovery Studio 3.5. The results of this study show significant conclusions to elucidate the resistance mechanism and lead to the design of new antibacterial agents as bacterial topoisomerase II inhibitors.     

表面抗菌功能涂层的构建及在生物医用材料中的应用研究

近年来,生物医用材料在使用过程中产生的医源性感染问题层出不穷,对人们健康和生命造成严重威胁.表面抗菌涂层构建是解决该类医源性感染问题最有效的策略之一.目前,按照作用机制和功能不同将表面抗菌涂层分为接触式抗菌涂层、抗黏附抑菌涂层、抗黏附杀菌涂层以及智能抗菌涂层.表面抗菌涂层的构建不仅赋予了生物医用材料抗菌性能,有效解决了...     

Hyaluronic acid-methacrylic anhydride/polyhexamethylene biguanide hybrid hydrogel with antibacterial and proangiogenic functions for diabetic wound repair

Diabetic wounds lead to a decrease in quality of life and an increase in mortality. Current treatment strategies include preventing bacterial adhesion while improving microcirculation. As a new type of wound dressing that imitates natural skin, hydrogel has gradually emerged with its excellent properties. However, existing hydrogels rarely achieve satisfactory results in promoting wound repair and antibacterial simultaneously. In this case, we prepared methacrylic anhydride chemically modified hyaluronic acid as a hydrogel matrix, added polyhexamethylene biguanide as an antibacterial component, and loaded sodium alginate/salidroside composite microspheres which could sustainably release salidroside and thus promote angiogenesis. Hybrid hydrogel (HAMA/PHMB-Ms) was synthesized via photocrosslinking, and its chemical structure, particle size distribution and microstructure were characterized. The satisfactory antibacterial properties of the HAMA/PHMB(15%)-Ms hydrogel were studied in vitro, and its antibacterial rates against E. coli and S. aureus were 97.85% and 98.56%, respectively. In addition, after demonstrating its good biocompatibility, we verified that the HAMA/PHMB-Ms hydrogel has increased granulation tissue formation, more collagen deposition, more subcutaneous capillary formation, and better wound healing than blank control, HAMA and HAMA/PHMB hydrogel on the back wound model of diabetic mice. The results confirmed that HAMA/PHMB-Ms hydrogel was a promising material for the treatment of the diabetic wounds.     

Zein‐Based Electrospun Fibers Containing Bioactive Glass with Antibacterial Capabilities

Zein, a natural protein from corn, has important applications in food and pharmaceutical industries due the fact that it is biodegradable and biocompatible. However, due its relatively low mechanical properties and water solubility, many inorganic compounds (e.g., bioactive glasses [BGs]) have been used in combination with zein to obtain composite materials with improved mechanical properties. Such inorganic additions provide further biological functionality to zein. In this work, fiber mats of zein with incorporation of BG and copper doped BG particles are successfully obtained by electrospinning. At first the electrospinnability of the blends is assessed, then the morphological and chemical characterization of the mats is done. Degradation study in cell culture medium (Dubelcco’s modified Eagle’s medium) reveals a sufficient strength of the fibers, which in turn is necessary for in vitro cellular studies. Cell culture studies using MG‐63 and C2C12 cells show promising results, demonstrating increased cell proliferation and growth for fiber mats containing both types of BGs. Also, evaluation with Staphylococcus aureus and Escherichia coli bacteria confirms the antibacterial activity of the scaffolds containing copper. The presence of Cu thus imparts antibacterial properties without influencing cell behavior. The developed electrospun fibers represent a novel scaffold system for tissue engineering applications.     

Electrospun poly(lactic acid) nanofibers loaded with silver sulfadiazine/[Mg–Al]‐layered double hydroxide as an antimicrobial wound dressing

Poly(lactic acid) (PLA) is a versatile, bioabsorbable, and biodegradable polymer with excellent biocompatibility and ability to incorporate a great variety of active agents. Silver sulfadiazine (SDZ) is an antibiotic used to control bacterial infection in external wounds. Aiming to combine the properties of PLA and SDZ, hydrotalcite ([Mg–Al]‐LDH) was used as a host matrix to obtain an antimicrobial system efficient in delivering SDZ from electrospun PLA scaffolds intended for wound skin healing. The structural reconstruction method was successfully applied to intercalate silver sulfadiazine in the [Mg–Al]‐LDH, as evidenced by X‐ray diffraction and thermogravimetric analyses. Observations by scanning electron microscopy revealed a good distribution of SDZ‐[Mg–Al]‐LDH within the PLA scaffold. Kinetics studies revealed a slow release of SDZ from the PLA scaffold due to the intercalation in the [Mg–Al]‐LDH. In vitro antimicrobial tests indicated a significant inhibitory effect of SDZ‐[Mg–Al]‐LDH against Escherichia coli and Staphylococcus aureus. This antibacterial activity was sustained in the 2.5‐wt% SDZ‐[Mg–Al]‐LDH–loaded PLA nanofibers, which also displayed excellent biocompatibility towards human cells. The multifunctionality of the PLA/SDZ‐[Mg–Al]‐LDH scaffold reported here is of great significance for various transdermal applications.     

The effects of low dose leukotriene receptor antagonist therapy on airway remodeling and cysteinyl leukotriene expression in a mouse asthma model

Airway structural changes that occur in patients with asthma in response to persistent inflammation are termed airway remodeling. The cysteinyl leukotrienes (LTC(4), D(4) and E(4)) are known to play important roles in the pathobiology of asthma. To evaluate the effect of low dose montelukast (MK) on the development of airway remodeling using a chronic murine model of allergic airway inflammation with subepithelial fibrosis, BALB/c mice, after intraperitoneal ovalbumin (OVA) sensitization on days 0 and 14, received intranasal OVA periodically on days 14-75. MK treated mice received montelukast sodium intraperitoneally on days 26-75. The OVA sensitized/challenged mice developed an extensive eosinophil cell inflammatory response, goblet cell hyperplasia, mucus occlusion, and smooth muscle hypertrophy of the airways. In addition, in OVA sensitized/challenged mice, dense collagen deposition/fibrosis was seen throughout the lung interstitium surrounding the airways, blood vessels, and alveolar septae. The cysteinyl leukotriene 1 (CysLT1) receptor antagonist, MK significantly reduced the airway eosinophil infiltration, goblet cell hyperplasia, mucus occlusion, and lung fibrosis except airway smooth muscle hypertrophy in the OVA sensitized/challenged mice. The OVA sensitized/challenged mice had significantly increased epithelial desquamation compared with control mice. MK markedly reduced epithelial desquamation of airways in OVA/MK treated animals compared with OVA sensitized/challenged mice. MK treatment did not affect the levels of CysLT in lung tissue. Our results show that the important role of cysteinyl leukotrienes in the pathogenesis of asthma. Lower dose of CysLT1 receptor antagonism has a significant anti-inflammatory effect on allergen-induced lung inflammation and fibrosis but not airway smooth muscle hypertrophy in an animal model of asthma.     

Smart Titanium Coating Composed of Antibiotic Conjugated Peptides as an Infection‐Responsive Antibacterial Agent

Antibacterial coating is rapidly emerging as a pivotal strategy for mitigating spread of bacterial pathogens. However, many challenges still need to be overcome in order to develop a smart coating that can achieve on‐demand antibacterial effects. In this study, a Staphylococcus aureus (S. aureus) sensitive peptide sequence is designed, and an antibiotic is then conjugated with this tailor‐made peptide. The antibiotic‐peptide conjugate is then linked to the surface of a titanium implant, where the peptide can be recognized and cleaved by an enzyme secreted by S. aureus. This allows for the release of antibiotics in the presence of S. aureus, thus achieving delivery of an antibacterial specifically when an infection occurs.     

A modified polyvinylchloride surface with antibacterial and antifouling functions

Surfaces with antibacterial and hydrophilic properties are very attractive to cardiovascular applications. The objective of this study was to synthesize and immobilize a novel antibacterial and hydrophilic polymer onto surface of polyvinylchloride via an effective and mild surface coating technique. The surface coated with a terpolymer constructed with N‐vinylpyrrolidone, 3,4‐dichloro‐5‐hydroxy‐2(5H)‐furanone derivative, and succinimide residue was evaluated with cell adhesion, bacterial adhesion, and bacterial viability. 3T3 mouse fibroblast cells and two bacteria species were used to evaluate surface adhesion and antibacterial activity. Results showed that the polymer‐modified polyvinylchloride surface exhibited not only significantly decreased 3T3 fibroblast cell adhesion with a 66% to 87% reduction but also significantly decreased bacterial adhesion with 69% to 87% and 52% to 74% reduction of Pseudomonas aeruginosa and Staphylococcus aureus attachment, respectively, as compared with original polyvinylchloride. Furthermore, the modified polyvinylchloride surfaces exhibited significant antibacterial functions by inhibiting bacterial growth (75%‐84% and 78–94% inhibition of P aeruginosa and S aureus, respectively, as compared to original polyvinylchloride) and killing bacteria. These results demonstrate that covalent polymer attachment conferred antifouling and antibacterial properties to the polyvinylchloride surface.     

Dictamnine Inhibits the Adhesion to and Invasion of Uropathogenic Escherichia Coli (UPEC) to Urothelial Cells

Uropathogenic Escherichia coli (UPEC) is the most common pathogenic bacteria associated with urinary tract infection (UTI). UPEC can cause UTI by adhering to and invading uroepithelial cells. Fimbriae is the most important virulence factor of UPEC, and a potentially promising target in developing novel antibacterial treatments. In this study, the antibacterial properties and effects of the compound dictamnine, extracted from the traditional Chinese medicine Cortex Dictamni, on the bacterial morphology, cell adhesion, and invasion of UPEC were studied. Dictamnine exhibited no obvious antibacterial activity against UPEC, but significantly impeded the ability of UPEC to adhere to and invade uroepithelial cells. RT-qPCR analysis showed that treatment downregulated the expression of type 1 fimbriae, P fimbriae, and curli fimbriae adhesion genes, and also downregulated adhesion-related receptor genes of uroepithelial cells. Transmission electron microscopy showed that dictamnine destroyed the structure of the fimbriae and the surface of the bacteria became smooth. These results suggest that dictamnine may help to prevent UTI by simultaneously targeting UPEC fimbriae and urothelial adhesin receptors, and may have a potential use as a new anti-UPEC drug.     

Antibacterial Activity and Mechanism of Oxidized Bacterial Nanocellulose with Different Carboxyl Content

Oxidized bacterial nanocellulose (OBC) is reported to prevent microbial growth, but its antibacterial characteristics and mechanism are still unclear. Here, the antibacterial mechanism of OBC is explored by detecting and assessing the interaction of OBC with different carboxyl content on Staphylococcus aureus and Escherichia coli. The results show that OBC has strong antibacterial activity and antibiofilm activity against S. aureus and E. coli, which is positively correlated with the carboxyl content of OBC. After OBC treatment, the bacteria adhesion is inhibited and the cell membrane is destroyed leading to increased permeability. Further investigation reveals that the concentration of cyclic diguanosine monophosphate (c-di-GMP) that induced biofilm formation is significantly decreased to 1.81 pmol mg⁻¹ after OBC treatment. In addition, OBC inactivates mature biofilms, with inactivation rates up to 79.3%. This study suggests that OBC has excellent antibacterial and antiadhesion properties, which can increase the cell membrane permeability and inhibit c-di-GMP formation. In addition, OBC also has a strong inactivation effect on mature biofilm, which can be used as an effective antibiofilm agent.