Long-term Antibacterial Activity Research Articles

A comparative study on stabilizing and releasing thymol by pre-formed V-type starch and β-cyclodextrin

Cyclodextrins (CD) are well known to form host-guest assemblies with hydrophobic compounds. As a structural homologue, starch-guest inclusion complexes (ICs) have become promising in the food, agriculture, and pharmaceutical industries due to their low cost and versatility. This study compared the stabilizing and releasing abilities for thymol of three kinds of pre-formed V-type starch (Water-V, Salt-V, and Alkali-V) and β-CD. The loading efficiency for thymol decreased in the order of Water-V > Alkali-V > CD > Salt-V when removing the free thymol. Water-V, β-CD, and their ICs had better thermal stability with maximum thermal decomposition temperatures over 320 °C. Under non-cold chain daily storage conditions for 4 d, the percentage of thymol released from starch/CD-thymol ICs was 14% (Water-V), 35% (Salt-V), 34% (Alkali-V), and 43% (CD). The Water-V made ICs had good sustained release properties and long-term antibacterial activity, which kept strawberries fresh for 6 d without decay.

Elastic and Self-Healing Copolymer Coatings with Antimicrobial Function.

The revolutionary self-healing function for long-term and safe service processes has inspired researchers to implement them in various fields, including in the application of antimicrobial protective coatings. Despite the great advances that have been made in the field of fabricating self-healing and antimicrobial polymers, their poor transparency and the trade-off between the mechanical and self-healing properties limit the utility of the materials as transparent antimicrobial protective coatings for wearable optical and display devices. Considering the compatibility in the blending process, our group proposed a self-healing, self-cross-linkable poly{(n-butyl acrylate)-co-[N-(hydroxymethyl)acrylamide]} copolymer (AP)-based protective coating combined with two types of commercial cationic antimicrobial agents (i.e., dimethyl octadecyl (3-trimethoxysilylpropyl) ammonium chloride (DTSACL) and chlorhexidine gluconate (CHG)), leading to the fabrication of a multifunctional modified compound film of (AP/b%CHG)-grafted-a%DTSACL. The first highlight of this research is that the reactivity of the hydroxyl group in the N-(hydroxymethyl)acrylamide of the copolymer side chains under thermal conditions facilitates the "grafting to" process with the trimethoxysilane groups of DTSACL to form AP-grafted-DTSACL, yielding favorable thermal stability, improvement in hydrophobicity, and enhancement of mechanical strength. Second, we highlight that the addition of CHG can generate covalent and noncovalent interactions in a complex manner between the two biguanide groups of CHG with the AP and DTSACL via a thermal-triggered cross-linking reaction. The noncovalent interactions synergistically serve as diverse dynamic hydrogen bonds, leading to complete healing upon scratches and even showing over 80% self-healing efficiency on full-cut, while covalent bonding can effectively improve elasticity and mechanical strength. The soft nature of CHG also takes part in improving the self-healing of the copolymer. Moreover, it was discovered that the addition of CHG can enhance antimicrobial effectiveness, as demonstrated by the long-term superior antibacterial activity (100%) against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria and the antifouling function on a glass substrate and/or a silica wafer coated by the modified polymer.

Nanofiber-reinforced self-healing polysaccharide-based hydrogel dressings for pH discoloration monitoring and treatment of infected wounds

The escalating global health concern arises from chronic wounds induced by bacterial infections, posing a significant threat to individuals. Consequently, an imperative exist for the development of hydrogel dressings to facilitate prompt wound monitoring and efficacious wound management. To this end, pH-sensitive bromothymol blue (BTB) and pH-responsive drug tetracycline hydrochloride (TH) were introduced into the polysaccharide-based hydrogel to realize the integration of wound monitoring and controlled treatment. Polysaccharide-based hydrogels were formed via a Schiff base reaction by cross-linking carboxymethyl chitosan (CMCS) on an oxidized sodium alginate (OSA) skeleton. BTB was used as a pH indicator to monitor wound infection through visual color changes visually. TH could be dynamically released through the pH response of the Schiff base bond to provide effective treatment and long-term antibacterial activity for chronically infected wounds. In addition, introducing polylactic acid nanofibers (PLA) enhanced the mechanical properties of hydrogels. The multifunctional hydrogel has excellent mechanical, self-healing, injectable, antibacterial properties and biocompatibility. Furthermore, the multifaceted hydrogel dressing under consideration exhibits noteworthy capabilities in fostering the healing process of chronically infected wounds. Consequently, the research contributes novel perspectives towards the advancement of intelligent and expeditious bacterial infection monitoring and dynamic treatment platforms.

Nano-microcapsules loaded with nano-antibacterial agents for long-term inhibition of drug-resistant strains

There are growing concerns and worries about the safety of public facilities and equipment. Therefore, coating products with antibacterial properties have become the key to solve this problem, and there is an urgent need to develop new antibacterial architectural coatings. In this study, polystyrene nano-microspheres (PS NMS) were prepared from styrene as raw material. PS nano-microcapsules (PS NMC) were prepared by solute co-diffusion method (SCM) using PS NMS as a template, which were modified to obtain PS-OH NMC. CuS nanoparticles (CuS NPs) with antibacterial activity were further loaded to prepare CuS@PS-OH NMC with long-term antibacterial activity. The SEM results showed that the particle size of CuS@PS-OH NMC was about 410 nm, which was larger than that of PS-OH NMC. The characterization of UV and IR spectra confirmed that CuS NPs were not only encapsulated into PS NMC in large quantities, but also adhered to its surface in a small amount. CuS@PS-OH NMC has good water solubility and can slowly release Cu2+, showing good long-term antibacterial properties against Methicillin-resistant Staphylococcus aureus (MRSA). The CuS@PS-OH NMC developed in this study has excellent performance, good antibacterial effect, environmental friendliness, low price, etc. More importantly, it can efficiently and long-term inhibit MRSA, and can be used as a potential antibacterial architectural coating for special scenarios such as hospitals, schools and densely populated places, which has excellent social and economic value.

Antibacterial and clinical effectiveness of a mouthwash with a novel active system of amine + zinc lactate + fluoride: a randomized controlled trial

ObjectivesTo support the daily oral hygiene of patients experiencing gum inflammation, a new mouthwash was developed containing an amine + zinc lactate + fluoride system. In vitro and clinical efficacy was assessed using traditional methods as well as using novel site-specific and subject-specific analyses of the clinical data.Materials and methodsThis mouthwash was evaluated in a 12-h biofilm regrowth assay against a negative control mouthwash and in a 6-month plaque and gingivitis clinical study as compared to a negative control mouthwash. Analyses of healthy versus inflamed sites, visible plaque versus non-visible plaque sites, as well as subject-level evaluations bring new perspectives to the overall performance of this mouthwash and its significance from a patient outcome perspective.ResultsStudies demonstrated that this new mouthwash provided long-term (12-h) antibacterial activity after single application in vitro and reduced clinically all plaque and gingivitis parameters after 3 months and 6 months of use when compared to the negative control mouthwash. Examination of site-level and subject-level data determined that this mouthwash significantly increased the number of healthy sites in the oral cavity and significantly improved the gum health of subjects in the study, as compared to the negative control mouthwash.ConclusionsIn vitro and clinical research has demonstrated the antibacterial and clinical benefits of this mouthwash containing an amine compound + zinc lactate + fluoride system.Clinical relevanceOur subject-specific and site-specific analyses provide the dental practitioner with tools that can be used to guide patients who suffer from gingivitis toward optimal product selection and use.Clinical trial registrationThe trial was registered at ClinicalTrials.gov (reference no. NCT05821712).

Recent Advances in Quaternary Ammonium Monomers for Dental Applications.

Resin-based dental materials have been one of the ideal choices among various materials in the treatment of dental caries. However, resin-based dental materials still have some drawbacks, such as the lack of inherent antibacterial activity. Extensive research has been conducted on the use of novel quaternary ammonium monomers (QAMs) to impart antibacterial activity to dental materials. This review provides a comprehensive overview of the recent advances in quaternary ammonium monomers (QAMs) for dental applications. The current progress and limitations of QAMs are discussed based on the evolution of their structures. The functional diversification and enhancement of QAMs are presented. QAMs have the potential to provide long-term antibacterial activity in dental resin composites, thereby prolonging their service life. However, there is a need to balance antibacterial performance with other material properties and the potential impact on the oral microbiome and general health. Finally, the necessity for further scientific progress in the development of novel quaternary ammonium monomers and the optimization of dental resin formulations is emphasized.

Long-term antibacterial activity of silver-containing hydroxyapatite coatings against Staphylococcus aureus in vitro and invivo

BackgroundThe potential of silver-containing hydroxyapatite (Ag-HA) coatings to prevent orthopaedic implant-associated infection was explored previously; however, the resistance of Ag-HA coatings to late-onset orthopaedic infections is unknown. This study aimed to evaluate the long-term Ag+ elution and antibacterial properties of the Ag-HA coatings through in vitro and in vivo experiments. MethodsAg-HA-coated disc specimens were immersed in fetal bovine serum (FBS) for six months. Ag concentration was measured over time using inductively coupled plasma-mass spectrometry to evaluate Ag release. The hydroxyapatite (HA)- or Ag-HA-coated disc specimens were immersed in FBS for 3 months to elute Ag+ for in vitro experiments. Methicillin-resistant Staphylococcus aureus (MRSA) suspensions were inoculated onto each disc; after 48 h, the number of colonies and the biofilm volume were measured. HA- or Ag-HA-coated disc specimens were inserted under the skin of Sprague-Dawley rats for three months for in vivo experiments. In in vivo experiment 1, specimens were inoculated with MRSA and the number of colonies was counted after 48 h. In in vivo experiment 2, the specimens were inoculated with bioluminescent S. aureus Xen36 cells, and bioluminescence was measured using an in vivo imaging system. ResultsThe Ag-HA-coated disc specimens continued to elute Ag+ after six months. The biofilm volume in the Ag-HA group was lower than in the HA group. In in vitro and in vivo experiment 1, the bacterial counts in the Ag-HA group were lower than those in the HA group. In in vivo experiment 2, the bioluminescence in the Ag-HA group was lower than that in the HA group on days 1–7 after inoculation. ConclusionsThe Ag-HA-coated discs continued to elute Ag+ for a long period and exhibited antibacterial activity and inhibition of biofilm formation against S. aureus. The Ag-HA coatings have the potential to reduce late-onset orthopaedic implant-associated infections.

Development of Novel Multifunctional Electroactive, Self-Healing, and Tissue Adhesive Scaffold To Accelerate Cutaneous Wound Healing and Hemostatic Materials.

Designing a multifunctional conducting hydrogel wound dressing of suitable mechanical properties, adhesiveness, self-healing, autolytic debridement, antibacterial properties, and radical scavenging ability, as well as retaining an appropriate level of moisture around the wound is highly desirable in clinical application for treating cutaneous wounds healing. Here, we designed a novel class of electroactive hydrogel based on thiol-functionalized silver-graphene oxide nanoparticles (GO/Ag/TGA) core polyaniline (PANI) shell GO/Ag/TGA/PANI nanocomposites. Thus, a series of physically cross-linked hydrogel based on GO/Ag/TGA/PANI and poly(vinyl alcohol) (PVA) was prepared by freeze-thawing method. The hydrogel was characterized by XRD, UV, FTIR, TGA, TEM, SEM, Raman spectroscopy, cyclic voltammetry (CV), and four probes test. The hydrogel showed favorable properties such as excellent tensile strength, suitable gelation time (30-56 s), tunable rheological properties (G' ∼ 1 kPa), adhesiveness, and interconnected porous structure (freeze-dried). Besides this, the hydrogel also exhibits excellent exudate uptake capacity (10.4-0.2 g/g), high swelling ratio (72.4 to 93.5%), long-term antibacterial activity against multidrug-resistant (MDR) bacterial isolates, promising antioxidant (radical scavenging) efficiency, keeping the wound moisturized, prominent hemostatic efficiency, and fast self-healing ability to bear deformation. Interestingly, in vivo experiments indicated that electroactive hydrogels can significantly promote the healing rate of artificial wounds in rats, and histological analysis by H&E reveals higher granulation tissue thickness, collagen deposition, hair follicles, dermal papillary, keratinocytes, and marked increase (P < 0.05) in hydroxyproline at the wound site during 15 days of healing of impaired wounds. On the basis of vivo and vitro assay results, it is concluded that electroactive-hydrogel-attributed multifunctional properties may serve as suitable scaffold for treating chronic wound healing and skin regeneration.

Electrospinning of chitosan/polyvinyl alcohol Pickering emulsion with tea tree essential oil loaded for anti-infection wound dressings

As a natural antibacterial agent, Tea tree oil (TTO) possesses low aqueous solubility. To load TTO in hydrophilic hydroxyethyl chitosan/polyvinyl alcohol nanofiber matrix, Pickering emulsion electrospinning strategy using ZnO/Ag nano composite (ZA) as stabilizer was proposed for anti-infection dressing development. Under the stabilizing assistance of ZA particles in the size range of 53 and 59 nm, Pickering emulsions with homogenously distributed TTO droplets show good stability, which can be further elctrospun into continuously bead-on-string nanofibers under optimized processing conditions. In spite of the volatilization of TTO during electrospinning, the nanofibers possess good and long-term antibacterial activity against both gram-positive and gram-negative bacteria. In vitro experiments indicated that the nanofibers possess superior hemocompatibility and cytocompatibility. Particularly, it can promote the cell proliferation and migration when its concentration is 800 μg/mL or less. In conclusions, Pickering emulsion electrospinning is a feasible strategy for the fabrication of nanofibers loaded with hydrophobic TTO and the as-obtained nanofibers can be potentially applied in infected wounds.

Immunomodulatory effect of Ti-Cu alloy by surface nanostructure synergistic with Cu2+ release

The inflammatory response induced by implant/macrophage interaction has been considered to be one of the vital factors in determining the success of implantation. In this study, TiCuNxOy coating with an immunomodulatory strategy was proposed for the first time, using nanostructured TiCuNxOy coating synthesized on Ti-Cu alloy by oxygen and nitrogen plasma-based surface modification. It was found that TiCuNxOy coating inhibited macrophage proliferation but stimulated macrophage preferential activation and presented an elongated morphology due to the surface nanostructure. The most encouraging discovery was that TiCuNxOy coating promoted the initial pro-inflammatory response of macrophages and then accelerated the M1-to-M2 transition of macrophages via a synergistic effect of fast-to-slow Cu2+ release and surface nanostructure, which was considered to contribute to initial infection elimination and tissue healing. As expected, TiCuNxOy coating released desirable Cu2+ and generated a favorable immune response that facilitated HUVEC recruitment to the coating, and accelerated proliferation, VEGF secretion and NO production of HUVECs. On the other hand, it is satisfying that TiCuNxOy coating maintained perfect long-term antibacterial activity (≥99.9%), mainly relying on Cu2O/CuO contact sterilization. These results indicated that TiCuNxOy coating might offer novel insights into the creation of a surface with immunomodulatory effects and long-term bactericidal potential for cardiovascular applications.

Caffeic acid-grafted chitosan/sodium alginate/nanoclay-based multifunctional 3D-printed hybrid scaffolds for local drug release therapy after breast cancer surgery

Breast cancer is one of the most common malignant tumors in women all over the world. Mastectomy is the most effective treatment, but there are serious problems such as high tumor recurrence rate and side effects of chemotherapy. Therefore, there is an urgent need for a therapeutic strategy that can effectively promote postoperative wound healing and inhibit local tumor recurrence. In this study, a 3D printing scaffold based on carbon dots-curcumin nano-drug release (CCNPs) was developed as a local drug delivery platform (named CCNACA using CCNPs, Sodium alginate, Nanoclay and Caffeic Acid grafted Chitosan as raw materials), which has the ability to visualize drug release. The 14-day drug release test in vitro showed that the tumor inhibition rate of CCNACA scaffolds on breast cancer cells (MCF-7) was 73.77 ± 1.68 %. And the CCNACA scaffolds had good long-term antibacterial (Escherichia coli and Staphylococcus aureus) activity. Animal experiments have shown that implanting CCNACA scaffolds into surgical defects can inhibit postoperative residual cancer cells, reduce inflammation, promote angiogenesis, and repair tissue defects caused by surgery. In summary, the local drug delivery system of this manuscript has great potential in wound healing and prevention of tumor recurrence after breast cancer surgery.

Ag+-Adsorbing Semiconducting Polymer Nanosponge for Smart Local Treatment of Wound Infection.

Nanoplatform combined with photothermal therapy (PTT) and silver nanoparticles have been widely used to combat bacterial infections. However, the development of environmentally benign antibacterial nanoplatforms with controllable and long-term antibacterial activity is still challenging. Herein, we synthesized an Ag+-adsorbing organic semiconducting polymeric nanosponge (PDPP3T NPe@Ag+) to realize Ag+ enhanced photothermal anti-infective therapy. Furthermore, the PDPP3T NPe@Ag+ sponge can also spatiotemporally release silver ions in a pH/NIR light-responsive manner for controllable and long-term antimicrobial therapy. Owing to good biocompatibility and controlled release of silver ions, PDPP3T NPe@Ag+ can effectively kill bacteria in vitro and promote wound healing in vivo. We expect that this antimicrobial platform could be utilized as a robust antibacterial agent for infective therapy.

Treatment of methicillin resistant Staphylococcus aureus wound infection usingvancomycin-loaded nanoparticles: Aninvitro and in vivo study.

Due to the rise of bacteria that are resistant to multiple drugs, treating infections in burn wounds has become a worldwide problem. It is important to find new ways to treat these infections. Lipid-based drug delivery systems have emerged as a promising type of carrier for antibiotics as well as antibacterial agents, such as antimicrobial peptides and nucleic acids, for wound infections. To this end, the current study assessed the antibacterial effects and wound healing properties of vancomycin-loaded solid lipid nanoparticles (SLN) against methicillin-resistant Staphylococcus aureus (MRSA) surgical wound infections. vancomycin-SLN was synthesized by double emulsion solvent evaporation techniques, and then in vitro antibacterial activity was evaluated by well diffusion and broth microdilution methods. A surgical wound was inflicted on 36 male rats; the infection was caused by MRSA, and free vancomycin and vancomycin-SLN were topically applied. Particle size, PDI, zeta potential, drug loading, and encapsulation efficiency of the optimum vancomycin-SLN were 350 ± 24 nm, 0.402 ± 0.014, -16.3 ± 2.5 mV, 13.9 ± 1.4%, and 92.14 ± 3.1%, respectively. In vitro antibacterial assays showed lower MICs for free vancomycin and killed bacteria more efficiently than vancomycin-SLN. However, the synthesized nanoparticles indicated long-term antibacterial activity against MRSA. Animals that were treated with vancomycin-SLN showed the best wound healing procedure. Treatment of rats with vancomycin-SLN increased re-epithelialization and decreased granulation tissue development, as seen by histological analysis. Antibiotic-loaded SLN could not only manage wound infection but also enhance wound healing. Therefore, this kind of treatment should be considered by scientists as an applicable treatment for wounds.

Green Synthesis of Antimicrobial Peptide-Protected Silver Nanoclusters with Regulated Antibacterial Behavior.

The antibacterial system based on the silver element has been a very promising antibacterial material. However, the antibacterial activity of silver nanomaterials largely depends on their chemical composition and physical properties. Herein, we prepared ultrasmall silver nanoclusters by directly reducing silver ions with antimicrobial peptide in a green way. The positively charged peptide ligands drove the silver nanoclusters binding to bacteria by electrostatic attraction. Contrary to the large-sized silver nanomaterials, the ultrasmall silver nanoclusters were able to rapidly penetrate bacteria membranes via strong hydrophobic association, significantly promoting the generation of reactive oxygen species, and the subsequent high oxidative stress led to bacterial death. Moreover, the silver nanoclusters with antibacterial peptide ligand exhibited good stability, low cytotoxicity, and long-term antibacterial activity. Besides, synergistic enhancement of silver nanoclusters on antibacterial activity was observed. Therefore, the silver nanoclusters conjugated with the antimicrobial peptide can act as a synergistic antibacterial agent, in which their bio-interactions with bacteria have been regulated to achieve a rapid, long-lasting, and broad-spectrum antibacterial effect.

Structural, cell culture, antibacterial and in vitro bioactivity analysis of highly-ordered Al2O3 nanotube coating with decorated Ag2O nanoparticles on Ti-6Al-4V

The alumina nanotubular arrays (Al2O3 NTs) are a promising candidate for application in bone and dental implants for their better mechanical and chemical behavior in the human body compared to titanium. Nevertheless, the biocompatibility and antibacterial activity of Al2O3 NTs still need further improvement to meet the requirements of safe implants. In this research, Al2O3 NTs coating was proposed on Ti-6Al-4 V via magnetron sputtering pure aluminum followed by an anodization and sealing process, then heat treated for 1 h at 450 °C. After that, Ag2O nanoparticles (NPs) were decorated on the nanotubular walls under controlled conditions using magnetron sputtering. The findings demonstrated that the proposed Al2O3 NTs-Ag2O NPs promoted in-vitro bioactivity alongside excellent antibacterial activity against E.coli and S.aureus bacteria within 4 h and 6 h, respectively. Additionally, the cell-culture showed healthy growth of the human osteoblast cells (HOb) on the Al2O3 NTs-Ag2O NPs. The new design of coating also shows that the total cumulative Ag+released after 14 days is significantly low which is safe and provides the long-term antibacterial activity. It is illustrated that Al2O3 NTs-Ag2O NPs have promising biomedical properties to enhance the biofunctionality of biomedical-grade Ti-6Al-4 V implants.

Fabrication of ionic liquid-functionalized aliphatic polycarbonate brushes for self-polishing antibacterial application

To meet the development of multifunctional surfaces with long-term antibacterial activity for biomaterials and implantable devices, herein, a novel self-polishing antibacterial surface was developed. The functionalized surface was prepared by first surface-initiated ring-opening grafting polymerization (SI-ROP) of a cyclic carbonate monomer 4′-(fluorosulfonyl)benzyl-5-methyl-2-oxo-1,3-dioxane-5-carboxylate (FMC) containing a sulfonyl fluoride group in the side chain onto the material surface and then by a “sulfur(IV)-fluorine” exchange (SuFEx) postclick modification reaction to link the imidazolium salt ionic liquid to the polyFMC (PFMC) brush. In vitro experimental results showed that the functionalized surface has good biocompatibility, enzymatic biodegradable properties and excellent bactericidal properties, which can effectively kill E. coli (∼94%) and S. aureus (∼93%). In addition, the functionalized surface can release the killed bacteria (∼90%) several times efficiently under the action of lipase enzymatic degradation, restoring the original bactericidal function of the surface, thus forming a dynamic self-polishing and self-renewing antibacterial surface. Therefore, this method for the fabrication of self-polishing antibacterial surfaces may offer innovative insights into applications of biomedical implant materials.

Comparison of antibacterial activity and biocompatibility of non-leaching nitrofuran bone cement loaded with vancomycin, gentamicin, and tigecycline

BackgroundNon-leaching antibacterial bone cement can generate long-term antibacterial activity, it cannot treat serious infections that have occurred like antibiotic-loaded bone cement. Currently, the antibacterial activity and biocompatibility of non-leaching cement when loaded with antibiotics have yet to be determined.MethodsNon-leaching antibacterial nitrofuran bone cement (NFBC) specimens were prepared with low-dose and high-dose antibiotics. The antibacterial activity and biocompatibility of NFBC loaded with vancomycin, gentamicin, and tigecycline were compared. The agar diffusion method was employed to observe the inhibition zone of the samples against two bacterial strains from day one to day seven. The CCK-8 assay and acute liver and kidney toxicity test were conducted to assess the effects of the samples on mouse embryo osteoblast precursor cells and C57 mice, respectively.ResultsGentamicin-loaded cement exhibited the most potent antibacterial activity, effectively inhibiting both bacterial strains at a low dose. Tigecycline-loaded cement demonstrated superior biocompatibility, showing no acute liver and kidney toxicity in mice and minimal cytotoxicity to osteoblasts.ConclusionsNFBC loaded with gentamicin, vancomycin, and tigecycline not only maintains sustained antibacterial activity but also exhibits excellent biocompatibility.

A Natural Self-Assembled Gel-Sponge with Hierarchical Porous Structure for Rapid Hemostasis and Antibacterial.

Developing hemostatic agents with reliable biosafety and high efficiency has paramount clinical significance for saving lives. Herein, inspired from traditional Chinese medicine, a sponge (BC-S) with hierarchical porous structure is proposed for the treatment of bleeding. The BC-S is prepared by a simple self-assembly method employing Bletilla Striata polysaccharide and quaternary amine alkaloids (QA) from Bletilla Striata and Coptidis Rhizoma. The ideal cation donor encapsulated in the helical structure of BSP enlarges the inter-layer space of sponge by the action of electrostatic repulsion, forming wider channels which can accelerate the diversion speed of absorbed blood. Then, platelets and erythrocytes are trapped tightly in the reticular structure and extruded to deformation, activation. Subsequently, fibrin network forms and reinforces the internal multilayer mesh, blocks the outflow of blood. QA is released from the sponge skeleton mainly driven by a combination of surface erosion and potentially solution diffusion among pore to provide long-term antibacterial activity. Benefiting from the well-designed structure and the effective hemostatic mechanism, the BC-S displays more excellent hemostatic performance in different models in vivo and in vitro compared with typical gelatin hemostatic sponge. This work is expected to boost the development of emerging hemostatic agents.

Flexible Curcumin-Loaded Zn-MOF Hydrogel for Long-Term Drug Release and Antibacterial Activities.

Management of chronic inflammation and wounds has always been a key issue in the pharmaceutical and healthcare sectors. Curcumin (CCM) is an active ingredient extracted from turmeric rhizomes with antioxidant, anti-inflammatory, and antibacterial activities, thus showing significant effectiveness toward wound healing. However, its shortcomings, such as poor water solubility, poor chemical stability, and fast metabolic rate, limit its bioavailability and long-term use. In this context, hydrogels appear to be a versatile matrix for carrying and stabilizing drugs due to their biomimetic structure, soft porous microarchitecture, and favorable biomechanical properties. The drug loading/releasing efficiencies can also be controlled via using highly crystalline and porous metal-organic frameworks (MOFs). Herein, a flexible hydrogel composed of a sodium alginate (SA) matrix and CCM-loaded MOFs was constructed for long-term drug release and antibacterial activity. The morphology and physicochemical properties of composite hydrogels were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and mechanical property tests. The results showed that the composite hydrogel was highly twistable and bendable to comply with human skin mechanically. The as-prepared hydrogel could capture efficient CCM for slow drug release and effectively kill bacteria. Therefore, such composite hydrogel is expected to provide a new management system for chronic wound dressings.

Antibacterial AgNPs-PAAm-CS-PVP nanocomposite hydrogel coating for urinary catheters

Catheter-associated urinary tract infections (CAUTI) account for 40% of all hospital-acquired infections and more than 1 million CAUTIs occur annually in the United States and Europe with increased morbidity and mortality. Although anti-bacterial coating is an effective way to solve this problem, so far only limitted progress has been made. In this paper we prepared a novel antibacterial silver nanoparticles poly(acrylamide)-chitosan-polyvinylpyrrolidone (AgNPs-PAAm-CS-PVP) composite hydrogel coating on latex urinary catheters by a simple dipping method. The average particle size, the size distribution as well as the polydispersity index (PDI) value of the AgNPs were examined by using TEM analysis. The surface morphology and roughness, the element contents, the functional groups, the static contact angles, and the surface energy of the coatings were characterized by using SEM, EDS, AFM, FTIR, XPS, and a video optical contact angle instrument, respectively. The amount of the total Ag released from the hydrogel was tested by ICP-MS. The antibacterial and antiadhesion efficacies against Gram-negative E. coli of the coated urinary catheters were evaluated with an inhibition zone test and fluorescence microscopy. A synergistic antibacterial mechanism of AgNPs and CS was also presented. The results showed that the synthesized AgNPs in the hydrogel had a spherical shape with an average diameter of 25.9 nm. The AgNPs-PAAm-CS-PVP hydrogel had a more durable release of the antibacterial agents of AgNPs and Ag+, which explains why the coated urinary catheters had long-term antibacterial activity. The mathematical modelling of Ag release kinetics supported Case I or Fickian diffusion mechanism for the AgNPs-PAAm-CS-PVP hydrogel. The hydrogel-coated urinary catheters became smoother and more hydrophilic which further explains why the coated urinary catheter decreased bacterial adhesion. More importantly, bacterial activity and bacterial adhesion assays showed that both the outer and inner surfaces of the AgNPs-PAAm-CS-PVP hydrogel-coated urinary catheters had strong antibacterial property against E. coli. Furthermore, the hydrogel-coated urinary catheters showed high hemocompatibility and cytocompatibility for promising biomedical applications. The AgNPs-PAAm-CS-PVP hydrogel-coated urinary catheters have great potential for decreasing CAUTIs.