Long-term Antibacterial Effect Research Articles

In-Situ and Green Synthesis of Silk Fibroin-Silver Nanoparticles Composite Microfibers for Enhanced Antibacterial Applications.

The antibacterial properties of modified silk fibroin microfibers (SF MFs) have been widely studied. Among various modifications, integration of silver nanoparticles (Ag NPs) and SF MFs has garnered significant attention due to the broad-spectrum antibacterial activities and long-term antibacterial effect of Ag nanomaterials. However, the traditional introduction of reducing agents or other additives during the synthesis of Ag-SF composite MFs potentially affects their structure and antibacterial properties. Facile, green and effective methods for the preparation of Ag-SF MFs with enhanced antibacterial properties are therefore highly desired. In this study, Ag NPs were uniformly in-situ deposited onto the optimized SF MFs by adjusting the pH and duration conditions under the guidance of green chemistry. The loaded Ag NPs have a good dispersibility and an average size of ~10 nm. The stability of SF MFs after the deposition of Ag NPs and the crystalline features of the loaded Ag NPs have been carefully investigated. Moreover, antibacterial experiments confirmed that Ag-SF MFs exhibited superior antibacterial activities. After co-incubating Ag-SF MFs with L929 cells, the cell viability reached 90%, demonstrating the great biocompatibility of the modified fibers. This green in-situ synthetic method will promote the further medical use of Ag-SF MFs in antibacterial fields.

Multifunctional Bioactivity Electrospinning Nanofibers Encapsulating Emodin Provides a Potential Postoperative Management Strategy for Skin Cancer

Skin cancer is threatening more and more people’s health; its postoperative recurrence and wound infection are still critical challenges. Therefore, specialty wound dressings with multifunctional bioactivity are urgently desired. Emodin is a natural anthraquinone compound that has anti-cancer and anti-bacterial properties. Herein, we fabricated coaxial electrospinning nanofibers loaded with emodin to exploit a multifunctional wound dressing for skin cancer postoperative management, which encapsulated emodin in a polyvinylpyrrolidone core layer, combined with chitosan-polycaprolactone as a shell layer. The nanofibers were characterized via morphology, physicochemical nature, drug load efficiency, pH-dependent drug release profiles, and biocompatibility. Meanwhile, the anti-cancer and anti-bacterial effects were evaluated in vitro. The emodin-loaded nanofibers exhibited smooth surfaces with a relatively uniform diameter distribution and a clear shell-core structure; remarkably, emodin was evenly dispersed in the nanofibers with significantly enhanced dissolution of emodin. Furthermore, they not only display good wettability, high emodin entrapment efficiency, and biphasic release profile but also present superior biocompatibility and anti-cancer properties by increasing the levels of MDA and ROS in A-375 and HSC-1 cells via apoptosis-related pathway, and long-term anti-bacterial effects in a dose-independent manner. The findings indicate that the emodin-loaded nanofiber wound dressing can provide a potential treatment strategy for skin cancer postoperative management.

Antibacterial and oral tissue effectiveness of a mouthwash with a novel active system of amine + zinc lactate + fluoride.

Reflecting the need for an effective support for the daily oral hygiene routine of patients experiencing (symptoms of) gum inflammation, a new mouthwash has been developed containing an amine + zinc lactate + fluoride system. The in vitro efficacy of this product was assessed using traditional laboratory methods, as well as novel experimentation. This mouthwash has been evaluated in a series of laboratory tests including two short interval kill tests (SIKTs), a 12-h (longer term) biofilm regrowth assay, a plaque glycolysis assay, and an aerobic, repeated exposure biofilm model, as well as tests for soft tissue uptake and LPS neutralization. Several laboratory studies demonstrate that a mouthwash containing an amine + zinc lactate + fluoride system provides short-term and long-term antibacterial activity. While the immediate efficacy of this formula has been shown to be driven by the presence of the amine, zinc lactate provides a long-term antibacterial effect, as well as is able to inhibit bacterial metabolism. This research provides the basis for understanding the mode of action of this new mouthwash formulation and explains the previously observed clinical efficacy of this formula against plaque and gingivitis.

AAO-ZnO nanocomposite coatings on aluminum alloy surface with high bonding strength and long-lasting antibacterial properties

A robust and durable antibacterial nanocomposite coating consisting of anodic aluminum oxide (AAO) and zinc oxide (ZnO) was synthesized by sol–gel deposition of ZnO onto AAO nanotubes. This unique coating features a dual-layer structure: an intermediate AAO + ZnO layer (∼3.9 μm) and a ZnO layer (∼0.8 μm). Nanosized ZnO particles, ranging from 20 to 40 nm, nucleate and grow along the walls of AAO nanotubes within this structure. AAO nanotubes, functioning as “nanocontainers”, offer appropriate sites for the deposition of ZnO particles. The mechanically interlocked AAO + ZnO interlayer enhances the adhesion between the external layer and the inner substrate. Meanwhile, this interlayer facilitates the sustained release of both Zn2+ ions and reactive oxygen species (ROS), effectively impeding bacterial proliferation. Ultraviolet antibacterial tests reveal that the AAO + ZnO interlayer maintains exceptional antibacterial efficacy, even after removing the outermost ZnO layer. The antibacterial rates of the AAO + ZnO interlayer against the above two typical bacteria (E. coli and S. aureus) after 1 h could still reach 91.4 % and 89.0 %, respectively. Specifically, AAO nanopores serve as an inert container for ZnO nanoparticles with consistently release of Zn2+ ions and reactive oxygen species (ROS), thereby ensuring the long-term antibacterial effectiveness of the AAO-ZnO coating. This research also demonstrates the significant potential of AAO-ZnO nanocomposite coating on aluminum alloys for durable antibacterial applications.

Broadband microwave absorption and antibiosis effect of Cu@C@Fe3O4 nanocomposites

Metal Cu nanoparticles have been recognized as the long-standing presence in the fields of antibacterial and low-induced bacterial resistance, however, the uncontrollable Cu ion concentration from Cu nanoparticle leads to the unstable release of copper ions, limiting their controllable antibacterial application. Based on stable release of copper ions from Cu@C nanocapsules, herein, we report a novel A/B/C structure Cu@C@Fe3O4 nanocomposite to present integrated functionalities of highly controllable antibiosis and electromagnetic wave (EMW) absorption to realize a bifunctional EMW absorption system. With stable concentration, the Cu@C@Fe3O4 nanocomposite can slowly release Cu ions to experience an efficient reactive oxygen species process to realize extreme stable antibiosis behavior and long-term antibacterial effect that is 100 % bactericidal effect. With the sustained antibacterial conditions, the Cu@C@Fe3O4 with magnetic component simultaneously exhibits a good impedance matching to lead a broad microwave absorption with a bandwidth of 5.87 GHz. Considering above two functions, the multifunctional Cu@C@Fe3O4 provides a pathway for multifunctional EMW absorption materials exploration in antibacterial and microwave absorption applications. This strategy also indicates the possibility to functionalize magnetic nanocapsules towards even broader applications.

Developing a multifunctional gradient pore structure Janus membrane loaded with MB@ZIF-8 nanoparticles and hydroxyapatite for guided periodontal bone regeneration

The guided tissue regeneration (GTR) procedure has become an important process for the treatment of periodontal tissue regeneration, using the membrane as a mechanical barrier to generate a distance across the defect that subsequently allowing bone regeneration. Due to the complexity of periodontal microenvironment caused by bacterial infections, inflammation, and fibrous tissue penetration, the guided tissue regeneration membrane is required to have antibacterial and barrier functions. We developed a loaded methylene blue @ ZIF-8 and hydroxyapatite gradient thermoplastic polyurethane Janus membrane for antibacterial osteogenic and barrier. This Janus membrane with a porous gradient structure was prepared to use phase-conversion method. The rough layer facilitated cell growth and promoted periodontal bone regeneration, whereas the smooth layer isolated the growing fiber tissue.The rapid release of reactive oxygen species in the early stage and continuous release of zinc ions by methylene blue @ZIF-8 can achieve long-term synergistic antibacterial effect, with antibacterial rates of 84 % and 72 % against Escherichia coli and Staphylococcus aureus, respectively, which can effectively reduce the local inflammation caused by bacteria. In summary, we applied the Janus membrane to a rat periodontal bone defect model, and the membrane showed good surgical performance, barrier properties, osteogenic properties, and antibacterial effects, which could have broad application prospects in the treatment of periodontal bone defects.

Superhydrophobic synergistic antibacterial ZrO2-based surfaces with tertiary hierarchical structures fabricated by femtosecond laser texturing and surface modification

Zirconia (ZrO2) is a hard and brittle dental implant material without anti-infective property. This work reports the preparation of a tertiary micro-nano hierarchical structure on a ZrO2 surface via femtosecond laser texturing combined with magnetron sputtering deposition of an Ag layer (Ag/ZrO2), aiming to achieve a superhydrophobic synergistic antibacterial effect. Laser-scanning pitch and Ag layer thickness were systematically optimized for obtaining the tertiary hierarchical structure. The wettabilities, antibacterial properties and durabilities of various ZrO2 and stearic acid modified Ag/ZrO2 (S-Ag/ZrO2) surfaces were further tested and comparatively analyzed. The results revealed that the optimal process parameters were a laser-scanning pitch of 30 μm and an Ag layer thickness of 100 nm. The as-obtained S-Ag/ZrO2 sample displayed a tertiary micro-nano hierarchical structure, which was featured by a periodic regular conical micro-convex structure covered with ZrO2 nano-protrusions and Ag nanoparticles. This structure could not only greatly reduce the solid-liquid contact area to achieve outstanding superhydrophobicity and durability, it could also sustainably release bacteria-killing Ag+ to obtain an antibacterial ratio of 95.1 % and ensure a long-term antibacterial effect. In addition, the optimal S-Ag/ZrO2 sample having this structure showed a PC12 cell survival rate of up to 81.75 %, demonstrating its good biocompatibility. This work may be of great inspiration and reference for the expansion of the use of ZrO2 in dentistry.

Hydrogels containing composite of Ag3Sn intermetallic compounds and tin oxide for enhanced anti-bacterial and wound healing

Bacterial infection has become a serious clinical challenge and a great threat to human health due to antibiotic resistance. Therefore, developing new antimicrobial agents are essential. It is noteworthy that the new antibacterial strategy, photocatalytic antimicrobial therapy, addresses the issue of bacterial resistance. Metal oxides, particular tin oxide, hold great promise in the photocatalytic antimicrobial properties. In addition, noble metal Ag has an excellent improvement effect on the visible light photocatalytic activity of photocatalyst. However, the pure Ag has some shortcomings, such as instability at high temperature. Here, Ag3Sn intermetallic compounds are synthesized, wherein the tin atoms are naturally oxidized to SnOx in the air. The composites (Ag3Sn-SnOx) possess a narrow band gap energy, rendering it suitable as a photocatalytic material responsive to visible light. Meanwhile, Ag3Sn-SnOx will slowly release Ag and play a long-term antibacterial effect. In addition, carboxymethyl chitosan-hyaluronic acid hydrogel are synthesized via amidation reaction, and Ag3Sn-SnOx is loaded into the hydrogel (Ag3Sn-SnOx@Gel), which is also endowed with ability to promote the proliferation and migration of fibroblasts. Coupled with its good biosafety profile, Ag3Sn-SnOx@Gel is expected to emerge as a reliable and effective alternative to the currently used clinical wound dressings.

Spatiotemporally responsive cascade bilayer microneedles integrating local glucose depletion and sustained nitric oxide release for accelerated diabetic wound healing

High glucose level, bacterial infection, and persistent inflammation within the microenvironment are key factors contributing to the delay of diabetic ulcers healing, while traditional therapeutic methods generally fail to address these issues simultaneously. Here, we present a spatiotemporally responsive cascade bilayer microneedle (MN) patch for accelerating diabetic wound healing via local glucose depletion and sustained nitric oxide (NO) release for long-term antibacterial and anti-inflammatory effects. The MN patch (G/AZ-MNs) possesses a degradable tip layer loading glucose oxidase (GOx), as well as a dissolvable base layer encapsulating l-arginine (Arg)-loaded nanoparticles (NPs). After wound administration, the base part rapidly dissolved, resulting in prompt separation of the MN tip within the wound tissue, which subsequently responded to the overexpressed matrix metalloproteinase-9 (MMP-9) in diabetic lesions, leading to the responsive release of GOx. The released enzyme catalyzed glucose into gluconic acid and hydrogen peroxide (H2O2), which not only reduced glucose level within the diabetic wound, but also initiated the cascade reaction between H2O2 with the Arg that was released from NPs, thereby achieving continuous production of NO for 7 days. Our findings demonstrate that a single administration of the MN patch could effectively heal non-infected or biofilm-infected diabetic wounds with the multifunctional properties.

Antibacterial nanofibrous film encapsulated with 4-terpineol/β-cyclodextrin inclusion complexes: Relative humidity-triggered release and shrimps preservation application

Antibacterial active packaging enables extensive biological effects to improve food safety. However, it still remains difficult to achieve controlled and precise release of bioactive compounds to the specific target location with required quantity in food packaging applications. Here, a novel relative humidity (RH) - responsive polyvinyl alcohol/chitosan (PVA/CS) composite nanofibrous film incorporated with 4-terpineol/β-cyclodextrin inclusion complexes (4-TA@β-CD ICs) was engineered by electrospinning that can be exploited as a functional packaging materials. The characterization results showed the thermal stability of the films was enhanced after the incorporation due to the hydrogen bonds between ICs and biopolymers. Besides, the 4 wt% 4-TA@β-CD ICs/PVA/CS film exhibited optimized morphology, crystallinity, mechanical properties, and water vapor permeability. The incorporation of ICs dramatically promoted the antioxidant and inhibition activity of the film especially towards Shewanella putrefaciens. Moreover, the release behavior of 4-TA indicated that high RH accelerated the releasing rate, and the film obtained a sustained-release effect. Finally, the film with long-term antibacterial effectiveness succeeded in extending the shelf life of Litopenaeus vannamei shrimps by an additional 2 days at 4 °C. This work developed a RH-responsive release packaging material, which may serve as an effective active food packaging.

Green synthesis of ZnO NPs with long-lasting and ultra-high antimicrobial activity

The continual onslaught of pathogenic microorganisms against humans, coupled with the escalating global challenge of antibiotic resistance, has led to a pervasive health crisis. To produce efficient antibacterial agents and combat bacterial resistance, zinc oxide nanoparticles (ZnO NPs) were synthesized, through green synthesis method by using Magnolia officinalis, Goldthread, and Lonicera japonica as extracts, respectively. Notably, there were no additional chemical reagents used in the synthesis route, emphasizing its eco-friendly nature. The antimicrobial efficacy of these ZnO NPs was assessed against Escherichia coli, Staphylococcus aureus, and Botrytis cinerea. The results revealed the ZnO NPs exceptional antimicrobial properties, demonstrating a minimum antimicrobial concentration (MIC) of 10 mg/L. Magnolia officinalis-ZnO NPs (M-ZnO NPs) exhibited 99.99 % antimicrobial activity against both E. coli and Staphylococcus aureus, along with 99.63 % effectiveness against Botrytis cinerea. Additionally, it was observed that the antibacterial characteristics of ZnO NPs exhibited minimal degradation after being stored in ambient air conditions at standard room temperature for a half-year. This study conclusively affirms the potent antimicrobial efficacy of green-synthesized ZnO nanoparticles. Transmission electron microscopy revealed that the particle size of ZnO NPs is 20–40 nm. Plant extracts contribute to the reduction processes of metal ions, and can also control the size and stability of formed nanostructures while avoiding the use of hazardous solvents. This green synthesis results in smaller particle sizes and sustains a long-term high antibacterial effect. Overall, this research expands the prospects for development involving nanomaterials, offering promising avenues for further exploration and innovation in this field.

Development and application of mathematical modeling of thymol release from environmental-responsive potato starch active packaging films

Traditional active packaging materials are easily affected by the environment, resulting in their inability to release active substances in specified quantities at specified times and locations. In this study, MCM-41 was used as a thymol (THY) carrier and added to the potato starch (PS) matrix to design an intelligent release active packaging film based on storage microenvironment. MCM-41 encapsulation improved thermal stability of THY. THY–MCM-41 addition significantly improved the tensile strength (TS, 7.18 MPa) of the film (P < 0.05) and endowed the film excellent gas and water barrier protection. THY release was responsive to temperature and relative humidity (RH), and the First–order model better explained the THY release pattern (R2 > 0.980). The THY-MCM-41/PS film exhibited long-term antibacterial effect during 10-day storage due to the sustained release of THY. Additionally, strawberries packaged in the THY–MCM-41/PS film exhibited the best sensory characteristics during 5-day storage (25 °C and 50 % RH). Overall, the present THY–MCM-41/PS film provides a novel alternative for the sustained release of active substances in order to achieve the excellent preservation of goods such as fruits and vegetables.

Antimicrobial and hydrophobic cellulose paper prepared by covalently attaching cinnamaldehyde for strawberries preservation

The demand for paper-based packaging materials as an alternative to incumbent disposable petroleum-derived polymers for food packaging applications is ever-growing. However, typical paper-based formats are not suitable for use in unconventional applications due to inherent limitations (e.g., excessive hydrophilicity, lack antimicrobial ability), and accordingly, enabling new capabilities is necessity. Herein, a simple and environmentally friendly strategy was proposed to introduce antimicrobial and hydrophobic functions to cellulose paper through successive chemical grafting of 3-aminopropyltriethoxysilane (APS) and cinnamaldehyde (CA). The results revealed that cellulose paper not only showed long-term antibacterial effect on different bacteria, but also inhibited a wide range of fungi. Encouragingly, the modified paper, which is fluorine-free, displays a high contact angle of 119.7°. Thus, even in the wet state, the modified paper can still maintain good mechanical strength. Meanwhile, the multifunctional composite papers have excellent biocompatibility and biodegradability. Compared with ordinary cellulose paper, multifunctional composite paper can effectively prolong the shelf life of strawberries. Therefore, the multifunctional composite paper represents good application potential as a fruit packaging material.

Novel bioactive nanospheres show effective antibacterial effect against multiple endodontic pathogens

AimThe current study evaluated the antibacterial activity of a newly developed quaternary ammonium polymethacrylate (QAPM)-containing bioactive glasses (BGs) via a two-step method by our group, namely BGs-HAEMB, and explored its cytotoxicity and biocompatibility. MethodsThe antibacterial effects of the BGs-HAEMB against planktonic bacteria, bacterial biofilm formation, and experimental root canal biofilms of persistent pathogens (Enterococcus faecalis, Streptococcus sanguis and Porphyromonas endodontalis) associated with endodontic infection were evaluated in vitro by agar diffusion tests, direct contact tests and live/dead staining. The cytotoxicity and biocompatibility of BGs-HAEMB were evaluated by CCK-8 assays in vitro and a skin implantation model in vivo. ResultsCompared to three clinically used endodontic sealers (Endofill, AH Plus, and iRoot SP), BGs-HAEMB exhibited the relatively strongest antibacterial effect against E. faecalis, S. sanguis and P. endodontalis after sitting for 14 and 28 days (P < 0.01). SEM images and CLSM images also showed that for each tested bacteria, BGs-HAEMB killed the most microorganism among all the experimental groups, regardless of treatment for 7 days or 28 days (P < 0.05). Besides, the BGs-HAEMB-treated groups showed a relatively low cytotoxicity (RGRs ranging from 88.6% to 102.9%) after 1, 3, and 7 days of exposure. Meanwhile, after 28 days of implantation, the inflammatory grade in BGs-HAEMB treated group was assessed as Grade I, in which the average numbers of inflammatory cells (6.7 ± 2.1) were less than 25. ConclusionsBGs-HAEMB exerted a long-term and stable antibacterial effect. The remarkable biocompatibility of BGs-HAEMB in vitro and in vivo confirmed its possible clinical application as a potential alternative in the development of the next generation of endodontic sealers.

Novel Injectable, Self-Healing, Long-Effective Bacteriostatic, and Healed-Promoting Hydrogel Wound Dressing and Controlled Drug Delivery Mechanisms.

Multivalent ion cross-linking has been used to form hydrogels between sodium alginate (SA) and hyaluronic acid (HA) in previous studies. However, more stable and robust covalent cross-linking is rarely reported. Herein, we present a facile approach to fabricate a SA and HA hydrogel for wound dressings with injectable, good biocompatibility, and high ductility. HA was first reacted with ethylenediamine to graft an amino group. Then, it was cross-linked with oxidized SA with dialdehyde to form hydrogel networks. The dressing can effectively promote cell migration and wound healing. To increase the antibacterial property of the dressing, we successfully loaded tetracycline hydrochloride into the hydrogel as a model drug. The drug can be released slowly in the alkaline environment of chronic wounds, and the hydrogel releases drugs again in the more acidic environment with wound healing, achieving a long-term antibacterial effect. In addition, one-dimensional partial differential equations based on Fickian diffusion with time-varying diffusion coefficients and hydrogel thicknesses were used to model the entire complex drug release process and to predict drug release.

One-step preparation of MnO2 nanozyme by PS-CDs for antibacterial, inhibition of S. aureus biofilm growth and colorimetric assay of tiopronin

The novel nanozyme has been used in the detection field as biosensor, but has also been employed in new fields like antibacterial and inhibiting of biofilm growth applications. This paper reports the rapid preparation of the nanozyme PS-CDs-MnO2 with oxidase activity by using PS-CDs as reducing agent to reduce KMnO4. The mechanisms of positive electrical property of PS-CDs-MnO2 and the single linear oxygen (1O2) have promised the broad-spectrum antibacterial ability and high efficiency in eliminating bacteria, with 48 h long-term antibacterial effect. The minimum inhibitory concentration (MIC) against Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) at 7.50 μg/mL, 60 μg/mL, 15 μg/mL and 60 μg/mL, respectively. The prepared PS-CDs-MnO2 could effectively inhibit the formation of S. aureus biofilm at the concentration of 10 μg/mL. The visually sensitive and selective sensing platform based on PS-CDs-MnO2-TMB was established, and realized the colorimetric detection of tiopronin (TPN) with a detection range at 285.71 nM–14.28 μM and detection limit at 6.30 nM. This research provides a good theoretical and practical basis for the preparation of oxidase nanozyme and its application in detection, antibacterial and inhibition of biofilm formation fields.

Antimicrobial and Antibiofilm Properties of Latvian Honey against Causative Agents of Wound Infections.

Honey is widely used in traditional medicine and modern wound healing biomaterial research as a broad-spectrum antimicrobial, anti-inflammatory and antioxidant agent. The study's objectives were to evaluate the antibacterial activity and polyphenolic profiles of 40 monofloral honey samples collected from beekeepers in the territory of Latvia. The antimicrobial and antifungal activity of Latvian honey samples were compared with commercial Manuka honey and the honey analogue sugar solutions-carbohydrate mixture and tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, clinical isolates Extended-Spectrum Beta-Lactamases produced Escherichia coli, Methicillin-resistant Staphylococcus aureus and Candida albicans. Antimicrobial activity was evaluated with the well-diffusion method (80% honey solution w/v) and microdilution method. The honey samples with the highest antimicrobial potential were tested to prevent biofilm development and activity against a preformed biofilm. The principal component analysis of the antimicrobial properties of honey samples vs. polyphenolic profile was performed. Eleven honey samples exhibited antibacterial activity to all investigated bacteria. The antibacterial effect of the samples was most significant on the Gram-positive bacteria compared to the studied Gram-negative bacteria. Latvian honey presents promising potential for use in wound healing biomaterials, opening the possibility of achieving long-term antibacterial effects.

Construction of ZnO/PCL Antibacterial Coating Potentially for Dental Unit Waterlines

The formation of bacterial biofilms and the contamination of treatment water within dental unit waterlines can lead to a risk of secondary bacterial infections in immunocompromised patients. Although chemical disinfectants can reduce the contamination of treatment water, they can also cause corrosion damage to dental unit waterlines. Considering the antibacterial effect of ZnO, a ZnO-containing coating was prepared on the surface of polyurethane waterlines using polycaprolactone (PCL) with a good film-forming capacity. The ZnO-containing PCL coating improved the hydrophobicity of polyurethane waterlines, thus inhibiting the adhesion of bacteria. Moreover, the continuous slow release of Zn ions endowed polyurethane waterlines with antibacterial activity, thus effectively preventing the formation of bacterial biofilms. Meanwhile, the ZnO-containing PCL coating had good biocompatibility. The present study suggests that ZnO-containing PCL coating can realize a long-term antibacterial effect on the polyurethane waterlines by itself, providing a novel strategy for the manufacture of autonomous antibacterial dental unit waterlines.

Plasma-Activated Hydrogels for Microbial Disinfection.

A continuous risk from microbial infections poses a major environmental and public health challenge. As an emerging strategy for inhibiting bacterial infections, plasma-activated water (PAW) has proved to be highly effective, environmental-friendly, and non-drug resistant to a broad range of microorganisms. However, the relatively short lifetime of reactive oxygen and nitrogen species (RONS) and the high spreadability of liquid PAW inevitably limit its real-life applications. In this study, plasma-activated hydrogel (PAH) is developed to act as reactive species carrier that allow good storage and controlled slow-release of RONS to achieve long-term antibacterial effects. Three hydrogel materials, including hydroxyethyl cellulose (HEC), carbomer 940 (Carbomer), and acryloyldimethylammonium taurate/VP copolymer (AVC) are selected, and their antibacterial performances under different plasma activation conditions are investigated. It is shown that the composition of the gels plays the key role in determining their biochemical functions after the plasma activation. The antimicrobial performance of AVC is much better than that of PAW and the other two hydrogels, along with the excellent stability to maintain the antimicrobial activity for more than 14 days. The revealed mechanism of the antibacterial ability of the PAH identifies the unique combination of short-lived species (1 O2 , ∙OH, ONOO- and O2 - ) stored in hydrogels. Overall, this study demonstrates the efficacy and reveals the mechanisms of the PAH as an effective and long-term disinfectant capable of delivering and preserving antibacterial chemistries for biomedical applications.

Long-term antibacterial activity by synergistic release of biosafe lysozyme and chitosan from LBL-structured nanofibers

Biosafe antibacterial agents are urgently demanded in treating infection especially chronic infection. However, efficient and controlled release of those agents remains great challenging. Two nature-derived agents, lysozyme (LY) and chitosan (CS), are selected to establish a facile method for long-term bacterial inhibition. We incorporated LY into the nanofibrous mats, then deposited CS and polydopamine (PDA) on the surface by layer-by-layer (LBL) self-assembly. In this vein, LY is gradually released with the degradation of nanofibers, and CS is rapidly disassociated from the nanofibrous mats to synergistically result in a potent inhibition against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) over a period of 14 days. Besides long-term antibacterial capacity, LBL-structured mats could readily achieve a strong tensile stress of 6.7 MPa with an increase percentage of up to 103%. The enhanced proliferation of L929 cells arrives at 94% with help of CS and PDA on the surface of nanofibers. In this vein, our nanofiber has a variety of advantages including biocompatibility, strong long-term antibacterial effect, and skin adaptability, revealing the significant potential to be used as highly safe biomaterial for wound dressings.