Effective Antibacterial Material Research Articles

Aluminum doped CuS nanocrystals for efficient antibacterial activity via photothermal and photodynamic pathways

The overuse of antibiotics has led to the emergence of drug-resistant bacteria, presenting a significant risk to public health and human well-being. A novel antibacterial material with safe and effective antibacterial properties is a viable strategy to address these issues. In this work, Al ions doped CuS particles (CuS@Al) with a flower-like nanostructure were synthesized through a simple hydrothermal method, exhibiting good photothermal and photodynamic antibacterial properties. The morphological, microstructural and crystallinity of CuS@Al were evaluated by SEM, EDS, TEM, FTIR, XRD and XPS analyses. The introduction of Al ions significantly enhanced the photothermal effects of CuS@Al, and the temperature increased from 50.7 ℃ (CuS) to 58.1 ℃ (CuS-6) under irradiation (808nm, 2.0W·cm-2, 10min). The resulting CuS@Al exhibited a good photothermal conversion efficiency, effective release of reactive oxygen species (ROS), and remarkable photothermal antibacterial activity. Both E. coli and S. aureus were completely inactivated by CuS@Al (0.5mg/mL) under photodynamic conditions. The synthesis of CuS@Al provides a strategy for creating highly effective antibacterial materials in particulate form.

Modification of magnetic mesoporous silica nanoparticles with antimicrobial peptide as recyclable and durable antibacterial agents

Antimicrobial peptides (AMPs) play a significant role in combating antimicrobial resistance. However, the applications of AMPs are constricted by insufficient stability under physiological conditions. Therefore, developing novel and effective antibacterial materials with AMPs is an urgent demand. In this study, magnetic mesoporous silica nanoparticles were fabricated through a facile method and stable modifications of AMPs through the bond formation of Fe-S in the mesopores. The resultant nanoparticles (denoted as Fe3O4@mSiO2@CysHHC10) consisted of Fe3O4 core, SiO2 out layer with cylindrical mesoporous channels, and abundant CysHHC10 immobilized in the mesopores. Fe3O4@mSiO2@CysHHC10 exhibited powerful antibacterial performance against both Gram-negative and Gram-positive bacteria. Also, owing to the CysHHC10 being sheltered with mesoporous channels, Fe3O4@mSiO2@CysHHC10 retained almost more than 99.9% antibacterial efficiency for bacteria throughout nine cycles. Furthermore, the resultant nanoparticles exhibit favorable biocompatibility in vitro. This work provides a novel way for the fabrication of antibacterial magnetic materials with recyclable and durable antibacterial activity.

A novel graphene oxide-1,3,4-oxadiazole-2,5-diamine nanomaterial with enhanced bactericide activity

BackgroundThe development of effective nanomaterials is becoming important to safeguard the human health from the bacteria-induced infectious diseases. Among the popular nanomaterials, graphene oxide (GO) owns functional groups and exhibits noticeable benefits which are helpful for biological applications. For raising the antibacterial activity with the reinforcement of the active organic molecules like oxadiazoles, a novel GO-1,3,4-oxadiazole-2,5-diamine (ODA) nanomaterial was prepared and characterized for the first time in our study. MethodsGO-diamine nanomaterials were synthesized by simply reacting GO with ODA or aliphatic diamine in a water bath at room temperature. In an in vitro antimicrobial activity investigation, 5 mg of the nanomaterial was immersed in 20 mL of the Escherichia coli culture in agar media at 37 °C, and the growth of bacteria was evaluated after 24 h. Significant FindingsBy XRD analysis, it was found that the increase in d-spacing after the intercalation of aliphatic diamine into GO layers was close to the molecular length of aliphatic diamine, indicating a perpendicular bridging configuration. Conversely, the aromatic ODA reacted with the oxygenated functionalities on the outer surface of GO layer and a free amine was left behind in the terminal. In the bactericide activity test, a near complete E. coli inhibition was achieved only with GO-ODA, much better than pure ODA (30–60 %) and pristine GO (0–20 %). The pure aliphatic diamines showed some extent of antibacterial activity (20–60 %) due to their natural toxicity, but their GO-aliphatic diamine derivatives demonstrated negligible bactericide activity (0–10 %). Conclusively, this study provides a greener and effective antibacterial material without using any catalyst or organic solvent.

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

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

2-Pyridinecarboxaldehyde-Modified Chitosan-Silver Complexes: Optimized Preparation, Characterization, and Antibacterial Activity.

The widespread prevalence of infectious bacteria is one of the greatest threats to public health, and consequently, there is an urgent need for efficient and broad-spectrum antibacterial materials that are antibiotic-free. In this study, 2-pyridinecarboxaldehyde (PCA) was grafted onto chitosan (CS) and the modified CS coordinated with silver ions to prepare PCA-CS-Ag complexes with antibacterial activity. To obtain complexes with a high silver content, the preparation process was optimized using single-factor experiments and response surface methodology. Under the optimal preparation conditions (an additional amount of silver nitrate (58 mg), a solution pH of 3.9, and a reaction temperature of 69 °C), the silver content of the PCA-CS-Ag complex reached 13.27 mg/g. The structure of the PCA-CS-Ag complex was subsequently verified using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. Furthermore, three possible complexation modes of the PCA-CS-Ag complex were proposed using molecular mechanics calculations. The results of the antibacterial assay in vitro showed that the PCA-CS-Ag complex exhibited strong antibacterial activity against both Gram-positive and Gram-negative bacteria, exerting the synergistic antibacterial effect of modified chitosan and silver ions. Therefore, the PCA-CS-Ag complex is expected to be developed as an effective antibacterial material with promising applications in food films, packaging, medical dressings, and other fields.

Exploring the biophysical properties, synergistic antibacterial activity, and cell viability of nanocomposites containing casein phosphopeptides and amorphous calcium phosphate

The application of nanotechnology in restorative and preventive dentistry has the potential to significantly improve the treatment of tooth structure diseases, which are common and harmful. This study primarily focuses on the production of a nanocomposite that utilizes amorphous calcium phosphate (ACP) and casein phosphopeptides (CPPs), which are widely employed in oral care products. The aim is to investigate the manufacturing process and characteristics of this nanocomposite, as it holds potential for applications in the field of oral care. The nanocomposite was formed by mixing the in-house synthesized CPP and in situ prepared ACP in the presents of gel extracted from the Aloe Vera. The physico-chemical characteristics of the product were comprehensively studied by various techniques. The findings suggest that a novel substance developed by a chelating reaction between the carboxyl groups and amino groups leads to forming a stable nanocomposite. The antibacterial activity of CPP-ACP nanocomposite and its individual component was tested against E. Faecalis and S. mutans, demonstrating potent antibacterial activity against both bacteria. Importantly, the cytotoxicity of CPP-ACP nanocomposite against Human epithelial type 2 cell line showed very low toxicity representing a good cytocompatibility. These findings suggest that the CPP-ACP nanocomposite has potential as an effective antibacterial material for healthcare products while supporting cell viability.

Synthesis and Characteristics of a Fish Scale-Based Biochar–Nanosilver Antibacterial Material

Microbial contamination has caused various diseases via pathogenic bacteria, endangering people’s lives every day. Recently, increasing attention has been paid to the exploration of new and effective antibacterial materials. In this paper, we attempted to synthesize a fish scale charcoal nanosilver antibacterial composite using waste fish scale as a carbon substrate. X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, and scanning electron microscopy showed that the structure of the nanosilver fish scale material formed and the nanosilver particles formed account for 72.1% of the silver element. Its antibacterial ability against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa was examined using the plate counting method and inhibition zones; the maximum inhibition zone was 32 mm. The antibacterial rate could reach >99.9%, indicating that this prepared material had excellent antibacterial activity. After 20 batches of bacteriostasis, the bacteriostasis rate was more than 90%, indicating that the fish scale/silver composite had sustained antibacterial ability and excellent antibacterial reusability. Finally, potential antibacterial mechanism was proposed. Overall, the fish scale/silver composite has a good application prospect and a wide range of applications in the handling of microbial pollution in the future.

Electrospun Metal-Organic Framework-Fabric Nanocomposites as Efficient Bactericides.

In this work, we utilized electrospinning to develop advanced composite membranes of polyvinyl chloride (PVC) loaded with postmetalated metal-organic frameworks (MOFs), specifically UiO-66(COOH)2-Ag and ZIF-8-Ag. This innovative technique led to the creation of highly stable PVC/MOFs-Ag membrane composites, which were thoroughly characterized using various analytical techniques, including scanning electron microscopy, powder X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, porosity analysis, and water contact angle measurement. The results verified the successful integration of MOF crystals within the nanofibrous PVC membranes. The obtained composites exhibited larger fiber diameters for 5 and 10% MOF loadings and a smaller diameter for 20% loading. Additionally, they displayed greater average pore sizes than traditional PVC membranes across most MOF loading percentages. Furthermore, we examined the antibacterial properties of the fabricated membranes at different MOFs-Ag loadings. The findings revealed that the membranes demonstrated significant antibacterial activity up to 95% against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria as the MOFs-Ag loading increased, even when maintaining a constant silver concentration. This indicates a contact-based inhibition mechanism. The outcomes of this study have crucial implications for the development of novel, stable, and highly effective antibacterial materials, which could serve as superior alternatives for face masks and be integrated into materials requiring regular decontamination, as well as potential water filtration systems.

NIR-dependent photothermal-photodynamic synergistic antibacterial mechanism for titanium carbide nanosheets intercalated and delaminated by tetramethylammonium hydroxide

The infectious disease epidemics caused by pathogens are a serious and growing worldwide public health problem. More seriously, the multiple resistant bacteria extensively spread in hospitals or communities due to antibiotic abuse. In this paper, we fabricate two-dimensional Ti3C2 nanosheets with excellent biocompatibility and photothermal-photodynamic synergistic antibacterial activity against E. coli and S. aureus based on the strategy of tetramethylammonium hydroxide (TMAOH)-driven intercalation and delamination. Compared with the traditional Ti3C2 nanosheets exfoliated by HF or situ HF (HCl + LiF), the photothermal-photodynamic Ti3C2 nanosheets show higher synergistic antibacterial efficiency. In addition, the antibacterial mechanism demonstrates that biofilm disruption and leakage of bacterial contents contribute to reactive oxygen species reaction (ROS) and photothermal antibacterial activity irradiated by NIR after most Ti3C2 nanosheets adhering to target bacteria. In conclusion, the Ti3C2 nanosheets have great potential as an effective antibacterial material without causing drug resistance, relying on intercalating and delaminating by TMAOH.

Impact of microwave synthesis time on the shape of silver nanostructures and their antibacterial activity

Silver is a well-known effective antibacterial and disinfectant material with relatively few side effects. Nanosilver derived from it, have strong antibacterial, antifungal and broad-spectrum antiviral properties. This study describes how the microwave synthesis durations of silver nanoparticles affect their shape, and the effect of the shapes of these nanoparticles on their antibacterial activity. The optical properties of the nanosilver were examined through UV-Vis absorption spectroscopy. The morphology of the grain was determined by transmission electron microscopy (TEM), and the crystallinity of the nanosilver was confirmed by X-ray diffraction (XRD). The antibacterial activities were assessed using bacterial pathogens Bacillus cereus and Bacillus megaterium, and were performed using the disk diffusion method. The obtained results show that (i) the shape and size of the nanosilver change when the microwave time is increased. They are of various sizes but almost all circular in shape when microwaved for 1.5 min, of larger sizes and different non-spherical geometric shapes after 3 min of microwave, and converted to nanowires after 5 min of microwave. (ii) Bacillus cereus and Bacillus megaterium were sensitive to all nanosilver but the antibacterial activity was more potent when the nanosilver possessed a defined shape than when they were silver nanowires.

Cationic Liposomes with Different Lipid Ratios: Antibacterial Activity, Antibacterial Mechanism, and Cytotoxicity Evaluations.

Due to their strong bacterial binding and bacterial toxicity, cationic liposomes have been utilized as effective antibacterial materials in many studies. However, few researchers have systematically compared their antibacterial activity with their mammalian cell cytotoxicity or have deeply explored their antibacterial and cytotoxicity mechanisms. Here, we prepared a series of cationic liposomes (termed CLs) using dimethyldioctadecylammonium chloride (DODAC) and lecithin at different molar ratios. CLs have the ability to effectively bind with Gram-positive and Gram-negative bacteria through electrostatic and hydrophobic interactions. Further, the CLs with high molar ratios of DODAC (30 and 40 mol%) can disrupt the bacterial wall/membrane, efficiently inducing the production of reactive oxygen species (ROS). More importantly, we carefully compared the antibacterial activity and the mammalian cell cytotoxicity of various CLs differing in DODAC contents and liposomal concentrations and revealed that, whether they are bacterial or mammalian cells, an increasing DODAC content in CLs can lead to an elevated cytotoxicity level. Further, there exists a critical DODAC contents (>20 mol%) in CLs to endow them with effective antibacterial ability. However, the variation in the DODAC content and liposomal concentration of CLs has different degrees of influence on the antibacterial activity or cytotoxicity. For example, CLs at high DODAC content (i.e., CL0.3 and CL0.4) could effectively kill both types of bacterial cells but only cause negligible toxicity to mammalian cells. We believe that a systematic comparison between the antibacterial activity and the cytotoxicity of CLs with different DODAC contents will provide an important reference for the potential clinical applications of cationic liposomes.

Silver nanoparticles based on sulfobutylether-β-cyclodextrin functionalized graphene oxide nanocomposite: Synthesized, characterization, and antibacterial activity

In this work, an effective method was explored to prepare silver nanoparticles/graphene oxide-sulfobutylether-β-cyclodextrin (AgNPs/GO-SBE-β-CD) antibacterial nanocomposite. Dopamine (DA) was used as a green and mild reductant to directly in situ reduce silver nitrate on Sulfobutylether-β-cyclodextrin (SBE-β-CD) modified graphene oxide (GO-SBE-β-CD). Its synthesized, antibacterial properties and biocompatibility were studied. Results showed that silver nanoparticles with an average size of 73 nm were uniformly distributed on the GO-SBE-β-CD sheets. In addition, AgNPs/GO-SBE-β-CD were proved an effective antibacterial material against both gram-negative and gram-positive, reduced the viability of E. coli and S. aureus by 90 % at 40 µg/mL. At the same time, AgNPs/GO-SBE-β-CD co-cultured with L929 cells did not show cytotoxicity. In vivo experiment, AgNPs/GO-SBE-β-CD showed good biocompatibility. Collectively, AgNPs/GO-SBE-β-CD is a promising material to prevent bacterial infection, expecting to be applied in wound healing.

Sliver nanoparticles@carbon dots for synergistic antibacterial activity

A novel composite material named sliver nanoparticles@carbon dots (AgNPs/CDs) was fabricated with CDs as the capping agents through one simple method. The images of TEM showed that CDs were embedded in the gaps of AgNPs and the as-prepared AgNPs/CDs can be self assembled into nanochains through electrosatic interaction between silver nanoparticles and carbon dots. With higher redox properties than AgNPs, the as-prepared composites exhibited excellent synergistic antibacterial performance against Gram-positive bacterium and Gram-negative bacterium in the antibacterial assays, which indicates potential application as an effective antibacterial material. And the results of antibacterial assy showed that the minimum inhibitory concentrations (MIC) of AgNPs/CDs were 40 μg/mL for E. coli and 20 μg/mL for S. aureus in LB medium. In addition, the oxidative stress induced by AgNPs/CDs-mediated reactive oxygen species further confirmed good application prospects in antibacterial.

Silver nanoparticles with vanadium oxide nanowires loaded into electrospun dressings for efficient healing of bacterium-infected wounds

Silver nanoparticles (AgNPs) have been widely recognised as effective antibacterial materials in textiles for enhancing wound healing. However, high loadings of AgNPs are toxic and expensive. Thus, it is ideal to prepare AgNPs in a favourable nanostructure for stable and effective conjugation with the textile carrier by selecting a reductant and stabiliser that contributes to the antibacterial effect. Here, silver nanoparticles/vanadium oxide nanowires (Ag/VOx NWs) were prepared via a one-step reduction strategy using vanadium oxide quantum dots (VOx QDs) as both the reductant and stabiliser. VOx QDs possess antibacterial properties, which aid in minimising the applied silver content while enhancing bactericidal performance. Silver can self-aggregate into nanoparticles as well as promote the formation of vanadium oxide nanowires (VOx NWs). Accordingly, the Ag/VOx NWs exhibited remarkable antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The nanowire structure of the Ag/VOx NWs was favourable for effective loading into a sodium alginate (SA) gel fabric to form a wound dressing. The effective loading of Ag/VOx NWs on SA was conducive to the complete dispersion of the bacteriostatic agent and enhanced the antibacterial activity of AgNPs. The wound dressing efficiently suppressed the growth of wound bacteria and promoted wound healing in vivo.

Graphene nanoplatelets/CeO2 nanotiles nanocomposites as effective antibacterial material for multiple drug-resistant bacteria.

Antibacterial agents with low toxicity to normal cells, redox activity and free radical scavenging property are urgently needed to address the global health crisis. The phenomenal conducting nature of graphene is a best fit to enhance the antibacterial properties of metal oxides. In this work, CeO2 nanotiles and graphene nanoplatelets/CeO2 nanotiles nanocomposites (G/CeO2) have been synthesized by a solvothermal method. The prepared materials have been characterized using XRD, FE-SEM, EDX, and UV–visible spectroscopy techniques to investigate their crystallinity, morphology, composition, and optical bandgap energies. The CeO2 and G/CeO2 nanocomposites have also been tested for antibacterial applications. The neat CeO2 nanotiles sample inhibits the bacterial growth of Pseudomonas aeruginosa and Staphylococcus aureus up to 14.21% and 39.53% respectively. The antibacterial activity was tremendously enhanced using 25% graphene-loaded sample (G/CeO2-II) i.e., approximately 83% loss of P. aeruginosa and 89% in case of S. aureus has been observed. This can be attributed to the unique nano-architecture, oxidative stress due to the excellent ability of reversible conversion between the two electronic states of CeO2 and the stress exerted by the planar graphene and CeO2 nanotiles. Therefore, the G/CeO2 nanocomposites can find potential application as nano-antibiotics for controlling pathogens.

Improvement of physicochemical properties of ternary nanocomposites based on hydroxyapatite/CuO/graphene oxide for biomedical usages

The nanocomposites (NCs) based on hydroxyapatite (HAP) could be improved into biologically safe and effective antibacterial materials. Combining HAP with copper oxide (CuO) and graphene oxide (GO) in a ternary nanocomposite (TNC) increased the human osteoblast viability in vitro to about 98.3% ± 3%. The structure was also analyzed with XRD, FTIR, XPS. The average roughness (Ra) decreased from 68.2 to 42.4 nm, while the root mean square roughness (Rq) changed slightly from 55.5 to 54.4 nm. The TEM investigation showed a decrease in the diameter and length of nanorod particles from 14 to 37 nm to 11 and 34 nm. In addition, the nano strip particles decreased from 17 to 14 nm in diameter, while a change in length was from 151 to 139 nm in diameter and length, respectively. The nanorods belong to HAP, while nanostrips belong to CuO. The polarization resistance decreased from 108 to around 44.5 (ohm.cm2). The antibacterial activity was done against the gram-negative E. coli, and the gram-positive S. aureus where inhibition zones reached 17.1 ± 1.3 and 14.3 ± 0.7 mm, respectively. The enhancement in cell viability and antibacterial behavior indicate the biocompatibility of the biomaterials for biomedical applications.

Preparation, characterisation and antibacterial activity evaluation of N-acetylneuraminic acid-crosslinked chitosan hydrogels

In this study, CS-NeuAc hydrogel was prepared from chitosan (CS) and N-acetylneuraminic acid (NeuAc) using cyclic freeze/thaw under 1-ethyl-3-(3-dimethylaminopropyl)-carbodiiminde/N-hydroxysuccinimide catalysis. Fourier transformed infrared spectroscopy, X-ray diffraction, and scanning electron microscopy analyses confirmed the successful synthesis of CS-NeuAc hydrogel. CS-NeuAc hydrogels were found to be equipped with suitable swelling behaviour, porosity, water evaporation rate, degradation rate, and good mechanical properties compared to CS. The swelling rate, water evaporation rate, and degradation rate of prepared hydrogel with a CS/NeuAc molar ratio of 10:1 were 710.7 ± 28.6%, 78.2 ± 1.6%, and 58.6 ± 1.5%, respectively. Moreover, CS-NeuAc hydrogel exhibited excellent biocompatibility. The evaluation of CS-NeuAc hydrogels’ antibacterial activity confirmed that they serve as effective antibacterial materials against Escherichia coli and Staphylococcus aureus with antibacterial rates above 95% and 92%, respectively, and the minimum inhibitory concentrations was above 400 μg/ml. In conclusion, CS-NeuAc hydrogel can be a candidate for biological antibacterial materials.

Radiation synthesis of Poly(N-vinylpyrrolidone/acrylic acid/pectin/silver) nanocomposite hydrogel and its antimicrobial activity

ABSTRACT Recently, the need for effective antibacterial materials is growing day after day. Hydrogels with antimicrobial activities are strongly recommended in many biomedical applications. This work aims to prepare natural based nanocomposite hydrogel composed of N-vinyl pyrrolidone (NVP), acrylic acid (AAc) and pectin (PEC) embedded with silver nanoparticles (AgNPs). The prepared Poly(NVP/AAc/PEC/Ag) pH-sensitive nanocomposite hydrogel was characterized by gel (%), equilibrium swelling, FTIR, SEM, and XRD. Additionally, in order to confirm the incorporation of AgNPs within the nanocomposite hydrogel matrix during irradiation, TEM analysis was carried out. The AgNPs have average particles size 5.9 ± 1 nm for 10 kGy, 6.7 nm ± 2 for 20 kGy, and 8.9 ± 3 nm for 30 kGy, respectively. The XRD data are in good agreement with TEM analysis. The antibacterial activities of the selected Poly(NVP/AAc/PEC/Ag) nanocomposite hydrogel prepared at 30 kGy irradiation dose towards S. aureus, and E. coli has a higher antibacterial activity than other irradiation doses.

Long-term, synergistic and high-efficient antibacterial polyacrylonitrile nanofibrous membrane prepared by “one-pot” electrospinning process

Enhancing long-term antibacterial activity of membrane materials is an effective strategy to reduce biological contamination. Herein, we developed a long-term, synergistic antibacterial polyacrylonitrile (PAN) nanofiber membrane by a “one-pot” electrospinning process. In the reaction solution of PAN and N, N-dimethylformamide (DMF), silver-silicon dioxide nanoparticles (Ag@SiO2 NPs) are in-situ synthesized and stabilized using silane coupling agent; and [2-(methacryloyloxy)-ethyl] trimethylammonium chloride (MT) monomers are then in-situ cross-linked to obtain a polyquaternary ammonium salt (PMT). Subsequently, the casting solution is directly used to fabricate Ag@SiO2/PMT-PAN nanofibrous membrane (NFM) via electrospinning. The antibacterial activity, reusability, synergy effect and biological safety of the Ag@SiO2/PMT-PAN NFM are systematically investigated, and the synergistic antibacterial mechanism is also explored. Even at very low (0.3 wt%) content of silver, the Ag@SiO2/PMT-PAN NFM exhibits excellent antibacterial activity against E. coli (99%) and S. aureus (99%). Also, the antibacterial ability of the NFM remains the same level after three cycles of antibacterial processes with the efficient synergy effects of Ag@SiO2 and PMT components. When the Ag@SiO2/PMT-PAN contacts with bacteria, the PMT attracts and kills the bacteria through electrostatic action. The bacteria with damaged cell membranes are deposited on the nanofibrous membrane, which could greatly promote the release of Ag+ and further enhance the antibacterial activity. Moreover, L929 fibroblasts are co-cultured with the extract of 4 mg/mL Ag@SiO2/PMT-PAN for 5 days, which exhibits a low cytotoxicity with a cell proliferation ratio of 95%. This work opens new pathways for developing long-term effective and synergistic antibacterial nanofibrous membrane materials to prevent infections associated with biomedical equipment.

Synthesis, Structures, and Antibacterial Activities of Hydrazone Compounds Derived from 4-Dimethylaminobenzohydrazide

A series of three new hydrazone compounds derived from the condensation reactions of 4-dimethylaminobenzohydrazide with 4-dimethylaminobenzaldehyde, 2-chloro-5-nitrobenzaldehyde and 3-methoxybenzaldehyde, respectively, were prepared. The compounds were characterized by elemental analysis, infrared and UV-vis spectra, HRMS, 1H NMR and 13C NMR spectra, and single crystal X-ray diffraction. Crystals of the compounds are stabilized by hydrogen bonds. The compounds were assayed for antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus) and antifungal (Aspergillus niger and Candida albicans) activities by MTT method. The results indicated that compound 2 is an effective antibacterial material.