Good Antibacterial Properties Research Articles

Temperature-dependent heterojunction ternary nanocomposite: Assessing photocatalytic and antibacterial applications

Heterojunction nanocomposites (ZnO:NiO:CuO) were synthesized via a hydrothermal method and annealed at three different temperatures (400 °C, 600 °C, and 800 °C). The structural, optical, and electrical properties were examined by employing XRD, SEM, UV–Vis, FTIR, and LCR meter techniques to investigate the effects of annealing. Increasing the annealing temperature resulted in the nanocomposites (NCPs) exhibiting enhanced crystallinity, purity, optical properties, and improved electrical and dielectric behavior. The calculated crystalline sizes (Debye-Scherrer method) of the NCPs were determined to be 21, 26 and 34 nm for annealing temperature 400 °C, 600 °C, and 800 °C, respectively. The calculated bandgaps of synthesized samples were found in the range of 2.92-2.55 eV. This temperature-dependent annealing process notably influenced particle size, morphology, band-gap characteristics, and photocatalytic efficiency. EDX analysis affirmed the sample purity, with elemental peaks of Zn, Cu, Ni, and O. These NCPs demonstrated exceptional photocatalytic activity against various dyes solutions (Methyl orange (MO), Methylene Blue (MB), and mixed solution of dyes) under sunlight and also showed good antibacterial properties assessed by the disc diffusion method. Notably, the nanocomposite annealed at 400 °C exhibited a particularly high degradation efficiency by degrading 96% MB and 91% MO in just 90 min under sunlight.

Synthesis, Antimicrobial Activities and Molecular Docking Studies of New N-Acylated Derivatives of 5-(2-Phenyl-1,8-naphthyridin-3-yl)-1,3,4-oxadiazol-2-amine

Present study establishes a novel synthetic route of N-acetylated derivatives of 5-(2-phenyl-1,8-naphthyridine-3-yl)-1,3,4-oxadiazole-2-amine (6a-j), which was achieved in four steps with good yields. 2-Amino nicotinaldehyde and ethyl 3-oxo-3-phenylpropanoate on refluxing with triethylamine in ethanol undergoes Friedlander synthesis to furnish ethyl 2-phenyl-1,8-naphthyridine-3-carboxylate, which further converted into 2-phenyl-1,8-naphthyridine-3-carbohydrazide by reacting with hydrazine hydrate upon reflux, followed by cyclization with cyanogen bromide in the presence of water and 1,4-dioxane with sodium bicarbonate to afford 5-(2-phenyl-1,8-naphthyridin-3-yl)-1,3,4-oxadiazol-2-amine (5). Compound 5 was acetylated using numerous symmetrical anhydrides to synthesize novel N-acetylated derivatives (6a-j). The IR, 1H, 13C NMR and mass spectral analysis were used to characterize the structure of synthetic compounds. The synthesized compounds were evaluated for their antimicrobial efficiency against bacteria (S. aureus and E. coli) using ampicillin as a standard reference and against fungi (C. albicans) using fluconazole as a standard reference. Compound 6e exhibited good antibacterial properties while compounds 6c and 6e had shown high antifungal activity, whereas remaining compounds shown moderate to weaker antimicrobial activity. The synthesized derivatives verified their docking strength against Mtb MurB (PDB ID: 5JZX) and showed significant docking activity, however, compound 6f (-10.98 kcal/mol) and compound 6b (-10.52 kcal/mol) had a strong binding affinity compared to the other synthesized compounds.

Natural Extracts and Their Applications in Polymer-Based Active Packaging: A Review.

At a time when food safety awareness is increasing, attention is paid not only to food and additives but also to packaging materials. Most current food packaging is usually made of traditional petroleum-based polymeric materials, which are not biodegradable and have adverse effects on the environment and health. In this context, the development of new non-toxic and biodegradable materials for extending the best-before date of food is receiving increasing attention. In addition, additives in packaging materials may migrate outward, resulting in contact with food. For this reason, additives are also seen as a transition from synthetic additives to natural extracts. Active extracts from animals and plants having good antioxidant and antibacterial properties are also beneficial for human health. It is indisputable that active extracts are ideal substitutes for synthetic additives. Polymer packaging materials combined with active extracts not only maintain their original mechanical and optical properties and thermal stability but also endow polymers with new functions to extend the shelf life of food. This review paper provides an overview of this promising natural extract-containing polymer-based active packaging, with a focus on plant essential oils (containing phenolics, monoterpenes, terpene alcohols, terpene ketones, and aldehydes), pigments (procyanidins), vitamins (vitamin B), and peptides (nisin). In particular, this paper covers the research progress of such active extracts, in single or compound forms, combined with diverse polymers (mostly biopolymers) for food packaging applications with particular focus on the antioxidant and antibacterial properties of packaging materials.

Chitosan–fucoidan encapsulating cinnamaldehyde composite coating films: Preparation, pH-responsive release, antibacterial activity and preservation for litchi

In this study, an edible composite film with pH-responsive release was prepared by the formation of Schiff-base imine bonds between chitosan (CS) and oxidized fucoidan (CS–FU) and encapsulating cinnamaldehyde (CA). Fourier-transform infrared, 1H nuclear magnetic resonance, X-ray photoelectron spectroscopy and gel permeation chromatography confirmed the formation of CS–FU. The result showed that, oxidation degree of FU, degrees of substitution, average molecular weight and yield of CS–FU were 25.57 %, 10.48 %, 23.3094 kDa and 45.63 ± 0.64 %, respectively. Scanning electron microscopy revealed that CA was encapsulated within the CS–FU matrix. Increasing the CA content could improve the mechanical properties and ultraviolet and visible-light resistances of the CS–FU coating films but enhance their water vapor permeabilities. The release of CA increased as the pH decreased, and the antibacterial rate at pH 5 was 2.3-fold higher than that at pH 7, indicating good pH-responsive release and antibacterial properties in mildly acidic environments. Owing to their excellent properties, the CA/CS–FU-0.1 coating films maintained the appearance and quality indices of litchis for at least eight days. Hence, multifunctional composite coating films are prospective eco-friendly and intelligently responsive controlled-release packaging materials for fruit preservation.

Antibacterial activities of titanium dioxide (TiO2) nanotube with planar titanium silver (TiAg) to prevent orthopedic implant infection

BackgroundOrthopedic implant infection has become a common catastrophic complication after various orthopedic implants, which can lead to prolonged use of antibiotics and even surgical failure. The quality of care (QoC) of orthopedic implant infection is very important.MethodsTitanium dioxide (TiO2) nanotube array with planar TiAg was prepared, and their antibacterial rates were tested. 400 patients hospitalized in the Department of Orthopedics of Wuhan Fourth Hospital from May 2019 to May 2020 were selected as controls (before QoC evaluation system of orthopedics), and 400 patients hospitalized from June 2020 to June 2021 were selected as observation group (after QoC evaluation system of orthopedics).ResultsRegardless of Staphylococcus aureus or Escherichia coli, the antibacterial rate of TiO2 nanotube array with planar TiAg was clearly higher than that of pure iron film on the 10th and 20th days (P < 0.05). The accuracy of hospitalization assessment, disease assessment, adverse event intervention, nursing record filing and nursing satisfaction in observation group were higher as against controls (P < 0.05).ConclusionThe TiO2 nanotube array with planar TiAg has good antibacterial property, which can effectively prevent orthopedic implant infection. The construction of QoC evaluation system for orthopedic specialists can effectively improve the QoC of orthopedic specialists.

Tuning oxidant and antioxidant activities of ceria by anchoring copper single-site for antibacterial application

The reaction system of hydrogen peroxide (H2O2) catalyzed by nanozyme has a broad prospect in antibacterial treatment. However, the complex catalytic activities of nanozymes lead to multiple pathways reacting in parallel, causing uncertain antibacterial results. New approach to effectively regulate the multiple catalytic activities of nanozyme is in urgent need. Herein, Cu single site is modified on nanoceria with various catalytic activities, such as peroxidase-like activity (POD) and hydroxyl radical antioxidant capacity (HORAC). Benefiting from the interaction between coordinated Cu and CeO2 substrate, POD is enhanced while HORAC is inhibited, which is further confirmed by density functional theory (DFT) calculations. Cu-CeO2 + H2O2 system shows good antibacterial properties both in vitro and in vivo. In this work, the strategy based on the interaction between coordinated metal and carrier provides a general clue for optimizing the complex activities of nanozymes.

Fabrication of Air Conditioning Antimicrobial Filter for Electrically Powered Port Tractors via Electrospinning Coating

With the stricter emission regulations for internal combustion engines, electric vehicles, including electrically powered port tractors, have received increasing attention. However, currently, most of the filters used in electric vehicles are conventional membranes that only have the function of filtering particles and foreign objects. Therefore, in order to improve the above issues, the surface of commercial non-woven filter membranes was coated with Ag nanopowder nanofibers and AgNO3 nanofibers via electrospinning. At present, the comparative research on the antibacterial ability of Ag nanopowder and AgNO3 is still blank in the same research system, especially with the use of electrospun coating technology. The morphologies and structures of non-woven fabrics and electrospinning coated samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The characterization results indicate that both pure PVA and PVA composite fibers can be successfully coated on the surface of non-woven fabrics. The average diameter of all electrospun PVA composite fibers is distributed in the range of 470–700 nm. The PVA nanofibers with a low content of 1 wt% AgNO3 have good antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with clearance clear zones of inhibition of 26.00 mm and 17.30 mm, respectively.

Formulation and development of herbal facewash using Beal leaves: Aegle marmelos

In this study, herbal anti-acne face wash gels were prepared using polymers Carbopol and extract of aegle marmelos (beal patra), which show the antibacterial property and are widely used in modern herbal medicine. Results showed that the gels were non-irritating, stable, and possess anti-acne activity. Acne is a common skin problem that 85% of teenagers face today. Herbal drugs have been used for many years, not only in Asian countries but also worldwide for social well-being. Herbal formulations have rising demand in the global market. This study demonstrated the stability of herbal Gel, which is now regarded as an efficient herbal acne treatment formulation. A number of characteristics, including color, appearance, consistency, pH, and foamability, were assessed for the prepared formulation. Because natural remedies are safer and have fewer side effects than synthetic ones, they are more widely accepted.The demand for herbal formulations is rising on the international scene. The creation and assessment of a herbal anti-acne cleanser with aqueous bael leaf (Aegle marmelos) extracts are the subjects of this study. Despite the fact that there are many topical herbal remedies for acne on the market, the plant has good antibacterial, antioxidant, and anti-inflammatory properties according to published research.

Banana fibre-chitosan-guar gum composite as an alternative wound healing material

Bio-composites, which can be obtained from the renewable natural resources, are fascinating material for use as sustainable biomaterials with essential properties like biodegradable, bio-compatibility as well cyto-compatibility etc. These properties are useful for bio-medical including wound healing applications. In this study, fibre obtained banana pseudo stem of banana plant, which is otherwise wasted, was used as a material along with chitosan and guar gum to fabricate a banana fibre-biopolymer composite patch. The physiochemical properties of the patches were examined using Fourier Transformed Infra-red spectrophotometer (FT-IR), tensile tester, Scanning Electron Microscope (SEM), contact angle tester, swelling and degradation studies. We further demonstrated that a herbal drug, Nirgundi could be loaded to the patch showed controlled its release at different pHs. The patch had good antibacterial property and supported proliferation of mouse fibroblast cells. The study thus indicates that banana fibre-chitosan-guar gum composite can be developed into an alternative wound healing material.

Biological activities and chemical composition of essential oil isolated from &lt;i&gt;Artemisia herba-alba&lt;/i&gt;

&lt;i&gt;Artemisia herba-alba &lt;/i&gt;(AHA), known as sheeh in Jordan, is recommended by regional traditional healers for the treatment of a variety of diseases. AHA&lt;i&gt; &lt;/i&gt;has been used in folk medicine to treat colds, coughing, bronchitis, intestinal disturbances, diarrhea, neuralgias, arterial hypertension, and diabetes. The objectives of the current study were to identify the chemical compositions of the essential oil extracted from dried leaf powder of AHA cultivated in Jordan and investigate its antibacterial and antioxidant activities. The essential oil was isolated using hydro distillation, and the identification of &lt;i&gt;artemisia herba-alba &lt;/i&gt;essential oil &lt;i&gt;(&lt;/i&gt;AHEO) composition was performed using validated gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of AHEO was assessed against &lt;i&gt;escherichia coli, pseudomonas aeruginosa, klebsiella pneumonia&lt;/i&gt;,&lt;i&gt; &lt;/i&gt;and &lt;i&gt;staphylococcus aureus &lt;/i&gt;and two clinical isolates (methicillin-resistant &lt;i&gt;staphylococcus aureus&lt;/i&gt; and methicillin-resistant &lt;i&gt;staphylococcus&lt;/i&gt; &lt;i&gt;epidermidis&lt;/i&gt; [MRSE]) using a disc diffusion method, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) values, using the micro-dilution broth method. Additionally, antioxidant activities were determined using DPPH and ABTS radical scavenging assays. The results revealed that the yield of AHEO was 4.41% v/w, with nearly 22 identified compounds, constituting approximately 96.80% of the total mass of essential oils. Monoterpenoids was the major compounds (71.90%), with alpha pinene being the major component, accounting for 17.20% of the composition. The total phenolic and flavonoid contents were 43.97 mg GAE/g and 30.11 mg CE/g, respectively. The antibacterial activity of AHEO against MRSE exhibited the highest inhibitory effect, while &lt;i&gt;E.coli&lt;/i&gt; showed the highest MBC value. Furthermore, AHEO demonstrated significant antioxidant activity (IC&lt;sub&gt;50=&lt;/sub&gt; 64.57 and 34.01 for DPPH and ABTS, respectively). The results indicate that AHEO possess good antioxidant and antibacterial properties, suggesting that they may be used as a supplementary food and antimicrobial agent.

Significant room-temperature phosphorescence enhancement induced by matrix complexes

Incorporating phosphors into polymer matrix is a relatively mature method to develop organic room-temperature phosphorescent (RTP) materials but still needs to be further explored because of limited investigations about the effect of different matrix on the RTP properties of the same guest molecule. Colorful RTP (from blue to red, with τafterglow up to 1736 ms) in carboxymethyl chitosan (CC) systems was achieved in this work. To improve the RTP performance, quaternary chitosan (QC) was introduced to build a binary matrix system, which extended the lifetime by 200 ms and increased the phosphorescence quantum yield to 3.51 times. Systematic characterizations and theoretical calculations indicated that the RTP materials obtained from binary matrix had higher ion group density and stronger dipole–dipole interactions, which could narrow the singlet–triplet energy gap and promote the triplet excitons generation. Compared to single matrix, binary matrix could also provide more crosslinked networks to better stabilize triplet excitons, thus synergistically enhancing the RTP. Finally, based on the good biocompatibility and antibacterial properties of chitosan and phosphorescent emission, the films were expected to be used for monitoring the integrity of the package and multiple antibacterial coating films.

Green Synthesis of Bacopa monnieri-Mediated Magnesium Oxide Nanoparticles and Analysis of Their Antimicrobial, Antioxidant, and Cytotoxic Properties.

Background The management of aggressive forms of periodontal disease has become an issue of concern due to the emergence of bacterial resistance. Nanoparticles (NPs) have emerged as a potential therapeutic agent with a multitude of biological functions. The green synthesis of these NPs is more eco-friendly than conventional methods. The present study aimed at the green synthesis of magnesium oxide nanoparticles using Bacopa monnieri (bMgO NPs) and its antibacterial, antioxidant, and cytotoxic analysis. Materials and methods Magnesium oxide NPs were green synthesized using B. monnieri extract using a wet chemical method. The resultant bMgO NPs were assessed for antibacterial activity against Staphylococcus aureus and Escherichia coli. Antioxidant activity was assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the hydrogen peroxide (H2O2) assay. Cytotoxicity was assessed using zebrafish viability on treatment with bMgO NPs. Results Compared to the antibiotic standard, the green synthesized bMgO NPs showed good antibacterial properties against S. aureus and E. coli. It also showed excellent antioxidant activity and biocompatibility. Conclusion The bMgO NPs have great potential as a local drug delivery agent and should be further explored for their antibacterial and antioxidant properties in vivo.

Electrospun Konjac Glucomannan/Polyvinyl Alcohol Long Polymeric Filaments Incorporated with Tea Polyphenols for Food Preservations.

In this study, nanofiber films were prepared by electrospinning technology with polyvinyl alcohol (PVA) and konjac glucomannan (KGM) as raw materials. Tea polyphenols (TPs) were incorporated in the above matrix, which increased physicochemical (thermal and mechanical characteristics) and antibacterial properties of the nanofiber films. The release behavior of phenolic compounds from PVA/KGM-TPs nanofiber films was determined in different food simulants; antioxidant and antibacterial activity of the films were also evaluated. The results showed that the addition of KGM increased the physical and chemical properties of the films. The tensile strength (TS) and elongation at break (EB) increased from 5.40 ± 0.33 to 10.62 ± 0.34 and from 7.24 ± 0.32 to 18.10 ± 0.91, respectively. PVA/KGM-TPs nanofiber films performed controlled release of TPs, with final release of 49.17% in 3% acetic acid, 43.6% in 10% ethanol, and 59.42% in 95% ethanol. The nanofiber films showed good antioxidation properties, with the free radical scavenging rate increasing from 1.33% to 25.61%, and good antibacterial properties with inhibition zones against E. coli and S. aureus of 24.33 ± 0.47 mm and 34.33 ± 0.94 mm, respectively. In addition, the as-prepared films showed significant preservation performance for raw bananas at 25 °C.

Which Gelatin and Antibiotic Should Be Chosen to Seal a Woven Vascular Graft?

Among the vascular prostheses used for aortic replacement, 95% are woven or knitted grafts from polyester fibers. Such grafts require sealing, for which gelatin (Gel) is most often used. Sometimes antibiotics are added to the sealant. We used gelatin type A (GelA) or type B (GelB), containing one of the three antibiotics (Rifampicin, Ceftriaxone, or Vancomycin) in the sealant films. Our goal was to study the effect of these combinations on the mechanical and antibacterial properties and the cytocompatibility of the grafts. The mechanical characteristics were evaluated using water permeability and kinking radius. Antibacterial properties were studied using the disk diffusion method. Cytocompatibility with EA.hy926 endothelial cells was assessed via indirect cytotoxicity, cell adhesion, and viability upon direct contact with the samples (3, 7, and 14 days). Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were used to visualize the cells in the deep layers of the graft wall. "GelA + Vancomycin" and "GelB + vancomycin" grafts showed similar good mechanical characteristics (permeability~10 mL/min/cm2, kinking radius 21 mm) and antibacterial properties (inhibition zones for Staphilococcus aureus~15 mm, for Enterococcus faecalis~12 mm). The other samples did not exhibit any antibacterial properties. The cytocompatibility was good in all the tested groups, but endothelial cells exhibited the ability to self-organize capillary-like structures only when interacting with the "GelB + antibiotics" coatings. Based on the results obtained, we consider "GelB + vancomycin" sealant to be the most promising.

Copper ions reinforced flexible carboxymethylcellulose/polyethyleneimine composite films with enhanced mechanical properties, UV-shielding performance, thermal stability, solvent resistance, and antibacterial activity

A composite film (CMC/PEI) consisting of anionic carboxymethylcellulose (CMC) and cationic polyethyleneimine (PEI) can be easily produced through the solution casting method using self-assembly based on electrostatic interaction and hydrogen bonding. Subsequently, the resulting CMC/PEI polyelectrolyte composite film with a network structure was crosslinked with divalent Cu2+ ions through ionic and coordination bonds, resulting in a strengthened Cu(II)@CMC/PEI film. The composite film was characterized based on its structural, surface, thermal, UV protection, antibacterial, and degradation aspects. The results demonstrated this film has impressive mechanical properties, remarkable solvent resistance, good antibacterial properties, and excellent UV-shielding performance by completely blocking ultraviolet light with wavelengths below 360 nm. These properties can be attributed to the presence of Cu2+ ions and PEI in the film. This work is valuable for the development of novel UV-shielding materials and should contribute to the design of carboxymethylcellulose composite films with desirable properties and exceptional performance.

Dopamine-mediated copper-loaded ZnTiO3 antimicrobial coating with immunomodulatory properties effectively enhances vascularised osteogenesis on titanium implants

In this study, zinc (Zn) with osteogenic activity and copper (Cu) with angiogenic activity were simultaneously introduced into titanium dioxide nanotubes (TN) by means of anodic oxidation technique, hydrothermal reaction and dopamine (PDA) polymerisation effect (ZnTN-PDA-Cu). The ZnTN-PDA-Cu coating had favourable mechanical, hydrophilic, corrosion-resistant, and bioactive characteristics, according to the results. Zn2+ and Cu2+ could be continuously released from the coating and was pH-responsive. In addition, ZnTN-PDA-Cu showed good antibacterial properties against E. coli and S. aureus. Cellular assays revealed that RAW264.7 (immune), HUVEC (angiogenic) and MC3T3-E1 (osteogenic) exhibited good adhesion and proliferation activities on the ZnTN-PDA-Cu coated Ti. The expression of anti-inflammatory markers, angiogenic markers and osteogenic markers was significantly up-regulated in ZnTN-PDA-Cu coatings at both the gene level and protein level. ZnTN-PDA-Cu also demonstrated the capacity to stimulate RAW264.7 towards M2 polarisation and HUVEC tube formation. In addition, it demonstrated the capacity to stimulate MC3T3-E1 towards osteogenic differentiation. In summary, the ZnTN-PDA-Cu coating had better antibacterial, anti-inflammatory, angiogenic and osteoinductive properties. The multifunctional coatings prepared in this study provide a promising new strategy and experimental basis for the design of antibacterial titanium surfaces with immunomodulatory functions.

Structural Si3N4-SiO2 glass ceramics with bioactive and anti-bacterial properties

Silicon nitride-based bioceramics have been investigated for biomedical applications due to their good thermo-mechanical, tribological and antibacterial properties. However, biological properties, such as bioactivity that promotes the interaction with tissue, are also important. Silicon dioxide has been found to promote bioactivity. With the aim of combining both advantages, a new Si3N4-SiO2 glass ceramic was developed. Three different compositions were synthesized and sintered by spark plasma sintering. The results showed that β-Si3N4 crystalline is well distributed in the SiO2 matrix. 70SiN samples exhibited the highest mechanical properties with a flexural strength of 452 ± 33 MPa and a toughness of 6.4 ± 0.5 MPa∙m1/2. 50SiN samples exhibited the best bacteriostatic effect due to the synergistic effect of surface chemistry and topography. Apatite was observed on the surfaces of all groups. This study shows that the newly developed Si3N4-SiO2 glass ceramics exhibit promising mechanical and biological properties for biomedical applications.

Evaluation of osteogenic properties of a novel injectable bone-repair material containing strontium in vitro and in vivo.

Objective: This study aims to develop and evaluate the biocompatibility and osteogenic potential of a novel injectable strontium-doped hydroxyapatite bone-repair material. Methods: The properties of strontium-doped hydroxyapatite/chitosan (Sr-HA/CS), hydroxyapatite/chitosan (HA/CS) and calcium phosphate/chitosan (CAP/CS) were assessed following their preparation via physical cross-linking and a one-step simplified method. Petri dishes containing Escherichia coli and Staphylococcus epidermidis were inoculated with the material for in vitro investigations. The material was also co-cultured with stem cells derived from human exfoliated deciduous teeth (SHEDs), to assess the morphology and proliferation capability of the SHEDs, Calcein-AM staining and the Cell Counting Kit-8 assay were employed. Osteogenic differentiation of SHEDs was determined using alkaline phosphatase (ALP) staining and Alizarin Red staining. For in vivo studies, Sr-HA/CS was implanted into the muscle pouch of mice and in a rat model of ovariectomy-induced femoral defects. Hematoxylin-eosin (HE) staining was performed to determine the extent of bone formation and defect healing. The formation of new bone was determined using Masson's trichrome staining. The osteogenic mechanism of the material was investigated using Tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical studies. Results: X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) showed that strontium was successfully doped into HA. The Sr-HA/CS material can be uniformly squeezed using a syringe with a 13% swelling rate. Sr-HA/CS had a significant antibacterial effect against both E. coli and S. epidermidis (p < 0.05), with a stronger effect observed against E. coli. The Sr-HA/CS significantly improved cell proliferation and cell viability in vitro studies (p < 0.05). Compared to CAP/CS and CS, Sr-HA/CS generated a substantially greater new bone area during osteoinduction experiments (p < 0.05, p < 0.001). The Sr-HA/CS material demonstrated a significantly higher rate of bone repair in the bone defeat studies compared to the CAP/CS and CS materials (p < 0.01). The OCN-positive area and TRAP-positive cells in Sr-HA/CS were greater than those in control groups (p < 0.05). Conclusion: A novel injectable strontium-doped HA bone-repair material with good antibacterial properties, biocompatibility, and osteoinductivity was successfully prepared.

A chitosan-coated PCL/nano-hydroxyapatite aerogel integrated with a nanofiber membrane for providing antibacterial activity and guiding bone regeneration.

A guided bone regeneration (GBR) membrane can act as a barrier to prevent the invasion and interference from foreign soft tissues, promoting infiltration and proliferation of osteoblasts in the bone defect area. Herein, a composite scaffold with dual functions of osteogenesis and antibacterial effects was prepared for GBR. A polycaprolactone (PCL)/nano-hydroxyapatite (n-HA) aerogel produced by electrospinning and freeze-drying techniques was fabricated as the loose layer of the scaffold, while a PCL nanofiber membrane was used as the dense layer. Chitosan (CS) solution served as a middle layer to provide mechanical support and antibacterial effects between the two layers. Morphological results showed that the loose layer had a porous structure with n-HA successfully dispersed in the aerogels, while the dense layer possessed a sufficiently dense structure. In vitro antibacterial experiments illustrated that the CS solution in the middle layer stabilized the scaffold structure and endowed the scaffold with good antibacterial properties. The cytocompatibility results indicated that both fibroblasts and osteoblasts exhibited superior cell activity on the dense and loose layers, respectively. In particular, the dense layer made of nanofibers could work as a barrier layer to inhibit the infiltration of fibroblasts into the loose layer. In vitro osteogenesis analysis suggested that the PCL/n-HA aerogel could enhance the bone induction ability of bone mesenchymal stem cells, which was confirmed by the increased expression of the alkaline phosphatase activity. The loose structure facilitated the infiltration and migration of bone mesenchymal stem cells for better osteogenesis. In summary, such a composite scaffold exhibited excellent osteogenic and antibacterial properties as well as the barrier effect, thus holding promising potential for use as GBR materials.

Cold-resistant, highly stretchable ionic conductive hydrogels for intelligent motion recognition in winter sports.

Conductive hydrogels have attracted much attention for their wide application in the field of flexible wearable sensors due to their outstanding flexibility, conductivity and sensing properties. However, the weak mechanical properties, lack of frost resistance and susceptibility to microbial contamination of traditional conductive hydrogels greatly limit their practical application. In this work, multifunctional polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC)/poly(acrylamide-co-1-vinyl-3-butylimidazolium bromide) (P(AAm-co-VBIMBr)) (PCPAV) ionic conductive hydrogels with high strength and good conductive, transparent, anti-freezing and antibacterial properties were constructed by introducing a network of chemically crosslinked AAm and VBIMBr copolymers into the base material of PVA and CMC by in situ free radical polymerization. Owing to the multiple interactions between the polymers, including covalent crosslinking, multiple hydrogen bonding interactions, and electrostatic interactions, the obtained ionic conductive hydrogels exhibit a high tensile strength (360.6 kPa), a large elongation at break (810.6%), good toughness, and fatigue resistance properties. The introduction of VBIMBr endows the PCPAV hydrogels with excellent transparency (∼92%), a high ionic conductivity (15.2 mS cm-1), antimicrobial activity and good flexibility and conductivity at sub-zero temperatures. Notably, the PCPAV hydrogels exhibit a wide strain range (0-800%), high strain sensitivity (GF = 3.75), fast response, long-term stability, and fantastic durability, which enable them to detect both large joint movements and minute muscle movements. Based on these advantages, it is believed that the PCPAV-based hydrogel sensors would have potential applications in health monitoring, human motion detection, soft robotics, ionic skins, human-machine interfaces, and other flexible electronic devices.