Antibacterial Evaluation Research Articles

Bimetallic Gold–Iron Oxide Nanoparticles as Carriers of Methotrexate: Perspective Tools for Biomedical Applications

Bimetallic nanoparticles (BMNPs) combine unique and synergistic properties of two metals, allowing new specific applications. In this study, bimetallic AuFe nanoparticles and their conjugates with methotrexate (MTX) were obtained with an environmentally safe method of metal-vapor synthesis. The composition and electronic structure of the particles were investigated with X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) spectrum and X-ray absorption spectroscopy (XANES and EXAFS). The effects of BMNP-MTX conjugates on human primary cells and tumor cell lines were evaluated with neutral red uptake and MTT in vitro cytotoxicity assays. Bright-field microscopy analyses of tumor spheroid size and evaluations of tumor spheroid vitality based on SFDA AM staining were carried out. In vitro assays for an antibacterial activity evaluation of the generated samples were performed. The influence of BMNP-MTX on cytokine production with normal leukocytes was assessed using ELISA. X-ray analyses of the samples demonstrated that gold was in the ground state Au0 as well as Au+ and Au3+ states are present in small quantities, whereas iron existed as a mixture of non-histometric oxides with states close to Fe2+ and Fe3+. The modification of the AuFe system with MTX is accompanied by a threefold increase in the relative proportion of the Au+ state. BMNP-MTX conjugates demonstrated significant antitumor activity compared to the drug alone, which proves the ability of the generated nanoconjugates to improve the effectiveness of MTX therapy. This was confirmed by a marked reduction in the size and vitality of AuFe-MTX-treated 3D tumor spheroids. In addition to their selective antitumor activity, AuFe-MTX exhibited moderate antibacterial activity and induced sample-specific cytokine production with normal human leukocytes—which points to an immunostimulatory potential. The present findings indicate important and diverse biological properties of BMNP-MTX conjugates and thus highlight perspectives for their biomedical applications and new immune-specific abilities.

Structural and antibacterial evaluation of copper, silver, and bimetallic silver/copper nanoalloys synthesized in chitosan biopolymer

Silver nanoparticles (AgNP) have been used as an alternative to microbial resistance. Nevertheless, AgNP high cost and moderate toxicity to humans limit their use. Copper nanoparticles (CuNP) emerge as an alternative, but their fast oxidation hampers large-scale use. In this scenario, this work propose the synthesis optimization of Ag, Cu, and bimetallic Ag/Cu nanoparticles in a chitosan aqueous solution using factorial design statistics. UV-Vis spectroscopy, zetasizer, and transmission electron microscopy (TEM) measurements demonstrated that the optimized synthetic procedure formed highly stable and monodisperse nanoparticles. X-ray diffraction (XRD) confirmed the nanoparticle's crystalline structure and indicated the presence of an oxide state in CuNP. In addition, X-ray photoelectron spectroscopy (XPS) measurements confirmed that this oxidation occurs at the CuNP surface level. Considering Ag/CuNP, Rietveld refinement of XRD diffractogram demonstrates the formation of an unusual and novel Ag/Cu nanoalloy structure, which was possible due to the metallic ion chelation to chitosan nitrogens before and during nanoparticle growth. In addition, silver presence in the nanoalloy inhibited copper oxidation through an electromigration mechanism. Comparing CuNP, AgNP, and Ag/CuNP, it was possible to reveal the microbicide abilities of the nanoparticles against both Gram-positive and Gram-negative bacteria, emphasizing that the Ag/Cu nanoalloy is a viable option due its high antimicrobial activity and colloidal stability. Therefore, the rational design allowed the synthesis of highly stable NP in the chitosan matrix which exhibited strong antimicrobial activity, indicating that Ag/Cu nanoalloys can act as the next-generation nanomaterials for pathogenic microorganism inactivation.

In Situ Synthesis of Polyaniline Nanohybrid and Formulation of Polyaniline/ Carboxymethyl cellulose/Ethylene Glycol Nanocomposite: Study of its Conducting and Antibacterial Properties

Polyaniline (PANI) has received great attention as a conducting polymer from researchers in the field of organic synthesis and development of conducting nanocomposite polymer technology for superconductors. Different methods of PANI synthesis are being sought for the obtainment of electrically robust PANI composites for electronic and other useful applications. Different inorganic matrices have been considered for this purpose. This study attempts to prepare PANI In situ on arginine-modified nanoclay template by chemical oxidation polymerization. Further, the PANI/Arginine-modified nanoclay was used to prepare PANI/Arginine-Nanoclay/Carboxymethyl cellulose/Ethylene glycol conducting film with robust electric conductivity (EC). Electrical conductivities, anti-bacterial evaluation, Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA), differential thermogravimetry analysis (DTG) and Scanning Electron Microscopy (SEM) were used for the characterization studies and property evaluation. The electrical conductivities of PANI/Arginine-Nanoclay/Carboxymethyl cellulose/Ethylene glycol nanocomposite film reached 1900 S/Cm. FT-IR data, 3304–3196, 2926–2828, 2200–2022, 1733, 1620 and 1052 cm-1 respectively, confirmed the presence of organic intercalates, CMC, quinoid and benzenoid rings of PANI, and the inorganic nanoclay matter in the nanocomposite film. SEM revealed the presence of spine-like nanoflowers with elongated and expanded particle agglomerations. Thermal stability of the prepared nanocomposite thin film reached 700oC. The zone of inhibition ranged from 24-36 mm against S. typhi, E. coli and S. aureus. In conclusion, PANI nanocomposite thin conducting films had robust EC and antibacterial properties. In addition, the In-situ synthesis of PANI on Arginine-modified nanoclay platform aided the electric conductivity of the nanocomposite system.

Bio-extract-mediated microwave-assisted synthesis of Cr2O3 nanoparticles: Characterization, antibacterial, antioxidant, and photocatalytic activity evaluation

Bio-extract-mediated microwave-assisted synthesis of Cr2O3 nanoparticles: Characterization, antibacterial, antioxidant, and photocatalytic activity evaluation

Preparation and characterization of spiked gold nanobipyramids and its antibacterial effect on methicillin-resistant Staphylococcus aureus and methicillin-sensitive Staphylococcus aureus

BackgroundThis paper reports the preparation of a new family of spiked gold nanoparticles, spiked gold nanobipyramids (SNBPs). This protocol includes the process to synthesize gold nanobipyramids (NBPs) using combined seed-mediated and microwave-assisted method and procedure to form spikes on whole surface of gold nanobipyramid. We also evaluated the antibacterial activity against both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) in various concentrations of SNBPs and NBPs by well diffusion assay, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) determination. The effect of SNBPs on exposed bacteria was observed by scanning electron microscopy. ResultsThe UV-Vis of purified NBPs exhibited two absorption bands located at 550 nm and 849 nm with yield of bipyramidal particles more than 90%. The average size of NBPs was 76.33 ± 10.11 nm in length and 26.57 ± 2.25 nm in diameter, respectively, while SNBPs were prolongated in length and achieved 182.37 ± 21.74 nm with multi-branches protruding whole surface areas. In antibacterial evaluations, SNBPs and NBPs showed antibacterial activity with MIC of 6.25 μl/ml and 12.5 μl/ml, respectively, for MSSA while 12.5 μl/ml and 25 μl/ml, respectively, for MRSA. Besides, MBC values of SNBPs and NBPs were found to be 12.5 μl/ml and 25 μl/ml, respectively, against MSSA while 25 μl/ml and 50 μl/ml, respectively, against MRSA. Furthermore, scanning electron microscopy observation showed the mechanism that SNBPs damaged the outer membrane, released cytoplasm, and altered the normal morphology of MRSA and MSSA, leading to bacterial death. ConclusionsThis report suggests that these SNBPs are potential antibacterial agents that can be applied as antibacterial materials to inhibit the growth of human bacterial pathogen infections related to antibiotic-resistant bacteria.

A mild catalyzed imino Diels-Alder reaction for the synthesis of N-(2-(o-tolyl)-1,2,3,4-tetrahydroquinoline-4-yl)formamide derivatives as regulators of Quorum Sensing in Pseudomonas aeruginosa

Bacterial resistance is one of the major global public health problems. In addition, virulence factors promoted multiple drug resistance through cell-to-cell communications by molecules within microbial communities, denominated Quorum Sensing (QS). The regulation of QS by small molecules appears as a therapeutic alternative through the use of synthetic analogs of agonists. The present work developed the construction of a series of derivatives of N-(2-(o-tolyl)-1,2,3,4-tetrahydroquinoline-4-yl) formamide (1a-h) via Povarov-type sequential reactions to deliver the tetrahydroquinoline (THQ) derivatives in moderate to good yields (24–78%). To evaluate the potential in molecular diversity of THQ-type autoinducers, a study of these agents as potential inhibitors of bacterial growth and virulence factors involved in QS systems on P. aeruginosa was carried out both as antibacterial evaluation on E. coli strain. THQs showed significant activity values for molecules with halogen substituents at the C-6 position (-F, -Cl, and I), revealing at a concentration of 75 µg/mL a percentage inhibition between 27 and 40%. Furthermore, autoinducers with halogen substitutes in phenotypic studies on P. aeruginosa showed good results. Also, they exhibited weak formation of both biofilm and low pyocyanin formation, which are indicators of virulence in P. aeruginosa. Overall, the results suggest that compound N-(6-fluor-2-(o-tolyl)-1,2,3,4-tetrahydroquinoline-4-yl)formamide (1a) stands out as the most representative within this series of THQ derivatives.

In vitro and in silico antibacterial evaluation of nitrocatechol chalcone and pyrazoline derivatives

The aim of this study was to determine the in vitro antibacterial activity of nitrocatechol chalcone and pyrazoline derivatives previously synthesised by our research group against Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii and Klebsiella aerogenes, and to create and validate a pharmacophore model using this data. The enrichment factor (EF10%) and the area under the receiver operating characteristic (ROC-AUC) curve were used to validate the pharmacophore model. Using the validated pharmacophore model novel derivatives were designed and synthesised, whereafter the in vitro antibacterial activity of these derivatives was also determined against the susceptible bacteria. After the initial screening, the derivatives only had activity against S.aureus, with compound 2a, 2b and 1b (1–2 µg/ml) having comparable activity to tetracycline (2 µg/ml). A common feature pharmacophore model (max. fit: 4, rank score: 84.02) was able to accurately identify active nitrocatechol chalcones and pyrazoline derivatives within a decoy test set. The best performing pharmacophore model, i.e., hypothesis 9 (EF10%: 6.7, ROC-AUC: 0.85 ± 0.00) indicated that four hydrogen bond acceptors are important for antibacterial activity. This model was used to guide the design and synthesis of novel nitrocatechol chalcone and pyrazoline derivatives of which the in vitro antibacterial activity against both the susceptible and resistant S. aureus strains were determined. The most active compounds were 3i (0.5 µg/ml) and 3c (0.5 µg/ml) against the susceptible and resistant strain respectively, which were more active than tetracycline.

Synthesis, Antibacterial, and Antifungal Evaluation of New Class of Pyrimido[4,5-d]pyrimidine, Pyrazolo[3,4-d]pyrimidine, and Pyrimido[4,5-b]quinoline Derived from α,α-Ketene Dithioacetals as fused Five and Six-membered Heterocycle Derivatives

Synthesis, Antibacterial, and Antifungal Evaluation of New Class of Pyrimido[4,5-d]pyrimidine, Pyrazolo[3,4-d]pyrimidine, and Pyrimido[4,5-b]quinoline Derived from α,α-Ketene Dithioacetals as fused Five and Six-membered Heterocycle Derivatives

Synthesis, Cytotoxic, and Antibacterial Evaluation of C-12 Substituted Ocotillol-type Derivatives

Synthesis, Cytotoxic, and Antibacterial Evaluation of C-12 Substituted Ocotillol-type Derivatives

Engineering Phenothiazine-Based Functional Mimics of Host Defense Peptides as New Agrochemical Candidates: Design, Synthesis, and Antibacterial Evaluation.

In the protracted "arms race" between host and plant pathogenic bacteria, host organisms have evolved powerful weapons known as host defense peptides (HDPs). However, natural HDPs are not suitable for large-scale applications; therefore, researchers have chosen to develop bespoke small-molecule functional mimics. Phenothiazine derivatives were developed as functional HDPs mimics, owing to their broad biological activity and high lipophilicity. The phenothiazine analogues designed in this study exhibited excellent in vitro bioactivity against the three Gram-negative bacteria Xanthomonas oryzae pv oryzae, Xanthomonas axonopodis pv citri, and Pseudomonas syringae pv actinidiae, with optimal EC50 values of 0.80, 0.31, and 1.91 μg/mL, respectively. Preliminary evidence suggests that compound C2 may act on bacterial cell membranes and interact with bacterial Deoxyribonucleic acid in the groove binding mode. In vivo trials showed that compound C2 was highly effective against rice leaf blight (51.97-56.69%), with activity superior to those of bismerthiazol (40.7-43.4%) and thiodiazole copper (30.2-37.1%). Our study provides strong evidence to support the development of phenothiazine derivatives into pesticide candidates.

Characterization, Antibacterial and Toxicity Evaluation of Biosynthesized Zinc Oxide Nanoparticles Utilizing Eleuthrine Bulbosa Bulb Extract

In the current study, Eleuthrine bulbosa bulb extract was utilized to synthesize zinc oxide nanoparticles (ZnO NPs) in a simple, sustainable, and environmentally friendly manner. The bioactive compounds of E. bulbosa extract were identified by gas chromatography-mass spectrometry (GC-MS). Following synthesis of the ZnO NPs via the green method with E. bulbosa bulb extract as the reducing and capping agent, ZnO NPs were characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-Visible Spectroscopy (UV-Vis), and Photoluminescence (PL) further evaluated for antibacterial and cytotoxic activities. GC-MS analysis showed the presence of phytochemical compounds acting as reducing and capping agents. The UV-Vis spectra of ZnO nanoparticles containing E. bulbosaextract showed an optical energy bandgap between 3.12 and 3.89 eV. In addition, XRD showed that the crystalline size of ZnO NPs ranged from 21 to 68 nm with a wurtzite crystal structure. FTIR analysis showed that the plant extract contains identified functional groups including alcohols, phenols, alkene, and flavonoid compounds that influenced the mechanism of bonding with ZnO NPs. Particularly, the peaks of formation of Zn-O stretching vibrations at 470 to 480 cm-1 were successfully shown. In addition, ZnO NPs displayed antibacterial activity, which was greatest against Staphylococcus aureus, and were cytotoxic to MCF-7 and MCF-10A breast cells with IC50 values of 5.540 µg/mL and 15.77 µg/mL, respectively. ZnO NPs were successfully synthesized utilizing a green method, resulting in intriguing biocompatible potential candidates for use in both biomedical and environmental fields due to their eco-friendly synthesis and nontoxic.

Heliotropium bacciferum essential oil extraction: Compositions determination by GC-MS and anti-inflammatory and antibacterial activities evaluation

Heliotropium bacciferum plant is very important and has been used for medicinal values since ancient times. The present study deals with the extraction of essential oil (0.14 w/w) of this plant and its GC-MS analysis, anti-inflammatory, and anti-bacterial activities evaluation. GC analysis of essential oil confirmed 76 compounds with 49 terpenes and oxygenated hydrocarbons. The main components of this essential oil are agarospirol (15.15 %), rosifoliol (9.41 %), elemol (8.96 %), tau.-cadinol (8.05 %), linalool (5.37 %), shyobunol (5.36 %) cyclohexylmethyl tridecyl ester of oxalic acid (4.74 %), respectively. The essential oil showed quite good anti-inflammatory activity while this oil indicated excellent anti-bacterial activity against 3 g-positive pathogenic bacteria (Bacillus subtilusATCC 6633, Entrococcus faecalis ATCC 29212, and Bacillus cereusATCC 11778). The essential oil of Heliotropium bacciferum showed great potential as an anti-inflammatory and anti-bacterial agent. Therefore, the reported extraction and GC-MS analysis methods are useful to extract the essential oil and determine the composition of other plants. The extracted essential oil may be used to treat several diseases.

Design, synthesis, antibacterial evaluation, and molecular docking studies of diethyl((substituted phenyl)((4-(N-(5-methyl-4,5-dihydroisoxazol-3-yl)sulfamoyl)phenyl) amino)methyl)phosphonates

An efficient green synthesis of diethyl((substituted phenyl)((4-(N-(5-methyl-4,5-dihydroisoxazol-3-yl)sulfamoyl)phenyl) amino)methyl)phosphonates was accomplished by the condensation of 4-amino-N-(5-methyl-4,5-dihydroisoxazol-3yl) benzenesulfonamide with various aldehydes and diethyl phosphite using mesoporous titania-ceria mixed oxide (MTCMO) as a nanocatalyst under microwave irradiation and solvent-free conditions. Antimicrobial activity was performed for the synthesized compounds and the compounds 4a, 4c, 4d, 4e and 4f exhibited highest inhibitory activity against Escherichia coli using Penicillin and Tetracycline as standards. In addition, molecular docking studies were also carried out against Cox-2 with Celocoxib as the standard.

Highly Selective Colorimetric Sensor of Mercury(II) Ions by Andrographolide-Stabilized Silver Nanoparticles in Water and Antibacterial Evaluation.

Silver nanoparticles (AgNPs) are well known for their exceptional properties and versatility in various applications. This study used andrographolide as a biochemical stabilizer to synthesize AgNPs (andro-AgNPs). The andro-AgNPs were characterized by using UV-vis spectroscopy, revealing a surface plasmon resonance peak at 440 nm. Fourier transform infrared spectroscopy was also used to confirm the presence of AgNPs. Transmission electron microscopy was used to investigate the morphology of andro-AgNPs, which showed a spherical shape with an average diameter of 18.30 ± 5.57 nm (n = 205). Andro-AgNPs were utilized as a colorimetric sensor to detect mercury ions (Hg2+) in water, and the optimized detection conditions were evaluated using UV-vis spectroscopy with a linear range of 15-120 μM. The limit of detection and the limit of quantification for Hg2+ detection were found to be 11.15 and 37.15 μM, respectively. Furthermore, andro-AgNPs exhibited antibacterial properties against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The results imply that andro-AgNPs hold promising potential for future biomedical applications.

Synthesis, antibacterial activity evaluation and molecular docking studies of coumarin modified thiouracil derivatives as SecA inhibitor

A series of thiouracil derivatives containing coumarin were designed and synthesized with SecA inhibitor 1 as the lead. The in vitro antibacterial activities of the newly synthesized compounds were evaluated, and the results revealed that some of the new compounds (such as 14k and 14q) had strong inhibitory effect against the tested bacteria. The inhibitory activities of 14k, 14 l, 14r, 14p and 14q against SecA were tested, and the IC50 of 14K was 17.6 μg/mL which was significantly lower than that of lead compound 1. The molecular docking of the compounds 14k, 14 l, 14r, 14p and 14q with SecA were investigated and these compounds can successfully bind to SecA in the two selected pocket. Compound 14k had strong SecA inhibitory activity and antibacterial activity, which was worthy of further study.

Microwave-assisted green synthesis of silver nanoparticles by extracts of fig fruits and myrrh oleogum resin and their role in antibacterial activity

Multidrug-resistant bacteria hindering disease management have become a matter of serious concern. Nanotechnology has evolved as a fresh promise for managing infectious diseases. The intended purpose of this study was to synthesize silver nanoparticles using fig fruit (Ficus carica) and myrrh oleogum resin (Commiphora sp.) extracts and microwave irradiation. UV–visible, FTIR, TEM, DLS and Zeta-potential analysis were deployed to characterise silver nanoparticles. The synthesized nanoparticles were assessed for antibacterial activity against four pathogenic bacteria, and their effects on the bacteria's cells were examined as well through SEM. Fig fruit and myrrh’s extract reaction solution changed color (reddish brown) after 90 and 120 s of microwave operation, respectively. UV–Vis-validated the synthesis of silver nanoparticles with fig fruit extract (FAgNPs) and myrrh extract (MAgNPs), showing absorption bands between 434.41 nm and 434.95 nm. TEM revealed that the FAgNPs and MAgNPs were predominantly spherical and of various sizes. The average diameter of FAgNPs and MAgNPs was 33.79 nm and 31.63 nm, respectively, and both of them were moderately polydispersed and relatively stable colloids. The antibacterial evaluation of FAgNPs shows that the highest level of inhibition was against S. aureus and it was higher than that of Augmentin, and next to it were E. coli and S. pyogenes. While in case of MAgNPs the most sensitive pathogen was S. aureus, followed by E. coli and S. pyogenes, respectively. FAgNPs and MAgNPs had MIC values of 15 µg/ml against S. aureus, compared to 30 µg/ml against E. coli. SEM images showed that treatment with FAgNPs and MAgNPs caused S. aureus cells to become malformed. Similar cell damage was also observed in E. coli cells treated with FAgNPs and MAgNPs. This study for the first time report the synthesis of silver nanoparticles utilizing fig fruit and myrrh extracts and microwave irradiation.

Design, synthesis, antibacterial and antiviral evaluation of chalcone derivatives containing benzoxazole

In this study, 24 chalcone derivatives containing benzoxazole were designed and synthesized, and the structures of all target compounds were confirmed by NMR and HRMS. The results of antibacterial activity showed that the median effective concentration (EC50) value of Z2 against Xanthomonas oryzae pv.oryzae (Xoo) was 8.10 μg/mL, which was better than thiodiazole copper (60.62 μg/mL), the antibacterial activity of Z2 was verified by scanning electron microscopy (SEM). Antibacterial mechanism of Z2 on Xoo was preliminarily explored, and the results showed concentrations were 100, 50 mg/L, which had a good cell membrane permeability to Xoo and can inhibit the EPS content and the production of extracellular enzymes, affecting the formation of biofilm, preliminary validation of the antibacterial effect of Z2 on Xoo. At 200 mg/L, Z2 had a better protective activity on harvested potatoes, which was comparable with thiodiazole copper. The activity against tobacco mosaic virus (TMV) was determined with half leaf dry spot method. The EC50 value of curative activity of Z15 was 101.97 μg/mL, which was superior to ningnanmycin (NNM) 294.27 μg/mL, and the EC50 value of protective activity of Z16 was 104.05 μg/mL, which was superior to NNM 185.73 μg/mL. Molecular docking results showed Z15, Z16 had a significantly higher affinity with tobacco mosaic virus coat protein (TMV-CP) than NNM. The above results indicated that chalcone derivatives containing benzoxazole have the potential to become antibacterial and antivirial agents.

Chemical and antibacterial evaluation of the essential oil from the leaves, petals and calyx of Calea phyllolepis Baker in Brazil

In the face of the complex context of resistance of human pathogenic bacteria, essential oils act in a synergistic way preventing the bacterial mechanism to create resistance. This article brings the chemical identification of the essential oils of the leaves, petals, and calyx of C. phyllolepis and the evaluation of these in the control of S. aureus and E. coli (Minimum Inhibitory Concentration (MIC) and Disc Diffusion). Thirteen compounds were identified in the EOs, being five monoterpenes and eight sesquiterpenes. Sabinene, (-)-α-Pinene and ρ-Cymene presented with high concentrations in all the evaluated parts. The minimum concentrations to effectively inhibit the development of bacteria varied between 0.3% to 4.0% against S. aureus and 0.3% to 8.0% for E. coli in the colorimetric assay. The most effective action against the bacteria studied were found for petal and calyx EOs, which presented MICs of 0.063% and 0.03%, respectively. In the study with the disk diffusion method, a halo of inhibition higher than that of the control groups was obtained. The effectiveness of the oils against the treated microorganisms, can be correlated with the chemical composition. The study with this plant is unprecedented and the results obtained are promising in the search for new antibacterial products

Gold@mesoporous polydopamine nanoparticles modified self-healing hydrogel for sport-injuring therapy

Sports-related damage is a prevalent issue, which a combination therapy including photothermal irradiation, self-healing dressing and antibacterial treatment is an effective way to rehabilitate it. In the study, a multifunctional hydrogel was developed to meet the requirement. Firstly, mesoporous polydopamine (MPDA) was prepared, where gold nanoparticles (Au NPs) were formed in its mesoporous structure, to construct Au@MPDA NPs with nanosize about 200 nm. Synergetic and efficient photothermal effect was achieved by the combination of the two photothermal agents. The Au@MPDA NPs were then added to modify polyvinyl alcohol-carboxymethyl chitosan-borax (PCB) hydrogel. Via rheological property characterization, cell experiments and antibacterial evaluation, high photothermal efficiency and effective antibacterial activity of Au@MPDA@PCB hydrogel was obtained with the aid of Au@MPDA NPs, together with self-healing property. When treated in motion-related tissue, the modified hydrogel showed excellent adaptive property and photothermal effect in situ. This study is beneficial for developing a novel rehabilitation treatment strategy for sports-related injuries.

Antimicrobial property, corrosion resistance and tarnish resistance of cold-sprayed additive manufactured copper-nickel alloy

The management of infectious diseases has posed a significant challenge in recent years, drawing the attention of scientific communities. Copper is renowned for its robust antimicrobial properties; however, it is susceptible to tarnishing. In contrast, copper-nickel alloy demonstrates not only commendable mechanical strength and corrosion resistance but also exceptional antimicrobial efficacy. A suitable copper-nickel alloy was synthesised using cold spray additive manufacturing, blending copper and nickel powders. The resultant as-printed coupons underwent heat treatment at varying temperatures to ensure alloy formation, porosity reduction, and property enhancement. Both corrosion properties and hardness were investigated across different selected heat treatment conditions. The specimens exhibiting the highest corrosion resistance and hardness were selected for antibacterial and tarnish resistance testing. Stainless Steel 316 was employed in the antibacterial evaluation as a negative control for comparison. Notably, a fair well distribution of copper and nickel was observed within the as-printed product. The optimal heat treatment condition for the copper-nickel alloy was determined to be 1030 °C followed by air cooling, as it exhibited superior material properties compared to alternative heat treatment conditions. An assessment of antimicrobial performance underscored the alloy’s effectiveness in rapidly eradicating bacteria. Additionally, the highest strength samples underwent a tarnish resistance study, revealing elevated tarnish resistance. The nature of material performance in response to the heat-treatment process and antibacterial performance are discussed.