Electrochemical synthesis of copper-arabinoxylan nanocomposite for applications as antimicrobial agent and CO2 conversion catalyst

This study reports the electrochemical synthesis, antimicrobial and catalytic activity of copper-arabinoxylan nanocomposite. The synthesis was achieved without use of any hazardous reducing and stabilizing agent. The spherical copper nanoparticles (size approx. 40 nm) dispersed in the arabinoxylan matrix as they formed and got stabilized. In the absence of arabinoxylan the particles rapidly converted to copper oxide suggesting a high stability for the composite. Electrolysis was carried out with copper plate as the sacrificial anode, carbon rod as the cathode and sodium nitrate (1.00 % in 1 % arabinoxylan suspension) as an electrolyte. The copper nanoparticles dispersed in arabinoxylan were characterized by surface plasmon resonance spectroscopy, X-ray diffraction, electron microscopy and zeta potential measurements. The synthesized composite exhibited good antimicrobial activity against P. aeruginosa, Staph. aureus and E. coli and a catalytic activity in conversion of CO₂ to methanol.     

Preparation,Characterization and Antibacterial Property Analysis of Cellulose Nanocrystals (CNC) and Chitosan Nanoparticles Fine-Tuned Starch Film

To improve the mechanical and antibacterial properties of traditional starch-based film, herein, cellulose nanocrystals (CNCs) and chitosan nanoparticles (CS NPs) were introduced to potato starch (PS, film-forming matrix) for the preparation of nanocomposite film without incorporation of additional antibacterial agents. CNCs with varied concentrations were added to PS and CS NPs composite system to evaluate the optimal film performance. The results showed that tensile strength (TS) of nanocomposite film with 0, 0.01, 0.05, and 0.1% (w/w) CNCs incorporation were 41, 46, 47 and 41 MPa, respectively. The elongation at break (EAB) reached 12.5, 10.2, 7.1 and 13.3%, respectively. Due to the reinforcing effect of CNCs, surface morphology and structural properties of nanocomposite film were altered. TGA analysis confirmed the existence of hydrogen bondings and electrostatic attractions between components in the film-forming matrix. The prepared nanocomposite films showed good antibacterial properties against both E. coli and S. aureus. The nanocomposite film, consist of three most abundant biodegradable polymers, could potentially serve as antibacterial packaging films with strong mechanical properties for food and allied industries.     

Biodegradable electrospun poly(l-lactide) fibers containing antibacterial silver nanoparticles

Biodegradable poly(l-lactide) (PLA) ultrafine fibers containing nanosilver particles were prepared via electrospinning. Morphology of the Ag/PLA fibers and distribution of the silver nanoparticles were characterized. The release of silver ions from the Ag/PLA fibers and their antibacterial activities were investigated. These fibers showed antibacterial activities (microorganism reduction) of 98.5% and 94.2% against Staphylococcus aureus and Escherichia coli, respectively, because of the presence of the silver nanoparticles.     

Phytochemical fabrication,characterization, and antioxidant application of copper and cobalt oxides nanoparticles using <Emphasis Type="Italic">Sesbania sesban</Emphasis> plant

In this work, an ecofriendly and economic strategy for synthesize of CuO and Co₃O₄ were developed using extracted Sesbania sesban solution (ESS) as a reducing and stabilizing agent, and bioreactor. These novel nano metal oxides (NMOs) were characterized by high-resolution-transmission electron microscopy (TEM), EDAX thermo gravimetric analysis and X-ray diffraction (XRD). Morphology and size of them were investigated by TEM and the average sizes of for spherical CuO and Co₃O₄ nanoparticles are 20–40 and 15–30 nm, respectively. The XRD and EDAX confirmed the high purity for NMOs. The thermal behaviors of the NMOs exhibited good crystallographic stability within the investigated temperature range. The antioxidant and antibacterial activities of NMOs were investigated and compared to manganese(III) meso-tetraphenylporphyrin complex/Ag nanocomposite (Ag/P nanocomposite) synthesizing by ESS. The results obtained from this work showed that copper(II) oxide, cobalt oxide nanoparticles, and Ag/P nanocomposite have DPPH scavenging activity. On the other hand, NMOs have no antibacterial activity against Gram-negative bacterial strains. Cobalt oxide nanoparticles have antibacterial activity against Staphylococcus aureus, while Ag/P nanocomposite showed the antibacterial activities against both Gram-negative and Gram-positive bacterial strains.     

Synthesis,characterization and antibacterial properties of a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag

In this study, a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag (PANI/PVA/Ag) has been successfully synthesized. The chemical reduction method was used to produce Ag nanoparticle colloidal solution from Ag⁺ ions. The polymerization of aniline occurred in situ for the preparation of polyaniline (PANI) in the presence of ammonium persulfate. With exposure to Ag nanoparticles on the PANI/PVA composite, a new nanocomposite was obtained. The morphology and particle size of the novel nanocomposite was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) analyses. According to XRD analysis, the size of nanoparticles was found to be in the range of 10–17 nm. SEM images showed the favored shape of nanoparticles as triangle which is a benign shape for antibacterial analysis. The antibacterial activity of the obtained nanocomposite was also evaluated against Gram positive bacteria Staphylococcus aureus (Staph. aureus) and Gram negative Escherichia coli (E. coli) using the paper disk diffusion method. The antibacterial study showed that the PANI/PVA composite did not have a very good antibacterial activity but PANI/PVA/Ag nanocomposites were found to be effective against two bacteria.     

Comparative evaluation of antibacterial potentials of nano cobalt oxide with standard antimicrobials

Development of suitable potent antimicrobial is the urgent need of modern era to cope up the problem of antimicrobial resistance. The applications of nanotechnology in metal oxides have shown favorable effects to some extent in this area. Thus, the present study was investigated to evaluate the antibacterial properties of cobalt oxide (Co₃O₄) nanoparticles at different concentrations and their comparison with standard antimicrobials i.e. tetracycline and gentamicin. Nanoparticles were synthesized and characterized by standard techniques. The antibacterial potentials of Co₃O₄ nanoparticles against S. aureus and E. coli were determined at various concentrations. The maximum zone of inhibitions of Co₃O₄ nanoparticles against S. aureus and E. coli at 500 μg/ml were 21.17 mm and 24.00 mm, respectively. The Co₃O₄ nanoparticles seemed more effective than gentamicin against S. aureus and E. coli. The nanoparticles with respect to tetracycline showed higher than 1 activity index at ≥ 125 μg/ml for E. coli and ≥31.25 μg/ml for S. aureus. It was also higher than 1 at all compared concentrations with respect to gentamicin against both bacteria. In conclusion, Co₃O₄ nanoparticles seemed to have potent antibacterial potential and these might be very helpful to replace the conventional antimicrobials to solve the problem of antibacterial resistance.     

Optical and antibacterial activity of biogenic core-shell ZnO@TiO2 nanoparticles

Inorganic nanocomposites, due to increased stability and safety, are gaining importance in wide range of engineering and medical applications. In view of this, the present study demonstrates the optical and antibacterial activity of core-shell ZnO@TiO₂ nanoparticles synthesized via biogenic method using Azadirachta indica flower extract. The synthesized nanocomposite is characterized by XRD, TEM and EDS. The optical activity of the ZnO@TiO₂ nanoparticle, assessed by photoluminescence spectra, indicated concentration dependent increase in the number of defects. The antibacterial activity of synthesized core-shell ZnO@TiO₂ nanoparticles was determined by agar disc diffusion method against 9 clinical isolates (Gram positive - S. aureus, S. pneumonia, B. subtilis and Gram negative - E. coli, S. dysenteriae, K. pneumonia, V. cholera, P. aeruginosa, and P. vulgaris). The synthesized nanoparticle exhibited significant antibacterial activity against all the strains tested. The synthesized core-shell ZnO@TiO₂ nanoparticle can be a potential antimicrobial candidate for various biomedical applications.     

Preparation and antibacterial activity of electrospun chitosan/poly(ethylene oxide) membranes containing silver nanoparticles

Fairly uniform chitosan (CS)/poly(ethylene oxide) (PEO) ultrafine fibers containing silver nanoparticles (AgNPs) were successfully prepared by electrospinning of CS/PEO solutions containing Ag/CS colloids by means of in situ chemical reduction of Ag ions. The presence of AgNPs in the electrospun ultrafine fibers was confirmed by X-ray diffraction patterns. The AgNPs were evenly distributed in CS/PEO ultrafine fibers with the size less than 5 nm observed under a transmission electron microscope. X-ray photoelectron spectroscopy suggested that the existence of Ag―O bond in the composite ultrafine fibers led to the tight combination between Ag and CS. Evaluation of antimicrobial activities of the electrospun Ag/CS/PEO fibrous membranes against Escherichia coli showed that the AgNPs in the ultrafine fibers significantly enhanced the inactivation of bacteria.     

Preparation of quaternarized N-halamine-grafted graphene oxide nanocomposites and synergetic antibacterial properties

At present, frequent outbreaks of bacteria and viruses have seriously affected people's normal lives. Therefore, the study of broad-spectrum antibacterial nanocomposites is very promising. However, most antibacterial materials have some disadvantages, such as single bactericidal mechanisms and unrepeatable use. Based on the current situation, a kind of nanocomposite with three structures of graphene oxide (GO), quaternary ammonium salt (QAs) and N-halamine was prepared, which showed synergistic effect to improve antibacterial activity and combined with a variety of sterilization mechanisms. Meanwhile, GO can provide richer ways of sterilization and high specific surface area, which is conducive to the grafting of quaternarized N-halamine. The advantages of physical sterilization of GO, charge adsorption of QAs, reuse of N-halamine and efficient sterilization are fully utilized. The results showed that the quaternarized N-halamine-grafted GO was obtained successfully. GO grafted with quaternarized N-halamine polymer showed strong speedy bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) (99%). It had good storage and regeneration properties.     

Impact of Electrospinning Parameters and Post-Treatment Method on Antibacterial and Antibiofilm Activity of Chitosan Nanofibers

Chitosan, a natural biopolymer, is an ideal candidate to prepare biomaterials capable of preventing microbial infections due to its antibacterial properties. Electrospinning is a versatile method ideally suited to process biopolymers with minimal impact on their physicochemical properties. However, fabrication parameters and post-processing routine can affect biological activity and, therefore, must be well adjusted. In this study, nanofibrous membranes were prepared using trifluoroacetic acid and dichloromethane and evaluated for physiochemical and antimicrobial properties. The use of such biomaterials as potential antibacterial agents was extensively studied in vitro using Staphylococcus aureus and Escherichia coli as test organisms. The antibacterial assay showed inhibition of bacterial growth and eradication of the planktonic cells of both E. coli and S. aureus in the liquid medium for up to 6 hrs. The quantitative assay showed a significant reduction in bacteria cell viability by nanofibers depending on the method of fabrication. The antibacterial properties of these biomaterials can be attributed to the structural modifications provided by co-solvent formulation and application of post-treatment procedure. Consequently, the proposed antimicrobial surface modification method is a promising technique to prepare biomaterials designed to induce antimicrobial resistance via antiadhesive capability and the biocide-releasing mechanism.     

Synthesis and Antimicrobial Activity Screening of Piperazines Bearing N,N′-Bis(1,3,4-thiadiazole) Moiety as Probable Enoyl-ACP Reductase Inhibitors

A new N,N′-disubstituted piperazine conjugated with 1,3,4-thiadiazole and 1,2,4-triazole was prepared and the chemical structures were identified by IR, NMR and elemental analysis. All the prepared compounds were tested for their antimicrobial activity. The antimicrobial results indicated that the tested compounds showed significant antibacterial activity against gram-negative strains, especially E. coli, relative to gram-positive bacteria. Docking analysis was performed to support the biological results; binding modes with the active site of enoyl reductase amino acids from E. coli showed very good scores, ranging from −6.1090 to −9.6184 kcal/mol. Correlation analysis was performed for the inhibition zone (nm) and the docking score.     

Structure,surface analysis and bioactivity of Mn doped zinc oxide nanoparticles

Undoped zinc oxide nanoparticles and Mn (5 atomic % & 10 atomic %) doped zinc oxide nanoparticles were prepared by soft chemical method. Antibacterial, antioxidant and anticancer activities in breast cancer cell line MDAMB231 of prepared nanoparticles were investigated. The nanoparticles were characterized using XRD, SEM, EDAX, UV–Vis, FT-IR, and room temperature PL Analysis. Antimicrobial activity was tested against both gram positive and gram negative human pathogens. The antioxidant potential of prepared nanoparticles was estimated using Phosphomolybdate and DPPH assay. The MTT assay was used for cytotoxicity evaluation of prepared nanoparticles against breast cancer cell line MDAMB231. XRD patterns confirmed the nanoparticles were crystallized hexagonal wurtzite structure with an average size of 38.95 ?nm. The absorption wavelength was observed at 361 ?nm in UV–Vis spectrum of Mn (10 atomic %) doped ZnO nanoparticles. The Mn (5 atomic %) doped ZnO nanoparticles exhibited significant antibacterial activity against the gram negative bacteria Escherichia coli, Klebsiella pneumonia at all concentrations. Undoped zinc oxide nanoparticles and Mn doped zinc oxide nanoparticles were effective against the breast cancer cell line MDAMB231.     

Evaluation of biological activities of some Schiff bases and metal complexes

Several Schiff bases were synthesised from sulphonamide and resacetophenone. The characterisation was done by CHN analysis, IR and NMR spectral data. These Schiff bases were evaluated for their antimicrobial activity against both Gram-positive and Gram-negative bacteria as well as fungi. The antibacterial activity was studied against B. megaterium, E. coli, B. subtilis, P. fluorescens and antifungal activity against A. awamori. In addition, copper, nickel, cobalt, and iron complexes of two Schiff bases were also synthesised. Their structural characterisation was performed using CHN analysis and IR spectral data and their antibacterial and antifungal activities were also evaluated. The comparison of antimicrobial activities of the ligands and complexes shows that the presence of metal causes more inhibition i.e., more activity. Out of the four metals studied, cobalt and iron were found to have more antimicrobial activity.     

A novel approach for fabrication ZnO/CuO nanocomposite via laser ablation in liquid and its antibacterial activity

Pulsed laser ablation in liquid (PLAL) has verified its surpassing advantages in the fabrication of several high purity nanostructured metals and metal oxides. In this work, ZnO/CuO heterostructure nanocomposites have been fabricated by laser ablation a Q switched Nd: YAG laser beam (1064 nm, 10 Hz, pulse energy and pulse with 30 mJ and 10 ns) is focused on the surface of the ZnO thin film for 10 min. The fabricated ZnO/CuO nanocomposite was then characterized using transmission electron microscopy (TEM), UV–vis spectrophotometer, X-ray diffraction (XRD), and Raman spectroscopy to investigate the structural, compositional, and optical properties of the fabricated nanocomposite. The synthesized nanocomposites were evaluated as antibacterial agents against both the gram-positive bacterium S. aureus subsp. aureus ATCCBAA-977, and the gram-negative bacteria E. coli ATCC8739, K. pneumoniae subsp. pneumoniae ATCC700603, and P. aeruginosa ATCC27853. The as-fabricated ZnO/CuO nanocomposite demonstrated outstanding antibacterial activity except in the case of K. pneumoniae subsp. pneumoniae ATCC700603 while the maximum activity was observed against E. coli ATCC8739.     

Microcalorimetric investigation on antibacterial activity of the peptide from Plutella xylostella

The antibacterial activities of a kind of novel peptide from Plutella xylostella (pxCECA1) on methicillin-resistant staphylococcus aureus (MRSA) and Escherichia coli (E. coli) growth were investigated by microcalorimetry. The heat flow power–time curves of MRSA and E. coli growth in the presence of pxCECA1 were recorded using the 3114/3115 Thermal Activity Monitor Air Isothermal Calorimeter based on ampoule mode at 37 °C. Some parameters including growth rate constant k, maximum power output P _max, total heat output Q_t, generation time t _g, growth inhibitory ratio I, and half-inhibitory concentration of the drugs IC₅₀ were obtained to elucidate the antibacterial activity of pxCECA1. The results showed that k, P _max, and Q _t decreased, but I and t _g increased or delayed with the increase in pxCECA1 concentration. The IC₅₀ of pxCECA1 on E. coli was 6.122 μg mL^?1 and MRSA was 7.809 μg mL^?1. It could be concluded that pxCECA1 had stronger inhibitory effect on E. coli than MRSA. In vivo test was simultaneously performed using an E. coli and MRSA infection model to validate the antibacterial activity of pxCECA1. The results revealed that pxCECA1 with broad spectrum antimicrobial activities hopefully represented a class of promising substitute of antimicrobial agents.     

Functional Characterization of Porcine NK-Lysin: A Novel Immunomodulator That Regulates Intestinal Inflammatory Response

Porcine NK-Lysine (PNKL) is a new antimicrobial peptide (AMP) identified in the small intestine. In this study, PNKL protein was obtained through heterologous expression in Escherichia coli and was estimated by SDS-PAGE at 33 kDa. The antibacterial activities of PNKL were determined using various bacterial strains and showed broad-spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria. Furthermore, E. coli K88-challenged IPEC-J2 cells were used to determine PNKL influences on inflammatory responses. Hemolytic assays showed that PNKL had no detrimental impact on cell viability. Interestingly, PNKL elevated the viability of IPEC-J2 cells exposure to E. coli K88. PNKL significantly decreased the cell apoptosis rate, and improved the distribution and abundance of tight junction protein ZO-1 in IPEC-J2 cells upon E. coli K88-challenge. Importantly, PNKL not only down regulated the expressions of inflammatory cytokines such as the IL-6 and TNF-α, but also down regulated the expressions of NF-κB, Caspase3, and Caspase9 in the E. coli K88-challenged cells. These results suggest a novel function of natural killer (NK)-lysin, and the anti-bacterial and anti-inflammatory properties of PNKL may allow it a potential substitute for conventionally used antibiotics or drugs.     

Biochemical study for the effect of henna (Lawsonia inermis) on Escherichia coli

Leaf samples of Lawsonia inermis (Li) were examined for their antimicrobial potential. Broth extracts in different concentrations were prepared and bioassayed in vitro for the growth of Escherichia coli. The growth of E. coli pathogen was inhibited to various degrees by increasing the concentration of the herbal powder. In addition to the observed alterations which were detected electrophoretically in the protein pattern, were activities of the amylase enzyme and glycoprotein fractions. The protein pattern has one common band of Rf 0.47 and two characteristic bands of Rf 0.36 and Rf 0.42 for E. coli sample. The quantitative mutation was observed in the bacteria with different concentrations of L. inermis compared with the control. Some types of proteins in E. coli completely disappeared upon being S.I affected. The amylase pattern showed one common band with Rf 0.037 and two characteristic bands with Rf 0.18 and Rf 0.37 for E. coli sample. The obvious quantitative mutation observed in bacteria with different concentrations of L. inermis compared with E. coli. The glycoprotein pattern recorded one common band at R₁ with Rf 0.94 for E. coli sample and bacteria inoculated with different concentrations of L. inermis. These results confirmed the antibacterial activity of henna leaves and supported the traditional use of the plant in therapy of bacterial infections and disturbances that occurred at the biochemical level. The broth extract of the L. inermis leaves showed obvious antibacterial activity against E. coli.     

Effect of Mg doping on morphology,photocatalytic activity and related biological properties of Zn1−xMgxO nanoparticles

The objective of this study is to synthesize ZnO and Mg doped ZnO (Zn_1−xMg_xO) nanoparticles via the sol-gel method, and characterize their structures and to investigate their biological properties such as antibacterial activity and hemolytic potential.Nanoparticles (NPs) were synthesized by the sol-gel method using zinc acetate dihydrate (Zn(CH₃COO)₂.2H₂O) and magnesium acetate tetrahydrate (Mg(CH₃COO)₂.4H₂O) as precursors. Methanol and monoethanolamine were used as solvent and sol stabilizer, respectively. Structural and morphological characterizations of Zn_1−xMg_xO nanoparticles were studied by using XRD and SEM-EDX, respectively. Photocatalytic activities of ZnO and selected Mg-doped ZnO (Zn_1−xMg_xO) nanoparticles were investigated by degradation of methylene blue (MeB). Results indicated that Mg doping (both 10% and 30%) to the ZnO nanoparticles enhanced the photocatalytic activity and a little amount of Zn0.90 Mg0.10 O photocatalyst (1.0 mg/mL) degraded MeB with 99% efficiency after 24 h of irradiation under ambient visible light. Antibacterial activity of nanoparticles versus Escherichia coli ( E. coli ) was determined by the standard plate count method. Hemolytic activities of the NPs were studied by hemolysis tests using human erythrocytes. XRD data proved that the average particle size of nanoparticles was around 30 nm. Moreover, the XRD results indicatedthat the patterns of Mg doped ZnO nanoparticles related to ZnO hexagonal wurtzite structure had no secondary phase for x ≤ 0.2 concentration. For 0 ≤ x ≤ 0.02, NPs showed a concentration dependent antibacterial activity against E. coli . While Zn_0.90Mg_0.10 O totally inhibited the growth of E. coli , upper and lower dopant concentrations did not show antibacterial activity.     

Bionanocomposite of Au decorated MnO2 via in situ green synthesis route and antimicrobial activity evaluation

Green synthesis gaining a significant importance for the preparation of nanoparticles (NPs) and NPs-based biocomposites gained much attention in biological applications. In the current study, gold (Au) nanoparticles were prepared via green approach using cinnamon extract. The Au nanocomposite (NC) was prepared with MnO₂ nanofiber mesh structure. The NC was characterized by XRD, SEM, FT-IR, EDX, UV–visible and DLS techniques. The MnO₂ nanofibers diameter was in 10–25 nm range, which was arranged in a mesh form and Au NPs was combined with nanofibers randomly. The MnO₂-Au NC antimicrobial activity was measured against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains. The antimicrobial activity of MnO₂-Au NC was highly promising against tested microorganisms in comparison to control (ciprofloxacin, a standard drug). The antimicrobial activity of MnO₂-Au NC was found in following order; > S. aureus > E. coli > P. aeruginosa with the zones inhibition of 22, 18 and 15 (mn), respectively. The MIC (minimum inhibitory concentration) values were 316, 342 and 231 (µg/mL) for E. coli, P. aeruginosa and S. aureus, respectively. In view of promising antimicrobial activity, the MnO₂-Au NC prepared via green approach could have potential applications in medical field and future study can be engrossed on the biocompatibility evaluation of MnO₂-Au NC using bioassays.     

Biosynthesis,characterization, biological and photo catalytic investigations of Elsholtzia blanda and chitosan mediated copper oxide nanoparticles

Bio synthesis of nanoparticles using plant parts has gained considerable attention, given the fact that the method is green, environment friendly, cheaper, simple and involves no hazardous substances. The present study involves the green synthesis of copper oxide nanoparticles (CuO NPs) using chitosan and the aqueous leaf extract of Elsholtzia blanda, an aromatic medicinal herb. The synthesized E.blanda-chitosan mediated copper oxide nanoparticles (CPCE) and E. blanda mediated copper oxide nanoparticles (PCE) were subjected to different characterization techniques, Ultraviolet–visible (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Analysis (EDAX), High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED). The absorbance peaks in UV–Vis spectroscopy at 286 nm and 278 nm for CPCE and PCE respectively indicated the formation of nanoparticles. TEM and SEM employed for studying the surface morphology showed rod-like and spherical morphology bearing average size of 47.71 nm for CPCE and 36.07 nm for PCE. The antibacterial activities of the prepared nanoparticles were tested against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Salmonella typhi by agar well diffusion method. The results indicate that CuO NPs possess effective antibacterial potential against all tested bacteria with a maximum zone of inhibition of 18 mm for Enterococcus faecalis. Antioxidant studies revealed the highest DPPH scavenging activity of 89% at 25 μg/mL concentration of the nanoparticles. The percentage of the photo catalytic degradation of Congo red was found to be 95% after 10 h.