Synthesis and characterization of marine seagrass (Cymodocea serrulata) mediated titanium dioxide nanoparticles for antibacterial, antibiofilm and antioxidant properties.

Cymodocea serrulata mediated titanium dioxide nanoparticles (TiO2 NPs) were successfully synthesized. The XRD pattern and FTIR spectra demonstrated the crystalline structure of TiO2 NPs and the presence of phenols, flavonoids and alkaloids in the extract. Further SEM revealed that TiO2 NPs has uniform structure and spherical in shape with their size ranged from 58 to 117 nm. Antibacterial activity of TiO2 NPs against methicillin-resistant Staphylococcus aureus (MRSA) and Vibrio cholerae (V. cholerae), provided the zone of inhibition of 33.9 ± 1.7 and 36.3 ± 1.9 mm, respectively at 100 µg/mL concentration. MIC of TiO2 NPs against MRSA and V. cholerae showed 84% and 87% inhibition at 180 µg/mL and 160 µg/mL respectively. Subsequently, the sub-MIC of V. cholerae demonstrated minimal or no impact on bacterial growth at concentration of 42.5 µg/mL concentration. In addition, TiO2 NPs exhibited their ability to inhibit the biofilm forming V. cholerae which caused distinct morphological and intercellular damages analysed using CLSM and TEM. The antioxidant properties of TiO2 NPs were demonstrated through TAA and DPPH assays and exposed its scavenging activity with IC50 value of 36.42 and 68.85 µg/mL which denotes its valuable antioxidant properties with potential health benefits. Importantly, the brine shrimp based lethality experiment yielded a low cytotoxic effect with 13% mortality at 100 µg/mL. In conclusion, the multifaceted attributes of C. serrulata mediated TiO2 NPs encompassed the antibacterial, antioxidant and anti-biofilm inhibition effects with low cytotoxicity in nature were highlighted in this study and proved the bioderived TiO2 NPs could be used as a promising agent for biomedical applications.

Size- and oxidative potential-dependent toxicity of environmentally relevant expanded polystyrene styrofoam microplastics to macrophages.

Expanded polystyrene (EPS), also known as Styrofoam, is a widespread global pollutant, and its lightweight floating property increases its chances of weathering by abrasion and ultraviolet (UV) irradiation, resulting in microplastics. Herein, we investigated the effects of particle size ((1 µm versus 10 µm), UV irradiation (pristine versus UV oxidation), and origin (secondary versus primary) on the toxicity of Styrofoam microplastics. The target cells used in this study were selected based on human exposure-relevant cell lines: differentiated THP-1 cells for macrophages, Caco-2 for enterocytes, HepG2 for hepatocytes, and A549 for alveolar epithelial cells. In the differentiated THP-1 cells, the levels of cytotoxicity and inflammatory cytokines showed size- (1 µm > 10 µm), UV oxidation- (UV > pristine), and origin- (secondary > primary) dependency. Furthermore, the intrinsic oxidative potential of the test particles was positively correlated with cellular oxidative levels and toxicity endpoints, suggesting that the toxicity of Styrofoam microplastics also follows the oxidative stress paradigm. Additionally, all microplastics induced the activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome and the release of interleukin-1ß (IL-1ß). These results imply that weathering process can aggravate the toxicity of Styrofoam microplastics due to the increased oxidative potential and decreased particle size.

Morphological modification of silver nanoparticles against multi-drug resistant gram-negative bacteria and cytotoxicity effect in A549 lung cancer cells through in vitro approaches.

In the present study, the individual cultures of Proteus mirabilis (P. mirabilis) and Klebsiella pneumoniae (K. pneumoniae) were treated with morphologically modified silver nanoparticles (Ag NPs) and were found to display zones of inhibition of ~ 8 mm, 16 mm, 20 mm, and 22 mm (P. mirabilis) and 6 mm, 14 mm, 20 mm, and 24 mm (K. pneumoniae) at concentrations of 25 µg/ml, 50 µg/mL, 75 µg/mL, and 100 µg/mL, respectively. In addition, turbidity tests were performed based on O. D. values, which exhibited 92% and 90% growth inhibitions at 100 µg/mL concentration for P. mirabilis and K. pneumoniae, respectively. Furthermore, the IC50 concentration of Ag NPs was established for A549 lung cancer cells and found to be at 500 µg/mL. Evidently, the morphological variation of Ag NPs treated A549 lung cancer cells was exhibited with differential morphology studied by phase-contrast microscopy. The results demonstrated that the synthesized Ag NPs was not only efficient against gram-positive bacteria but also against gram-negative bacteria and A549 cancer cells, suggesting that the potential of these biosynthesized Ag NPs is a future drug discovery source for inhibiting bacteria and cancer cells.

Metal tolerance and biosorption of Pb ions by Bacillus cereus RMN 1 (MK521259) isolated from metal contaminated sites.

Recent years, metal pollution is an alarming factor to know about protects the environmental ecosystem due to the toxic, persistent and abundant in nature. Metals are present everywhere in the biotic and abiotic samples including soil, water, and microbes. The rate of bioaccumulation and biotransformation are very high. The excess concentration of the metals causes heavy metal pollution or contamination. Due to these defects, the removal of metals using biological sources is heightened in the current research. In this current investigation, the biosorption potential ability of the metal tolerable Bacillus cereus on Pb and Cu rich environment was chosen and thoroughly monitored. The 16s rRNA of the Bacillus cereus was sequenced, and named as Bacillus cereus RMN 1 (MK521259). The various test concentration (10-60 mg/mL) of Pb and Cu was exhibited the maximum removal percentages of 85.2% and 60.2%. The result of bisorption factors exhibited, 300 mg/mL of the biosorbent potency, 60 min contact time and pH 7, and they found to be optimal to remove the maximum of Pb ion from the solution. In the regression coefficients, the Freundlich and Langmuir isotherm models were used to study the adsorption kinetics of metal ions. In addition, the isotherm model confirmed that the of B. cereus biomass medicated metal adsorption was more favourable reaction for metal degradation. With the above evidences, the results of the present investigation proved that B. cereus derived biomass was actively adsorbing the metals ions. Thus we are recommending for the implementation of effective waste water treatment.

Biokinetics of fluorophore-conjugated polystyrene microplastics in marine mussels.

Biokinetic information on microplastics in bivalves is required to reduce the human exposure, but little is known about the time-course and size effect on tissue absorption and clearance. The biokinetics of fluorophore-labeled polystyrene microbeads with diameters 10 µm (PL10) and 90 µm (PL90) in Mytilus galloprovincialis marine mussels was investigated in the present study. It was found that both PL10 and PL90 showed a biphasic tissue distribution pattern in digestive and non-digestive tissues, highlighting the significant tissue distribution starting from 48 h post-treatment. The differential size effect on tissue distribution was observed only in the gills, which suggests that PL10 accumulates more than PL90. The depuration kinetics show that particles of both sizes can be cleared in any tissue, but non-digestive tissue requires a longer duration for depuration than digestive tissue. The differential size effect on depuration was observed for both digestive and non-digestive tissues, suggesting that PL10 needed a longer duration for depuration than PL90. More than seven days were needed for depuration of microplastics in mussels, which is an exceptionally longer period compared to conventional depuration of bivalves. The most significant improvement of this study is providing the biokinetics of two different-sized microplastics in mussels and the differential time for purging microplastics from mussels.

Preparation of antibacterial Zn and Ni substituted cobalt ferrite nanoparticles for efficient biofilm eradication.

Zinc (Zn) and, alternatively, nickel (Ni) substituted cobalt ferrite (CF) nanoparticles (NPs) were prepared by sol-gel method. X-ray diffraction analysis revealed the formation of cubic structure of cobalt ferrite. FTIR analysis confirmed the vibrational band located at 550-580 cm-1 that belongs to the M - O bond (M = Ni, and Zn). The alteration of the surface morphology of CF after the addition of Zn and Ni ions was observed from scanning electron microscopic images. The additional peaks in the energy dispersive X-ray diffraction (EDX) analysis spectra were found to correspond to Zn and Ni. The presence of Zn and, alternatively, Ni ions enhanced the biocidal properties of CF NPs against gram negative organisms, in a concentration and time-dependent manner. Furthermore, exposure to CF, CF-Zn and CF-Ni NPs decreased metabolic activity due to the damage of extra polymorphic substances, live/dead cell variation, architecture and surface integrity of the cells. Altogether, the present investigation provides the basis of metal ion substituted metal oxide NPs as anti-biofilm agents against gram-positive and gram-negative bacteria.

Biosorption and adsorption isotherm of chromium (VI) ions in aqueous solution using soil bacteria Bacillus amyloliquefaciens.

This study looked at the development of effective biosorbents to recover the most toxic elements from industrial water. B. amyloliquefaciens was isolated from marine soils showing extreme resistance to Chromium (Cr(VI)) ions. During the 60 min of contact time, 79.90% Cr(VI) was adsorbed from the aqueous solution. The impact of important factors such as biomass concentration, pH of the medium, and initial metal ions concentration on biosorption rate was also examined. The desorption study indicated that 1 M HCl (91.24%) was superior to 0.5 M HCl (74.81%), 1 M NaOH (64.96%), and distilled water (3.66%). Based on the Langmuir model, the maximum adsorption capacity of the bio-absorbent was determined to be 48.44 mg/g. The absorption mechanism was identified as monolayer, and 1/n from the Freundlich model falls within 1, thus indicating favorable adsorption. Based on the findings of the present study, the soil bacterium B. amyloliquefaciens was found to be the best alternative and could be used to develop strategies for managing existing environmental pollution through biosorption.

Development of chitosan decorated Fe3O4 nanospheres for potential enhancement of photocatalytic degradation of Congo red dye molecules.

Fe3O4 nanospheres (Nsps) and chitosan (Cts)/Fe3O4 Nsps were prepared using a one-pot hydrothermal method and subsequently used as photocatalysts against the degradation of Congo red (CR) dye molecules. The sphere-shaped Fe3O4 nanoparticles were heterogeneously decorated by the Cts matrix, which was confirmed by powder X-ray diffraction, scanning and transmission electron microscopies. The Cts/Fe3O4 Nsps demonstrated 98% efficient photocatalytic activity against CR dye molecules upon 60 min exposure to visible light compared to Fe3O4 Nsps (77% for 60 min). When compared to Fe3O4 Nsps, the visible light photocatalytic efficiency of Cts/Fe3O4 Nsps against CR dye molecules was significantly improved.

Laccase producing bacteria influenced the high decolorization of textile azo dyes with advanced study.

Recent year, bacterial laccases are increasing interest in the field of industry and environmental applications especially decolorization of azo dyes. In industry, the dyes are present in stable nature including chemicals and lights. Due to these defects, the novel approaches are needed to removal of dyes before discharging into the environment. Among the various technologies, biological treatment methods and their strategies are very important, because of the decolorization and detoxification. Consecutively, biological mediated dyes removal are emerged with high potential especially microbes. Microbial laccases creates up new opportunities for their commercial applications. In this study, laccases were produced from Bacillus cereus (B. Cereus) and Pseudomonas parafulva (P. parafulva) by sub merged fermentation. For immobilization, the produced laccases were subjected to purify using 80% saturated ammonium sulphate and followed by dialysis. Then, crude laccases were immobilized through copper-alginate entrapment method. The maximum immobilized enzyme activity of the immobilized laccases were shown pH 8 at 50 °C and pH 7 at 40 °C for B. Cereus and P. parafulva respectively. In contrast, the normal enzyme activity was pH 10 at 40 °C and pH 8 at 40 °C were indicated for Bacillus cereus and P. parafulva respectively. Next, the free and immobilized laccases were performed the decolorization of three azo dyes T-blue, yellow GR and orange 3R, and exhibited that the 91.69 and 89.21% of Orange 3R were completely decolorized by both the B. Cereus and P. parafulva laccases when compared with free laccases enzymes. The confirmation of decolorization was monitored by UV-vis spectroscopy and FTIR spectroscopy, which clearly confirm the changes of peaks when compared with normal laccases. Finally, we have concluded that the B. Cereus and P. parafulva laccases are very important in azo dye decolorization and these used in future biological treatment of dyeing effluents.

Effective removal of heavy metals in industrial wastewater with novel bioactive catalyst enabling hybrid approach.

Recent years, heavy metal reduction of contaminated atmosphere using microbes is heightened worldwide. In this context, the current study was focused on heavy metal resistant actinomycete strains were screened from effluent mixed contaminated soil samples. Based on the phenotypic and molecular identification, the high metal resistant actinomycete strain was named as Nocardiopsis dassonvillei (MH900216). The highest bioflocculent and exopolysaccharide productions of Nocardiopsis dassonvillei (MH900216) was confirmed by various invitro experiments result. The heavy metal degrading substances was characterized and effectively confirmed by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning electron microscope (SEM). Further, the heavy metal sorption ability of actinomycete substances bioflocculent was exhibited 85.20%, 89.40%, 75.60%, and 51.40% against Cd, Cr, Pb and Hg respectively. Altogether, the bioflocculent produced actinomycete Nocardiopsis dassonvillei (MH900216) as an excellent biological source for heavy metal reduction in waste water, and it is an alternative method for effective removal of heavy metals towards sustainable environmental management.

Acute and subacute repeated oral toxicity study of fragmented microplastics in Sprague-Dawley rats.

Polypropylene (PP) is the second most highly produced plastic worldwide, and its microplastic forms are found in water and food matrices. However, the effects of PP microplastics on human health remain largely unknown. Here, we prepared 85.2 µm-sized weathered PP (w-PP) microplastics by sieving the microplastic particles after fragmentation and accelerated weathering processes. The prepared particles are irregular in shape and no chemical additives including phthalates and bisphenol A were not released in simulated body fluids. Then, the w-PP samples were gavaged to rats for acute and subacute toxicity testing in accordance to the Organization for Economic Co-operation and Development (OECD) test guidelines under good laboratory practice regulations. The highest dose for gavaging to rats was 25 mg/kg bw/day, which was the maximum feasible dose based on the dispersibility of microplastics. Both toxicity testings for w-PP microplastics showed no adverse effects and mutagenicity. Thus, the no observed adverse effect level (NOAEL) of w-PP microplastics is higher than 25 mg/kg bw/day. Furthermore, the w-PP microplastics did not show any skin or eye irritation potentials in the 3-dimensional reconstructed human skin or corneal culture model. The dose of 25 mg/kg of w-PP microplastics is roughly equal to 2.82 × 105 particles/kg, which suggests that human exposure to w-PP microplastics in a real-life situation may not have any adverse effects.

Enlightening the characteristics of bioflocculant of endophytic actinomycetes from marine algae and its biosorption of heavy metal removal.

The removal of toxic heavy metal ions from contaminated environments is a great challenge and requires an alternative rapid, efficient, economical bioremediation approach. Henceforth, bioflocculant producing endophytic actinobacterial sp. was isolated from heavy metal contaminated marine environments for heavy metal biosorption process. After molecular characterization, the isolated actinomycete starin was Nocardiopsis sp. GRG 3 (KT235642). It was indicated that the maximum flocculating activity of 80.90% with glucose, and yield is 4.52 g L1. The optimum flocculating activity was reached at pH 7 in the presence of CaCl2 ions. Further, the bioflocculent produced Nocardiopsis sp. GRG 3 (KT235642) was characterized by fourier transform infrared analysis spectra (FTIR) and displayed the presence of carboxyl, hydroxyl, amino groups and characteristic of more polysaccharide and protein. The heavy metal sorption by bioflocculant Nocardiopsis sp. GRG 3 (KT235642) was effectively removed 55.90% Cd, 85.90% Cr, 74.7% Pb, and 51.90% Hg. Therefore, this study was proved that the bioflocculant derived from endophytic actinobacteria, Nocardiopsis sp. GRG 3 (KT235642) as a effective alternative method for decreasing the heavy metals towards sustainable environmental management.

Highly efficient antibacterial activity of graphene/chitosan/magnetite nanocomposites against ESBL-producing Pseudomonas aeruginosa and Klebsiella pneumoniae.

In the present study, chitosan-containing nanocomposites were investigated as new antibacterial agents. Magnetite (Fe3O4) nanoparticles (NPs) as well as chitosan (CS)/Fe3O4 nanocomposites (NCs) and graphene(Gr)/CS/Fe3O4 NCs were synthesized by simple hydrothermal method. Their composition, structure and morphology were studied, followed by the evaluation of their antibacterial activity against ESBL-producing and gram-negative P. aeruginosa and K. pneumoniae bacterial strains. The Gr/CS/Fe3O4 NCs showed significantly higher antibacterial activity compared to Fe3O4 NPs and CS/Fe3O4 NCs (105 and 69 % higher against P. aeruginosa as well as 91 and 77 % higher against K. pneumoniae, respectively). The minimum inhibitory concentration (MIC) of Gr/CS/Fe3O4 NCs against P. aeruginosa and K. pneumoniae were 60 and 70 µg/mL, respectively. The synergistic antibacterial activity and facile synthesis of Gr/CS/Fe3O4 NCs suggests their applicability as novel highly efficient antibacterial agents with potential for a wide range of biomedical applications, where antibacterial properties are needed.

Effect of CO2 driven ocean acidification on calcification, physiology and ovarian cells of tropical sea urchin Salmacis virgulata - A microcosm approach.

In the present study, we depict the structural modification of test minerals, physiological response and ovarian damage in the tropical sea urchin Salmacis virgulata using microcosm CO2 (Carbon dioxide) perturbation experiment. S. virgulata were exposed to hypercapnic conditions with four different pH levels using CO2 gas bubbling method that reflects ambient level (pH 8.2) and elevated pCO2 scenarios (pH 8.0, 7.8 and 7.6). The variations in physical strength and mechanical properties of S. virgulata test were evaluated by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction analysis and scanned electron microscopy analysis. Biomarker enzymes such as glutathione-S-transferase, catalase, acetylcholine esterase, lipid peroxidase and reduced glutathione showed physiological stress and highly significant (p < 0.01) towards pH 7.6 and 7.8 treatments. Ovarian cells were highly damaged at pH 7.6 and 7.8 treatments. This study proved that the pH level 7.6 and 7.8 drastically affect calcification, physiological response and ovarian cells in S. virgulata.

Photocatalytic reduction and anti-bacterial activity of biosynthesized silver nanoparticles against multi drug resistant Staphylococcus saprophyticus BDUMS 5 (MN310601).

In this study, silver nanoparticles (Ag NPs) was eco-friendly synthesized using purified flavonoid rich content of Morinda citrifolia (M. citrifolia) extract. The synthesized Ag NPs was exhibited at 420 nm in UV-spectrometer, and surface morphology with available chemical composition, shape and size of the Ag NPs were confirmed by X-ray diffraction (XRD) variation, scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) and transmission electron microscope (TEM). In addition, the excellent phytochemicals and anti-oxidant activity of the Ag NPs were confirmed by total anti-oxidant and DPPH free radical scavenging assays. Further, the concentration dependent inhibition of synthesized Ag NPs against biofilm forming Staphylococcus aureus (S. aureus) was confirmed by minimum inhibition concentration (MIC). The growth cells were arrested in the log phase of the culture and detected by flow cytometry analysis. In addition, the bacterial viability, exopolysaccharide degradation, intracellular membrane damage, matured biofilm inhibition, architectural damage and morphological alteration were confirmed by confocal laser scanning electron microscope (CLSM) and SEM. Furthermore, the synthesized Ag NPs reacted with methylene blue (MB) dye molecules has 100% degradation at an irradiation time of 140 min. Conclusively, the eco-friendly synthesized Ag NPs has excellent anti-oxidant, anti-bacterial through intracellular membrane damage, cell cycle arrest and methylene blue dye removal.

Highly efficient multifunctional graphene/chitosan/magnetite nanocomposites for photocatalytic degradation of important dye molecules.

Multifunctional chitosan/magnetite (CS/Fe3O4) and graphene/chitosan/magnetite (Gr/CS/Fe3O4) nanocomposites (NCs) were synthesized using a simple hydrothermal method. The NCs were subsequently evaluated as magnetic photocatalysts towards the photodegradation of dye molecules that are detrimental to the environment. In the present study, sphere shaped Fe3O4 nanoparticles (NPs) were found to uniformly decorate CS and Gr surfaces. The synthesized Fe3O4 NPs, CS/Fe3O4 and Gr/CS/Fe3O4 NCs were characterized by powder X-ray diffraction, Fourier-transform infrared and Raman spectroscopy, thermogravimetric analysis, UV-visible diffuse reflectance and photoluminescence spectroscopy, and field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The Gr/CS/Fe3O4 NCs showed 100% photocatalytic efficiency against rhodamine B (40 min), bromothymol blue (60 min), methylene blue (80 min) and methyl orange (100 min) compared to Fe3O4 NPs (100 min for Rh-B, 120 min for BTB, 160 min for MB and 180 min for MO) and CS/Fe3O4 NCs (90 min for Rh-B, 100 min for BTB, 140 min for MB and 150 min for MO). The photocatalytic irradiation efficiency of Fe3O4 NPs, CS/Fe3O4 and Gr/CS/Fe3O4 NCs, evaluated against visible light, was found to be significantly higher for Rh-B (100% within 40 min) compared to the other tested dyes.

Allyl isothiocyanate encapsulated halloysite covered with polyacrylate as a potential antibacterial agent against food spoilage bacteria.

Allyl isothiocyanate (AITC) is a highly volatile organic compound that is a potential antibacterial agent against food spoilage bacteria. Naturally formed halloysite nanotubes (HNTs) have a length of 1 µm and diameter ranging from 10 to 50 nm. The biocompatibility of HNT allows safe release of drugs to bacterial cells at a relatively low concentration compared to other systems. We encapsulated AITC inside HNTs that were then coated with sodium polyacrylate (PA). The HNT-AITC-PA nanocomposites (NCs) were characterized by Fourier-transform infrared spectroscopy, thermal gravimetric, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. In vitro antibacterial activity was evaluated against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria capable of food spoilage. HNT-AITC-PA NCs effectively inhibited the growth of both bacteria. The activity was pronounced against E. coli at 100 µg/mL, with concentrations of 25 µg/mL and 200 µg/mL reducing the viable cell population by 41% and 96%, respectively. Thus, HNT-AITC-PA NCs are a novel and promising material against food spoilage bacteria for use in active antibacterial food packaging.

Biosynthesized silver nanoparticles for inhibition of antibacterial resistance and biofilm formation of methicillin-resistant coagulase negative Staphylococci.

The ability of a natural stabilizing and reducing agent on the synthesis of silver nanoparticles (Ag NPs) was explored using a rapid and single-pot biological reduction method using Nocardiopsis sp. GRG1 (KT235640) biomass. The UV-visible spectral analysis of Ag NPs was found to show a maximum absorption peak located at a wavelength position of ∼422 nm for initial conformation. The major peaks in the XRD pattern were found to be in excellent agreement with the standard values of metallic Ag NPs. No other peaks of impurity phases were observed. The morphology of Ag NPs was confirmed through TEM observation, demonstrating that the particle size distribution of Ag NPs entrenched in spherical particles is in a range between 20 and 50 nm. AFM analysis further supported the nanosized morphology of the synthesized Ag NPs and allowed quantifying the Ag NPs surface roughness. The synthesized Ag NPs showed significant antibacterial and antibiofilm activity against biofilm positive methicillin-resistant coagulase negative Staphylococci (MR-CoNS), which were isolated from urinary tract infection as determined by spectroscopic methods in the concentration range of 5-60 µg/ml. The inhibition of biofilm formation with coloring stain was morphologically imaged by confocal laser scanning microscopy (CLSM). Morphological alteration of treated bacteria was observed by SEM analysis. The results clearly indicate that these biologically synthesized Ag NPs could provide a safer alternative to conventional antibiofilm agents against uropathogen of MR-CoNS.

Graphene/nickel oxide nanocomposites against isolated ESBL producing bacteria and A549 cancer cells.

The synthesis of nickel oxide nanoparticles (NiO NPs) and graphene/nickel oxide nanocomposites (Gr/NiO NCs) was performed using a simple chemical reduction method. Powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to examine the crystalline nature and thermal stability of the synthesized NiO NPs and Gr/NiO NCs, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to observe the morphology of NiO NPs and Gr/NiO NCs and estimate their size range. TEM suggested that the NiO NPs were speared onto the surface of Gr nanosheet. The efficiency of NiO NPs and Gr/NiO NCs against extended spectrum ß-lacamase (ESBL) producing bacteria, which was confirmed by specific HEXA disc Hexa G-minus 24 (HX-096) and MIC strip methods (CLSI); namely Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) was investigated using the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) methods. MIC results suggested that the NiO NPs and Gr/NiO NCs possess maximum growth inhibition of 86%, 82% and 94%, 92% at 50 and 30 µg/mL concentrations, respectively. Similarly, both nanomaterials were found to inhibit the ß-lacamase enzyme at concentrations of 60 µg/mL and 40 µg/mL, respectively. The cytotoxicity of NiO NPs and Gr/NiO NCs was quantified against A549 human lung cancer cells. Cell death percentage values of 52% at 50 µg/mL against NiO NPs and 54% at 20 µg/mL against Gr/NiO NCs were obtained, respectively. The NCs were found to reduce cell viability, increase the level of reactive oxygen species (ROS) and modify both the mitochondrial membrane permeability and cell cycle arrest.

Anti-ESBL investigation of chitosan/silver nanocomposites against carbapenem resistant Pseudomonas aeruginosa.

In the present investigation functional chitosan/silver nanocomposites (CS/Ag NCs) were successfully synthesized and found to possess favorable antibacterial activity against extended spectrum beta-lactasame (ESBL) producing Pseudomonas aeruginosa. Powder X-ray diffraction showed that the obtained CS/Ag NCs are constituted of highly crystalline Ag nanoparticles (NPs) embedded in an amorphous CS matrix material. Transmission electron microscopy (TEM) analysis provided structural information about CS/Ag NCs, revealing the formation of spherical cluster structures constituted of Ag NPs with size ranging from 6 to 18 nm embedded in the amorphous CS matrix. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Ag NPs and CS/Ag NCs were found to inhibit the ESBL producing P. aeruginosa at 80 µg/mL (76%) and 50 µg/mL (92%), respectively. Confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM) images revealed that P. aeruginosa experienced reduced cell viability and morphological cell membrane damage at desired MIC. The in-vivo toxicity effect of Ag NPs and CS/Ag NCs suggested an increased mortality rate when Artemia franciscana were exposed for 24 h to increasing concentrations of Ag NPs and CS/Ag NCs. Anti-ESBL activity and toxicity effect of CS/Ag NCs revealed that these NCs possess promising antibacterial properties to overcome numerous communicable bacterial strains.