Preparation, characterization, and antibacterial activity of CoFe2O4/polyaniline/Ag nanocomposite

A facile one-pot γ-radiation formation of gum arabic-stabilized cobalt ferrite nanoparticles as an efficient magnetically retrievable heterogeneous catalyst

Currently, there is a demand for an effective solution to address toxic pollutants in aqueous environments. Consequently, creating a cost-efficient and effective catalytic system with the added benefits of easy recovery from the medium and the ability to be reused is essential. In this study, gamma (γ) radiolysis as a simple and environmentally friendly process under ambient settings was used to successfully manufacture a nanocatalyst of cobalt ferrite nanoparticles (CoFe2O4 NPs) modified gum arabic (GA) as a nontoxic, biocompatible, and inexpensive biopolymer. The prepared GA-CoFe2O4 NPs were evaluated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX) mapping, and vibrating sample magnetometer analysis. XRD analysis illustrates the formation of CoFe2O4 NPs through the appearance of the characteristic peaks. TEM analysis shows the spherical shape of CoFe2O4 NPs with an average particle size diameter ranging from 20 to 30 nm. FTIR analysis of GA-CoFe2O4 NPs confirmed both the functionalization of GA with the CoFe2O4 NPs and the appearance of the specific signal of CoFe2O4 NPs. The atomic ratio obtained from EDX analysis matches the stoichiometric ratio of cobalt ferrite. The GA-CoFe2O4 NPs exhibit an excellent magnetic response of saturation magnetization of 47.619 emu g-1. The prepared CoFe2O4NPs were then evaluated as a catalyst for the catalytic reduction of p-NP, MO dye, and a mixture of these pollutants. The results showed that CoFe2O4 NPs have high catalytic efficiency in the reduction of mono or mixed compounds. Furthermore, recycling of the CoFe2O4 NPs catalyst was also confirmed and it could be magnetically recovered and reused for at least six times with a good catalytic efficiency.

An advanced photo-oxidation process for pharmaceuticals using plasmon-assisted Ag-CoFe2O4 photocatalysts

The discharge of amoxicillin (AMX) from pharmaceutical intermediates has adverse effects on aquatic ecosystems. The elimination of AMX requires advanced oxidation processes (AOPs) that utilize high-performance photocatalysts. Furthermore, the design of highly visible light photocatalysts for AOPs demands both cost-effectiveness and efficiency. In this work, a plasmon-assisted visible light photocatalyst of 2D Ag-CoFe2O4 nanohybrids was successfully synthesized and characterized with several analytical tools to degrade AMX in aqueous solutions through advanced AOPs. The results showed that the Ag-CoFe2O4 nanohybrids had excellent photocatalytic activity and stability, which could efficiently reduce the AMX concentration by 99% within 70 min under visible light irradiation. In particular, CoFe2O4 and Ag have an interfacial contact that prevents electron-hole pair recombination more effectively than pure CoFe2O4, which results in electrons in its conduction band (CB) migrating to metallic Ag sites. Thus, charge transfers between the two materials are more efficient, leading to higher photocatalytic oxidation of AMX. Furthermore, the surface plasmon of Ag nanoparticles are excited by their plasmonic resonance, which increases the absorption of visible light. The plasmon-assisted visible light photocatalyst could replace expensive and energy-intensive advanced oxidation processes (AOPs). AOPs pathways associated with AMX have been discussed in detail. The HPLC chromatogram clearly showed AMX was oxidized by four-membered B-lactam ring opening and hydroxylation with •OH. 2D Ag-CoFe2O4 heterostructure was found to be efficient, selective, and cost-effective for the degradation of several pharmaceutical compounds. Additionally, it was found to be eco-friendly and sustainable, making it a viable alternative to AOPs.

Exploring the antibacterial potential of magnetite/Quince seed mucilage/Ag nanocomposite: Synthesis, characterization, and activity assessment

In this study, we present a novel core-shell antibacterial agent designed for water disinfection purposes. The nanocomposite is synthesized by combining quince seed mucilage (QSM) as the shell material and Fe3O4 as the core material. The integration of antibacterial silver nanoparticles (Ag NPs) onto the QSM shell effectively prevents agglomeration of the Ag NPs, resulting in a larger contact surface area with bacteria and consequently exhibiting enhanced antibacterial activity. The incorporation of magnetic Fe3O4 NPs with a saturation magnetization of 55.2 emu·g-1 as the core allows for easy retrieval of the nanocomposites from the medium using a strong magnetic field, enabling their reusability. The Fe3O4/QSM/Ag nanocomposite is extensively characterized using XRD, FT-IR, VSM, DLS, FE-SEM, and TEM techniques. The characterization results confirm the successful synthesis of the nanocomposites, with an average particle size of 73 nm and no contamination or impurities detected. The nanocomposites exhibit superparamagnetic properties, with a saturated magnetization of 22.69 emu·g-1, ensuring facile separation from water. The antibacterial activity of the synthesized nanocomposite is evaluated using the disk diffusion method against both Gram-positive and Gram-negative bacteria. The results reveal excellent antibacterial efficacy, with minimum inhibition concentrations (MIC) of 0.8 mg·mL-1 against E. coli and S. typhimurium. Furthermore, the measurement of released silver ions in water using ICP-OES indicates a low concentration of remaining silver ions in the medium, highlighting the controlled release of antimicrobial agents. Overall, this study provides valuable insights into the development of advanced antibacterial agents for water disinfection applications, offering potential solutions to combat microbial contamination effectively.

Materials for restoring lost Activity: Old drugs for new bugs

The escalation of bacterial resistance to conventional medical antibiotics is a serious concern worldwide. Improvements to current therapies are urgently needed to address this problem. The synergistic combination of antibiotics with other agents is a strategic solution to combat multi-drug-resistant bacteria. Although these combinations decrease the required high dosages and therefore, reduce the toxicity of both agents without compromising the bactericidal effect, they cannot stop the development of further resistance. Recent studies have shown certain elements restore the ability of antibiotics to destroy bacteria that have acquired resistance to them. Due to these synergistic activities, organic and inorganic molecules have been investigated with the goal of restoring antibiotics in new approaches that mitigate the risk of expanding resistance. Herein, we summarize recent studies that restore antibiotics once thought to be ineffective, but have returned to our armamentarium through innovative, combinatorial efforts. A special focus is placed on the mechanisms that allow the synergistic combinations to combat bacteria. The promising data that demonstrated restoration of antimicrobials, supports the notion to find more combinations that can combat antibiotic-resistant bacteria.

Antimicrobial and antifungal properties of NiCu-PANI/PVA quaternary nanocomposite synthesized by chemical oxidative polymerization of polyaniline

Increasing antimicrobial resistance has led to use of novel technologies such as nanomaterials and nanocomposites that have shown effective antimicrobial and/or antifungal activities against several gram-positive and gram-negative bacteria. There have been limited studies on antimicrobial properties of the combined polymer nanocomposites with transitional bimetallic nanoparticles such as nickel (Ni) and copper (Cu). Thus, the main objective of this study was to synthesis, characterize and investigate the antibacterial and antifungal properties of NiCu-PANI/PVA nanocomposite. The nanocomposite films with different amount of Ni and Cu salts were synthesized by chemical oxidative polymerization of polyaniline using HCl as oxidant and PVA as a stabilizer. Optical, chemical composition, and morphological characteristics as well as thermal stability were evaluated using UV-Visible, FTIR, SEM-EDX, and TGA analyses. Antimicrobial properties were then determined using the disc diffusion assay against gram-negative bacteria (i.e., Escherichia coli ATCC 25922, Klebsiella pneumonia ATCC 700603, Proteus sp.,) and gram-positive bacteria (i.e., Staphylococcus aureus ATCC 2593). Fungal plant pathogens including Aspergillus niger and Fusarium oxysporum f. sp. pisi were also evaluated for determination of antifungal activity of NiCu-PANI/PVA films. Among the synthesized films, Ni₆₅Cu₃₅-PANI/PVA showed excellent antibacterial activity against all the bacteria strains examined in this study. The diameters of inhibition zones for Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603, Proteus sp., and Staphylococcus aureus ATCC 2593 were 23, 23, 17, and 18 mm, respectively indicating good antibacterial activities. Additionally, NiCu-PANI/PVA, particularly the films with higher Cu intake, showed better antifungal activity against Fusarium oxysporum f. sp. pisi. However, NiCu-PANI/PVA was ineffective against Aspergillus niger.

Immobilization of GOx Enzyme on SiO2-Coated Ni-Co Ferrite Nanocomposites as Magnetic Support and Their Antimicrobial and Photocatalytic Activities

The present study used a sol-gel auto-combustion approach to make silica (SiO2)-coated Ni-Co ferrite nanocomposites that would be used as a platform for enzyme immobilization. Using glutaraldehyde as a coupling agent, glucose oxidase (GOx) was covalently immobilized on this magnetic substrate. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), and fourier transform infrared spectroscopy (FTIR) was used to determine the structural analysis and morphology of Ni-Co ferrite/SiO2 nanocomposites. FTIR spectra confirmed the binding of GOx to Ni-Co ferrite/SiO2 nanocomposites, with a loading efficiency of around 85%. At alkaline pH and higher temperature, the immobilized GOx enzyme exhibited increased catalytic activity. After 10 times of reuses, it still had 69% catalytic activity. Overall, the immobilized GOx displayed higher operational stability than the free enzyme under severe circumstances and was easily recovered by magnetic separation. With increased doping concentration of the nanocomposites, the photocatalytic activity was assessed using a degradation process in the presence of methylene blue dye under UV light irradiation, which revealed that the surface area of the nanocomposites with increased doping concentration played a significant role in improving photocatalytic activity. The antibacterial activity of Ni-Co ferrite/SiO2 nanocomposites was assessed using the agar well diffusion method against Escherichia coli, a gram-negative bacteria (ATCC 25922). Consequently, it was revealed that doping of Ni2+ and Co2+ in Fe2O4/SiO2 nanocomposites at varied concentrations improved their antibacterial properties.

Investigation on NiWO4/PANI composite as an electrode material for energy storage devices

NiWO4/PANI was synthesized by an in situ chemical oxidative polymerization route. Incorporation of NiWO4 in a PANI matrix rendered high specific capacitance and salient morphological features.

Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (B R) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The B R values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

Synthesis and potent antimicrobial activity of CoFe2O4 nanoparticles under visible light

The nanoparticles of Cobalt ferrite are synthesized using polyethylene glycol as a solvent by the solvothermal method in a surfactant-free condition. Nanoparticles that were synthesized were determined by using various techniques such as Diffuse Reflection Spectroscopy (DRS), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive X-ray spectroscopy (EDAX). The Scanning electron microscope confirmed the range of spherical nanoparticles in the size of 20–33 nm.

An excellent match was observed between the calculated particles size in the X-ray diffraction and electron microscopes results. Furthermore, their antimicrobial efficacy was determined by MIC, MBC, IC50 and disc diffusion method on Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus, Bacillus cereus) bacteria. The results indicated an acceptable bacteriostatic and bactericidal effects of this nanoparticles. Additionally, it was seen that by the increase in the concentration of nanoparticles, their antimicrobial property would increase.

Background and objective

In recent years, antibacterial materials have found a special place to avoid the overuse of antibiotics. In this study, the antibacterial effects of CoFe₂O₄ nanoparticles on Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus cereus, were investigated due to their importance as human pathogens in nosocomial infection.

Methodology

In this study, the antibacterial effects of CoFe₂O₄ nanoparticles such as MIC, MBC, IC50, and disc diffusion method were examined.

Findings

According to the results, CoFe₂O₄ nanoparticles exhibited potent antibacterial activity against the bacteria that were examined, especially Bacillus cereus. The MBC (Minimum Bactericidal Concentration) of CoFe₂O₄ nanoparticle on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus was between 0.12-0.48 mg/ml and MIC (Minimum Inhibition Concentration) on these bacteria detected between 0.06-0.24 mg/ml. The least IC50 determined for Bacillus cereus with a concentration of 0.061 mg/ml. Pseudomonas aeruginosa and Bacillus cereus identified as the most resistant and sensitive bacteria in the disc diffusion method, respectively.

Biosynthesis of Fe3O4@Ag Nanocomposite and Evaluation of Its Performance on Expression of norA and norB Efflux Pump Genes in Ciprofloxacin-Resistant Staphylococcus aureus

At present, the universal health problem with Staphylococcus aureus is the emergence of multidrug-resistant strains due to the overuse of antibiotics. Drug extrusion through efflux pumps is one of the bacterial mechanisms to neutralize the bactericidal effect of antibiotics. The antibacterial activity of silver nanoparticle as well as Fe₃O₄ nanoparticle had been previously studied and widely described. Today, the development of green methods for nanomaterial synthesis is an important aspect of research in the field of nanotechnology. Here, we report the biosynthesis and characterization of Fe₃O₄@Ag nanocomposite by Spirulina platensis cyanobacterium and it impacts on the expression of efflux pump genes in ciprofloxacin-resistant S. aureus (CRSA). The physical properties of biosynthesized nanocomposite measured and confirmed by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning and transmission electron microscopy. The minimum inhibitory concentration (MIC) of ciprofloxacin in CRSA strains was determined in the presence of Fe₃O₄@Ag nanoparticles by broth microdilution method. The effect of Fe₃O₄@Ag nanocomposite on the expression of norA and norB genes was evaluated by real-time PCR. The physical analysis confirmed well-dispersed, highly stable, and mostly spherical Fe₃O₄/Ag NPs with the average size of 30-68 nm. The results of antibacterial tests showed the synergistic effects of nanocomposite and antibiotics in MIC reduction. Additionally, in the presence of Fe₃O₄@Ag nanocomposite, the expression of norA and norB genes was decreased more than twofold compared to control. In conclusion, the Fe₃O₄/Ag nanocomposite can use as an effective inhibitor of antibiotic resistance in medicine.

Tuning the properties of cobalt ferrite: a road towards diverse applications

Cobalt ferrite nanostructures have been established to be promising material for future aspects.

Facile synthesis of water soluble silver ferrite (AgFeO2) nanoparticles and their biological application as antibacterial agents

The syntheses and antibacterial activity of AgFeO₂ and AgFO₂ modified polyethylene glycols are reported.