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

Apoptosis induction in colon cancer cells (SW480) by BiFe2O4@Ag nanocomposite synthesized from Chlorella vulgaris extract and evaluation the expression of CASP8, BAX and BCL2 genes

BACKGROUND

The use of nanomaterials in cancer diagnosis and treatment has received considerable interest. Preparation of nanoscale complex molecules could be considered to improve the efficacy and minimize toxicity of the product. This work aimed to biosynthesize BiFe2O4@Ag nanocomposite using the Chlorella vulgaris extract and its cytotoxic effect on colon cancer cell line.

METHODS

The physicochemical properties of the bioengineered BiFe2O4 @Ag were investigated by Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), Zeta potential, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDX), Vibrating-sample Magnetometer (VSM) and X-ray Diffraction Analysis (XRD). The cytotoxic potential of BiFe2O4 @Ag was evaluated by MTT assay against SW480 colon cancer cell line. The expression levels of apoptotic genes including BAX, BCL2 and CASP8 were determined by Real-time PCR. The rate of apoptosis and necrosis of the cancer cells as well as the cell cycle analysis were evaluated by flow cytometry.

RESULTS

Physicochemical assays indicated the nanoscale synthesis (10-70 nm) and functionalization of BiFe2O4 nanoparticles by Ag atoms. The VSM analysis revealed the magnetism of BiFe2O4 @Ag nanocomposite. According to the MTT assay, colon cancer cells (SW480) were considerably more sensitive to BiFe2O4 @Ag nanocomposite than normal cells. Apoptotic cell percentage increased from 1.93% to 73.66%, after exposure to the nanocomposite. Cell cycle analysis confirmed an increase in the number of the cells in subG1 and G0/G1 phases among nanocomposite treated cells. Moreover, treating the colon cancer cells with BiFe2O4 @Ag caused an increase in the expression of CASP8, BAX, and BCL2 genes by 3.1, 2.6, and 1.2 folds, respectively. Moreover, activity of Caspase-3 protein increased by 2.4 folds and apoptotic morphological changes appeared which confirms that exposure to the nanocomposite induces extrinsic pathway of apoptosis in colon cancer cells.

CONCLUSION

The considerable anticancer potential of the synthesized BiFe2O4 @Ag nanocomposite seems to be related to the induction of oxidative stress which leads to inhibit cell cycle progression and cell proliferation. This study reveals that the BiFe2O4 @Ag is a potent compound to be used in biomedical fields.

Apoptosis Induction by ZnFe2O4-Ag Biosynthesized by Chlorella vulgaris in MCF-7 Breast Cancer Cell Line

The incidence and mortality of breast cancer are growing which indicates the inefficiency of the current chemotherapy drugs. Due to the anticancer potential of Zn and Ag and the magnetic feature of iron oxide, in this work, we synthesized ZnFe2O4-Ag nanocomposite using Chlorella vulgaris and investigated its anticancer effect on breast cancer cell line. Physicochemical characterization was performed by FT-IR, XRD, SEM, TEM, VSM, EDS mapping, UV, and zeta potential assays. Cell cytotoxicity and apoptosis frequency were studied by the MTT and flow cytometry assays. Also, cell cycle analysis, Hoechst staining, and measuring ROS (reactive oxygen species) level were performed. The synthesized particles were almost spherical with a size range of 14-52 nm. The FT-IR and XRD assays confirmed the proper synthesis of the particles and VSM analysis showed that particles had magnetic property and the maximum saturation magnetization was 0.8 Emu/g. Also, the EDS mapping of the nanocomposite showed the Zn, Fe, O, and Ag elements. The MTT assay showed that the 50% inhibitory concentration (IC50) of ZnFe2O4-Ag for breast cancer and normal cells were 28 and 154 µg/mL, respectively, and the nanocomposite had stronger anticancer activity than cisplatin (IC50 = 84 µg/mL). Flow cytometry analysis showed that the exposure to the nanocomposite induced cell apoptosis by 77.5% and significantly induced ROS generation. Also, treating breast cancer cells with the nanocomposite induced cell cycle arrest and apoptotic features, including chromatin condensation and fragmentation. In conclusion, ZnFe2O4-Ag nanocomposite synthesized by C. vulgaris could suppress the proliferation of breast cancer cells by the generation of oxidative stress, apoptosis induction, and cell cycle arrest.

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.

Algal Extracts for Green Synthesis of Zinc Oxide Nanoparticles: Promising Approach for Algae Bioremediation

Zinc oxide nanoparticles (ZnO-NPs) possess unique properties, making them a popular material across various industries. However, traditional methods of synthesizing ZnO-NPs are associated with environmental and health risks due to the use of harmful chemicals. As a result, the development of eco-friendly manufacturing practices, such as green-synthesis methodologies, has gained momentum. Green synthesis of ZnO-NPs using biological substrates offers several advantages over conventional approaches, such as cost-effectiveness, simplicity of scaling up, and reduced environmental impact. While both dried dead and living biomasses can be used for synthesis, the extracellular mode is more commonly employed. Although several biological substrates have been successfully utilized for the green production of ZnO-NPs, large-scale production remains challenging due to the complexity of biological extracts. In addition, ZnO-NPs have significant potential for photocatalysis and adsorption in the remediation of industrial effluents. The ease of use, efficacy, quick oxidation, cost-effectiveness, and reduced synthesis of harmful byproducts make them a promising tool in this field. This review aims to describe the different biological substrate sources and technologies used in the green synthesis of ZnO-NPs and their impact on properties. Traditional synthesis methods using harmful chemicals limit their clinical field of use. However, the emergence of algae as a promising substrate for creating safe, biocompatible, non-toxic, economic, and ecological synthesis techniques is gaining momentum. Future research is required to explore the potential of other algae species for biogenic synthesis. Moreover, this review focuses on how green synthesis of ZnO-NPs using biological substrates offers a viable alternative to traditional methods. Moreover, the use of these nanoparticles for industrial-effluent remediation is a promising field for future research.

The Major Facilitator Superfamily and Antimicrobial Resistance Efflux Pumps of the ESKAPEE Pathogen Staphylococcus aureus

The ESKAPEE bacterial pathogen Staphylococcus aureus has posed a serious public health concern for centuries. Throughout its evolutionary course, S. aureus has developed strains with resistance to antimicrobial agents. The bacterial pathogen has acquired multidrug resistance, causing, in many cases, untreatable infectious diseases and raising serious public safety and healthcare concerns. Amongst the various mechanisms for antimicrobial resistance, integral membrane proteins that serve as secondary active transporters from the major facilitator superfamily constitute a chief system of multidrug resistance. These MFS transporters actively export structurally different antimicrobial agents from the cells of S. aureus. This review article discusses the S. aureus-specific MFS multidrug efflux pump systems from a molecular mechanistic perspective, paying particular attention to structure-function relationships, modulation of antimicrobial resistance mediated by MFS drug efflux pumps, and direction for future investigation.

Anti-inflammatory effect, antibiotic potentiating activity against multidrug-resistant strains of Escherichia coli and Staphylococcus aureus, and evaluation of antibiotic resistance mechanisms by the ibuprofen derivative methyl 2-(-4-isobutylphenyl)propanoate

The prevalence of multidrug-resistant (MDR) bacteria and the limited efficacy of current available antibiotics cause every year approximately 700 000 deaths per year. This study aimed to evaluate the anti-inflammatory effect and antibacterial potential of the ibuprofen derivative Methyl 2-(-4-isobutylphenyl)propanoate (MET-IBU). The molecular structure of MET-IBU was confirmed by Nuclear Magnetic Resonance (NMR) and, Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) spectroscopy. Our in vivo study using adult zebrafish model demonstrated that the ibuprofen derivative MET-IBU also possesses anti-inflammatory effect, and in vitro antibacterial activity assays showed that in the association of ampicillin, norfloxacin, and gentamicin with MET-IBU occurred reduction in the minimum inhibitory concentration (MIC) for MDR bacterial strains of Escherichia coli 06 and Staphylococcus aureus 10, indicating a potentiating in the growth inhibition of these pathogenic bacteria. Regarding the strain of Staphylococcus aureus K2068 (overexpressing mepA gene), a potentiation of ethidium bromide was found in the association with MET-IBU, indicating the action of this compound on the efflux pump mechanism present in this strains. This result corroborates the molecular docking study that indicated a high affinity of the MET-IBU with the MepA efflux pump. It was also noticed an antibiotic potentiating activity in the association MET-IBU with norfloxacin against strains of Staphylococcus aureus 1199B (overexpressing norA gene) when compared to the norfloxacin control. This enhanced antibiotic effect of MET-IBU is associated with a second resistance mechanism, which is due to the modification in the topoisomerase enzyme. These results bring attention to the ibuprofen derivative MET-IBU as possible candidate for the development of new options for the treatment of bacterial infections with protective anti-inflammatory action.

Synergetic Antimicrobial Effect of Silver Nanoparticles Conjugated with Iprodione against Valsa mali

Apple tree canker induced by Valsamali is a vital disease in apple production around the world, and it highlyimpacts the development of apple industry. It is of great significance to study the inhibition effect of common fungicides and develop new fungistats for comprehensive control of apple tree canker. In this experiment, the inhibition activity of five fungicides, including mancozeb, metalaxyl, iprodione, prochloraz, and difenoconazole along with biosynthesized nanosilver against V. mali, were measured with the mycelium growth rate and agar well diffusion methods. The results showed that iprodione exhibited the best inhibitory effect, the median inhibition concentration (IC₅₀) of iprodione and nanosilver was 0.62 μg.mL⁻¹ and 45.50 μg.mL⁻¹, the suppression rate achieved 67.93% at 200 μg.mL⁻¹ of nanosilver. Moreover, a remarkable additive and synergistic antimicrobial effect was verified when silver nanoparticles were conjugated with iprodione at 9:1, 8:2, 7:3, and 6:4 (v/v), and the toxicity ratio was 1.04, 1.13, 1.01, and 0.98, respectively. It is proven that biosynthesized silver nanoparticles could effectively inhibit Valsamali, and it is possible to develop and screen silver nanoparticle-based nano pesticides to manage plant diseases synthetically.

Nano delivery systems to the rescue of ciprofloxacin against resistant bacteria "E. coli; P. aeruginosa; Saureus; and MRSA" and their infections

Ciprofloxacin (CIP) a broad-spectrum antibiotic, is used extensively for the treatment of diverse infections and diseases of bacteria origin, and this includes infections caused by E. coli; P. aeruginosa; S. aureus; and MRSA. This extensive use of CIP has therefore led to an increase in resistance by these infection causing organisms. Nano delivery systems has recently proven to be a possible solution to resistance to these organisms. They have been applied as a strategy to improve the target specificity of CIP against infections and diseases caused by these organisms, thereby maximising the efficacy of CIP to overcome the resistance. Herein, we proffer a brief overview of the mechanisms of resistance; the causes of resistance; and the various approaches employed to overcome this resistance. The review then proceeds to critically evaluate various nano delivery systems including inorganic based nanoparticles; lipid-based nanoparticles; capsules, dendrimers, hydrogels, micelles, and polymeric nanoparticles; and others; that have been applied for the delivery of CIP against E. coli; P. aeruginosa; S. aureus; and MRSA infections. Finally, the review highlights future areas of research, for the optimisation of various nano delivery systems, to maximise the therapeutic efficacy of CIP against these organisms. This review confirms the potential of nano delivery systems, for addressing the challenges of resistance to caused by E. coli; P. aeruginosa; S. aureus; and MRSA to CIP.

Improved Antibacterial Activity of Water-Soluble Nanoformulated Kaempferol and Combretastatin Polyphenolic Compounds

Kaempferol and combretastatin are polyphenolic compounds derived from plant sources which are known for their antibacterial activity. However, owing to their large size and water insolubility, their antibacterial activity is limited. In this context, the present study focused on the nanoformulation of kaempferol (NF-k) and combretastatin (NF-c) and their influence on water solubility and antibacterial properties. The NF-k and NF-c were prepared using the solvent evaporation method and were thoroughly characterized for evaluating the morphology, molecular vibrations, size, etc. Based on the results, it is observed that the pristine forms of kaempferol and combretastatin drugs get nanoformulated and completely soluble in water. Using particle size analyzer, the particle sizes of NF-k and NF-c were estimated as 334 nm and 260 nm, respectively, which are very fine compared to pristine kaempferol and combretastatin (5193 nm and 1217 nm, respectively). The molecular vibrations that exist in NF-k and NF-c were confirmed by the Fourier transform infrared spectra, where the nanoformulated drug showed lower intensities than the pristine form of kaempferol and combretastatin. The drug release kinetics of the nanoformulated drugs were carried out using the dialysis membrane method and were compared with their pristine forms. Owing to the size effect, the NF-k and NF-c release up to 50% of the drug in a sustained manner till 50 h showing twofold higher concentration than the control where it released 25%. The antibacterial activity was assessed by measuring the optical density at 600 nm using UV-vis spectrophotometer and displayed significant activity against gram-positive Staphylococcus aureus strain. The mechanisms behind the antibacterial activity of NF-k and NF-c were discussed in detail. The activation of ATP-dependent efflux pump system and the blockage of porin channels could be the cause for the bactericidal activity. Our understanding of efflux pumps and their role in antibacterial activity is still in its early stages. No studies have been performed to date using nanoformulations of kaempferol and combretastatin to investigate their roles. This complicates the determination of the exact mechanisms acting against bacterial growth when using nanoformulation drugs. Our increasing knowledge of water-soluble nanoformulation drugs and their roles in reduced bacterial activity will pave the way to developing effective treatments in the future.

Gelatin Loaded Titanium Dioxide and Silver Oxide Nanoparticles: Implication for Skin Tissue Regeneration

Treatment of burn wounds has many requirements to ensure wound closure with healthy tissue, increased vascularization, guarantee edema resolution, and control bacterial infection. We propose that titanium oxide (TiO₂) nanoparticles (NPs) will be more efficient than silver dioxide (Ag₂O) in the treatment of burn wounds. Herein, gelatin loaded NPs (GLT-NPs) were evaluated for their efficacy to regenerate second-degree burn wound in rabbit skin. TEM results revealed that the average particle sizes were ⁓ 7.5 and 17 nm for Ag₂O and TiO₂ NPs, respectively. The results of the in vivo application of GLT-NPs on burn wound in the rabbit revealed that both Ag₂O and TiO₂ NPs were efficient than the control none treated (CTRL) and GLT group. In terms of the healing rate, the GLT-TiO₂ did not show any significant difference than GLT-Ag₂O (99.57% vs. 99.85%, p = 0.2). Meanwhile, the healing rate was significantly higher in both NPs' treated groups than CTRL (94.16%, p < 0.01) and GLT group (95.07%, p < 0.05). Also, the histological analysis using H&E staining showed re-epithelization, less edema, and enhanced vascularization in both GLT-NPs than CTRL and GLT groups. Furthermore, immunohistochemical analysis of TGF-β1 and α-SMA revealed significantly a higher expression in both GLT-NPs groups than CTRL and GLT groups at weeks 1 and 2 (p < 0.05). Interestingly, TGF-β1 and α-SMA were substantially higher in GLT- TiO₂ than GLT-Ag₂O at weeks 1 and 2 (p < 0.05), but the expression was not significant at week 3. In conclusion, GLT-NPs showed higher regenerative capacity and enhanced the healing quality after burn wound compared to CTRL and GLT. Graphical abstract.

Anti-cancer & anti-metastasis properties of bioorganic-capped silver nanoparticles fabricated from Juniperus chinensis extract against lung cancer cells

The current study evaluated the anti-cancer properties of bio-functionalized silver nanoparticles fabricated by Juniperus chinensis leaf extracts. The nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, UV–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, dynamic light scattering, Zeta potential and X-ray spectroscopy. Further, this study elucidated the cellular and molecular mechanisms of nanoparticles for anti-proliferative and apoptotic effects on human lung cancer cells (A549) and compared them with commercial drug cisplatin. The size of the spherical nanoparticle was 12.96 nm with negative zeta potential. Up-regulation of caspase 3,9 and p53, Annexin V-FITC/PI, DAPI staining, and ROS production indicated the remarkable apoptotic effect of AgNPs compared to cisplatin. Moreover, down-regulation of MMP2/MMP9 scratch and matrigel assays revealed anti-metastatic properties of AgNPs. Cell cycle analysis and downregulation of cyclin D1 indicated cancer cell cessation in the G0/G1 phase. Overall, the results revealed that the green-synthetized AgNPs had anti-metastasis and anti-proliferation effects on lung cancer cells in comparison to cisplatin with lower side effects on the normal cell line.

Iron Oxide Nanoparticles Combined with Cytosine Arabinoside Show Anti-Leukemia Stem Cell Effects on Acute Myeloid Leukemia by Regulating Reactive Oxygen Species

BACKGROUND AND AIM

Acute myeloid leukemia (AML), initiated and maintained by leukemia stem cells (LSCs), is often relapsed or refractory to therapy. The present study aimed at assessing the effects of nanozyme-like Fe3O4 nanoparticles (IONPs) combined with cytosine arabinoside (Ara-C) on LSCs in vitro and in vivo.

METHODS

The CD34+CD38-LSCs, isolated from human AML cell line KG1a by a magnetic activated cell sorting method, were treated with Ara-C, IONPs, and Ara-C+ IONPs respectively in vitro. The cellular proliferation, apoptosis, reactive oxygen species (ROS), and the related molecular expression levels in LSCs were analyzed using flow cytometry, RT-qPCR, and Western blot. The nonobese diabetic/severe combined immune deficiency mice were transplanted with LSCs or non-LSCs via tail vein, and then the mice were treated with Ara-C, IONPs and IONPs plus Ara-C, respectively. The therapeutic effects on the AML bearing mice were further evaluated.

RESULTS

LSCs indicated stronger cellular proliferation, more clone formation, and more robust resistance to Ara-C than non-LSCs. Compared with LSCs treated with Ara-C alone, LSCs treated with IONPs plus Ara-C showed a significant increase in apoptosis and ROS levels that might be regulated by nanozyme-like IONPs via improving the expression of pro-oxidation molecule gp91-phox but decreasing the expression of antioxidation molecule superoxide dismutase 1. The in vivo results suggested that, compared with the AML bearing mice treated with Ara-C alone, the mice treated with IONPs plus Ara-C markedly reduced the abnormal leukocyte numbers in peripheral blood and bone marrow and significantly extended the survival of AML bearing mice.

CONCLUSION

IONPs combined with Ara-C showed the effectiveness on reducing AML burden in the mice engrafted with LSCs and extending mouse survival by increasing LSC's ROS level to induce LSC apoptosis. Our findings suggest that targeting LSCs could control the AML relapse by using IONPs plus Ara-C.

Transcriptome analysis of Escherichia coli K1 after therapy with hesperidin conjugated with silver nanoparticles

Backgrounds

Escherichia coli K1 causes neonatal meningitis. Transcriptome studies are indispensable to comprehend the pathology and biology of these bacteria. Recently, we showed that nanoparticles loaded with Hesperidin are potential novel antibacterial agents against E. coli K1. Here, bacteria were treated with and without Hesperidin conjugated with silver nanoparticles, and silver alone, and 50% minimum inhibitory concentration was determined. Differential gene expression analysis using RNA-seq, was performed using Degust software and a set of genes involved in cell stress response and metabolism were selected for the study.

Results

50% minimum inhibitory concentration with silver-conjugated Hesperidin was achieved with 0.5 μg/ml of Hesperidin conjugated with silver nanoparticles at 1 h. Differential genetic analysis revealed the expression of 122 genes (≥ 2-log FC, P< 0.01) in both E. coli K1 treated with Hesperidin conjugated silver nanoparticles and E. coli K1 treated with silver alone, compared to untreated E. coli K1. Of note, the expression levels of cation efflux genes (cusA and copA) and translocation of ions, across the membrane genes (rsxB) were found to increase 2.6, 3.1, and 3.3- log FC, respectively. Significant regulation was observed for metabolic genes and several genes involved in the coordination of flagella.

Conclusions

The antibacterial mechanism of nanoparticles maybe due to disruption of the cell membrane, oxidative stress, and metabolism in E. coli K1. Further studies will lead to a better understanding of the genetic mechanisms underlying treatment with nanoparticles and identification of much needed novel antimicrobial drug candidates.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02097-2.

Green Synthesis of Metallic Nanoparticles and Their Prospective Biotechnological Applications: an Overview

The green synthesis of nanoparticles (NPs) using living cells is a promising and novelty tool in bionanotechnology. Chemical and physical methods are used to synthesize NPs; however, biological methods are preferred due to its eco-friendly, clean, safe, cost-effective, easy, and effective sources for high productivity and purity. High pressure or temperature is not required for the green synthesis of NPs, and the use of toxic and hazardous substances and the addition of external reducing, stabilizing, or capping agents are avoided. Intra- or extracellular biosynthesis of NPs can be achieved by numerous biological entities including bacteria, fungi, yeast, algae, actinomycetes, and plant extracts. Recently, numerous methods are used to increase the productivity of nanoparticles with variable size, shape, and stability. The different mechanical, optical, magnetic, and chemical properties of NPs have been related to their shape, size, surface charge, and surface area. Detection and characterization of biosynthesized NPs are conducted using different techniques such as UV-vis spectroscopy, FT-IR, TEM, SEM, AFM, DLS, XRD, zeta potential analyses, etc. NPs synthesized by the green approach can be incorporated into different biotechnological fields as antimicrobial, antitumor, and antioxidant agents; as a control for phytopathogens; and as bioremediative factors, and they are also used in the food and textile industries, in smart agriculture, and in wastewater treatment. This review will address biological entities that can be used for the green synthesis of NPs and their prospects for biotechnological applications.

Green Synthesis of CuFe2O4@Ag Nanocomposite Using the Chlorella vulgaris and Evaluation of its Effect on the Expression of norA Efflux Pump Gene Among Staphylococcus aureus Strains

Increasing drug resistance among Staphylococcus aureus is a global health threat and finding alternative antimicrobial agents against it has been considered. Multidrug resistance efflux pumps, including NorA, are involved with resistance to different drugs, especially fluoroquinolones, in S. aureus. Using metal nanoparticles against pathogenic bacteria is a promising approach; however, physio-chemical synthesis of nanoparticles has limitations. Biosynthesis of metal nanoparticles with antibacterial activity has gained interest, recently. In this study, biosynthesis of CuFe₂O₄@Ag nanocomposite using aqueous extract from microalgae Chlorella vulgaris was performed, and its antibacterial property and effect on expression of norA efflux pump gene were investigated. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive X-ray mapping analysis (EDX-map), differential reflectance spectroscopy (DRS), and dynamic light scattering (DLS) were used to characterize synthesized nanocomposite. Antibacterial activity of the prepared nanocomposite individually and combined with ciprofloxacin against S. aureus strains was evaluated using the disk assay method, and minimum inhibitory concentration (MIC) of each agent was determined using the broth dilution method. Anti-biofilm activity of this nanocomposite was checked. Finally, the effect of CuFe₂O₄@Ag nanocomposite alone and in combination with ciprofloxacin on the expression of norA was assessed by real-time PCR. The physical analysis revealed proper synthesis of spherical and well-dispersed CuFe₂O₄@Ag nanocomposite with an average diameter of 20 nm. Synthesized nanocomposite had synergistic antibacterial activity with ciprofloxacin. Moreover, expression of norA gene among clinical and standard strains treated with CuFe₂O₄@Ag nanocomposite combined with ciprofloxacin reduced by 59% and 65%, respectively. Thus, CuFe₂O₄@Ag nanocomposite synthesized in this study can be considered as a promising candidate to be used to inhibit staphylococcal efflux pump genes and increasing the antibiotic efficacy.

Beneficial Effect of TaON-Ag Nanocomposite Titanium on Antibacterial Capacity in Orthopedic Application

Purpose

In this study, a novel oxygenated nanocomposite thin film, TaON-Ag, was investigated in vitro and in vivo to evaluate its biocompatibility and antibacterial ability.

Material and Methods

The antibacterial ability of TaON-Ag nanocomposite-coated titanium (Ti) was evaluated using the Kirby-Bauer disk diffusion susceptibility test. The effects of TaON-Ag nanocomposite-coated metal on osteogenesis were further evaluated in an in vitro osteogenic culture model with rat marrow-derived mesenchymal stem cells (rMSCs). Furthermore, titanium rods coated with TaON-Ag were implanted into a rat femur fracture model either with or without osteomyelitis to investigate the effects of TaON-Ag in osteogenesis.

Results

The TaON-Ag-coated Ti exhibited an effective antibacterial effect against Staphylococcus aureus, coagulase-negative Staphylococcus, and the Gram-negative strains Escherichia coli and Pseudomonas aeruginosa. Using an osteogenic culture with rMSCs and a rat femoral fracture model, the TaON-Ag-coated Ti did not interfere with the ossification of rMSCs in vitro or during fracture healing in vivo. Field-emission scanning electron microscopy (FE-SEM) revealed that coating with TaON-Ag could inhibit pathogen adhesion and biofilm formation in both Staphylococcus aureus and Escherichia coli.

Conclusion

Using the proposed novel oxygenation process, TaON-Ag nanocomposite-coated Ti yielded robust biocompatibility and antibacterial ability against common microorganisms in orthopedic infections, thereby demonstrating potential for use in clinical applications.

Biosynthesis of NiFe2 O4 @Ag Nanocomposite and Assessment of Its Effect on Expression of norA Gene in Staphylococcus aureus

Activity of norA efflux pump has been known as a resistance mechanism to antibiotics like ciprofloxacin in Staphylococcus aureus. This study was carried out to assess the effect of biosynthesized NiFe₂ O₄ @Ag nanocomposite on expression of norA gene in Staphylococcus aureus. In this experimental study, 30 clinical samples were collected from patients hospitalized at different hospitals in Guilan Province, Iran. Then, clinical isolates of S. aureus were identified by standard microbiological tests. Antimicrobial susceptibility tests of clinical and standard strains of S. aureus were done by disk diffusion method according to CLSI guideline. Fourier transform infrared spectroscopy (FT-IR) was used to analyze the various functional groups present in the biosynthesized NiFe₂ O₄ @Ag nanocomposite. This analysis confirmed the formation of alga proteins coated on magnetite nanocomposite. X-ray diffraction (XRD) verified the crystalline structure of NiFe₂ O₄ @Ag and the deposition of silver on the surface of NiFe₂ O₄ . Energy dispersive X-ray mapping (EDX-map) analysis confirmed the existence of Ag, Ni, Fe and O in the final product. Scanning electron microscopy (SEM) confirmed that the nanocomposites were spherical in shape and Transmission electron microscopy (TEM) results revealed that the NiFe₂ O₄ @Ag had the particle size about 100 nm. Antibacterial activity of NiFe₂ O₄ @Ag alone and combined with ciprofloxacin was evaluated using the disk assay method, and minimum inhibitory concentration (MIC) by broth dilution method. Afterwards, the expression of norA efflux pump gene with and without of NiFe₂ O₄ @Ag nanocomposite and ciprofloxacin was evaluated by Real-Time PCR. Real-Time PCR results demonstrated that the expression of norA gene in the strains exposed to both NiFe₂ O₄ @Ag nanocomposite (1/4 MIC) and ciprofloxacin (1/8 MIC) significantly reduced in comparison to untreated strains. This study reveals that, when NiFe₂ O₄ @Ag nanocomposite is combined with ciprofloxacin, the inhibitory effect of ciprofloxacin increases against growth of S. aureus. Therefore, NiFe₂ O₄ @Ag nanocomposite can be considered as an effective factor to decrease the growth of S. aureus along with ciprofloxacin.