Effect of glutathione-stabilized silver nanoparticles on expression of las I and las R of the genes in Pseudomonas aeruginosa strains

Immunomodulatory poly(L-lactic acid) nanofibrous membranes promote diabetic wound healing by inhibiting inflammation, oxidation and bacterial infection

Background

Given the significant impact on human health, it is imperative to develop novel treatment approaches for diabetic wounds, which are prevalent and serious complications of diabetes. The diabetic wound microenvironment has a high level of reactive oxygen species (ROS) and an imbalance between proinflammatory and anti-inflammatory cells/factors, which hamper the healing of chronic wounds. This study aimed to develop poly(L-lactic acid) (PLLA) nanofibrous membranes incorporating curcumin and silver nanoparticles (AgNPs), defined as PLLA/C/Ag, for diabetic wound healing.

Methods

PLLA/C/Ag were fabricated via an air-jet spinning approach. The membranes underwent preparation and characterization through various techniques including Fourier-transform infrared spectroscopy, measurement of water contact angle, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, assessment of in vitro release of curcumin and Ag+, testing of mechanical strength, flexibility, water absorption and biodegradability. In addition, the antioxidant, antibacterial and anti-inflammatory properties of the membranes were evaluated in vitro, and the ability of the membranes to heal wounds was tested in vivo using diabetic mice.

Results

Loose hydrophilic nanofibrous membranes with uniform fibre sizes were prepared through air-jet spinning. The membranes enabled the efficient and sustained release of curcumin. More importantly, antibacterial AgNPs were successfully reduced in situ from AgNO3. The incorporation of AgNPs endowed the membrane with superior antibacterial activity, and the bioactivities of curcumin and the AgNPs gave the membrane efficient ROS scavenging and immunomodulatory effects, which protected cells from oxidative damage and reduced inflammation. Further results from animal studies indicated that the PLLA/C/Ag membranes had the most efficient wound healing properties, which were achieved by stimulating angiogenesis and collagen deposition and inhibiting inflammation.

Conclusions

In this research, we successfully fabricated PLLA/C/Ag membranes that possess properties of antioxidants, antibacterial agents and anti-inflammatory agents, which can aid in the process of wound healing. Modulating wound inflammation, these new PLLA/C/Ag membranes serve as a novel dressing to enhance the healing of diabetic wounds.

Targeting bacterial biofilm-related genes with nanoparticle-based strategies

Persistent infection caused by biofilm is an urgent in medicine that should be tackled by new alternative strategies. Low efficiency of classical treatments and antibiotic resistance are the main concerns of the persistent infection due to biofilm formation which increases the risk of morbidity and mortality. The gene expression patterns in biofilm cells differed from those in planktonic cells. One of the promising approaches against biofilms is nanoparticle (NP)-based therapy in which NPs with multiple mechanisms hinder the resistance of bacterial cells in planktonic or biofilm forms. For instance, NPs such as silver (Ag), zinc oxide (ZnO), titanium dioxide (TiO2), copper oxide (Cu), and iron oxide (Fe3O4) through the different strategies interfere with gene expression of bacteria associated with biofilm. The NPs can penetrate into the biofilm structure and affect the expression of efflux pump, quorum-sensing, and adhesion-related genes, which lead to inhibit the biofilm formation or development. Therefore, understanding and targeting of the genes and molecular basis of bacterial biofilm by NPs point to therapeutic targets that make possible control of biofilm infections. In parallel, the possible impact of NPs on the environment and their cytotoxicity should be avoided through controlled exposure and safety assessments. This study focuses on the biofilm-related genes that are potential targets for the inhibition of bacterial biofilms with highly effective NPs, especially metal or metal oxide NPs.

Antibiofilm activity of biosynthesized silver and copper nanoparticles using Streptomyces S29

Microbial resistance and biofilm formation have been considered as the main problems associated with microbial resistance. Several antimicrobial agents cannot penetrate biofilm layers and cannot eradicate microbial infection. Therefore, the aim of this study is the biological synthesis of silver and copper nanoparticles to assess their activities on bacterial attachment and on the viability of dormant cells within the biofilm matrix. Ag-NPs and Cu-NPs were biosynthesized using Streptomyces isolate S29. The biologically synthesized Ag-NPs and Cu-NPs exhibited brown and blue colors and were detected by UV/Vis spectrophotometry at 476 and 594 nm, respectively. The Ag-NPs showed an average size of 10-20 nm as indicated by TEM, and 25-35 nm for Cu-NPs. Both Ag-NPs and Cu-NPs were monodispersed with a polydispersity index of 0.1-0.546 and zeta potential were - 29.7, and - 33.7 mv, respectively. The biologically synthesized Ag-NPs and Cu-NPs significantly eliminated bacterial attachment and decreased the viable cells in the biofilm matrix as detected by using crystal violet and tri-phenyl tetrazolium chloride assays. Furthermore, Ag-NPs and Cu-NPs significantly eradicated mature biofilms developed by various Gram-negative pathogens, including A. baumannii, K. pneumoniae and P. aeruginosa standard strains and clinical isolates. Data were also confirmed at the molecular level with prominent elimination of biofilm gene expression carO, bssS and pelA in A. baumannii, K. pneumoniae and P. aeruginosa, respectively compared to untreated cells under the same conditions. As indicated, Ag-NPs and Cu-NPs could be used as adjuvant therapy in eradication of antibiotic resistance and biofilm matrix associated with Gram-negative bacterial infection.

Comparative assessment of green and chemically synthesized glutathione capped silver nanoparticles for antioxidant, mosquito larvicidal and eco-toxicological activities

A comparative assessment of AgNPs synthesized through three different routes viz. clove bud extract mediated AgNPs, sodium borohydride AgNPs and Glutathione (GSH) capped AgNPs for antioxidant and mosquito larvicidal activities was the major focus of the present study. The nanoparticles were characterized using UV-VIS spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Characterization studies revealed the synthesis of stable, crystalline AgNPs measuring 28 nm, 7 nm and 36 nm for green, chemical and GSH-capped AgNPs respectively. FTIR analysis exhibited the surface functional moieties that were responsible for reduction, capping and stabilizing AgNPs. Antioxidant activity was found to be 74.11%, 46.62% and 58.78% for clove, borohydride and GSH-capped AgNPs respectively. Mosquito larvicidal bioactivity of AgNPs against Aedes aegypti IIIrd instar larvae depicted clove AgNPs being most effective (LC₅₀-4.9 ppm, LC₉₀-30.2 ppm) followed by GSH-capped (LC₅₀-20.13 ppm, LC₉₀-46.63 ppm) and borohydride AgNPs (LC₅₀-13.43 ppm, LC₉₀-160.19 ppm) after 24 h. Toxicity screening against aquatic model Daphnia magna revealed Clove mediated and GSH-capped AgNPs to be safer as compared to the borohydride AgNPs. It may be envisaged that green and capped AgNPs may be further explored for diverse biomedical and therapeutic applications.

An investigation on glutathione derived from spinach and red cabbage leaves and their effects of adding to meat patties

Plants that produce leaves have been cultivated by humans for thousands of years because of the benefits they provide in terms of food and other necessities. Because of their high nutritional value and key phyto-components like glutathione, Leaf producing vegetables (LPVs) are being studied for their potential uses and health benefits. As a result, the focus of this study was using efficient methods for isolating and identifying glutathione from spinach and red cabbage. Glutathione was extracted using three extraction solvents: water (100%), ethanol (100%), and a combination of ethanol and water (30% and 70%, respectively) by volume (v/v), while separation was accomplished using ultrafiltration equipment. In our investigation, the best extraction solvent was a mixture of ethanol and water at a ratio of 30:70% (v/v), which extracted 951 µg/g glutathione. The antioxidant activity of plant leaf extract was measured using DPPH, with butylated hydroxytoluene serving as a comparative standard. Identification and characterization of glutathione from plant leaf extracts were revealed by thin-layer chromatography (TLC), ultraviolet-visible (UV-Vis) spectrophotometry studies, Fourier transform infrared (FTIR) spectroscopy, and high-performance liquid chromatography (HPLC). In addition, the physical and chemical properties (pH, water holding capacity, extracted liquid volume, peroxide value, free fatty acids, and thiobarbituric acid) of meat patties prepared with three different concentrations of determined glutathione were tested for susceptibility to preservation during 10 days of refrigeration at 4 ± 1 °C. The findings of the current study provide vast prospects for subsequent research to researchers and scientists that the glutathione obtained from leaf extract has no toxicity that might be applied to developed functional foods and other food formulations. Because foods containing plant-derived glutathione improve health, biological function, and food spoilage. It may be utilized as high-quality antioxidants that are safe and non-toxic. Furthermore, glutathione preserves food quality and prevents oxidation.

Investigation the effects of silver nanoparticles and gold nanoparticles on expression of bap and csu genes in biofilm formation of Acinetobacter baumannii

Background and Objectives

Acinetobacter baumannii is one of the main pathogens of the hospital and causes various infections. csu A/BABCDE involved in the initial surface attachment during biofilm formation and bap gene produces specific proteins at the cell surface that play a direct role in formation of biofilm and the infectivity of this bacterium. The aim of this study was to investigate the effect of silver nanoparticles and gold nanoparticles on the expression of bap and csu genes in the Acinetobacter baumannii biofilm formation.

Materials and Methods

The susceptibility test was performed to determine the MIC of silver nanoparticles, gold nanoparticles and gold-vancomycin nanoparticles performed by broth dilution method on A. baumannii strains. The ability of biofilms formation in strains treated by MIC of silver nanoparticles and gold-vancomycin nanoparticles were evaluated by microtiter plate method and A. baumannii ATCC19606 used as control. Expression of the csu and bap genes were determinded by measuring the cognate mRNA level by real-time PCR.

Results

In present study, gold nanoparticles could not prevent the growth and biofilm formation of A. baumannii strains. The MIC concentration of silver nanoparticles and vancomycin- gold nanoparticles were 6.25 μg/ml and 0.625 μg/ml respectively and MBC concenteration of nanoparticles for 70% of strain was 12.5 μg/ml and 1.25 μg/ml respectively. Real-time PCR and data analysis, determined that the expression of bap, csuC and csuE genes in A. baumannii strains treated with MIC concentration (6.25 μg/ml) of silver nanoparticles decreased compared to control groups. Also, the expression of csuC and csuE genes in strains treated with MIC concentration (0.625 μg/ml) of vancomycin -gold nanoparticles increased, however the expression of bap was decreased compared to the control groups.

Conclusion

Due to the inhibitory effect of silver nanoparticles and gold-vancomycin nanoparticles against A. baumannii biofilm formation and genes expression, they can probably be used for prevent of biofilm formation in medical instrument or can be use for treatment of infections with or without antibiotic.

Knocking down Pseudomonas aeruginosa virulence by oral hypoglycemic metformin nano emulsion

Long-term antibiotic treatment results in the spread of multi-drug resistance in Pseudomonas aeruginosa that complicates treatment. Anti-virulence agents can be viewed as alternative options that cripple virulence factors of the bacteria to facilitate their elimination by the host immunity. The use of nanoparticles in the inhibition of P. aeruginosa virulence factors is a promising strategy. This study aims to study the effect of metformin (MET), metformin nano emulsions (MET-NEs), silver metformin nano emulsions (Ag-MET-NEs) and silver nanoparticles (AgNPs) on P. aeruginosa virulence factors’ expression. The phenotypic results showed that MET-NEs had the highest virulence inhibitory activity. However, concerning RT-PCR results, all tested agents significantly decreased the expression of quorum sensing regulatory genes of P. aeruginosa; lasR, lasI, pqsA, fliC, exoS and pslA, with Ag-MET-NEs being the most potent one, however, it failed to protect mice from P. aeruginosa pathogenesis. MET-NEs showed the highest protective activity against pseudomonal infection in vivo. Our findings support the promising use of nano formulations particularly Ag-MET-NEs as an alternative against multidrug resistant pseudomonal infections via inhibition of virulence factors and quorum sensing gene expression.

Effect of Titanium Dioxide Nanoparticles on the Expression of Efflux Pump and Quorum-Sensing Genes in MDR Pseudomonas aeruginosa Isolates

Most of the infections caused by multi-drug resistant (MDR) P. aeruginosa strains are extremely difficult to be treated with conventional antibiotics. Biofilm formation and efflux pumps are recognized as the major antibiotic resistance mechanisms in MDR P. aeruginosa. Biofilm formation by P. aeruginosa depends mainly on the cell-to-cell communication quorum-sensing (QS) systems. Titanium dioxide nanoparticles (TDN) have been used as antimicrobial agents against several microorganisms but have not been reported as an anti-QS agent. This study aims to evaluate the impact of titanium dioxide nanoparticles (TDN) on QS and efflux pump genes expression in MDR P. aeruginosa isolates. The antimicrobial susceptibility of 25 P. aeruginosa isolates were performed by Kirby-Bauer disc diffusion. Titanium dioxide nanoparticles (TDN) were prepared by the sol gel method and characterized by different techniques (DLS, HR-TEM, XRD, and FTIR). The expression of efflux pumps in the MDR isolates was detected by the determination of MICs of different antibiotics in the presence and absence of carbonyl cyanide m-chlorophenylhydrazone (CCCP). Biofilm formation and the antibiofilm activity of TDN were determined using the tissue culture plate method. The effects of TDN on the expression of QS genes and efflux pump genes were tested using real-time polymerase chain reaction (RT-PCR). The average size of the TDNs was 64.77 nm. It was found that TDN showed a significant reduction in biofilm formation (96%) and represented superior antibacterial activity against P. aeruginosa strains in comparison to titanium dioxide powder. In addition, the use of TDN alone or in combination with antibiotics resulted in significant downregulation of the efflux pump genes (MexY, MexB, MexA) and QS-regulated genes (lasR, lasI, rhll, rhlR, pqsA, pqsR) in comparison to the untreated isolate. TDN can increase the therapeutic efficacy of traditional antibiotics by affecting efflux pump expression and quorum-sensing genes controlling biofilm production.

Anti-quorum Sensing and Anti-biofilm Activity of Zinc Oxide Nanospikes

This study evaluates the impact of two separate incubation periods (4 and 6 weeks) on the morphology of sol-gel-fabricated ZnO nanospikes (ZNs), that is, ZN1 and ZN2, respectively. We further analyzed the inhibitory effects of ZN1 and ZN2 on quorum sensing (QS) and biofilm formation in Pseudomonas aeruginosa (PAO1) and Chromobacterium violaceum (strains 12472 and CVO26). The size of the synthesized ZNs was in the range of 40-130 nm, and finer nanoparticles were synthesized after an incubation period of 6 weeks. Treatment with ZNs decreased the production of violacein in the pathogen without affecting the bacterial growth, which indicated that ZNs inhibited the QS signaling regulated by N-acyl homoserine lactone. ZN2 had a higher inhibitory action on the virulence factor productivity than ZN1. Furthermore, ZN2-treated cells displayed a substantial decrease in azocasein-degrading protease activity (80%), elastase activity (83%), and pyocyanin production (85%) relative to untreated P. aeruginosa PAO1 cells. Treatment with ZN2 decreased swarming motility and exopolysaccharide production by 89 and 85%, respectively. ZN2 was effective against both the las & pqs systems of P. aeruginosa and exhibited broad-spectrum activity. Additionally, ZN2 was more efficient in inhibiting the biofilm formation at the attachment stage than ZN1. These findings revealed that in P. aeruginosa, ZN2 demonstrated inhibitory effects on QS as well as on the development of biofilms. Thus, ZN2 can be potentially used to treat drug-resistant P. aeruginosa infections.