Green Synthesized Silver Nanoparticles Using Lactobacillus Acidophilus as an Antioxidant, Antimicrobial, and Antibiofilm Agent Against Multi-drug Resistant Enteroaggregative Escherichia Coli

Mapping a sustainable approach: biosynthesis of lactobacilli-silver nanocomposites using whey-based medium for antimicrobial and bioactivity applications

This study explores a sustainable approach for synthesizing silver nanocomposites (AgNCs) with enhanced antimicrobial and bioactivity using safe Lactobacillus strains and a whey-based medium (WBM). WBM effectively supported the growth of Lactobacillus delbrueckii and Lactobacillus acidophilus, triggering a stress response that led to AgNCs formation. The synthesized AgNCs were characterized using advanced spectroscopic and imaging techniques such as UV‒visible, Fourier transform infrared (FT-IR) spectroscopy, transmission electron (TEM), and scanning electron microscopy with energy dispersive X-ray analysis (SEM-Edx). Lb acidophilus-synthesized AgNCs in WBM (had DLS size average 817.2-974.3 ± PDI = 0.441 nm with an average of metal core size 13.32 ± 3.55 nm) exhibited significant antimicrobial activity against a broad spectrum of pathogens, including bacteria such as Escherichia coli (16.47 ± 2.19 nm), Bacillus cereus (15.31 ± 0.43 nm), Clostridium perfringens (25.95 ± 0.03 mm), Enterococcus faecalis (32.34 ± 0.07 mm), Listeria monocytogenes (23.33 ± 0.05 mm), methicillin-resistant Staphylococcus aureus (MRSA) (13.20 ± 1.76 mm), and filamentous fungi such as Aspergillus brasiliensis (33.46 ± 0.01 mm). In addition, Lb acidophilus-synthesized AgNCs in WBM exhibit remarkable free radical scavenging abilities, suggesting their potential as bioavailable antioxidants. These findings highlight the dual functionality of these biogenic AgNCs, making them promising candidates for applications in both medicine and nutrition.

Probiotic-derived silver nanoparticles target mTOR/MMP-9/BCL-2/dependent AMPK activation for hepatic cancer treatment

Recent advances in nanotechnology have offered novel ways to combat cancer. By utilizing the reducing capabilities of Lactobacillus acidophilus, silver nanoparticles (AgNPs) are synthesized. The anti-cancer properties of AgNPs have been demonstrated in previous studies against several cancer cell lines; it has been hypothesized that these compounds might inhibit AMPK/mTOR signalling and BCL-2 expression. Consequently, the current research used both in vitro and in silico approaches to study whether Lactobacillus acidophilus AgNPs could inhibit cell proliferation autophagy and promote apoptosis in HepG2 cells. The isolated strain was identified as Lactobacillus acidophilus strain RBIM based on 16 s rRNA gene analysis. Based on our research findings, it has been observed that this particular strain can generate increased quantities of AgNPs when subjected to optimal growing conditions. The presence of silanols, carboxylates, phosphonates, and siloxanes on the surface of AgNPs was confirmed using FTIR analysis. AgNPs were configured using UV-visible spectroscopy at 425 nm. In contrast, it was observed that apoptotic cells exhibited orange-coloured bodies due to cellular shrinkage and blebbing initiated by AgNP treatment, compared to non-apoptotic cells. It is worth mentioning that AgNPs exhibited remarkable selectivity in inducing cell death, specifically in HepG2 cells, unlike normal WI-38 cells. The half-maximum inhibitory concentration (IC50) values for HepG2 and WI-38 cells were 4.217 µg/ml and 154.1 µg/ml, respectively. AgNPs induce an upregulation in the synthesis of inflammation-associated cytokines, including (TNF-α and IL-33), within HepG2 cells. AgNPs co-treatment led to higher glutathione levels and activating pro-autophagic genes such as AMPK.Additionally, it resulted in the suppression of mTOR, MMP-9, BCL-2, and α-SMA gene expression. The docking experiments suggest that the binding of AgNPs to the active site of the AMPK enzyme leads to inhibiting its activity. The inhibition of AMPK ultimately results in the suppression of the mechanistic mTOR and triggers apoptosis in HepG2 cells. In conclusion, the results of our study indicate that the utilization of AgNPs may represent a viable strategy for the eradication of liver cancerous cells through the activation of apoptosis and the enhancement of immune system reactions.

Fungus-mediated synthesis of Se-BiO-CuO multimetallic nanoparticles as a potential alternative antimicrobial against ESBL-producing Escherichia coli of veterinary origin

Bacterial infections emerge as a significant contributor to mortality and morbidity worldwide. Emerging extended-spectrum β-lactamase (ESBL) Escherichia coli strains provide a greater risk of bacteremia and mortality, are increasingly resistant to antibiotics, and are a major producer of ESBLs. E. coli bacteremia-linked mastitis is one of the most common bacterial diseases in animals, which can affect the quality of the milk and damage organ functions. There is an elevated menace of treatment failure and recurrence of E. coli bacteremia necessitating the adoption of rigorous alternative treatment approaches. In this study, Se-Boil-CuO multimetallic nanoparticles (MMNPs) were synthesized as an alternate treatment from Talaromyces haitouensis extract, and their efficiency in treating ESBL E. coli was confirmed using standard antimicrobial assays. Scanning electron microscopy, UV-visible spectroscopy, and dynamic light scattering were used to validate and characterize the mycosynthesized Se-BiO-CuO MMNPs. UV-visible spectra of Se-BiO-CuO MMNPs showed absorption peak bands at 570, 376, and 290 nm, respectively. The average diameters of the amorphous-shaped Se-BiO-CuO MMNPs synthesized by T. haitouensis extract were approximately 66-80 nm, respectively. Se-BiO-CuO MMNPs (100 μg/mL) showed a maximal inhibition zone of 18.33 ± 0.57 mm against E. coli. Se-BiO-CuO MMNPs also exhibited a deleterious impact on E. coli killing kinetics, biofilm formation, swimming motility, efflux of cellular components, and membrane integrity. The hemolysis assay also confirms the biocompatibility of Se-BiO-CuO MMNPs at the minimum inhibitory concentration (MIC) range. Our findings suggest that Se-BiO-CuO MMNPs may serve as a potential substitute for ESBL E. coli bacteremia.

Fabrication and characterisation of human gut microbiome derived exopolysaccharide mediated silver nanoparticles - An in-vitro and in-vivo approach of Bio-Pm-AgNPs targeting Vibrio cholerae

Utilising bacteria to produce silver nanoparticles was highly favoured due to its ability to minimise costs and mitigate any potential negative environmental impact. Exopolysaccharides (EPS) extracted from the human gut microbe have demonstrated remarkable efficacy in combating various bacterial infections. Exopolysaccharide (EPS), a naturally occurring biomolecule found in the human gut isolate Proteus mirabilis DMTMMR-11, was characterised using analytical techniques such as Fourier transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance, 13C-nuclear magnetic resonance (NMR), and chemical composition analysis, which confirms the presence of carbohydrates (81.03 ± 0.23), proteins (4.22 ± 1.2), uronic acid (12.1 ± 0.12), and nucleic acid content (2.44 ± 0.15) in exopolysaccharide. The one factor at a time (OFAT) and response surface methodology (RSM) - central composite design (CCD) approaches were used to optimise the production of Bio-Pm-AgNPs, leading to an increase in yield of up to 1.86 g/l. The Bio-Pm-AgNPs were then subjected to Fourier transform infrared spectroscopy (FTIR) which determines the functional groups, X-ray diffractometer confers that Bio-Pm-AgNPs are crystalline in nature, field emission-scanning electron microscopy (FE-SEM) reveals the morphology of Bio-Pm-AgNPs, energy dispersive X-ray spectroscopy (EDX) confirms the presence of elements like Ag, C and O, high-resolution transmission electron microscopy (HR-TEM) determines that the Bio-Pm-AgNPs are sphere-shaped at 75 nm. Dynamic light scattering (DLS) and zeta potential analysis were also carried out to reveal the physiological nature of Bio-Pm-AgNPs. Bio-Pm-AgNPs have a promising effect on the inhibitory mechanism of Vibrio cholerae cells at a MIC concentration of 20 μg/ml which significantly affects cellular respiration and energy metabolism through glycolysis and TCA cycles by deteriorating the enzyme responsible for ATP and NADH utilisation. The action of Bio-Pm-AgNPs reduces the purity and concentration of nucleic acids, which leads to higher DNA damage. In-vivo analysis reveals that the treatment of Bio-Pm-AgNPs decreased the colonisation of V. cholerae and improved the survival rates in C. elegans.

Biological Activities of Zinc Oxide Nanoparticles Green Synthesized Using the Aqueous Extract of Dracocephalum kotschyi Boiss

BACKGROUND

Dracocephalum kotschyi Boiss. is known as a native medicinal plant of Iran.

OBJECTIVE

In this study, aqueous extract of D. kotschyi was used to synthesize ZnO-NPs. To produce ZnO-NPs, aerial parts of D. kotschyi were powdered and then macerated for obtaining aqueous extract, after that, aqueous extract was used to reduse zinc nitrate to ZnO-NPs.

METHODS

To confirm nanoparticles synthesis, SEM, TEM, UV-Vis, FTIR, and XRD were used. The synthesized ZnO-NPs were studied for antimicrobial activities by microdilution method for calculating MIC and MBC. Analysis of ZnO-NPs confirmed successful synthesis by extract of D. kotschyi.

RESULTS

The sizes of ZnO-NPs were estimated 50-200 nm in diameter. Antibacterial and antifungal experiments showed potent activities against Staphylococos aureus, Pseudomonas aeruginosa and Candida albicans. The results of the studies showed that the nanoparticles synthesized with the aqueous extract of D. kotschyi have a much greater antimicrobial effect than the aqueous extract of D. kotschyi and zinc nanoparticles, each alone (MIC values 3.7 to 7.5 mg/ml).

CONCLUSION

The noteworthy point is that the inhibitory rate of synthesized zinc oxide nanoparticles is higher compared to broad-spectrum antibiotics, such as chloramphenicol (MIC values 15 mg/ml). Determining the therapeutic and toxic dose of this product for humans requires further investigation and clinical trials.

Silver Nanoparticles Prepared Using Magnolia officinalis Are an Effective Antimicrobial Agent on Candida albicans, Escherichia coli, and Staphylococcus aureus

Silver nanoparticles (AgNPs) prepared by plants are simple, eco-friendly, and economical. In this study, Magnolia officinalis (MO) extract was applied to synthesize MO@AgNPs. Ultraviolet-visible (UV-vis) spectrum analysis indicated a peak at 440 nm. Most of the particles were spherical with sizes from 1 to approximately 60 nm based on transmission electron microscopy (TEM). X-ray diffraction (XRD) patterns showed a face-centered cubic crystal structure. The zeta value of MO@AgNPs was - 36.5 ± 0.6 mV, which was stable at 25 °C and 4 °C. Growth kinetic studies and the Kirby-Bauer diffusion method showed significant inhibitory activity on Candida albicans (ATCC 10231), Escherichia coli (ATCC BAA-2340), and Staphylococcus aureus (ATCC 25923); the minimum inhibitory concentrations (MIC) were 3, 9, and 9 μg/mL, and corresponding minimum bactericidal concentrations (MBC) were 5, 11, and 9 μg/mL, respectively. MO@AgNPs exhibited better antifungal activity compared to AgNPs prepared using sodium citrate. Further research revealed that MO@AgNPs increased the permeability of bacterial cell membranes. Moreover, the effect of MO@AgNPs on Candida albicans was significantly enhanced by blocking autophagy. The reactive oxygen species (ROS) induced by MO@AgNPs in Candida albicans was limited and may be related to its good antioxidant activity. Finally, MO@AgNPs have no significant cytotoxicity to the human liver LO2 cell line under 20 μg/mL.

Antimicrobial and Antiproliferative Activity of Green Synthesized Silver Nanoparticles Using Bee Bread Extracts

Bee bread (BB) is a fermented mixture of bee pollen, is rich in proteins, amino acids, fatty acids, polyphenols, flavonoids, as well as other bioactive compounds, and is considered functional food for humans. In this study, we explored an innovative green synthesis of colloidal silver nanoparticles, using BB extracts as reducing and stabilizing agents. A preliminary chemical characterization of the BB extracts was conducted. The plasmonic response of the as-synthesized silver nanoparticles (BB-AgNPs) was evaluated by UV-Vis spectroscopy, while their hydrodynamic diameter and zeta potential were investigated by dynamic light spectroscopy (DLS). Transmission electron microscopy (TEM) analysis pointed out polydisperse NPs with quasi-spherical shapes. The newly synthesized nanoparticles showed good antioxidant activity against the tested free radicals, DPPH, ABTS^•+, and FRAP, the best results being obtained in the case of ABTS^•+. BB-AgNPs exhibited good antibacterial activity on the tested Gram-positive and Gram-negative bacterial strains: herein S. aureus, B. cereus, E. faecalis, E. coli, P. aeruginosa, S. enteritidis, and on yeast C. albicans, respectively. The inhibition diameters varied between 7.67 ± 0.59 and 22.21 ± 1.06 mm, while the values obtained for minimum inhibitory concentration varied between 0.39 and 6.25 µg/mL. In vitro antiproliferative activity was tested on colon adenocarcinoma, ATCC HTB-37 cell line, and the results have shown that the green synthetized BB-AgNPs induced a substantial decrease in tumor cell viability in a dose-dependent manner with an IC50 ranging from 24.58 to 67.91 µg/mL. Consequently, more investigation is required to comprehend the processes of the cytotoxicity of AgNPs and develop strategies to mitigate their potentially harmful effects while harnessing their antimicrobial properties.

Catalytic and antioxidant activity of silver nanoparticles fabricated by Neolamarckia cadamba bark extract

Plant parts have unfathomable potential in the synthesis of nanoparticles. The current study was designed for the photosynthesis of silver nanoparticles (NC-AgNPs) using bark extract of N. cadamba. Different analytical methods were used to characterize the synthesized nanoparticles. HR-TEM analysis identifies the formation of multi-shaped NC-AgNPs like spherical, quasi-spherical, rod-shaped, trigonal, square, pentagonal, and hexagonal with a size range of 18-91 nm. The crystallize size of NC-AgNPs was found to be 27.6 nm. The catalytic effectiveness of NC-AgNPs in degrading Crystal violet (CV) dye is remarkable. Important parameters such as the effect of catalyst dose and pH were investigated. Dose-dependentantioxidant activity of NC-AgNPs was determined by using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay. Low-cost synthesis and eco-friendly reagents were the salient features that made NC-AgNPs more attractive toward catalytic and antioxidant activities.

Green synthesis of AgNPs using Delonix regia bark for potential catalytic and antioxidant applications

Nanoparticle synthesis from plant resources has recently gained significant impact due to its low cost, simple equipment requirements, and ease of availability. In this work, DR-AgNPs were synthesized using bark extract of Delonix regia (D. regia) plant under microwave irradiation. The formation of DR-AgNPs has been confirmed with UV-Vis, XRD, FTIR, FESEM, HRTEM, EDS, DLS, and zeta potential analysis. Catalytic and antioxidant activities were tested on synthesized spherical nanoparticles with a size range of 10-48 nm. The effects of pH and catalyst dosage on the methylene blue (MB) dye degradation were carried out. It was observed from the treatment results that 95% MB dye degradation efficiency was achieved within 4 min with a degradation rate constant of 0.772 min^-1 . The synthesized nanoparticles showed a strong antioxidant property when analyzed by a 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The calculated IC₅₀ value for DR-AgNPs was 37.1 ± 0.12 μg mL^-1 . Therefore, DR-AgNPs are excellent in both catalytic and antioxidant activities when compared to previously reported works. HIGHLIGHTS: Green synthesis of silver nanoparticles (DR-AgNPs) using Delonix regia bark extract. The catalytic activity of DR-AgNPs is remarkable against Methylene Blue. DR-AgNPs also have a strong DPPH radical antioxidant effect. Short degradation time, high degradation rate constant, and a good scavenging activity are key features of this study compared to previously reported works.

The Effect of Cytotoxicity and Antimicrobial of Synthesized CuO NPs from Propolis on HEK-293 Cells and Lactobacillus acidophilus

Background

Drug resistance is currently possible anywhere in the world. Due to the discovery of antimicrobials, medicine, and health have made tremendous advances over the past several decades.

Aim

This research evaluated the antimicrobial and cytotoxicity effects of green synthesis of copper oxide nanoparticles (CuO NPs) on Lactobacillus acidophilus and human embryonic kidney 293 cells (HEK). Method and Materials. Propolis was sampled and extracted. Green synthesis of CuO NPs was synthesized and characterized using SEM, TEM, DLS, BET, and zeta potential methods. L. acidophilus (ATCC 4356) was used, and the antimicrobial tests were carried out at different concentrations (10≥ mg/ml). Moreover, the cytotoxicity was evaluated using an MTT assay on human embryonic kidney 293 cells (HEK).

Results

Synthesized CuO NPs using propolis extracts from Khalkhal (sample 1) and Gillan (sample 2) showed -13.2 and -14.4 mV, respectively. The hydrodynamic sizes of well-dispersed samples 1 and 2 were 3124.9 nm and 1726.7 nm, respectively. According to BET analysis, samples 1 and 2 had 5.37 and 8.45 m²/g surface area, respectively. The surface area was decreased due to the addition of propolis extract, and the pore size was increased. CuO NPs of samples 1 and 2 were visible on SEM images with diameters ranging from 75 to 145 nm and 120 to 155 nm, respectively. Based on TEM analysis, the size of CuO particles was increased in samples 1 and 2. CuO NPs particles had narrow size distributions with evenly dispersed NPs on all sides. The cell viability of the CuO NPs of samples 1 and 2 after 24, 48, and 72 hours was greater than 50%. As a result of the MIC and MBC tests, it was determined that samples 1 and 2 had the same effect against L. acidophilus (0.0024 mg/ml). Biofilm formation and degradation of sample 1 were more efficient against L. acidophilus.

Conclusion

There was no evidence of cytotoxicity in the samples. In addition, results showed that the green synthesized CuO NPs from Khalkhal propolis were effective against L. acidophilus. Thus, the green synthesized CuO NPs from Khalkhal propolis were the best candidates for clinical application.

Prospects for the next generation of artificial enzymes for ensuring the quality of chilled meat: Opportunities and challenges

As living standards rise, the demand for high-quality chilled meat among consumers also grows. Researchers and enterprises have been interested in ensuring the quality of chilled meat in all links of the downstream industry. Nanozyme has shown the potential to address the aforementioned requirements. Reasons and approaches for the application of nanozymes in the freshness assessment or shelf life extension of chilled meat were discussed. The challenges for applying these nanozymes to ensure the quality of chilled meat were also summarized. Finally, this review examined the safety, regulatory status, and consumer attitudes toward nanozymes. This review revealed that the freshness assessment of chilled meat is closely related to mimicking the enzyme activities of nanozymes, whereas the shelf life changes of chilled meat are mostly dependent on the photothermal activities and pseudophotodynamic activities of nanozymes. In contrast, studies regarding the shelf life of chilled meat are more challenging to develop, as excessive heat or reactive oxygen species impair its quality. Notably, meat contains a complex matrix composition that may interact with the nanozyme, reducing its effectiveness. Nanopollution and mass manufacturing are additional obstacles that must be overcome. Therefore, it is vital to choose suitable approaches to ensure meat quality. Furthermore, the safety of nanozymes in meat applications still needs careful consideration owing to their widespread usage.

Antimicrobial Efficacy of Green Synthesized Nanosilver with Entrapped Cinnamaldehyde against Multi-Drug-Resistant Enteroaggregative Escherichia coli in Galleria mellonella

The global emergence of antimicrobial resistance (AMR) needs no emphasis. In this study, the in vitro stability, safety, and antimicrobial efficacy of nanosilver-entrapped cinnamaldehyde (AgC) against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) were investigated. Further, the in vivo antibacterial efficacy of AgC against MDR-EAEC was also assessed in Galleria mellonella larval model. In brief, UV-Vis and Fourier transform infrared (FTIR) spectroscopy confirmed effective entrapment of cinnamaldehyde with nanosilver, and the loading efficiency was estimated to be 29.50 ± 0.56%. The AgC was of crystalline form as determined by the X-ray diffractogram with a mono-dispersed spherical morphology of 9.243 ± 1.83 nm in electron microscopy. AgC exhibited a minimum inhibitory concentration (MIC) of 0.008−0.016 mg/mL and a minimum bactericidal concentration (MBC) of 0.008−0.032 mg/mL against MDR- EAEC strains. Furthermore, AgC was stable (high-end temperatures, proteases, cationic salts, pH, and host sera) and tested safe for sheep erythrocytes as well as secondary cell lines (RAW 264.7 and HEp-2) with no negative effects on the commensal gut lactobacilli. in vitro, time-kill assays revealed that MBC levels of AgC could eliminate MDR-EAEC infection in 120 min. In G. mellonella larvae, AgC (MBC values) increased survival, decreased MDR-EAEC counts (p < 0.001), had an enhanced immunomodulatory effect, and was tested safe to the host. These findings infer that entrapment enhanced the efficacy of cinnamaldehyde and AgNPs, overcoming their limitations when used individually, indicating AgC as a promising alternative antimicrobial candidate. However, further investigation in appropriate animal models is required to declare its application against MDR pathogens.