Antimicrobial Activity of Biosynthesized Silver Nanoparticles Decorated Silica Nanoparticles

Antibacterial Potential of Biosynthesized Silver Nanoparticles Using Berberine Extract Against Multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa

The emergence of multidrug resistance in bacterial infections has limited the use of antibiotics. Helping the action of antibiotics is one of the needs of the day. Today, the biosynthesis of nanoparticles (NPs) is considered due to its safety and cost-effectiveness. In this study, we investigated the effect of biosynthesized silver nanoparticles (AgNPs) by Berberine plant extract against standard strains of multidrug-resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa. Utilized UV-Vis, FTIR, FESEM/EDX, XRD, DLS, and Zeta potential techniques to confirm the biosynthesis of NPs. Then, disk diffusion agar (DDA) and minimum inhibitory concentration (MIC) tests were performed using common classes of standard antibiotics and AgNPs on the mentioned bacteria. The synergistic action between AgNPs and antibiotics was evaluated by the checkerboard method. First, we obtained the confirmation results of the biosynthesis of AgNPs. According to the DDA test, both standard bacterial strains were sensitive to NPs and had an inhibition zone. Also, the MIC values showed that AgNPs inhibit the growth of bacteria at lower concentrations than antibiotics. On the other hand, the results obtained from checkerboard monitoring showed that AgNPs, in combination with conventional antibiotics, have a synergistic effect. The advantage of this study was comparing the antibacterial effect of AgNPs alone and mixed with antibiotics. The antibacterial sensitivity tests indicated that the desired bacterial strains could not grow even in low concentrations of AgNPs. This property can be applied in future programs to solve the drug resistance of microorganisms in bacterial diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01136-y.

Nanotechnology for controlling mango malformation: a promising approach

Mango (Mangifera indica L.) is one of the most important fruit crops in the world with yields of approximately 40 million tons annually and its production continues to decrease every year as a result of the attack of certain pathogens i.e. Colletotrichum gloeosporioides, Erythricium salmonicolor, Amritodus atkinsoni, Idioscopus clypealis, Idioscopus nitidulus, Bactrocera obliqua, Bactrocera frauenfeldi, Xanthomonas campestris, and Fusarium mangiferae. So F. mangiferae is the most harmful pathogen that causes mango malformation disease in mango which decreases its 90% yield. Nanotechnology is an eco-friendly and has a promising effect over traditional methods to cure fungal diseases. Different nanoparticles possess antifungal potential in terms of controlling the fungal diseases in plants but applications of nanotechnology in plant disease managements is minimal. The main focus of this review is to highlight the previous and current strategies to control mango malformation and highlights the promising applications of nanomaterials in combating mango malformation. Hence, the present review aims to provide brief information on the disease and effective management strategies.Communicated by Ramaswamy H. Sarma.

Multifaceted Assessment of Porous Silica Nanocomposites: Unraveling Physical, Structural, and Biological Transformations Induced by Microwave Field Modification

In response to the persistent challenge of heavy and noble metal environmental contamination, our research explores a new idea to capture silver through porous spherical silica nanostructures. The aim was realized using microwave radiation at varying power (P = 150 or 800 W) and exposure times (t = 60 or 150 s). It led to the development of a silica surface with enhanced metal-capture capacity. The microwave-assisted silica surface modification influences the notable changes within the carrier but also enforces the crystallization process of silver nanoparticles with different morphology, structure, and chemical composition. Microwave treatment can also stimulate the formation of core-shell bioactive Ag/Ag2CO3 heterojunctions. Due to the silver nanoparticles' sphericity and silver carbonate's presence, the modified nanocomposites exhibited heightened toxicity against common microorganisms, such as E. coli and S. epidermidis. Toxicological assessments, including minimum inhibitory concentration (MIC) and half-maximal inhibitory concentration (IC50) determinations, underscored the efficacy of the nanocomposites. This research represents a significant stride in addressing pollution challenges. It shows the potential of microwave-modified silicas in the fight against environmental contamination. Microwave engineering underscores a sophisticated approach to pollution remediation and emphasizes the pivotal role of nanotechnology in shaping sustainable solutions for environmental stewardship.

Biogenic synthesis of AuNPs using Solanum virginianum L. and their antibacterial, antioxidant and catalytic applications

Biogenic synthesis of nanoparticles is gaining popularity worldwide because of being ecofriendly as well as economical, with minimal production of hazardous by-products. The present study was targeted to determine the antibacterial, free radical scavenging and catalytic activity of gold nanoparticles synthesized from Solanum virginianum L. (Sv-AuNPs). After addition of auric chloride, the color of aqueous plant extract changed from light yellow to purple-red, indicating the formation of nanoparticles. A strong peak at 536 nm affirmed synthesis of Sv-AuNPs, and negative zeta potential (- 30.7) indicated their being wrapped in anions. They exhibited face-centered cubic and crystalline nature as revealed by X-ray diffraction. Elemental composition of Sv-AuNPs was ascertained by energy-dispersive X-ray spectroscopy, and a sharp peak at 2.2 keV confirmed the presence of gold. The shape of Sv-AuNPs synthesized was spherical with size ranging from 29.1 ± 1 nm to 51.2 ± 0.7 nm. Antibacterial potential was evaluated against E. coli, C. violaceum, K. pneumoniae, P. aeruginosa, B. subtilis, M. smegmatis, and S. aureus and was found to be greater than aqueous plant extract. Sv-AuNPs exhibited antioxidant potential comparable to ascorbic acid, demonstrating their vital role in the prevention of reactive oxygen species related diseases. Apart from their pharmaceutical potential, these nanoparticles also exhibited promising catalytic efficacy. They degraded harmful dyes i.e. 4-nitro phenol (4-NP) and congo red (CR) at a very low concentration of 50 µg/ml. This is the first report on the antibacterial, antioxidant, and catalytic properties of Sv-AuNPs and we hope it will lead the way for nanoparticles multifunctionality.

Graphical abstract

Emerging Field of Nanotechnology in Environment

The art of utilizing and manipulating micro materials have been dated back to antient era. With the advancement in technologies, the state-of-art methods of nano technologies and nano sciences has been employed in various sectors including environment, product designing, food industry, pharmaceuticals industries to way out solve standard problem of mankind. Due to rapid industrialization and the alarming levels of pollution there has been an urgent need to address the environmental and energy issues. Environmental sustainability concerns the global climate change and pollution including air, water, soil. The field of nanotechnology has proven to be a promising field where sensing and remediation, have been dramatically advanced by the use of nanomaterials. This emergent science of surface to mass ratio is the principle theorem for manipulating structure at molecular levels. The review sums up all the advancements in the field of nanotechnology and their recent application in the environment. New opportunities and challenges have also been discussed in detail to understand the use of nanotechnology as problem-to-solution ratio.

Graphical abstract

Image depicting the application of nanotechnology in environmental concerns. The combinations of technologies like bioremediations, bioaugmentations with state-of-the-art nanotechnology like carbon nanotubes and Nano capsules to answer the environmental challenges of soil quality, and plant productivity.

Microwave Irradiation vs. Structural, Physicochemical, and Biological Features of Porous Environmentally Active Silver–Silica Nanocomposites

Heavy metals and other organic pollutants burden the environment, and their removal or neutralization is still inadequate. The great potential for development in this area includes porous, spherical silica nanostructures with a well-developed active surface and open porosity. In this context, we modified the surface of silica spheres using a microwave field (variable power and exposure time) to increase the metal uptake potential and build stable bioactive Ag2O/Ag2CO3 heterojunctions. The results showed that the power of the microwave field (P = 150 or 700 W) had a more negligible effect on carrier modification than time (t = 60 or 150 s). The surface-activated and silver-loaded silica carrier features like morphology, structure, and chemical composition correlate with microbial and antioxidant enzyme activity. We demonstrated that the increased sphericity of silver nanoparticles enormously increased toxicity against E. coli, B. cereus, and S. epidermidis. Furthermore, such structures negatively affected the antioxidant defense system of E. coli, B. cereus, and S. epidermidis through the induction of oxidative stress, leading to cell death. The most robust effects were found for nanocomposites in which the carrier was treated for an extended period in a microwave field.

Novel Biocompatible Green Silver Nanoparticles Efficiently Eliminates Multidrug Resistant Nosocomial Pathogens and Mycobacterium Species

Bacterial infection is a major crisis of 21st era and the emergence of multidrug resistant (MDR) pathogens cause significant health problems. We developed, green chemistry-based silver nanoparticles (G-Ag NPs) using Citrus pseudolimon fruit peel extract. G-Ag NPs has a spherical shape in the range of ~ 40 nm with a surface charge of - 31 Mv. This nano-bioagent is an eco-friendly tool to combat menace of MDR. Biochemical tests prove that G-Ag NPs are compatible with human red blood cells and peripheral blood mononuclear cells. There have been many reports on the synthesis of silver nanoparticles, but this study suggests a green technique for making non-cytotoxic, non-hemolytic organometallic silver nanoparticles with a high therapeutic index for possible use in the medical field. On the same line, G-Ag NPs are very effective against Mycobacterium sp. and MDR strains including Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, and Acinetobacter baumannii isolated from patient samples. Based on it, we filed a patent to Indian Patent Office (reference no. 202111048797) which can revolutionize the prevention of biomedical device borne infections in hospital pre/post-operated cases. This work could be further explored in future by in vivo experimentation with mice model to direct its possible clinical utility.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01061-0.

Evaluation of TiO2 Nanoparticles Physicochemical Parameters Associated with their Antimicrobial Applications

Titanium dioxide nanoparticles (TiO2NPs) usage is increasing in everyday consumer products, hence, assessing their toxic impacts on living organisms and environment is essential. Various studies have revealed the significant role of TiO2NPs physicochemical properties on their toxicity. However, TiO2NPs are still poorly characterized with respect to their physicochemical properties, and environmental factors influencing their toxicity are either ignored or are too complex to be assessed under laboratory conditions. The outcomes of these studies are diverse and inconsistent due to lack of standard protocols. TiO2NPs toxicity also differs for in vivo and in vitro systems, which must also be considered during standardization of protocols to maintain uniformity and reproducibility of results. This review critically evaluates impact of different physicochemical parameters of TiO2NPs and other experimental conditions, employed in different laboratories in determining their toxicity towards bacteria. These important observations may be helpful in evaluation of environmental risks posed by these nanoparticles and this can further assist regulatory bodies in policymaking.

Therapeutic Applications of Self-assembled Indole-3-butanoyl-polyethylenimine Nanostructures

This study demonstrates the therapeutic potential of indole-3-butanoyl-polyethylenimine (IBP) nanostructures formed via self-assembly in aqueous system. Dynamic light scattering (DLS) analysis confirmed the formation of the nanostructures in the size range of ~ 194-331 nm. These nanostructures showed commendable antimicrobial activity against wide range of microbes including multi-drug resistant bacteria. Besides, appreciable antioxidant and anti-inflammatory activities were also observed. Results of cytotoxicity studies, performed on normal transformed human embryonic kidney (HEK 293) cells and human red blood cells (hRBCs), revealed almost non-toxic behavior of these nanostructures, however, remarkable toxicity on human breast cancer cells (MCF-7), human osteosarcoma cells (Mg63) and human liver cancer cells (HepG2) was observed. The pre-apoptotic and anti-proliferative activity of IBP nanostructures were confirmed by acridine orange/propidium iodide dual staining assay followed by confocal microscopy and scratch assay on Mg63 cells. Taken together, these results advocate the promising potential of the synthesized IBP nanostructures in the therapeutic applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-022-01015-y.

Preparation of g-C3N4/CQDs/Ag2S Composite Material and Its Antibacterial Properties

The emergence of bacterial resistance to traditional antibiotics and its global spread has brought huge threats to human life and health, and the need for new alternative antibacterial agents has become increasingly urgent. The rapid development of nanoscience provides a potential alternative to antibacterial therapy. In this study, g-C3N4 was synthesized using melamine as the raw material. It was then successfully combined with carbon quantum dots (CQDs) and silver sulfide to synthesize a g-C3N4/CQDs/Ag2S composite material. Such combination narrows the band gap of g-C3N4 from 2.53 eV to 2.21 eV and enhances the photocatalytic efficiency. Consequently, it indicated photocatalytic antimicrobial effects against three strands of bacteria, Shylococcus aureus (Grampositive), Escherichia coli (Gram-negative) and Methicillin-resistant Staphylococcus aureus under the irradiation of visible light. Other than the common pathogens, g-C3N4/CQDs/Ag2S exhibited an appreciable inhibition against the well-known drug-resistant bacteria. With its antimicrobial features and excellent photoelectric properties, the as prepared nanocomposites show its potential in the development of new antimicrobial and photocatalytic materials.

Ecofriendly phytofabrication of silver nanoparticles using aqueous extract of Cuphea carthagenensis and their antioxidant potential and antibacterial activity against clinically important human pathogens

The green synthesis of nanoparticles (NPs) is the safest, ecofriendly, cost-effective, and non-hazardous approach of nanotechnology. In the current study, we described the green synthesis of silver nanoparticles (AgNPs) using Cuphea carthagenensis aqueous leaf extract as a reducing, capping, and stabilizing agent. The study aims at the synthesis, characterization, optimization, and determination of the antibacterial activity of Cc-AgNPs against clinically important human pathogens. Coating of cotton fabrics with Cc-AgNPs and their efficacy against skin infection causing organisms was also evaluated. Furthermore, antioxidant activity, growth assay and time kill assay of Cc-AgNPs were also performed in the study. The biosynthesized Cc-AgNPs were characterized by UV-visible spectrometry, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The spectroscopic and microscopic analysis demonstrated biosynthesis of face-centered cubic (fcc) crystalline spherical Cc-AgNPs with an average particle size of 10.65 ± 0.1 nm. Optimized peak synthesis of Cc-AgNPs was reported at pH7, 55 °C, 4 mM silver nitrate, and 5:45 (plant extract: silver nitrate). Cc-AgNPs exhibited potent antioxidant effect and antibacterial activity against both Gram-positive and Gram-negative bacteria. The lowest MIC (15 μg/ml) and MBC (25 μg/ml) values were reported against S. typhimurium. The Cc-AgNPs coated fabrics demonstrated potent antibacterial activity against tested strains. This application could be helpful in wound healing management. Furthermore, the hemolytic analysis demonstrated that Cc-AgNPs exhibit non-toxic nature against Red Blood Cells (RBCs) at the tested concentrations. In conclusion, the investigation demonstrated a fast, stable, and eco-friendly approach to the biosynthesis of Cc-AgNPs along with their antibacterial and antioxidant properties.

Green Synthesis of Silver Nanoparticles Using Allium cepa var. Aggregatum Natural Extract: Antibacterial and Cytotoxic Properties

The chemical content of plant excerpts can be efficiently employed to reduce the metal ions to nanoparticles in the one-pot green production method. Here, green production of silver nanoparticles (AC-AgNPs) is performed by means of Allium cepa var. Aggregatum (shallot) extract as a stabilizer and reducer. The shape, size, and morphology of resultant AC-AgNPs are examined by optical spectroscopy analysis such as UV for nucleation and coalescence processes of the AC-AgNPs. Through FTIR functional group is determined and through DLS size is defined, it was confirmed that metallic AgNPs were successfully synthesized through the green synthesis route, and these results agreed well with the results obtained in the XRD pattern along with TEM spectroscopy, where the TEM images confirm the formation of sphere-like nanostructures along with SAED analysis. The chemical characterization is performed with XPS; the obtained molecular species in the materials are determined from the energy profile. Antioxidant activity of AC-AgNPs versus DPPH substrate is carried out. Antibacterial activity is well established against Gram-negative and Gram-positive organisms. Cell viability is accomplished, followed by an MTT assay, and a cytotoxicity assay of AC-AgNPs on MCF—7 cell lines is also carried out. Highlights: (1). This study highlights the eco-friendly synthesis of silver nanoparticles from Allium cepa var. Aggregatum Natural Extract. (2). The synthesized AC-AgNPs were characterized by UV-VIS, FT-IR, XRD, TEM, and XPS. (3). The synthesized nanoparticles were well dispersed in nature and the size range of 35 ± 8 nm. (4). The anti-candidal activity of biosynthesized silver nanoparticles was evaluated against the following Gram-Negative organisms: Escherichia coli (E. coli), and the following Gram-positive organisms: Staphylococcus aureus strains. The biosynthesized AC-AgNPs showed enhanced antiseptic features anti both Gram-positive and negative organisms. (5). Besides, the in vitro cytotoxic outcomes of AC-AgNPs were assessed versus MCF-7 cancerous cells, and the reduction in the feasibility of cancer cells was established via MTT assay, which suggests potential biomedical applications.

Activity of Silver Nanoparticles against Staphylococcus spp

Staphylococcus epidermidis is a bacterium that is part of the human microbiota. It is most abundant on the skin, in the respiratory system and in the human digestive tract. Also, Staphylococcus aureus contributes to human infections and has a high mortality rate. Both of these bacterial species produce biofilm, a pathogenic factor increasing their resistance to antibiotics. For this reason, we are looking for new substances that can neutralize bacterial cells. One of the best-known substances with such effects are silver nanoparticles. They exhibited antibacterial and antibiofilm formation activity that depended on their size, shape and the concentration used. In this review, we presented the data related to the use of silver nanoparticles in counteracting bacterial growth and biofilm formation published in scientific papers between 2017 and 2021. Based on the review of experimental results, the properties of nanoparticles prompt the expansion of research on their activity.

Benefits of Usage of Immobilized Silver Nanoparticles as Pseudomonas aeruginosa Antibiofilm Factors

The aim of this study was to assess the beneficial inhibitory effect of silver nanoparticles immobilized on SiO2 or TiO2 on biofilm formation by Pseudomonas aeruginosa-one of the most dangerous pathogens isolated from urine and bronchoalveolar lavage fluid of patients hospitalized in intensive care units. Pure and silver doped nanoparticles of SiO2 and TiO2 were prepared using a novel modified sol-gel method. Ten clinical strains of P. aeruginosa and the reference PAO1 strain were used. The minimal inhibitory concentration (MIC) was determined by the broth microdilution method. The minimal biofilm inhibitory concentration (MBIC) and biofilm formation were assessed by colorimetric assay. Bacterial enumeration was used to assess the viability of bacteria in the biofilm. Silver nanoparticles immobilized on the SiO2 and TiO2 indicated high antibacterial efficacy against P. aeruginosa planktonic and biofilm cultures. TiO2/Ag0 showed a better bactericidal effect than SiO2/Ag0. Our results indicate that the inorganic compounds (SiO2, TiO2) after nanotechnological modification may be successfully used as antibacterial agents against multidrug-resistant P. aeruginosa strains.

Nano-Biocatalysts: Potential Biotechnological Applications

Biocatalysts are a biomolecule of interest for various biotechnological applications. Non-reusability and poor stability of especially enzymes has always limited their applications in large-scale processing units. Nanotechnology paves a way by conjugating the biocatalysts on different matrices. It predominantly enables nanomaterials to overcome the limited efficacy of conventional biocatalysts. Nanomaterial conjugated nanobiocatalyst have enhanced catalytic properties, selectivity, and stability. Nanotechnology extended the flexibility to engineer biocatalysts for various innovative and predictive catalyses. So developed nanobiocatalyst harbors remarkable properties and has potential applications in diverse biotechnological sectors. This article summaries various developments made in the area of nanobiocatalyst towards their applications in biotechnological industries. Novel nanobiocatalyst engineering is an area of critical importance for harnessing the biotechnological potential.

Biomolecules Production from Greenhouse Gases by Methanotrophs

Harmful effects on living organisms and the environment are on the rise due to a significant increase in greenhouse gas (GHG) emissions through human activities. Therefore, various research initiatives have been carried out in several directions in relation to the utilization of GHGs via physicochemical or biological routes. An environmentally friendly approach to reduce the burden of significant emissions and their harmful effects is the bioconversion of GHGs, including methane (CH4) and carbon dioxide (CO2), into value-added products. Methanotrophs have enormous potential for the efficient biotransformation of CH4 to various bioactive molecules, including biofuels, polyhydroxyalkanoates, and fatty acids. This review highlights the recent developments in methanotroph-based systems for methanol production from GHGs and proposes future perspectives to improve process sustainability via biorefinery approaches.

Anaerobic Digestion of Agri-Food Wastes for Generating Biofuels

Presently, fossil fuels are extensively employed as major sources of energy, and their uses are considered unsustainable due to emissions of obnoxious gases on the burning of fossil fuels, which can lead to severe environmental complications, including human health. To tackle these issues, various processes are developing to waste as a feed to generate eco-friendly fuels. The biological production of fuels is considered to be more beneficial than physicochemical methods due to their environmentally friendly nature, high rate of conversion at ambient physiological conditions, and less energy-intensive. Among various biofuels, hydrogen (H₂) is considered as a wonderful due to high calorific value and generate water molecule as end product on the burning. The H₂ production from biowaste is demonstrated, and agri-food waste can be potentially used as a feedstock due to their high biodegradability over lignocellulosic-based biomass. Still, the H₂ production is uneconomical from biowaste in fuel competing market because of low yields and increased capital and operational expenses. Anaerobic digestion is widely used for waste management and the generation of value-added products. This article is highlighting the valorization of agri-food waste to biofuels in single (H₂) and two-stage bioprocesses of H₂ and CH₄ production.

Antimicrobial and Antioxidant Potential of Vernonia Cinerea Extract Coated AuNPs

Abstract

Green synthesis of nanoparticles is an important tool to reduce the harmful effects associated with traditional methods. In the present investigation, we have synthesised gold nanoparticles (AuNPs) using aqueous extract prepared from fresh aerial parts (leaf and stem) of Vernonia cinerea as bioreducing agent. The visual indication of change in colour from pale yellow to brown to ruby-red indicated the successful formation of the AuNPs. Characterization of nanoparticles was carried out by UV-visible spectroscopy, X-ray crystallography (XRD), Transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). UV-Vis spectra showed a specific peak at 546 nm which was the initial confirmation of the biosynthesized AuNPs. TEM images showed spherical and triangular shape of AuNPs with an average size of 25 nm. From FTIR spectrum, different functional groups were identified that could be responsible for the formation, stabilization, and capping of biosynthesized AuNPs. Aqueous plant extract and biosynthesised AuNPs were separately tested for their antimicrobial activity against six bacterial strains and four fungal strains. Biosynthesised AuNPs (2 mg/ml) showed significantly high zone of inhibition against the selected bacterial strains as compared to the aqueous plant extract. Maximum zone of inhibition (18.2 mm) was observed with AuNPs against Streptococcus pyogenes whereas comparatively less value (12.5 mm) was recorded with the plant extract. Interestingly, the inhibitory activity observed against bacterial strains was even better than ampicillin. Antifungal activity recorded with AuNPs (5 mg/ml) was maximum (17.4 mm) against R. oryzae and it was higher than positive control (17.00 mm) and plant extract (13.2 mm).The present study clearly showed that AuNPs coated with Vernonia cinerea extract were as good as positive control in inhibiting bacterial and fungal growth. In addition, these AuNPs also showed good antioxidant potential which was comparable to ascorbic acid.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-021-00976-w.

Nanostructured Antimicrobial Peptides: Crucial Steps of Overcoming the Bottleneck for Clinics

The security issue of human health is faced with dispiriting threats from multidrug-resistant bacteria infections induced by the abuse and misuse of antibiotics. Over decades, the antimicrobial peptides (AMPs) hold great promise as a viable alternative to treatment with antibiotics due to their peculiar antimicrobial mechanisms of action, broad-spectrum antimicrobial activity, lower drug residue, and ease of synthesis and modification. However, they universally express a series of disadvantages that hinder their potential application in the biomedical field (e.g., low bioavailability, poor protease resistance, and high cytotoxicity) and extremely waste the abundant resources of AMP database discovered over the decades. For all these reasons, the nanostructured antimicrobial peptides (Ns-AMPs), based on a variety of nanosystem modification, have made up for the deficiencies and pushed the development of novel AMP-based antimicrobial therapies. In this review, we provide an overview of the advantages of Ns-AMPs in improving therapeutic efficacy and biological stability, reducing side effects, and gaining the effect of organic targeting and drug controlled release. Then the different material categories of Ns-AMPs are described, including inorganic material nanosystems containing AMPs, organic material nanosystems containing AMPs, and self-assembled AMPs. Additionally, this review focuses on the Ns-AMPs for the effect of biological activities, with emphasis on antimicrobial activity, biosecurity, and biological stability. The "state-of-the-art" antimicrobial modes of Ns-AMPs, including controlled release of AMPs under a specific environment or intrinsic antimicrobial properties of Ns-AMPs, are also explicated. Finally, the perspectives and conclusions of the current research in this field are also summarized.

Biosynthesis of Silver Nanoparticles from Citrobacter freundii as Antibiofilm Agents with their Cytotoxic Effects on Human Cells

BACKGROUND

Nanomaterials have recently been identified for their potential benefits in the areas of medicine and pharmaceuticals. Among these nanomaterials, silver nanoparticles (Ag-NPs) have been widely utilized in the fields of diagnostics, antimicrobials, and catalysis.

OBJECTIVE

To investigate the potential utility of Citrobacter freundii in the synthesis of silver Nanoparticles (Ag-NPs), and to determine the antimicrobial activities of the Ag-NPs produced.

METHODS

Aqueous Ag+ ions were reduced when exposed to C. freundii extract and sunlight, leading to the formation of Ag-NPs. Qualitative microanalysis for the synthesized Ag-NPs was done using UVvis spectrometry, Energy Dispersive X-ray analysis (EDX), and scanning and transmission electron microscopy. The hydrodynamic size and stability of the particles were detected using Dynamic Light Scattering (DLS) analysis. The Ag-NPs' anti-planktonic and anti-biofilm activities against Staphylococcus aureus and Pseudomonas aeruginosa, which are two important skin and wound pathogens, were investigated. The cytotoxicity on human dermal fibroblast cell line was also determined.

RESULTS

Ag-NPs were spherical with a size range between 15 to 30 nm. Furthermore, Ag-NPs displayed potent bactericidal activities against both S. aureus and P. aeruginosa and showed noticeable anti-biofilm activity against S. aureus biofilms. Ag-NPs induced minor cytotoxic effects on human cells as indicated by a reduction in cell viability, a disruption of plasma membrane integrity, and apoptosis induction.

CONCLUSION

Ag-NPs generated in this study might be a future potential alternative to be used as antimicrobial agents in pharmaceutical applications for wound and skin related infections.

Green synthesis and characterization of silver nanoparticles using Pteris vittata extract and their therapeutic activities

The bacterial infections have been substantially increasing with higher mortality and new regimens required for their management. The present work deals with the green synthesis of silver nanoparticles (AgNPs) using leaf extract of Pteris vittata at pH 9.0. The AgNPs showed a single absorption peak at 407 nm. The morphology of AgNPs was found to be spherical in shape analyzed by scanning electron micrographs. The X-ray diffraction studies revealed the face-centered cubic structure of AgNPs with a 17-nm average crystallite size. They showed the antimicrobial activity against Pseudomonas aeruginosa, and the cell growth was completely ceased at the minimum inhibitory concentration (MIC); 100 μg/mL, with rapidly decreased cell viability. This bactericidal effect was due to the enhancement of cell permeability caused by cell disruption. The AgNPs lead to show a promising antiquorum-sensing activity by inhibition of toxin protease and pyocyanin in P. aeruginosa by 88% and, 94% respectively, at the sub-MIC concentration (0.25× MIC). These results conclude that the green synthesis of AgNPs shows a promising antimicrobial and antivirulence activity against P. aeruginosa.

Comparison Study of Synthesized Red (or Blood) Orange Peels and Juice Extract-Nanoflowers and Their Antimicrobial Properties on Fish Pathogen (Yersinia ruckeri)

Abstract

In this work, we synthesized blood orange peel extract-copper (II) (Cu²⁺) ions nanoflower (NFs) and blood orange juice extract-copper (II) (Cu²⁺) ions nanoflower examine their antimicrobial properties on the fish pathogen (Yersinia ruckeri). The main compounds of the blood orange peel extract and the blood orange juice extract were organic components, and the copper (II) (Cu^{2 +}) ions were inorganic components. BOPE-Cu^{2 +} nanoflowers are quite compact, porous, and uniform as compared to BOJE-Cu²⁺ nanoflowers. Scanning Electron Microscopy, Fourier Transform Infrared spectrometry, and Energy-Dispersive X-ray spectroscopy were used to observe the structures of the NFs. The findings of FT-IR show Cu-O and Cu-N bonds in NF, which may be an indicator of the development of NFs. Although the antimicrobial actions of BOPE-hNFs and BOJE-hNFs against Yersinia ruckeri (NCTC 12,268) have been confirmed.

Graphic Abstract

Bioinspired Gold Nanoparticle Synthesis Using Terminalia bellerica Fruit Parts and Exploring Their Anti-bacterial Potency In Vitro

Gold nanoparticles with their excellent biocompatibility are extensively used in pharma and biological applications. Terminalia bellerica (TB) dry fruit parts mediated gold nanoparticles were synthesized using the aqueous extracts. The secondary metabolites screening of the aqueous extracts was done using phytochemical analysis. The green synthesized gold nanoparticles show vibrant colours. They were characterized using UV-Visible spectroscopy, FT-IR spectroscopy, XRD analysis and FE-SEM. The analytical characterization methods ensured the formation of nanoparticles and could predict the nanometric size of the nanoparticles. The study also lay to determine the antibacterial potential of the TB fruit parts and TB fruit parts mediated gold nanoparticles. The pathogens chosen for the study were pathogens from clinical species such as Acinetobacter pneumonia, Bacillus subtilis, and Enterococcus faecalis which cause common infections. The TB fruit part extracts, as well as TB fruit parts mediated gold nanoparticles were capable enough to destroy clinical pathogens.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-021-00937-3.

ClpC-Mediated Sporulation Regulation at Engulfment Stage in Bacillus anthracis

Bacterial sporulation is a conserved process utilized by members of Bacillus genus and Clostridium in response to stress such as nutrient or temperature. Sporulation initiation is triggered by stress signals perceived by bacterial cell that leads to shutdown of metabolic pathways of bacterial cells. The mechanism of sporulation involves a complex network that is regulated at various checkpoints to form the viable bacterial spore. Engulfment is one such check point that drives the required cellular rearrangement necessary for the spore assembly and is mediated by bacterial proteolytic machinery that involves association of various Clp ATPases and ClpP protease. The present study highlights the importance of degradation of an anti-sigma factor F, SpoIIAB by ClpCP proteolytic machinery playing a crucial role in culmination of engulfment process during the sporulation in Bacillus anthracis.

Epigenetic Regulation of Gut Microbial Dysbiosis

Microbiota inside the gut plays a vital role in maintaining human health. Microbial dysbiosis is associated with various complications leading to a range of diseases. Epigenetic changes enforced by various environmental and lifestyle factors lead to heritable modifications. These epigenetic modifications include DNA methylation, histone modifications, chromatin remodelling, and ribonucleic acid-based mechanisms. This review summarizes the impacts of environmental factors on the gut microbiome, epigenetic modifications, and their role in cardiovascular diseases.

Concrete Crack Restoration Using Bacterially Induced Calcium Metabolism

Concrete structures are prone to develop cracks and cause devastation. Repair and renovation are not enough to ensure complete eradication of crack development. The entire process is costly and laborious. The microbiologically induced calcium carbonated precipitation can be effective in restoring the cracks. The calcium-based nutrients along with specific bacterial strain have been used in the present investigation. The pellets of calcium as per Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy are deposited in the cracks of the concrete over a period of 7 days of incubation. The presence of bacteria in the calcium precipitates as demonstrated by scanning electron microscope provides adequate strength and adhering quality to the pellets. The effective filling of cracks is confirmed with the help ultrasonic pulse velocity test also. Since, elephantine heritage and high sky buildings have high maintenance costs, the use of present technique will cut down the cost and duration of restoration.

Supplementary Information

The online version of this article (10.1007/s12088-020-00916-0) contains supplementary material, which is available to authorized users.

Electrochemical Determination of Nicotine in Tobacco Products Based on Biosynthesized Gold Nanoparticles

In this work, gold nanoparticles were biosynthesized via Plectranthus amboinicus leaf extract as the reducing agent. A series of techniques were used for sample analysis. The biosynthesized gold nanoparticles (bAuNPs) are a uniform size with a spherical shape. The FTIR analysis reveals the presence of many oxygen-containing functional groups on the bAuNP surface. The cyclic voltammetry and electrochemical impedance spectroscopic characterizations reveal that while the bAuNPs have a slightly lower conductivity than chemically synthesized AuNPs (cAuNPs). However, the bAuNPs have a superior electrocatalytic performance toward nicotine reduction. After optimization, the bAuNP-modified SPE could detect nicotine linearly from 10 to 2,000 μM with a low detection limit of 2.33 μM. In addition, the bAuNPs/SPE have been successfully used for nicotine-containing-product analysis.

New Antivirals and Antibacterials Based on Silver Nanoparticles

The rediscovery of the medical uses of silver provides another noticeable example, this time at the interface of chemistry and medicine, of the real (and nonlinear) progress of scientific research. Several new silver-based antimicrobial products have thus been commercialized in the last two decades. Next-generation antibacterials and antivirals of broad scope, low toxicity and affordable cost, we argue in this study, will be based on microencapsulated Ag nanoparticles.

Biogenic Silver Nanoparticles: Evaluation of Their Biological and Catalytic Potential

The biogenic tailoring of silver nanoparticles using plant extract is becoming an attractive approach in the current scenario. Manilkara zapota (MZ) is well known for its antibacterial, hepato-protective, anti-inflammatory, anti-tussive, anti-fungal, anti-tumour, and free radical scavenging potential. Its plants extract is a rich source of secondary metabolites. Nowadays, silver nanoparticles (AgNPs) have been advocated for a variety of biomedical applications. In present work, silver nanoparticles have been synthesized using an aqueous extract of MZ, physicochemically characterized and finally evaluated for antimicrobial effects, catalytic reduction/degradation of organic dyes and cytotoxicity. The nanosized AgNPs (~ 84 nm) were found to possess prominent antibacterial potential against gram positive and gram negative pathogens (MIC 50 μg/ml) in comparison to native plant extract. Moreover, these particles were found to be non-toxic and efficient eradicators of environmental toxicants via rapid catalytic reduction of toxic chemicals and dyes. Altogether, these results suggest promising potential of these nanoparticles that can be used as multifunctional agents for future biomedical applications.

Biocidal Activity of Metal Nanoparticles Synthesized by Fusarium solani against Multidrug-Resistant Bacteria and Mycotoxigenic Fungi

Antibiotic resistance by pathogenic bacteria and fungi is one of the most serious global public health problems in the 21^st century, directly affecting human health and lifestyle. Pseudomonas aeruginosa and Staphylococcus aureus with strong resistance to the common antibiotics have been isolated from Intensive Care Unit patients at Zagazig Hospital. Thus, in this study we assessed the biocidal activity of nanoparticles of silver, copper and zinc synthesized by Fusarium solani KJ 623702 against these multidrug resistant-bacteria. The synthesized Metal Nano-particles (MNPs) were characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Zeta potential. The Fourier transform infrared spectroscopy (FTIR) result showed the presence of different functional groups such as carboxyl, amino and thiol, ester and peptide bonds in addition to glycosidic bonds that might stabilize the dispersity of MNPs from aggregation. The antimicrobial potential of MNPs by F. solani against the multidrug-resistant (MDR) P. aeruginosa and S. aureus in addition to the mycotoxigenic Aspergillus awamori, A. fumigatus and F. oxysporum was investigated, based on the visual growth by diameter of inhibition zone. Among the synthesized MNPs, the spherical AgNPs (13.70 nm) displayed significant effect against P. aeruginosa (Zone of Inhibition 22.4 mm and Minimum Inhibitory Concentration 21.33 µg/ml), while ZINC oxide Nano-Particles were the most effective against F. oxysporum (ZOI, 18.5 mm and MIC 24.7 µg/ml). Transmission Electron Microscope micrographs of AgNP-treated P. aeruginosa showed cracks and pits in the cell wall, with internalization of NPs. Production of pyocyanin pigment was significantly inhibited by AgNPs in a concentration-dependent manner, and at 5-20 µg of AgNPs/ml, the pigment production was reduced by about 15-100%, respectively.

Effects of Metal Oxide Nanoparticles on Toll-Like Receptor mRNAs in Human Monocytes

For the widespread application of nanotechnology in biomedicine, it is necessary to obtain information about their safety. A critical problem is presented by the host immune responses to nanomaterials. It is assumed that the innate immune system plays a crucial role in the interaction of nanomaterials with the host organism. However, there are only fragmented data on the activation of innate immune system factors, such as toll-like receptors (TLRs), by some nanoparticles (NPs). In this study, we investigated TLRs' activation by clinically relevant and promising NPs, such as Fe3O4, TiO2, ZnO, CuO, Ag2O, and AlOOH. Cytotoxicity and effects on innate immunity factors were studied in THP-1(Tohoku Hospital Pediatrics-1) cell culture. NPs caused an increase of TLR-4 and -6 expression, which was comparable with the LPS-induced level. This suggests that the studied NPs can stimulate the innate immune system response inside the host. The data obtained should be taken into account in future research and to create safe-by-design biomedical nanomaterials.

Aligning Microbial Biodiversity for Valorization of Biowastes: Conception to Perception

Generation of biowastes is increasing rapidly and its uncontrolled, slow and persistent fermentation leads to the release of Green-house gases (GHGs) into the environment. Exploration and exploitation of microbial diversity for degrading biowastes can result in producing diverse range of bioactive molecules, which can act as a source of bioenergy, biopolymers, nutraceuticals and antimicrobials. The whole process is envisaged to manage biowastes, and reduce their pollution causing capacity, and lead to a sustainable society. A strategy has been proposed for: (1) producing bioactive molecules, and (2) achieving a zero-pollution emission by recycling of the GHGs through biological routes.