Sunlight-induced rapid and efficient biogenic synthesis of silver nanoparticles using aqueous leaf extract of Ocimum sanctum Linn. with enhanced antibacterial activity

Rethinking Nanoparticle Synthesis: A Sustainable Approach vs. Traditional Methods

This review portrays a comparison between green protocols and conventional nanoparticle (NP) synthesis strategies, highlighting each method's advantages and limitations. Various top-down and bottom-up methods in NP synthesis are described in detail. The green chemistry principles are emphasized for designing safe processes for nanomaterial synthesis. Among the green biogenic sources plant extracts, vitamins, enzymes, polysaccharides, fungi (Molds and mushrooms), bacteria, yeast, algae, and lichens are discussed. Limitations in the reproducibility of green protocols in terms of availability of raw material, variation in synthetic protocol, and selection of material due to geographical differences are elaborated. Finally, a conclusion is drawn utilizing green chemical principles, & a circular economy strategy to minimize waste generation, offering a promising framework for the synthesis of NPs emphasizing sustainability.

Tiny but mighty: metal nanoparticles as effective antimicrobial agents for plant pathogen control

Metal nanoparticles (MNPs) have gained significant attention in recent years for their potential use as effective antimicrobial agents for controlling plant pathogens. This review article summarizes the recent advances in the role of MNPs in the control of plant pathogens, focusing on their mechanisms of action, applications, and limitations. MNPs can act as a broad-spectrum antimicrobial agent against various plant pathogens, including bacteria, fungi, and viruses. Different types of MNPs, such as silver, copper, zinc, iron, and gold, have been studied for their antimicrobial properties. The unique physicochemical properties of MNPs, such as their small size, large surface area, and high reactivity, allow them to interact with plant pathogens at the molecular level, leading to disruption of the cell membrane, inhibition of cellular respiration, and generation of reactive oxygen species. The use of MNPs in plant pathogen control has several advantages, including their low toxicity, selectivity, and biodegradability. However, their effectiveness can be influenced by several factors, including the type of MNP, concentration, and mode of application. This review highlights the current state of knowledge on the use of MNPs in plant pathogen control and discusses the future prospects and challenges in the field. Overall, the review provides insight into the potential of MNPs as a promising alternative to conventional chemical agents for controlling plant pathogens.

Revisiting the Green Synthesis of Nanoparticles: Uncovering Influences of Plant Extracts as Reducing Agents for Enhanced Synthesis Efficiency and Its Biomedical Applications

Background

Conventional nanoparticle synthesis methods involve harsh conditions, high costs, and environmental pollution. In this context, researchers are actively searching for sustainable, eco-friendly alternatives to conventional chemical synthesis methods. This has led to the development of green synthesis procedures among which the exploration of the plant-mediated synthesis of nanoparticles experienced a great development. Especially, because plant extracts can work as reducing and stabilizing agents. This opens up new possibilities for cost-effective, environmentally-friendly nanoparticle synthesis with enhanced size uniformity and stability. Moreover, bio-inspired nanoparticles derived from plants exhibit intriguing pharmacological properties, making them highly promising for use in medical applications due to their biocompatibility and nano-dimension.

Objective

This study investigates the role of specific phytochemicals, such as phenolic compounds, terpenoids, and proteins, in plant-mediated nanoparticle synthesis together with their influence on particle size, stability, and properties. Additionally, we highlight the potential applications of these bio-derived nanoparticles, particularly with regard to drug delivery, disease management, agriculture, bioremediation, and application in other industries.

Methodology

Extensive research on scientific databases identified green synthesis methods, specifically plant-mediated synthesis, with a focus on understanding the contributions of phytochemicals like phenolic compounds, terpenoids, and proteins. The database search covered the field's development over the past 15 years.

Results

Insights gained from this exploration highlight plant-mediated green synthesis for cost-effective nanoparticle production with significant pharmacological properties. Utilizing renewable biological resources and controlling nanoparticle characteristics through biomolecule interactions offer promising avenues for future research and applications.

Conclusion

This review delves into the scientific intricacies of plant-mediated synthesis of nanoparticles, highlighting the advantages of this approach over the traditional chemical synthesis methods. The study showcases the immense potential of green synthesis for medical and other applications, aiming to inspire further research in this exciting area and promote a more sustainable future.

De-novo fabrication of sunlight irradiated silver nanoparticles and their efficacy against E. coli and S. epidermidis

Silver nanoparticles (AgNPs) gained significant attention due to their activity against microbial pathogens, cancer cells, and viral particles etc. Traditional fabrication methods require hazardous chemicals as reducing agents and their usage and disposal pose a significant hazard to environmental ecosystem. Here, a de novo, robust, cost effective and an eco-friendly method is reported to fabricate AgNPs irradiated with sunlight (SL) while using Salvadora persica root extract (SPE) as reducing agent. Sunlight (SL) irradiated S. persica silver nanoparticles (SpNPs) i.e., SL-SpNPs were characterized using multiple techniques and their antibacterial efficacy was evaluated. The SL-SpNPs were synthesized in 10 min. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) analysis revealed their spherical morphology with a size range of 4.5-39.7 nm, while surface plasmon resonance (SPR) peaked at 425 nm. Fourier transform infrared spectroscopy (FTIR) analysis suggested that the reduction of SL-SpNPs was due to the presence of phytochemicals in the SPE. Furthermore, X-ray powder diffraction (P-XRD) pattern depicted the crystal structure of SL-SpNPs, hence proving the presence of AgNPs. Further the antibacterial studies were carried out against Escherichia coli (ATCC 11229) and Staphylococcus epidermidis (ATCC 12228) using Kirby Bauer method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for E. coli were determined to be 1.5 μg/mL and 3.0 μg/mL respectively while MIC and MBC values for S. epidermidis were found to be 12.5 μg/mL and 25 μg/mL respectively. The solar irradiation-based fabrication method and resulting SL-SpNPs can find their utility in many biomedical and environmental applications.

Green synthesis of silver nanoparticles and evaluation of their anti-bacterial activities: use of Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts

The presence of various phytochemicals makes the leaf extract-based green synthesis advantageous to other conventional methods, as it facilitates the production of non-toxic by-product. In the present study, leaf extracts from two different plants: Aloe barbadensis miller and Ocimum tenuiflorum, were used to synthesise Ag nanoparticles. The absorbance at 419-432 nm from UV-visible spectroscopy indicates the formation of Ag in the synthesised samples. The effect of precursors’ concentration on the stability, size and shape of the synthesised samples has also been investigated at constant heating temperature, stirring time, and the pH of the solution. The TEM results showed that all the synthesised samples of nanoparticles demonstrated stability with a size range of 7-70 and 9-48 nm with Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts, respectively. The formation of smaller Ag nanoparticles due to utilisation of different precursor concentration and leaf extracts was also explained. The synthesised samples’ anti-bacterial activity was examined against the pathogens, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. In general, the green synthesis approach established a prospective for developing highly stable Ag nanoparticles with rigid particle shape/size distribution from different leaf extracts for the development of better anti-bacterial agents.

Efficacy in degradation of carcinogenic pollutant sulforhodamine B by green synthesized silver nanoparticles

Colloidal Silver nano-particles were grown at room temperature using leaf extract of Ocimum tenuiflorum. The silver nanoparticles suspended in the solution were found to be stable for over a period of 2 months. Structural, optical and photo catalytic behavior of the suspended silver (Ag) nano-particles (NPs) was characterized. From TEM analysis the size of the silver nanoparticles was estimated to be 25–30 nm. Our findings suggest that the ratio between the molarity of AgNO3 and the volume of leaf extract does not have any role in controlling the size of the Ag nano-particles. These green synthesized Ag nano-particles exhibit degradation of the carcinogenic organic pollutant sulforhodamine B in absence of light.

Prospective Application of Nanoparticles Green Synthesized Using Medicinal Plant Extracts as Novel Nanomedicines

The use of medicinal plants in green synthesis of metal nanoparticles is increasing day by day. A simple search for the keywords "green synthesis" and "nanoparticles" yields more than 33,000 articles in Scopus. As of August 10, 2021, more than 4000 articles have been published in 2021 alone. Besides demonstrating the ease and environmental-friendly route of synthesizing nanomaterials, many studies report the superior pharmacological properties of green synthesized nanoparticles compared to those synthesized by other methods. This is probably due to the fact that bioactive molecules are entrapped on the surface of these nanoparticles. On the other hand, recent studies have confirmed the nano-dimension and biocompatibility of metal ash (Bhasma) preparations, which are commonly macerated with biological products and administered for the treatment of various diseases in Indian medicine since ancient times. This perspective article argues for the prospective medical application of green nanoparticles in the light of Bhasma.

Green synthesis of silver nanoparticles by Rivina humilis leaf extract to tackle growth of Brucella species and other perilous pathogens

Novel approaches are obligatory to treat chronic intracellular bacterial infectious diseases like Brucellosis specifically, are very complicated to deal with. The aim of the study to take upon nanotechnology approach to exploit the efficacy of the synthesized nanoparticles, to overcome barriers for treatment of Brucella species and other pathogens. Present study used Rivina humilis extract as reductant of silver ions for synthesis of silver nanoparticles for the first time. Rh-AgNP's was characterized by UV-visible spectroscopy, DLS, FT-IR, SEM, EDS, TEM and XRD. Radical scavenging, antibrucellosis, bactericidal activity was evaluated. Clinical application was assessed by Rate of haemolysis, fibrinolytic and Hemagglutination activity. UV-visible spectrum of synthesized Rh-AgNP's showed maximum peak at 440 nm indicating the formation of nanoparticles. TEM showed that the average particle size of nanoparticles 51 nm with spherical shape, DLS depicted monodisperse state in water; EDS confirmed the presence of silver metal. Rh-AgNP's exhibited potential antibrucellosis activity against B. abortus, B. melitensis and B. suis effective inhibition at 800 μg/mL. The bio-compatibility of Rh-AgNP's was established by rate of haemolysis, hemagglutination and fibrinolytic activity. For the first time it has been proved that Rh-AgNP's have efficacy as antimicrobial agent with potential application in the biological domain.

Sunlight-Driven Synthesis of Silver Nanoparticles Using Pomelo Peel Extract and Antibacterial Testing

A green approach, including using phytochemicals in pomelo peel extract (PPE) and direct sunlight, was used to synthesize silver nanoparticles (AgNPs). PPE was prepared by treating pomelo peel with a citric acid solution at 85°C for 2 h. PPE was then mixed with AgNO3 and exposed to sunlight to induce the formation of AgNPs. Time-dependent UV-vis spectra of the reaction mixture demonstrated that AgNPs are formed under sunlight irradiation faster than underheating at 90°C. Characterization techniques, including X-ray diffraction, transmission electron microscopy, and scanning electron microscopy, confirmed the formation of AgNPs with sizes of 20–30 nm. AgNPs synthesized in PPE were more stable toward electrolyte-induced aggregation than those synthesized using the conventional NaBH4/citrate method. The AgNPs synthesized in PPE showed antibacterial activities comparable to those of AgNO3 at the same silver concentration against four pathogenic bacterial strains. The obtained PPE containing AgNPs, pectin, and other phytochemicals can be utilized further to produce antibacterial and antioxidant films in food packaging and medical applications.

Green Synthesis of Silver Nanoparticles Using Parthenium Hysterophorus: Optimization, Characterization and In Vitro Therapeutic Evaluation

Traditional synthetic techniques for silver nanoparticles synthesis involve toxic chemicals that are harmful to humans as well as the environment. The green chemistry method for nanoparticle synthesis is rapid, eco-friendly, and less toxic as compared to the traditional methods. In the present research, we synthesized silver nanoparticles employing a green chemistry approach from Parthenium hysterophorus leaf extract. The optimized parthenium silver nanoparticles (PrSNPs) had a mean particle size of 187.87 ± 4.89 nm with a narrow size distribution of 0.226 ± 0.009 and surface charge −34 ± 3.12 mV, respectively. The physicochemical characterization of optimized SNPs was done by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Moreover, the transmission electron microscopy (TEM) analysis indicates the spherical shape of NPs with an average diameter of 20–25 nm. PrSNPs were investigated for in vitro antibacterial, antifungal, anti-inflammatory, and antioxidant properties, and showed excellent profiles. The cytotoxic activity was analyzed against two cancer cell lines, i.e., B16F10 and HepG2 for 24 h and 48 h. PrSNPs proved to be an excellent anticancer agent. These PrSNPs were also employed for the treatment of wastewater by monitoring the E. coli count, and it turned out to be reduced by 58%; hence these NPs could be used for disinfecting water. Hence, we can propose that PrSNPs could be a suitable candidate as an antimicrobial, antioxidant, anti-inflammatory, and antitumor agent for the treatment of several ailments.

ApAGP-fabricated silver nanoparticles induce amendment of murine macrophage polarization

M2 polarization of macrophages is predominant in case of tumors and some other infectious diseases for disease progression. Repolarization of the M2 phenotype to the M1 state may be required to cure diseases. Hence, it is of great interest to find out a material that would repolarize the M2 phenotype to the M1 state. Herein, the arabinogalactan protein from Andrographis paniculata (ApAGP) was used to prepare a silver nanoparticle-ApAGP (SNP-ApAGP) bioconjugate, which was characterized via UV-vis spectroscopy, zeta potential analysis, FT-IR spectroscopy, and HR-TEM. Studies suggest that SNP-ApAGP (2.5 μg mL^-1) up-regulates ROS generation, NO generation, and pro-inflammatory cytokine release (IL-12, IFN-γ, TNF-α, and IL-6). SNP-ApAGP also down-regulates the arginase-1 activity and anti-inflammatory cytokine release (IL-4 & IL-10) in M0, M1, and M2-polarized peritoneal macrophages in vitro. Therefore, SNP-ApAGP induces M1 polarization in M0 macrophages, enhances the pro-inflammatory activity of the M1 phenotype, and can also repolarize M2 macrophages into the M1 phenotype. Therefore, SNP-ApAGP could be used for treating various infectious diseases and cancers where repolarization of M2 macrophages may be required to cure the disease.

Exploring the Effectiveness of External Use of Bach Flower Remedies on Carpal Tunnel Syndrome: A Pilot Study

BACKGROUND

A randomized, pilot, placebo-controlled clinical trial was conducted with the aim of evaluating the effectiveness of a cream based on Bach flower remedies (BFR) on symptoms and signs of carpal tunnel syndrome.

METHODS

Forty-three patients with mild to moderate carpal tunnel syndrome during their "waiting" time for surgical option were randomized into 3 parallel groups: Placebo (n = 14), blinded BFR (n = 16), and nonblinded BFR (n = 13). These groups were treated during 21 days with topical placebo or a cream based on BFR.

RESULTS

Significant improvements were observed on self-reported symptom severity and pain intensity favorable to BFR groups with large effect sizes (η2partial > 0.40). In addition, all signs observed during the clinical exam showed significant improvements among the groups as well as symptoms of pain, night pain, and tingling, also with large effect sizes (φ > 0.5). Finally, there were significant differences between the blinded and nonblinded BFR groups for signs and pain registered in clinical exam but not in self-reports.

CONCLUSION

The proposed BFR cream could be an effective intervention in the management of mild and moderate carpal tunnel syndrome, reducing the severity symptoms and providing pain relief.

One pot green preparation of Seabuckthorn silver nanoparticles (SBT@AgNPs) featuring high stability and longevity, antibacterial, antioxidant potential: a nano disinfectant future perspective

In recent years antimicrobial resistance (AMR) threatens the effective prevention and treatment of an ever-increasing range of infections caused by bacteria, parasites, viruses, fungi and development of effective therapeutics is a major challenge to the scientific community.

Multi-functional nano silver: A novel disruptive and theranostic agent for pathogenic organisms in real-time

The present study was aimed at evaluating the fluorescence property, sporicidal potency against Bacillus and Clostridium endospores, and surface disinfecting ability of biogenic nano silver. The nano silver was synthesized using an actinobacterial cell-filtrate. The fluorescence property as well as imaging facilitator potency of this nano silver was verified adopting spectrofluorometer along with fluorescent and confocal laser scanning microscope wherein strong emission and bright green fluorescence, respectively, on the entire spore surface was observed. Subsequently, the endospores of B. subtilis, B. cereus, B. amyloliquefaciens, C. perfringens and C. difficile were treated with physical sporicides, chemical sporicides and nano silver, in which the nano silver brought about pronounced inhibition even at a very low concentration. Finally, the environmental surface-sanitizing potency of nano silver was investigated adopting cage co-contamination assay, wherein vital organs of mice exposed to the nano silver-treated cage did not show any signs of pathological lesions, thus signifying the ability of nano silver to completely disinfect the spore or reduce the count required for infection. Taken these observations together, we have shown the multi-functional biological properties of the nano silver, synthesized using an actinobacterial cell-filtrate, which could be of application in advanced diagnostics, biomedical engineering and therapeutics in the near future.