Multifunctional biosynthesized silver nanoparticles exhibiting excellent antimicrobial potential against multi-drug resistant microbes along with remarkable anticancerous properties

Novel strategies in melanoma treatment using silver nanoparticles

Melanoma has remarkably gained extensive attention owing to its high morbidity and mortality. Conventional treatment methods still have some problems and defects. Therefore, more and more novel methods and materials have been continuously developed. Silver nanoparticles (AgNPs) have attracted significant interest in the field of cancer research especially for melanoma treatment because of their excellent properties including antioxidant, antiproliferative, anti-inflammatory, antibacterial, antifungal, and antitumor abilities. In this review, the applications of AgNPs in the prevention, diagnosis, and treatment of cutaneous melanoma are mainly introduced. It also focuses on the therapy strategies of photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy for melanoma treatment. Taken together, AgNPs play an increasingly crucial role in cutaneous melanoma treatment, which have promising application in the future.

Green Synthesis of a Novel Silver Nanoparticle Conjugated with Thelypteris glandulosolanosa (Raqui-Raqui): Preliminary Characterization and Anticancer Activity

In the last decade, the green synthesis of nanoparticles has had a prominent role in scientific research for industrial and biomedical applications. In this current study, silver nitrate (AgNO3) was reduced and stabilized with an aqueous extract of Thelypteris glandulosolanosa (Raqui-raqui), forming silver nanoparticles (AgNPs-RR). UV-vis spectrophotometry, dynamic light scattering (DLS), and scanning transmission electron microscopy (STEM) were utilized to analyze the structures of AgNPs-RR. The results from this analysis showed a characteristic peak at 420 nm and a mean hydrodynamic size equal to 39.16 nm, while the STEM revealed a size distribution of 6.64–51.00 nm with an average diameter of 31.45 nm. Cellular cytotoxicity assays using MCF-7 (ATCC® HTB-22™, mammary gland breast), A549 (ATCC® CCL-185, lung epithelial carcinoma), and L929 (ATCC® CCL-1, subcutaneous connective tissue of Mus musculus) demonstrated over 42.70% of MCF-7, 59.24% of A549, and 8.80% of L929 cells had cell death after 48 h showing that this nanoparticle is more selective to disrupt neoplastic than non-cancerous cells and may be further developed into an effective strategy for breast and lung cancer treatment. These results demonstrate that the nanoparticle surfaces developed are complex, have lower contact angles, and have excellent scratch and wear resistance.

A Critical Review of the Antimicrobial and Antibiofilm Activities of Green-Synthesized Plant-Based Metallic Nanoparticles

Metallic nanoparticles (MNPs) produced by green synthesis using plant extracts have attracted huge interest in the scientific community due to their excellent antibacterial, antifungal and antibiofilm activities. To evaluate these pharmacological properties, several methods or protocols have been successfully developed and implemented. Although these protocols were mostly inspired by the guidelines from national and international regulatory bodies, they suffer from a glaring absence of standardization of the experimental conditions. This situation leads to a lack of reproducibility and comparability of data from different study settings. To minimize these problems, guidelines for the antimicrobial and antibiofilm evaluation of MNPs should be developed by specialists in the field. Being aware of the immensity of the workload and the efforts required to achieve this, we set out to undertake a meticulous literature review of different experimental protocols and laboratory conditions used for the antimicrobial and antibiofilm evaluation of MNPs that could be used as a basis for future guidelines. This review also brings together all the discrepancies resulting from the different experimental designs and emphasizes their impact on the biological activities as well as their interpretation. Finally, the paper proposes a general overview that requires extensive experimental investigations to set the stage for the future development of effective antimicrobial MNPs using green synthesis.

Nanoparticles of Bioactive Metals/Metal Oxides and Their Nanocomposites with Antibacterial Drugs for Biomedical Applications

The increasing appearance of new strains of microorganisms resistant to the action of existing antibiotics is a modern problem that requires urgent decision. A promising potential solution is the use of nanoparticles of bioactive metals and their oxides as new antibacterial agents, since they are capable of affecting pathogenic microorganisms by mechanisms different from the mechanisms of action of antibiotics. Inorganic nanoparticles possess a wide spectrum of antibacterial activity. These particles can be easily conjugated with drug molecules and become carriers in targeted drug-delivery systems. This paper discusses the benefits and prospects of the application of nanoparticles from metals and metal oxides and their nanocomposites with antibacterial drugs.

Facile green synthesis of non-genotoxic, non-hemolytic organometallic silver nanoparticles using extract of crushed, wasted, and spent Humulus lupulus (hops): Characterization, anti-bacterial, and anti-cancer studies

Since the last few decades, the green synthesis of metal nanoparticles was one of the most thrust areas due to its widespread application. The study proposed using wasted and unusable Humulus lupulus (Hops) extract to synthesize silver nanoparticles for biomedical application. The environment around us gives us many scopes to use the waste from environmental sources and turn it into something valuable. The spent Hops extract was used to synthesize silver nanoparticles (AgNP@HOPs), and the synthesized product exhibited an excellent therapeutic effect in terms of anti-bacterial and anti-cancer agents. The synthesis was optimized considering different factors like time and the concentration of AgNO₃. The silver nanoparticles were characterized in detail using different characterization techniques XRD, DLS, TEM, BET, XPS, Raman Spectroscopy, SEM, EDAX, AFM, which revealed the uniqueness of the silver nanoparticles. The average hydrodynamic size was found to be 92.42 ± 2.41 with a low polydispersity index. The presence of Ag-C and Ag-O bonds in the AgNP@HOPs indicated that it is composed of organo-silver and silver oxides. The nanoparticles were found to be spherical with an average size of 17.40 nm. The AgNPs were lethal to both E. coli and S. aureus with a MIC-50 of 201.881 μg/mL and 213.189 μg/mL, respectively. The AgNP@HOPs also exhibited an anti-cancer effect with an IC-50 of 147.175. The AgNP@HOPs exhibited less cytotoxicity and genotoxicity against normal cells and exhibited superior haemocompatibility (major criteria for drug selection). There are indeed various reports on the synthesis of silver nanoparticles, but this study proposes a green method for producing non-genotoxic, non-hemolytic organometallic silver nanoparticles using waste material with considerable therapeutic index from the environmental source with potential application in the medical industry. This work could be taken forward for in-vivo studies and for pre clinical studies.

Green synthesized silver nanoparticles obtained from Stachys schtschegleevii extract: ct-DNA interaction and in silico and in vitro investigation of antimicrobial activity

The aim of this study was the synthesis of Ag nanoparticles (AgNPs) by using Stachys schtschegleevii extract and checking the composition, morphology and size of the green synthesized AgNPs using the analytical techniques (UV-vis, DLS, zeta potential, SEM-EDX, FT-IR and TEM). The TEM images of AgNPs represent a smooth surface and are spherical in shape with an average particle size of 31.43 nm. The antioxidant activities of green synthesized AgNPs were appraised by radical scavenging 1, 1-diphenyl-2-picrylhydrazyl test and the green synthesized AgNPs showed a strong ability to scavenge free radicals. In addition, AgNPs displayed a remarkable antibacterial and antifungal activity against various microorganisms. We employed molecular docking to investigate the AgNPs interaction with Dihydrofolate reductase (DHFR) of Escherichia coli, Staphylococcus aureus, and Candida albicans and there is a good agreement between molecular docking and our experimental results. The result of ct-DNA-AgNPs interaction demonstrated that AgNPs can bind to ct-DNA through partial intercalation binding mode.Communicated by Ramaswamy H. Sarma.

In Vitro Antioxidant, Antitumor and Photocatalytic Activities of Silver Nanoparticles Synthesized Using Equisetum Species: A Green Approach

The ethanolic extracts of three Equisetum species (E. pratense Ehrh., E. sylvaticum L. and E. telmateia Ehrh.) were used to reduce silver ions to silver nanoparticles (AgNPs). The synthesized AgNPs were characterized using UV-Vis spectrophotometry, Fourier Transform Infrared Spectroscopy (FTIR), Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) measurements. FTIR data revealed the functional groups of biomolecules involved in AgNPs synthesis, such as O-H, C-H, C=O, C-O, and C-C. EDX spectroscopy was used to highlight the presence of silver, while DLS spectroscopy provided information on the mean diameter of AgNPs, that ranged from 74.4 to 314 nm. The negative Zeta potential values (−23.76 for Ep–AgNPs, −29.54 for Es–AgNPs and −20.72 for Et–AgNPs) indicate the stability of the obtained colloidal solution. The study also focused on establishing the photocatalytic activity of AgNPs, which is an important aspect in terms of removing organic dyes from the environment. The best photocatalytic activity was observed for AgNPs obtained from E. telmateia, which degraded malachite green in a proportion of 97.9%. The antioxidant action of the three AgNPs samples was highlighted comparatively through four tests, with the best overall antioxidant capacity being observed for AgNPs obtained using E. sylvaticum. Moreover, the biosynthesized AgNPs showed promising cytotoxic efficacy against cancerous cell line MG63, the AgNPs obtained from E. sylvaticum L. providing the best result, with a LD₅₀ value around 1.5 mg/mL.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Nanotechnology-based formulations toward the improved topical delivery of anti-acne active ingredients

Introduction: Acne vulgaris is a chronic inflammatory skin disorder that affects an extremely concerning percentage of teenagers (ca. 85%), gathering serious negative impacts on the social life and psychological well-being of individuals. Conventional topical formulations for acne show low tolerability and side effects, such as skin irritation, leading to a decrease in the user's adherence to therapy. Nanotechnology-based formulations were developed as new strategies for topical acne management, particularly to overcome the difficulties associated with conventional treatments.Areas covered: This paper presents a critical analysis of reviewed nanosized anti-acne technological strategies, strongly supporting controlled active ingredient release, improved skin permeation, and lower skin irritation. An updated regulatory framework, considering the promising applications in nanomedicine, and the toxicity of these nanosystems are also addressed.Expert opinion: Nanosystems evidence several advantages, attending to the possibility of controlled active ingredient release, better skin permeation, and lower skin irritation. However, novel nanotechnological strategies for acne treatment and care can lead to new side effects, but also environmental nano pollution. Little is known about the toxicology of these nanotechnology-based formulations, therefore, as future trends, more studies should be conducted to assure the consumers' health and environmental safety.

Biosynthesized silver nanoparticles using Caulerpa taxifolia against A549 lung cancer cell line through cytotoxicity effect/morphological damage

The Caulerpa taxifolia is excellent marine green algae, which produced enormous bioactive compounds with more biological activities. Also, it is an excellent source for synthesis of Ag NPs with increased bioactivity against various infections. In our study, the marine algae marine algae Caulerpa taxifolia mediated Ag NPs was synthesized effectively. The synthesized Ag NPs was characterized well using UV-spectrometer and X-ray powder diffraction (XRD) and confirmed as synthesized particle was Ag NPs. The available structure of the Ag NPs was morphologically identified by scanning electron microscope (SEM), and exact minimum size, polydispersive spherical shape of the entire Ag NPs structure was confirmed by Transmission electron microscope (TEM). Further, the anti-cancer efficiency of biosynthesized Ag NPs against A549 lung cancer cells was found at 40 µg/mL concentration by cytotoxicity experiment. In addition, the phase contrast images of the result were supported the Ag NPs, which damaged the A549 morphologically clearly. Finally, florescence microscopic images were effectively proved the anti-cancerous effect against A549 lung cancer cells due to the condensed morphology of increased death cells. All the confirmed in-vitro results were clearly stated that the Caulerpa taxifolia mediated Ag NPs has superior anti-cancer agent against A549 lung cancer cells.

Research Progress of Alzheimer's Disease Therapeutic Drugs: Based on Renin-Angiotensin System Axis

It is widely recognized that Alzheimer's disease (AD) has a complicate link to renin-angiotensin system (RAS). It is known that cerebrovascular disease has some connections with AD, but most of the studies are still conducted in parallel or independently. Although previous research came up with large number of hypotheses about the pathogenesis of AD, it does not include the mechanism of RAS-related regulation of AD. It has been found that many components of RAS have been changed in AD. For example, the multifunctional and high-efficiency vasoconstrictor Ang II and Ang III with similar effects are changed under the action of other RAS signal peptides; these signal peptides are believed to help improve nerve injury and cognitive function. These changes may lead to neuropathological changes of AD, and progressive defects of cognitive function, which are association with some hypotheses of AD. The role of RAS in AD gradually attracts our attention, and RAS deserved to be considered carefully in the pathogenesis of AD. This review discusses the mechanisms of RAS participating in the three current hypotheses of AD: neuroinflammation, oxidative stress and amyloid-β protein (Aβ) hypothesis, as well as the drugs that regulate RAS systems already in clinical or in clinical trials. It further demonstrates the importance of RAS in the pathogenesis of AD, not only because of its multiple aspects of participation, which may be accidental, but also because of the availability of RAS drugs, which can be reused as therapies of AD.

Preparation of Silver/Chitosan Nanofluids Using Selected Plant Extracts: Characterization and Antimicrobial Studies Against Gram-Positive and Gram-Negative Bacteria

Chitosan/silver nanofluids were prepared using Phoenix dactylifera (DPLE) or Rumex vesicarius (HEL) extracts as the reducing agent, characterized using Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis), X-ray diffraction (XRD), and transmission electron microscope (TEM). The antimicrobial effect of the nanofluids against Gram positive, Bacillus licheniformis, Staphylococcus haemolyticus, Bacillus cereus, and Micrococcus luteus, and Gram-negative Pseudomonas aeruginosa, Pseudomonas citronellolis, and Escherichia coli bacteria has been studied. The nanoparticles were polydispersed in the chitosan matrix and are highly stable. The zeta potential of the silver nanoparticles in DPLE- and HEL-mediated composites is +46 mV and +56 mV, respectively. The FTIR results reveal that the free carboxylate groups in the plant biomaterial took part in stabilization process. HEL is a stronger reducing agent than DPLE and nanoparticles generated with HEL are smaller (8.0-36 nm) than those produced with DPLE (10-43 nm). DPLE- and HEL-mediated composites effectively inhibit the growth of the studied bacteria but HEL-mediated composite exhibited higher effect. The higher antimicrobial activity of HEL-mediated composite is linked to the smaller nanoparticles. The foregoing results indicate that HEL extract can be used in the green production of potential antimicrobial chitosan/silver nanofluids for biomedical and packaging applications.

New avenues of controlling microbial infections through anti-microbial and anti-biofilm potentials of green mono-and multi-metallic nanoparticles: A review

Nanoparticles synthesized through the green route deserve special mention because this green technology is not only energy-efficient and cost-effective but also amenable to the environment. Various biological resources have been used for the generation of these 'green nanoparticles'. Biological wastes have also been focused in this direction thereby promoting the value of waste. Reports indicate that green nanoparticles exhibit remarkable antimicrobial activitiesboth singly as well as in combination with standard antibiotics. The current phenomenon of multi-drug resistance has resulted due to indiscriminate administration of high-doses of antibiotics followed by significant toxicity. In the face of this emergence of drug-resistant microbesthe efficacy of green nanoparticles might prove greatly beneficial. Microbial biofilm is another hurdle in the effective treatment of diseases as the microorganismsbeing embedded in the meshwork of the biofilmevade the antimicrobial agents. Nanoparticles may act as a ray of hope on the face of this challenge tooas they not only destroy the biofilms but also lessen the doses of antibiotics requiredwhen administered in combination with the nanoparticles. It should be further noted that the resistance mechanisms exhibited by the microorganisms seem not that relevant for nanoparticles. The current review, to the best of our knowledgefocuses on the structures of these green nanoparticles along with their biomedical potentials. It is interesting to note how a variety of structures are generated by using resources like microbes or plants or plant products and how the structure affects their activities. This study might pave the way for further development in this arena and future work may be taken up in identifying the detailed mechanism by which 'green' synthesis empowers nanoparticles to kill pathogenic microbes.

Preparation and antibacterial behaviour of nanostructured Ag@SiO2–penicillin with silver nanoplates

Preparation of Ag@SiO₂–penicillin NPs with superior synergistic and antibacterial properties against methicillin-resistant Staphylococcus aureus.

Facile Synthesis of Silver Nanoparticles with High Antibacterial Activity

We report on a reverse microemulsion method for the synthesis of silver nanocrystals and examine their antibacterial activities. As the molar ratio of water to sodium bis(2-ethylhexyl) sulfosuccinate (AOT) increases to 25, a morphology transition from a sphere-like nanocrystal to a wire-like one was observed. For both the gram-negative and gram-positive bacteria, the wire-like silver nanocrystal showed higher antibacterial activities. We conclude that the morphology of silver nanocrystals dominates their antibacterial activity.

Bifunctionally engineered polyethylenimines as efficient DNA carriers and antibacterials against resistant pathogens

In this study, we have designed and developed two series of bifunctional conjugates by tethering polyethylenimine with streptomycin. By varying the amount of streptomycin, conjugates, polyethylenimine-streptomycin, have been synthesized and characterized spectroscopically. Gel electrophoresis assay revealed a slight decrease in the cationic charge density on the conjugates as these retarded the mobility of pDNA at higher w/w ratios. Further, transfection studies showed that both the series of conjugates transfected the mammalian cells efficiently with low-molecular weight polyethylenimine-streptomycin conjugates were more competent (∼9-fold enhancement with respect to native bPEI) exhibiting high cell viability too. Besides, both the series of conjugates displayed excellent antibacterial activity on pathogenic bacteria, even better than native streptomycin on resistant strains. Altogether, these results ensure the promising potential of the projected bifunctional conjugates as safe and efficient gene delivery vectors as well as antibacterials for future biomedical applications.

In vivo antimicrobial activity of silver nanoparticles produced via a green chemistry synthesis using Acacia rigidula as a reducing and capping agent

Introduction

One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells.

Purpose

In this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo.

Materials and methods

The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet–visible, and Fourier transform infrared.

Results

We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and a clinical multidrug-resistant strain of P. aeruginosa) and Gram-positive (Bacillus subtilis) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the results demonstrate that Ag-NPs can be used safely as therapeutic agents in animal models.

Conclusion

Together, these results suggest the potential use of Ag-NPs, synthesized by green chemistry methods, as therapeutic agents against infections caused by resistant and nonresistant strains.