Extracellular directed ag NPs formation and investigation of their antimicrobial and cytotoxic properties

Plant-Based Synthesis, characterization Approaches, Applications and Toxicity of Silver Nanoparticles: A Comprehensive Review

The development of an environmentally benign method for the synthesis of nanoparticles has been facilitated by green chemistry. "Green synthesis" uses a range of biological elements like microbes, plants, and other biodegradable materials to produce NPs. Active biomolecules that are secreted by natural strains and present in the plant extracts serve as both reducing and capping/stabilizing agents. Microorganisms' intracellular enzymes can reduce metal ions, which explains how NPs might potentially nucleate. Plant-based synthesis of nanomaterials is particularly promising owing to abundant resources, simplicity of synthesis, and low cost. Silver nanoparticles (AgNPs) are attracting great attention in the research community due to their wide variety of applications in chemistry, food technology, microbiology, and biomedicine. Recent years have seen a large amount of research on the bio-genic synthesis of AgNPs employing biomaterials like plant extract and bacteria as reducing agents. Herein we discuss a thorough overview of the plant-based synthesis of silver nanoparticles (AgNPs), characterization approaches, applications, and toxicity. The review covers the green chemistry and nanotechnology elements of producing AgNPs, including a thorough discussion of the plant extract mediated synthesis, detailed formation mechanism, and a well-balanced emphasis on hazards and advantages. Based on current developments, the optimisation strategies, applications, and interdisciplinary characteristics are also covered in detail.

Green biologically synthesized metal nanoparticles: biological applications, optimizations and future prospects

In green biological synthesis, metal nanoparticles are produced by plants or microorganisms. Since it is ecologically friendly, economically viable and sustainable, this method is preferable to other traditional ones. For their continuous groundbreaking advancements and myriad physiochemical and biological benefits, nanotechnologies have influenced various aspects of scientific fields. Metal nanoparticles (MNPs) are the field anchor for their outstanding optical, electrical and chemical capabilities that outperform their regular-sized counterparts. This review discusses the most current biosynthesized metal nanoparticles synthesized by various organisms and their biological applications along with the key elements involved in MNP green synthesis. The review is displayed in a manner that will impart assertiveness, help the researchers to open questions, and highlight many points for conducting future research.

Evaluation of the antibacterial activity of dental adhesive containing biogenic silver nanoparticles decorated nanographene oxide nanocomposites (Ag@nGO NCs) and effect on bond strength to dentine

Our study aimed to evaluate the antibacterial activities and dentin bond strengths of silver nanoparticles (Ag NPs) and silver nano-graphene oxide nanocomposites (Ag@nGO NCs) produced by green and chemical synthesis methods added to the dental adhesive. Ag NPs were produced by green synthesis (biogenic) (B-Ag NPs) and chemical synthesis methods (C-Ag NPs) and deposited on nGO (nano-graphene oxide). Ag NPs and Ag@nGO NCs (0.05% w/w) were added to the primer and bond (Clearfil SE Bond). Group 1: control, Group 2: nGO, Group 3: B-Ag NPs, Group 4: B-Ag@nGO NCs, Group 5: C-Ag NPs, Group 6: C-Ag@nGO NCs. Streptococcus mutans (S. mutans) live/dead assay analysis, MTT metabolic activity test, agar disc diffusion test, lactic acid production, and colony forming units (CFUs) tests were performed. Bond strength values were determined by the microtensile bond strength test (μTBS). Failure types were determined by evaluating with SEM. Statistical analysis was performed using one-way ANOVA and two-way ANOVA (p < 0.05). There was a difference between the groups in the viable bacteria ratio and lactic acid production tests (p < 0.05). When the inhibition zone and S. mutans CFUs were evaluated, there was no difference between Group 3 and Group 4 (p > 0.05), but there was a difference between the other groups (p < 0.05). When the metabolic activity of S. mutans was evaluated, there was a difference between Group 1 and other groups, and between Group 2 and Group 5, and Group 6 (p < 0.05). There was no difference between the groups in the μTBS values (p > 0.05). As a result, although the antibacterial activity of B-Ag NPs and B-Ag@nGO Ag NPs obtained by green synthesis is lower than that of chemically synthesis obtained C-Ag NPs and C-Ag@nGO NCs, they provided higher antibacterial activity compared to the control group and did not reduce μTBS. The addition of biogenic Ag NPs to the adhesive system increased the antibacterial effect by maintaining the bond strength of the adhesive. Antibacterial adhesives can increase the restoration life by protecting the tooth-adhesive interface.

Promising antimicrobial and antibiofilm activities of Orobanche aegyptiaca extract-mediated bimetallic silver-selenium nanoparticles synthesis: Effect of UV-exposure, bacterial membrane leakage reaction mechanism, and kinetic study

In this research, Orobanche aegyptiaca extract was utilized as an eco-friendly, and cost-effective green route for the construction of bimetallic silver-selenium nanoparticles (Ag-Se NPs). Bimetallic Ag-Se NPs were characterized by XRD, EDX, FTIR, HR-TEM, DLS, SEM/mapping and EDX studies. Antimicrobial, and antibiofilm potentials were tested against some selected pathogenic bacteria and unicellular fungi by ZOI, MIC, effect of UV exposure, and inhibition %. Reaction mechanism was assessed through membrane leakage assay and SEM imaging. HRTEM analysis confirmed the spherical nature and was ranged from 18.1 nm to 72.0 nm, and the avarage particle size is determined to be 30.58 nm. SEM imaging prove that bimetallic Ag-Se NPs presents as a bright particles, and both Ag and Se were distributed equally across O. aegyptiaca extract and Guar gum stabilizers. ZOI results showed that, bimetallic Ag-Se NPs have antimicrobial activity against S. aureus (20.0 nm), E. coli (18.5 nm), P. aeruginosa (12.6 nm), and C. albicans (18.2 nm). In addition, bimetallic Ag-Se NPs were able to inhibit the biofilm formation for S. aureus by 79.48%, for E. coli by 78.79%, for P. aeruginosa by 77.50%, and for C. albicans by 73.73%. Bimetallic Ag-Se NPs are an excellent disinfectant once it had excited by UV light. It was observed that the quantity of cellular protein discharged from S. aureus is directly proportional to the concentration of bimetallic Ag-Se NPs and found to be 244.21 μg/mL after the treatment with 1 mg/mL, which proves the antibacterial characteristics, and explains the creation of holes in the cell membrane of S. aureus producing in the oozing out of the proteins from the S. aureus cytoplasm. Based on the promising properties, they showed superior antimicrobial potential at low concentration (to avoid toxicity) and continued-phase durability, they may use in pharmaceutical and biomedical applications.

Synergistic and antibiofilm potential of Curcuma aromatica derived silver nanoparticles in combination with antibiotics against multidrug-resistant pathogens

Hospital acquired infections caused due to ESKAPE pathogens pose a challenge for treatment due to their growing antimicrobial resistance. Curcuma aromatica (CA) is traditionally known for its antibacterial, wound healing and anti-inflammatory properties. The present study highlights the biogenic synthesis of silver nanoparticles (CAAgNPs) capped and stabilized by the compounds from CA rhizome extract, also further demonstrating their antibacterial, antibiofilm and synergistic effects against multidrug-resistant (MDR) pathogens. CAAgNPs were synthesized using aqueous rhizome extract of CA (5 mg/ml) and AgNO3 (0.8 mM) incubated at 60°C up to 144 h. UV-vis spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) revealed CAAgNPs with characteristic peak at 430 nm, 13 ± 5 nm size of spherical shape, showing presence of silver and crystalline nature, respectively. Dynamic light scattering (DLS) and zeta potential confirmed their monodispersed nature with average diameter of 77.88 ± 48.60 nm and stability. Fourier transform infrared spectroscopic (FTIR) analysis demonstrated the presence of phenolic -OH and carbonyl groups possibly involved in the reduction and stabilization of CAAgNPs. The minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs) and minimum biofilm inhibitory concentrations (MBICs) of CAAgNPs against Pseudomonas aeruginosa, NCIM 5029 and PAW1, and, Staphylococcus aureus, NCIM 5021 and S8 were in range from 8 to 128 μg/ml. Almost 50% disruption of pre-formed biofilms at concentrations 8-1,024 μg/ml was observed. Fluorescence microscopy and FESEM analysis confirmed cell death and disruption of pre-formed biofilms of P. aeruginosa PAW1 and S. aureus S8. Checkerboard assay demonstrated the synergistic effect of CAAgNPs (0.125-4 μg/ml) in combination with various antibiotics (0.063-1,024 μg/ml) against planktonic and biofilm forms of P. aeruginosa PAW1. The study confirms the antibacterial and antibiofilm activity of CAAgNPs alone and in combination with antibiotics against MDR pathogens, thus, reducing the dose as well as toxicity of both. CAAgNPs have the potential to be used in wound dressings and ointments, and to improve the performances of medical devices and surgical implants. In vivo toxicity of CAAgNPs however needs to be tested further using mice models.

Investigation of ellagic acid rich-berry extracts directed silver nanoparticles synthesis and their antimicrobial properties with potential mechanisms towards Enterococcus faecalis and Candida albicans

The essential goals of this present study are to elucidate the formation mechanism of ellagic acid rich-blackberry, BBE, (Rubus fruticosus L.) and raspberry, RBE, (Rubus idaeus L.) extracts directed silver nanoparticles and to investigate thier antimicrobial properties towards model dental pathogens E. faecalis and C. albicans compared to BBE, RBE, NaOCl, CHX and EDTA. Both %5 w/w of BBE and RBE reacted with 5 mM Ag ⁺ ions at room temperature (25 °C) under mild-stirring, the formation of BBE and RBE directed b@Ag NP and r@Ag NP was monitored over time by using an Uv-vis spectrophotometer. Both b@Ag and r@Ag NPs were also complementarily characterized with SEM and FT-IR. In terms of the antimicrobial studies, b@Ag NP, r@Ag NP, %5 BBE and RBE, 5 mM AgNO₃, %5 NaOCl, %1,5 CHX and %15 EDTA were separately incubated with E. faecalis and C. albicans suspensions. The results were evaluated with student t-test using GraphPad Prism 8.0.1 statistical software (P < 0.05). While formation of b@Ag NP was confirmed with characteristic absorbance at ~435 nm in 20 min (min) of incubation, r@Ag NP did not give absorbance till 80 min owing to concentration of ellagic acid acted as a reducing and stabilizng agent for formation of the Ag NPs. Intrestingly, 50 ppm r@Ag NP inactivated ∼89% and ∼99% of E. faecalis and C. albicans cell, respectively, ∼25% and ∼40% cell inactivations for E. faecalis and C. albicans were observed respectively with 50 ppm b@Ag NP. We showed that 50 ppm r@Ag NP has effective antimicrobial property as much as mostly used %5 NaOCl and %1,5 CHX solutions.

One-pot fabrication of Ag @Ag2O core-shell nanostructures for biosafe antimicrobial and antibiofilm applications

Microbial contamination is one of the major dreadful problems that raises hospitalization, morbidity and mortality rates globally, which subsequently obstructs socio-economic progress. The continuous misuse and overutilization of antibiotics participate mainly in the emergence of microbial resistance. To circumvent such a multidrug-resistance phenomenon, well-defined nanocomposite structures have recently been employed. In the current study, a facile, novel and cost-effective approach was applied to synthesize Ag@Ag₂O core-shell nanocomposites (NCs) via chemical method. Several techniques were used to determine the structural, morphological, and optical characteristics of the as-prepared NCs. XRD, Raman, FTIR, XPS and SAED analysis revealed a crystalline hybrid structure of Ag core and Ag₂O shell. Besides, SEM and HRTEM micrographs depicted spherical nanoparticles with size range of 19-60 nm. Additionally, zeta potential and fluorescence spectra illustrated aggregated nature of Ag@Ag₂O NCs by - 5.34 mV with fluorescence emission peak at 498 nm. Ag@Ag₂O NCs exhibited higher antimicrobial, antibiofilm, and algicidal activity in dose-dependent behavior. Interestingly, a remarkable mycocidal potency by 50 μg of Ag@Ag₂O NCs against Candida albican; implying promising activity against COVID-19 white fungal post-infections. Through assessing cytotoxicity, Ag@Ag₂O NCs exhibited higher safety against Vero cells than bulk silver nitrate by more than 100-fold.

Biological Nanofactories: Using Living Forms for Metal Nanoparticle Synthesis

Metal nanoparticles are nanosized entities with dimensions of 1-100 nm that are increasingly in demand due to applications in diverse fields like electronics, sensing, environmental remediation, oil recovery and drug delivery. Metal nanoparticles possess large surface energy and properties different from bulk materials due to their small size, large surface area with free dangling bonds and higher reactivity. High cost and pernicious effects associated with the chemical and physical methods of nanoparticle synthesis are gradually paving the way for biological methods due to their eco-friendly nature. Considering the vast potentiality of microbes and plants as sources, biological synthesis can serve as a green technique for the synthesis of nanoparticles as an alternative to conventional methods. A number of reviews are available on green synthesis of nanoparticles but few have focused on covering the entire biological agents in this process. Therefore present paper describes the use of various living organisms like bacteria, fungi, algae, bryophytes and tracheophytes in the biological synthesis of metal nanoparticles, the mechanisms involved and the advantages associated therein.

Comprehensive facts on dynamic antimicrobial properties of polysaccharides and biomolecules-silver nanoparticle conjugate

Based on progress for the green synthesis of nanoparticle (NPs), the mushrooms have also been utilized extensively for the biogenic synthesis of NPs. In recent years, silver NPs have been fabricated using mushrooms. The antimicrobial drugs are efficient to control the infectious diseases, but due to widespread of drugs, microbes became resistant to drugs, which demands develop of new bioactive agents. The silver NPs have been recognized as efficient broad spectrum antimicrobial agents, which have been fabricated using polysaccharides from mushrooms as reducing and capping agent. This review focused on the comprehensive study that deals silver NPs polysaccharides from Pleurotus mushroom, their synthesis mechanism, action mechanism of silver NPs and their characterization using advanced techniques i.e., ultraviolet-visible (UV-Vis), dynamic light scattering, Fourier transformation infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and XRD. The Pleurotus mushroom showed promising efficiency for the biogenic synthesis of polysaccharides‑silver NPS and as-prepared NPs showed excellent antimicrobial activity.

Ginkgo biloba mitigates silver nanoparticles-induced hepatotoxicity in Wistar rats via improvement of mitochondrial biogenesis and antioxidant status

Silver nanoparticles (AgNPs) are noble metal nanoparticles, due to their good physicochemical properties, which have been exploited in biological applications. Nanotechnological applications advance very quickly while few literatures assessed the effects of natural products on the risks of nanoparticles in vivo. Thirty male adult rats were enrolled equally into: control, AgNPs (50 mg/kg b.w i.p 3 times/week) and GBE (100 mg/kg b.w daily per os)+AgNPs. After 30 days, the assessment of liver function, antioxidative status, mitochondrial biogenesis, and histopathological analyses were performed. AgNP exposure enhanced the hepatic lipid peroxidation (+ 281.7%) along with a decline in the reduced glutathione (- 58.3%) levels. The apparent hepatic oxidative damage was associated with obvious hepatic dysfunction that was ascertained by alteration of serum liver enzymatic biomarkers, lipid profile, and pathological hepatic lesions. Following AgNP exposure, hepatic silver and calcium contents were increased without changes in the trace element concentrations. Finally, the mRNA transcripts of hepatic PGC-1α, mtTFA, and Nrf2 were downregulated after AgNP exposure. Interestingly, GBE has the ability to alleviate AgNP-induced hepatic damage assessed by augmentation of reduced glutathione level and mitochondrial biogenesis. This study explored the potential protective role of GBE on AgNPs-induced hepatotoxicity via attenuation of oxidative stress, substantial enhancement of cell viability with concomitant mitigating DNA damage, and mitochondrial dysfunction.