Synthesis and biological characterization of silver nanoparticles derived from the cyanobacterium Oscillatoria limnetica

Cyanobacteria: miniature factories for green synthesis of metallic nanomaterials: a review

Nanotechnology is one of the most promising and advanced disciplines of science that deals with synthesis, characterization and applications of different types of Nanomaterials (NMs) viz. nanospheres, nanoparticles, nanotubes, nanorods, nanowires, nanocomposites, nanoalloys, carbon dots and quantum dots. These nanosized materials exhibit different physicochemical characteristics and act as a whole unit during its transport. The unique characteristics and vast applications of NMs in diverse fields viz. electronics, agriculture, biology and medicine have created huge demand of different type of NMs. Conventionally physical and chemical methods were adopted to manufacture NMs which are expensive and end up with hazardous by-products. Therefore, green synthesis exploiting biological resources viz. algae, bacteria, fungi and plants emerged as a better and promising alternative due to its cost effective and ecofriendly approach and referred as nanobiotechnology. Among various living organisms, cyanobacteria have proved one of the most favourable bioresources for NMs biosynthesis due to their survival in diverse econiches including metal and metalloid contaminated sites and capability to withstand high levels of metals. Biosynthesis of metallic NMs is accomplished through bioreduction of respective metal salts by various capping agents viz. alkaloids, pigments, polysaccharides, steroids, enzymes and peptides present in the biological systems. Advancement in the field of Nanobiotechnology has produced large number of diverse NMs from cyanobacteria which have been used as antimicrobial agents against Gram positive and negative human pathogens, anticancer agents, luminescent nanoprobes for imaging of cells, antifungal agents against plant pathogens, nanocatalyst and semiconductor quantum dots in industries and in bioremediation in toxic pollutant dyes. In the present communication, we have reviewed cyanobacteria mediated biosynthesis of NMs and their applications in various fields.

Comparative Antimicrobial Activity of Silver Nanoparticles Obtained by Wet Chemical Reduction and Solvothermal Methods

The synthesis of nanoparticles from noble metals has received high attention from researchers due to their unique properties and their wide range of applications. Silver nanoparticles (AgNPs), in particular, show a remarkable inhibitory effect against microorganisms and viruses. Various methods have been developed to obtain AgNPs, however the stability of such nanostructures over time is still challenging. Researchers attempt to obtain particular shapes and sizes in order to tailor AgNPs properties for specific areas, such as biochemistry, biology, agriculture, electronics, medicine, and industry. The aim of this study was to design AgNPs with improved antimicrobial characteristics and stability. Two different wet chemical routes were considered: synthesis being performed (i) reduction method at room temperatures and (ii) solvothermal method at high temperature. Here, we show that the antimicrobial properties of the obtained AgNPs, are influenced by their synthesis route, which impact on the size and shape of the structures. This work analyses and compares the antimicrobial properties of the obtained AgNPs, based on their structure, sizes and morphologies which are influenced, in turn, not only by the type or quantities of precursors used but also by the temperature of the reaction. Generally, AgNPs obtained by solvothermal, at raised temperature, registered better antimicrobial activity as compared to NPs obtained by reduction method at room temperature.

Tannic Acid-Modified Silver Nanoparticles in Conjunction with Contact Lens Solutions Are Useful for Progress against the Adhesion of Acanthamoeba spp. to Contact Lenses

Acanthamoeba spp. are amphizoic amoebae that are widely distributed in the environment and capable of entering the human body. They can cause pathogenic effects in different tissues and organs, including Acanthamoeba keratitis (AK), which may result in a loss of visual acuity and blindness. The diagnostics, treatment, and prevention of AK are still challenging. More than 90% of AK cases are related to the irresponsible wearing of contact lenses. However, even proper lens care does not sufficiently protect against this eye disease, as amoebae have been also found in contact lens solutions and contact lens storage containers. The adhesion of the amoebae to the contact lens surface is the first step in developing this eye infection. To limit the incidence of AK, it is important to enhance the anti-adhesive activity of the most popular contact lens solutions. Currently, silver nanoparticles (AgNPs) are used as modern antimicrobial agents. Their effectiveness against Acanthamoeba spp., especially with the addition of plant metabolites, such as tannic acid, has been confirmed. Here, we present the results of our further studies on the anti-adhesion potential of tannic acid-modified silver nanoparticles (AgTANPs) in combination with selected contact lens solutions against Acanthamoeba spp. on four groups of contact lenses. The obtained results showed an increased anti-adhesion activity of contact lens solutions in conjunction with AgTANPs with a limited cytotoxicity effect compared to contact lens solutions acting alone. This may provide a benefit in improving the prevention of amoebae eye infections. However, there is still a need for further studies on different pathogenic strains of Acanthamoeba in order to assess the adhesion of the cysts to the contact lens surface and to reveal a more comprehensive picture of the activity of AgTANPs and contact lens solutions.

An In Vitro and In Vivo Study of the Efficacy and Toxicity of Plant-Extract-Derived Silver Nanoparticles

Silver nanoparticles (AgNPs) display unique plasmonic and antimicrobial properties, enabling them to be helpful in various industrial and consumer products. However, previous studies showed that the commercially acquired silver nanoparticles exhibit toxicity even in small doses. Hence, it was imperative to determine suitable synthesis techniques that are the most economical and least toxic to the environment and biological entities. Silver nanoparticles were synthesized using plant extracts and their physico-chemical properties were studied. A time-dependent in vitro study using HEK-293 cells and a dose-dependent in vivo study using a Drosophila model helped us to determine the correct synthesis routes. Through biological analyses, we found that silver nanoparticles’ cytotoxicity and wound-healing capacity depended on size, shape, and colloidal stability. Interestingly, we observed that out of all the synthesized AgNPs, the ones derived from the turmeric extract displayed excellent wound-healing capacity in the in vitro study. Furthermore, the same NPs exhibited the least toxic effects in an in vivo study of ingestion of these NPs enriched food in Drosophila, which showed no climbing disability in flies, even at a very high dose (250 mg/L) for 10 days. We propose that stabilizing agents played a superior role in establishing the bio-interaction of nanoparticles. Our study reported here verified that turmeric-extract-derived AgNPs displayed biocompatibility while exhibiting the least cytotoxicity.

Silver Nanoparticle-Intercalated Cotton Fiber for Catalytic Degradation of Aqueous Organic Dyes for Water Pollution Mitigation

Azo dyes are commonly used in textile color processing for their wide array of vibrant colors. However, in recent years these dyes have become of concern in wastewater management given their toxicity to humans and the environment. In the present work, researchers remediated water contaminated with azo dyes using silver nanoparticles (Ag NPs) intercalated within cotton fabric as a catalyst, for their enhanced durability and reusability, in a reductive degradation method. Three azo dyes—methyl orange (MO), Congo red (CR), and Chicago Sky Blue 6B (CSBB)—were investigated. The azo degradation was monitored by UV/vis spectroscopy, degradation capacity, and turnover frequency (TOF). The Ag NP−cotton catalyst exhibited excellent degradation capacity for the dyes, i.e., MO (96.4% in 30 min), CR (96.5% in 18.5 min), and CSBB (99.8% in 21 min), with TOFs of 0.046 min−1, 0.082 min−1, and 0.056 min−1, respectively, using a 400 mg loading of catalyst for 100 mL of 25 mg L−1 dye. To keep their high reusability while maintaining high catalytic efficiency of >95% degradation after 10 cycles, Ag NPs immobilized within cotton fabric have promising potential as eco-friendly bio-embedded catalysts.

Ajwa-Dates (Phoenix dactylifera)-Mediated Synthesis of Silver Nanoparticles and Their Anti-Bacterial, Anti-Biofilm, and Cytotoxic Potential

Green nanotechnology is the evolution of cost-effective and environmentally friendly processes for the production of metal-based nanoparticles due to medicinal importance and economic value. The aim of the present study was to biosynthesize and characterize silver nanoparticles (AgNPs) using the seed extract of Ajwa dates (Aw). The anti-bacteriostatic activity of biosynthesized Aw–AgNPs against Gram-positive and Gram-negative bacterial strains was evaluated. The anti-biofilm activity was examined by the tissue culture plate method. Lastly, the anti-cancer potential of Aw–AgNPs was investigated against the human breast cancer cell line HCC712. UV–visible absorption spectra exhibited the plasmon resonance peak at 430 nm, with the solution undergoing rapid color changes that verified the existence of biosynthesized silver nanoparticles in the solution. TEM and SEM images illustrated that the Aw–AgNPs were spherical and between 15 and 80 nm in diameter. The reduction and stabilization of Aw–AgNPs was due to the functional groups present in the biomolecules of the Ajwa seeds, as identified by FTIR. The Aw–AgNPs exhibited significant anti-bacterial activity against all the tested bacterial strains. Moreover, the Aw–AgNPs efficiently hampered the biofilm formation of the bacterial strains and exhibited cytotoxicity at various concentrations. Overall, these findings suggest that biosynthesized Aw–AgNPs may be used as a potential therapeutic formulation against bacterial infections and breast cancer.

In Vitro and In Vivo Anticancer and Genotoxicity Profiles of Green Synthesized and Chemically Synthesized Silver Nanoparticles

Silver nanoparticles were green synthesized (Ag-PTs) employing the crude extract of Padina tetrastromatica, a marine alga, and their anticancer and safety profile were compared with those of chemically synthesized silver nanoparticles (Ag-NPs) by in vitro and in vivo models. Ag-PT exhibited potent cytotoxicity against B16-F10 (IC₅₀ = 3.29), MCF-7 (IC₅₀ = 4.36), HEPG2 (IC₅₀ =3.89), and HeLa (IC₅₀ = 4.97) cancer cell lines, whereas they exhibited lower toxicity on normal CHO-K1 cells (IC₅₀ = 5.16). The potent anticancer activity of Ag-PTs on cancer cells is due to the liberation of ions from the nanoparticles. Increased ion internalization to the cells promotes reactive oxygen species (ROS) production and ultimately leads to cell death. The in vitro anticancer results and in vivo melanoma tumor regression study showed significant inhibition of melanoma tumor growth due to Ag-PT treatment. Ag-PT is involved in the upregulation of the p53 protein and downregulation of Sox-2 along with the Ki-67 protein. The antitumor effects of Ag-PTs may be due to the additional release of ions at a lower pH of the tumor microenvironment than that of the normal tissue. The results of safety investigations of Ag-PT by studying mitotic chromosome aberrations (CAs), micronucleus (MN) induction, and mitotic index (MI) demonstrated Ag-PT to be less genotoxic compared to Ag-NP. The bioefficacy and toxicology outcomes together demonstrated that the green synthesized silver nanoparticles (Ag-PTs) could be explored to develop a biocompatible, therapeutic agent and a vehicle of drug delivery for various biomedical applications.

Recent progression of cyanobacteria and their pharmaceutical utility: an update

Cyanobacteria (blue-green algae) are Gram-negative photosynthetic eubacteria that are found everywhere. This largest group of photosynthetic prokaryotes is rich in structurally novel and biologically active compounds; several of which have been utilized as prospective drugs against cancer and other ailments, as well. Consequently, the integument of nanoparticles-synthetic approaches in cyanobacterial extracts should increase pharmacological activity. Moreover, silver nanoparticles (AgNPs) are small materials with diameters below 100 nm that are classified into different classes based on their forms, sizes, and characteristics. Indeed, the biosynthesized AgNPs are generated with a variety of organisms, algae, plants, bacteria, and a few others, for the medicinal purposes, as the bioactive compounds of curio and some proteins from cyanobacteria have the potentiality in the treatment of a wide range of infectious diseases. The critical focus of this review is on the antimicrobial, antioxidant, and anticancer properties of cyanobacteria. This would be useful in the pharmaceutical industries in the future drug development cascades.Communicated by Ramaswamy H. Sarma.

Green Synthesis of Silver Nanoparticles Incorporated Aromatherapies Utilized for Their Antioxidant and Antimicrobial Activities against Some Clinical Bacterial Isolates

There is a need to synthesize eco-friendly nanoparticles with more effective and potent antibacterial activities. A green and cost-effective method for the synthesis of silver nanoparticles (AgNPs) using Thymus vulgaris, Mentha piperita, and Zingiber officinale extracts was developed. The analytical instrumentation, namely, UV/Vis, absorption spectroscopy, FTIR, and scanning electron microscopy (SEM), was used to determine the developed AgNPs, confirming the functional groups involved in their reduction. Acidic molybdate, DPPH, and FRAP regents were reacted with AgNPs extract to evaluate their antioxidant, scavenging, and oxidative activities. The agar well diffusion method was used to determine the antibacterial potential of AgNPs extracts using clinical isolates. The developed AgNPs showed peaks at 25 cum\Diff, 50 cum\Diff, and 75 cum\Diff, respectively, of 16.59 ± 0.78, 45.94 ± 1.07, and 81.04 ± 0.98 nm, for Thymus vulgaris, Mentha piperita, and Zingiber officinale. SEM revealed uniform prepared and encapsulated AgNPs by plant extracts matrix. The FTIR shows the involvement of amide (-CO-NH₂), carbonyl (-CO), and hydroxyl (-OH), which resulted in the reduction of AgNPs. The AgNPs extract showed significantly higher TAA, DPPH, and FRAP values than free AgNPs and plant extract (p < 0.05). Antibacterial of AgNPs extracts revealed various degrees of inhibition zones against Escherichia coli, Acinetobacter baumannii, and Staphylococcus aureus. The developed AgNPs extract showed acceptable antioxidant activities and noticeable antibacterial potential. The prepared green synthesized AgNPs showed a promising antibacterial activity against four multidrug-resistant clinical isolates, Escherichia coli, Acinetobacter baumannii, and Staphylococcus aureus. Further, fractionated extracts other than crude extracts will be utilized in the preparation of AgNPs to get more efficient antibacterial activities for future work.

Cytotoxic Activity and Antibiofilm Efficacy of Biosynthesized Silver Nanoparticles against Methicillin-Resistant Staphylococcus aureus Strains Colonizing Cell Phones

The interest for green synthesis of metallic nanoparticles (NPs) has acquired particular attention due to its low toxicity and economic feasibility compared with chemical or physical process. Here we carried out an extracellular synthesis approach of silver nanoparticles (AgNPs) using dried orange peel extract. Characterization studies revealed the synthesis of 25–30 nm AgNPs with distinct morphology as observed in transmission electron microscopes. Dynamic light scattering spectroscopy and Fourier transform infrared spectroscopy analyses further characterized nanoparticles confirming their stability and the presence of functional groups. The biological properties of biosynthesized AgNPs were subsequently investigated. Our results revealed anticancer activity of biogenic silver NPs against the B16 melanoma cell line with an IC50 value of 25 µg/ml. Additionally, the developed AgNPs displayed a considerable antagonistic activity against methicillin-resistant Staphylococcus aureus (MRSA) strains colonizing cell phones, with inhibition zones between 12 and 14 mm and minimum inhibitory concentration values between 1.56 and 12.5 µg/ml. Furthermore, the AgNPs exhibited potent antibiofilm activity against MRSA strains with the percent biofilm disruption reaching 80%. Our results highlighted the efficacy of biosynthesized AgNPs against bacterial biofilms and pointed to the exploration of orange peels as a natural and cost-effective strategy.

A review on the toxicity of silver nanoparticles against different biosystems

Despite significant progress made in the past two decades, silver nanoparticles (AgNPs) have not yet made it to the clinical trials. In addition, they showed both positive and negative effects in their toxicity from unicellular organism to well-developed multi-organ system, for example, rat. Although it is generally accepted that capped (bio)molecules have synergistic bioactivities and diminish the toxicity of metallic Ag core, convincing evidence is completely lacking. Therefore, in this review, we first highlight the recent in vivo toxicity studies of chemically manufactured AgNPs, biologically synthesized AgNPs and reference AgNPs of European Commission. Then, their toxic effects are compared with each other and the overlooked factors leading to the potential conflict of obtained toxicity results are discussed. Finally, suggestions are given to better design and conduct the future toxicity studies and to fast-track the successful clinical translation of AgNPs as well.

Recent Advances and Mechanistic Insights into Antibacterial Activity, Antibiofilm Activity, and Cytotoxicity of Silver Nanoparticles

The substantial increase in multidrug-resistant (MDR) pathogenic bacteria is a major threat to global health. Recently, the Centers for Disease Control and Prevention reported possibilities of greater deaths due to bacterial infections than cancer. Nanomaterials, especially small-sized (size ≤10 nm) silver nanoparticles (AgNPs), can be employed to combat these deadly bacterial diseases. However, high reactivity, instability, susceptibility to fast oxidation, and cytotoxicity remain crucial shortcomings for their uptake and clinical application. In this review, we discuss various AgNPs-based approaches to eradicate bacterial infections and provide comprehensive mechanistic insights and recent advances in antibacterial activity, antibiofilm activity, and cytotoxicity (both in vitro and in vivo) of AgNPs. The mechanistic of antimicrobial activity involves four steps: (i) adhesion of AgNPs to cell wall/membrane and its disruption; (ii) intracellular penetration and damage; (iii) oxidative stress; and (iv) modulation of signal transduction pathways. Numerous factors affecting the bactericidal activity of AgNPs such as shape, size, crystallinity, pH, and surface coating/charge have also been described in detail. The review also sheds light on antimicrobial photodynamic therapy and the role of AgNPs versus Ag⁺ ions release in bactericidal activities. In addition, different methods of synthesis of AgNPs have been discussed in brief.

Recent Advances in Green Synthesis of Ag NPs for Extenuating Antimicrobial Resistance

Combating antimicrobial resistance (AMR) is an on-going global grand challenge, as recognized by several UN Sustainable Development Goals. Silver nanoparticles (Ag NPs) are well-known for their efficacy against antimicrobial resistance, and a plethora of green synthesis methodologies now exist in the literature. Herein, this review evaluates recent advances in biological approaches for Ag NPs, and their antimicrobial potential of Ag NPs with mechanisms of action are explored deeply. Moreover, short and long-term potential toxic effects of Ag NPs on animals, the environment, and human health are briefly discussed. Finally, we also provide a summary of the current state of the research and future challenges on a biologically mediated Ag-nanostructures-based effective platform for alleviating AMR.

Influence of biosynthesized silver nanoparticles using red alga Corallina elongata on broiler chicks’ performance

Poultry meat is a great source of protein and provides lots of nutrients such as iodine, iron, zinc, vitamins, and essential fatty acids that humans require. The positive applications of metal nanoparticles (NPs) in the diets of various poultry species were studied, in relation to their metabolic, antibacterial effects on digestion and regulation of bowel function. This study was carried out to test the effects of fabrication green silver nanoparticles (AgNPs) of Corallina elongata extract and/or coating NPs with acetic acid on performance, immune response parameters and micro-flora population in Ross broiler. Chicks’ drinking water was mixed with bio-AgNPs (1 mM) and coating NPs with acetic acid for 35 days. Fourier-transform infrared spectroscopy, electron dispersive spectroscopy (EDS) analysis, scanning electron microscopy, and high resolution transmission electron microscope were used to determine the partial physiochemical characterizations of bio-AgNPs and coating ones. EDS analysis was used to determine the presence of AgNP in meat. Results confirmed that coating NPs with acetic acid reduced percentage of the micro-flora population, which were detected by VITEK® 2 system (BioMérieux, France) and identified as Pseudomonas orizihabitain 4211210040000210 and Sphinogomonas paucimobilis 5201210040000210. EDS analysis of meat chicks confirmed disappearance of Ag metals. Coating biogenic AgNPs with acetic acid on modulated intestinal microbial populations of the Ross broiler may be safe, and could be used as alternative antibiotics or antibacterial agents besides their physiological performance in small intestines of broiler chicken.

Cyanobacterial biorefinery: Towards economic feasibility through the maximum valorization of biomass

Cyanobacteria are well known for their plethora of applications in the fields of food industry, pharmaceuticals and bioenergy. Their simple growth requirements, remarkable growth rate and the ability to produce a wide range of bio-active compounds enable them to act as an efficient biorefinery for the production of valuable metabolites. Most of the cyanobacteria based biorefineries are targeting single products and thus fails to meet the efficient valorization of biomass. On the other hand, multiple products recovering cyanobacterial biorefineries can efficiently valorize the biomass with minimum to zero waste generation. But there are plenty of bottlenecks and challenges allied with cyanobacterial biorefineries. Most of them are being associated with the production processes and downstream strategies, which are difficult to manage economically. There is a need to propose new solutions to eliminate these tailbacks so on to elevate the cyanobacterial biorefinery to be an economically feasible, minimum waste generating multiproduct biorefinery. Cost-effective approaches implemented from production to downstream processing without affecting the quality of products will be beneficial for attaining economic viability. The integrated approaches in cultivation systems as well as downstream processing, by simplifying individual processes to unit operation systems can obviously increase the economic feasibility to a certain extent. Low cost approaches for biomass production, multiparameter optimization and successive sequential retrieval of multiple value-added products according to their high to low market value from a biorefinery is possible. The nanotechnological approaches in cyanobacterial biorefineries make it one step closer to the goal. The current review gives an overview of strategies used for constructing self-sustainable- economically feasible- minimum waste generating; multiple products based cyanobacterial biorefineries by the efficient valorization of biomass. Also the possibility of uplifting new cyanobacterial strains for biorefineries is discussed.

Bell Shape Curves of Hemolysis Induced by Silver Nanoparticles: Review and Experimental Assay

The hemolytic activity assay is a versatile tool for fast primary toxicity studies. This work presents a systematic study of the hemolytic properties of ArgovitTM silver nanoparticles (AgNPs) extensively studied for biomedical applications. The results revealed an unusual and unexpected bell-shaped hemolysis curve for human healthy and diabetic donor erythrocytes. With the decrease of pH from 7.4 and 6.8 to 5.6, the hemolysis profiles for AgNPs and AgNO3 changed dramatically. For AgNPs, the bell shape changed to a step shape with a subsequent sharp increase, and for AgNO3 it changed to a gradual increase. Explanations of these changes based on the aggregation of AgNPs due to the increase of proton concentration were suggested. Hemolysis of diabetic donor erythrocytes was slightly higher than that of healthy donor erythrocytes. The meta-analysis revealed that for only one AgNPs formulation (out of 48), a bell-shaped hemolysis profile was reported, but not discussed. This scarcity of data was explained by the dominant goal of studies consisting in achieving clinically significant hemolysis of 5-10%. Considering that hemolysis profiles may be bell-shaped, it is recommended to avoid extrapolations and to perform measurements in a wide concentration interval in hemolysis assays.

Plant-Mediated Green Synthesis of Ag NPs and Their Possible Applications: A Critical Review

The potential applications of Ag NPs are exciting and beneficial in a variety of fields; however, there is less awareness of the new risks posed by inappropriate disposal of Ag NPs. The Ag NPs have medicinal, plasmonic, and catalytic properties. The Ag NPs can be prepared via physical, chemical, or biological routes, and the selection of any specific route depends largely on the end-use. The downside of a physical and chemical approach is that it requires a wide space, high temperature, high temperature for a longer time to preserve the thermal stability of synthesized Ag NPs, and the use of toxic chemicals. Although these methods produce nanoparticles with high purity and well-defined morphology, it is critical to develop cost-effective, energy-efficient, and facile route, such as green synthesis; it suggests the desirable use of renewable resources by avoiding the use of additional solvents and toxic reagents in order to achieve the ultimate goal. However, each method has its pros and cons. The synthesized Ag NPs obtained using the green approach have larger biocompatibility and are less toxic towards the biotic systems. However, identifying the phytoconstituents that are responsible for nanoparticle synthesis is difficult and has been reported as a suitable candidate for biological application. The concentration of the effective bioreducing phytoconstituents plays a crucial role in deciding the morphology of the nanoparticle. Besides these reaction times, temperature, pH, and concentration of silver salt are some of the key factors that determine the morphology. Hence, careful optimization in the methodology is required as different morphologies have different properties and usage. It is due to which the development of methods to prepare nanoparticles effectively using various plant extracts is gaining rapid momentum in recent days. To make sense of what involves in the bioreduction of silver salt and to isolate the secondary metabolites from plants are yet challenging. This review focuses on the contribution of plant-mediated Ag NPs in different applications and their toxicity in the aquatic system.

Antibacterial Effect of Silver Nanoparticles Is Stronger If the Production Host and the Targeted Pathogen Are Closely Related

Microbial resistance to antibiotics is one of the key challenges that lead to the search for alternate antimicrobial treatment approaches. Silver nanoparticles (AgNPs) are well known for their antimicrobial effects against a wide variety of drug-resistant microorganisms. AgNPs can be synthesized using microbial hosts, using a green and economical synthesis route, which produces extremely stable and highly active nanoparticles. Such green AgNPs are coated with a biological coating often referred to as a corona, originating from the production microorganism. In this study, we asked whether the composition of the biological corona might influence the antimicrobial activity of green AgNPs. To investigate this, we produced AgNPs in Pseudomonas putida KT2440 and Escherichia coli K12 MG1655, and tested them against pathogen species from the corresponding genera. AgNPs exhibited a size range of 15–40 nm for P. putida and 30–70 nm for E. coli, and both types of nanoparticles were surrounded by a thick biological corona layer, providing extreme stability. The nanoparticles remained stable over long periods and exhibited negative zeta potential values. P-AgNPs (obtained from P. putida) were tested against pathogenic Pseudomonas aeruginosa PAO1, and E-AgNPs (obtained from E. coli) were tested against pathogenic Escherichia coli UTI 89. Antimicrobial studies were conducted by Minimum bactericidal concentration (MBC), live/dead staining and SEM analysis. MBC of P-AgNPs against P. aeruginosa was 1 μg/mL, and MBC of E-AgNPs against E. coli UTI 89 was 8 μg/mL. In both cases, the MBC values were superior to those of green AgNPs produced in organisms unrelated to the target pathogens, available in the literature. Our results suggest that NPs produced in microorganisms closely related to the target pathogen may be more effective, indicating that the composition of the biological corona may play a crucial role in the antimicrobial mechanism of AgNPs.

Antimicrobial activity of chemically and biologically synthesized silver nanoparticles against some fish pathogens

Pathogens isolated from fish appear to possess considerable antimicrobial resistance and represent a problem for the economy and public health. Natural antimicrobial substitutes to traditional antibiotics represent an essential tool in the fight against antibiotic resistance. Nanotechnology has shown considerable potential in different research fields, and the antimicrobial properties of silver nanoparticles are known. Silver has been used for medical purposes since ancient times because of its bactericidal properties, and the highly reactive surfaces of silver nanoparticles (AgNPs) indicate that they might have a function in antimicrobial applications. This work aimed to study the antimicrobial properties of biologically produced AgNPs from Origanum vulgare leaves compared to chemically produced AgNPs. Both types were characterized by UV–vis spectrophotometry, TEM, and dynamic light scattering and tested against three bacterial strains (Streptococcus agalactiae, and Aeromonas hydrophila, both isolated from Nile tilapia and Vibrio alginolyticus, isolated from sea bass) and three fungal strains (Aspergillus flavus, Fusarium moniliforme, and Candida albicans, all isolated from Nile tilapia). Disk diffusion test and evaluation of ultrastructure changes of tested microorganisms treated with AgNPs by transmission electron microscopy were performed. Moreover, the hemolytic properties of AgNPs were studied on chicken and goat red blood cells. The results obtained declare that the green biological production of silver nanoparticles is safer and more effective than the chemical one; moreover, AgNPs have interesting dose-dependent antimicrobial properties, with better results for biologically produced ones; their effectiveness against tested bacterial and fungal strains opens the way to their use to limit fish diseases, increase economy and improve human health.

Biosynthesis and Characterization of Silver Nanoparticles Produced by Phormidium ambiguum and Desertifilum tharense Cyanobacteria

The world faces a challenge with the pervasion of multidrug-resistant bacteria that encourages scientists to develop and discover alternative, ecofriendly, and easy-to-produce new antibacterial agents. Our work is part of the greater effort of scientists around the world to achieve this goal by the biological synthesis of silver nanoparticles using cyanobacterial extracellular and intracellular components as nonchemical reducing agents. Two Egyptian cyanobacteria were isolated and identified according to 16S rRNA gene sequencing as Phormidium ambiguum and a novel species Desertifilum tharense. The sequences were deposited with accession numbers MW762709 and MW762710 for Desertifilum tharense and Phormidium ambiguum, respectively, in the GenBank. The results of UV-Vis analysis showed promising extracellular Ag-NPs synthesis by Desertifilum tharense and Phormidium ambiguum under light conditions. Therefore, these Ag-NPs were characterized and evaluated for antibacterial and antioxidant activity. TEM and SEM analyses revealed the spherical crystals with face-centered cubic structures and size range of 6.24-11.4 nm and 6.46-12.2 nm for Ag-NPs of Desertifilum tharense and Phormidium ambiguum, respectively. XRD and EDX results confirmed the successful synthesis of Ag-NPs in their oxide form or chloride form. The FTIR spectrum data confirmed the presence of hydroxyl and amide groups. Desertifilum tharense Ag-NPs displayed the largest inhibition zone that ranged from 9 mm against Micrococcus luteus ATCC 10240 to 25 mm against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300. For Phormidium ambiguum Ag-NPs, the inhibition zone diameter was in the range of 9 mm to 18 mm. The biosynthesized Ag-NPs significantly inhibited the growth of medically important resistance-pathogenic Gram-positive and Gram-negative bacteria. The Ag-NPs of Phormidium ambiguum exhibited the highest scavenging activity of 48.7% when compared with that of Desertifilum tharense, which displayed 43.753%.

Exploiting Rhizobium for Cadmium Sulphide Nanoparticle Synthesis: Heterologous Expression of an Escherichia coli DH10B Enzyme, YbdK [EC: 6.3.2.2] in Sinorhizobium fredii NGR234

Escherichia coli DH10B has 1.1 kb ybdK gene which is responsible for encoding YbdK enzyme that possess a Gamma glutamyl cysteine synthetase activity. ybdK gene was ligated downstream of a constitutive derepressed lac promoter of a low copy number plasmid vector pBBR1MCS-2, giving rise to a recombinant plasmid pPAT. Sinorhizobium fredii NGR234 transformed with pPAT showed an augmented production of glutathione which in turn increased the production of cadmium sulphide nanoparticles to some extent. Also, a heterologous expression of YbdK in Sinorhizobium fredii NGR234 improved the oxidation status of bacterial cells which is confirmed by fluorescence microscopy images and fluorometry. Genetically modified (GM) cells stained by DCFDA showed a significant decrease in fluorescence compared to wild type (WT) cells. Physical and chemical properties of the nanoparticles produced by the pPAT transformed Sinorhizobium fredii NGR234 differed significantly compared to wild type (WT) Sinorhizobium fredii NGR234. Comparative analysis of the nanoparticles by FTIR and SEM analysis revealed the functional groups attached to nanoparticles and average nanoparticle size respectively. Nanoparticles synthesized by genetically modified (GM) bacteria were about 3 times smaller in size compared to those produced by wild type (WT) rhizobium. FTIR analysis revealed an augmented presence of peptide with the nanoparticles produced by GM bacteria compared to those produced by the WT bacteria. XRD data revealed that biosynthesized CdS nanoparticles are face centered crystalline particles which was confirmed by comparing the peaks to standard JCPDS data (JCPDS card no. 10-454).

Green Synthesis and Potential Antibacterial Applications of Bioactive Silver Nanoparticles: A Review

Green synthesis of silver nanoparticles (AgNPs) using biological resources is the most facile, economical, rapid, and environmentally friendly method that mitigates the drawbacks of chemical and physical methods. Various biological resources such as plants and their different parts, bacteria, fungi, algae, etc. could be utilized for the green synthesis of bioactive AgNPs. In recent years, several green approaches for non-toxic, rapid, and facile synthesis of AgNPs using biological resources have been reported. Plant extract contains various biomolecules, including flavonoids, terpenoids, alkaloids, phenolic compounds, and vitamins that act as reducing and capping agents during the biosynthesis process. Similarly, microorganisms produce different primary and secondary metabolites that play a crucial role as reducing and capping agents during synthesis. Biosynthesized AgNPs have gained significant attention from the researchers because of their potential applications in different fields of biomedical science. The widest application of AgNPs is their bactericidal activity. Due to the emergence of multidrug-resistant microorganisms, researchers are exploring the therapeutic abilities of AgNPs as potential antibacterial agents. Already, various reports have suggested that biosynthesized AgNPs have exhibited significant antibacterial action against numerous human pathogens. Because of their small size and large surface area, AgNPs have the ability to easily penetrate bacterial cell walls, damage cell membranes, produce reactive oxygen species, and interfere with DNA replication as well as protein synthesis, and result in cell death. This paper provides an overview of the green, facile, and rapid synthesis of AgNPs using biological resources and antibacterial use of biosynthesized AgNPs, highlighting their antibacterial mechanisms.

Phytosynthesis of silver nanoparticles from Jatropha integerrima Jacq. flower extract and their possible applications as antibacterial and antioxidant agent

Jatropha integerrima Jacq. flower extract was used for the synthesis of silver nanoparticles in the current study. Various spectroscopic analyses were used to characterize the synthesized nanoparticles (JIF-AgNPs). The antibacterial efficacy of JIF-AgNPs was studied by well diffusion and microdilution techniques. In addition, the impact of JIF-AgNPs on free radicals was evaluated. On the ultraviolet–visible spectrum, the nanoparticles exhibit the highest absorbance at 422 nm. Based on the Fourier transform infrared spectrum, phenols and amino acids were involved in capping the JIF-AgNPs. Crystalline sphere-shaped nanoparticles with an average size of 50.07 nm and zeta potential of −19.0 mV were confirmed by X-ray diffraction, transmission electron microscopy, and dynamic light scattering analysis respectively. The JIF-AgNPs exhibit the highest and lowest growth inhibitory activity towards E. coli and B. subtilis. The minimal inhibitory concentration of JIF-AgNPs against E. coli, K. pneumoniae, S. aureus, and B. subtilis were 2.5, 5.0, 5.0, and 7.5 μg/mL, respectively. The JIF-AgNPs exhibited significant radical scavenging activities against DPPH (IC₅₀-32.5 ± 0.06 µg/mL), hydroxyl (IC₅₀-25 ± 0.09 µg/mL), Superoxide (IC₅₀-42.5 ± 0.13 µg/mL), and ABTs (IC₅₀-33.5 ± 0.15 µg/mL). Thus, synthesized nanoparticles were a good alternative to develop an antibacterial and antioxidant agent.

Arthrospira platensis-Mediated Green Biosynthesis of Silver Nano-particles as Breast Cancer Controlling Agent: In Vitro and In Vivo Safety Approaches

Biogenic silver nanoparticles (bio-AgNPs) is one of the most fascinating nanomaterials used for several biomedical purposes. In the current study, we biosynthesized AgNPs (bio-AgNPs) using Arthrospira platensis (A-bio-AgNPs), Microcystis aeruginosa (M-bio-AgNPs), and Chlorella vulgaris (C-bio-AgNPs) active metabolites and evaluated their anticancer efficacy against breast cancer. The recovered bio-AgNPs were characterized using scanning and transmission electron microscopy (SEM and TEM). In addition, their safety profiles were monitored in vitro on PBMCs cells and in vivo on Albino mice. The obtained results indicated the safety usage of bio-AgNPs at concentrations of 0.1 mg/ml on PBMCs cells and 1.5 mg/ml on the Albino mice. The bio-AgNPs displayed dose-dependent cytotoxic effects against HepG-2, CaCO-2, and MCF-7 cell lines by inducing reactive oxygen species (ROS) and arresting the treated cells in G0/G1 and sub G0 phases. In addition, A-bio-AgNPs induced breast cancer cellular apoptosis by downregulating the expression of survivin, MMP7, TGF, and Bcl2 genes. Upon A-bio-AgNPs treatment, a significant reduction in tumor growth and prolonged survival rates were recorded in breast cancer BALB/c model. Furthermore, A-bio-AgNPs treatment significantly decreased the Ki-67 protein marker from 60% (in the untreated group) to 20% (in the treated group) and increased caspase-3 protein levels to 65% (in treated groups) comparing with 45% (in doxorubicin-treated groups).

Silver Nanoparticle Production by the Cyanobacterium Cyanothece sp.: De Novo Manipulation of Nano-Biosynthesis by Phytohormones

Background: Numerous cyanobacteria have the potential to reduce metallic ions to form pure metal nanoparticles in a green biosynthesis process. Aim: To investigate the production capacity of silver nanoparticles by the cyanobacterium Cyanothece sp. and to examine the effect of five different phytohormones, indole acetic acid, kinetin; gibberellic acid; abscisic acid; and methyl jasmonate, on this capacity. Methods: The cyanobacterial strain was grown for 60 days and the harvested cyanobacterium biomass was incubated with 0.1 mM of AgNO₃. Percentage conversion of Ag⁺ to Ag⁰ was calculated to indicate the AgNPs’ production capacity. Different concentrations of the five phytohormones were added to cultures and the AgNP production was monitored throughout different time intervals. Results: Cyanothece sp. biosynthesized spherical AgNPs (diameter range 70 to 140 nm, average diameter 84.37 nm). The addition of indole acetic acid and kinetin provoked the maximum conversion (87.29% and 55.16%, respectively) of Ag⁺ to Ag⁰, exceeding or slightly below that of the control (56%). Gibberellic and abscisic acids failed to elevate the Ag⁺ to Ag⁰ conversion rate (45.23% and 47.95%, respectively) above that of the control. Methyl jasmonate increased the Ag⁺ to Ag⁰ conversion rate to 90.29%, although nearly all the cyanobacterial cultures died at the end. Conclusion: Phytohormones could be used to induce or inhibit the green production of AgNPs with the cyanobacterium Cyanothece sp. This novel manipulation technique may have several applications in agriculture or biomedicine.

Biogenic Synthesis, Characterization and Antibacterial Properties of Silver Nanoparticles against Human Pathogens

Biogenic synthesis of silver nanoparticles (AgNPs) is more eco-friendly and cost-effective approach as compared to the conventional chemical synthesis. Biologically synthesized AgNPs have been proved as therapeutically effective and valuable compounds. In this study, the four bacterial strains Escherichia coli (MT448673), Pseudomonas aeruginosa (MN900691), Bacillus subtilis (MN900684) and Bacillus licheniformis (MN900686) were used for the biogenic synthesis of AgNPs. Agar well diffusion assay revealed to determine the antibacterial activity of all biogenically synthesized AGNPs showed that P. aeruginosa AgNPs possessed significantly high (p < 0.05) antibacterial potential against all tested isolates. The one-way ANOVA test showed that that P. aeruginosa AgNPs showed significantly (p < 0.05) larger zones of inhibition (ZOI: 19 to 22 mm) compared to the positive control (rifampicin: 50 µg/mL) while no ZOI was observed against negative control (Dimethyl sulfoxide: DMSO). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) concentration against four test strains also showed that among all biogenically synthesized NPs, P. aeruginosa AgNPs showed effective MIC (3.3-3.6 µg/mL) and MBC (4.3-4.6 µg/mL). Hence, P. aeruginosa AGNPs were characterized using visual UV vis-spectroscopy, X ray diffractometer (XRD), fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The formation of peak around 430 nm indicated the formation of AgNPs while the FTIR confirmed the involvement of biological molecules in the formation of nanoparticles (NPs). SEM revealed that the NPs were of approximately 40 nm. Overall, this study suggested that the biogenically synthesized nanoparticles could be utilized as effective antimicrobial agents for effective disease control.

Hypnea musciformis-mediated Ag/AgCl-NPs inhibit pathogenic bacteria, HCT-116 and MCF-7 cells' growth in vitro and Ehrlich ascites carcinoma cells in vivo in mice

In the present study, Ag/AgCl‐NPs were biosynthesised using Hypnea musciformis seaweed extract; NPs synthesis was confirmed by a change of colour and observation of a razor‐sharp peak at 424 nm by UV–visible spectroscopy. Synthesised nanoparticles were characterised by transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray powder diffraction and Fourier transform infrared spectroscopy. Bacterial cell growth inhibition proves that the Ag/AgCl‐NPs have strong antibacterial activity and cell morphological alteration was observed in treated bacterial cells using propidium iodide (PI). Ag/AgCl‐NPs inhibited Ehrlich ascites carcinoma (EAC) cells, colorectal cancer (HCT‐116) and breast cancer (MCF‐7) cell line in vitro with the IC₅₀ values of 40.45, 24.08 and 36.95 μg/ml, respectively. Initiation of apoptosis in HCT‐116 and MCF‐7 cells was confirmed using PI, FITC‐annexin V and Hoechst 33342 dye. No reaction oxygen species generation was observed in both treated and untreated cell lines. A significant increase of ATG‐5 gene expression indicates the possibility of autophagy cell death besides apoptosis in MCF‐7 cells. The initiation of apoptosis in EAC cells was confirmed by observing caspase‐3 protein expression. Ag/AgCl‐NPs inhibited 22.83% and 51% of the EAC cell growth in vivo in mice when administered 1.5 and 3.0 mg/kg/day (i.p.), respectively, for 5 consequent days.

Synthesis, Characterization and Biomedical Application of Silver Nanoparticles

Silver nanoparticles (AgNPs) have been employed in various fields of biotechnology due to their proven properties as an antibacterial, antiviral and antifungal agent. AgNPs are generally synthesized through chemical, physical and biological approaches involving a myriad of methods. As each approach confers unique advantages and challenges, a trends analysis of literature for the AgNPs synthesis using different types of synthesis were also reviewed through a bibliometric approach. A sum of 10,278 publications were analyzed on the annual numbers of publication relating to AgNPs and biological, chemical or physical synthesis from 2010 to 2020 using Microsoft Excel applied to the Scopus publication database. Furthermore, another bibliometric clustering and mapping software were used to study the occurrences of author keywords on the biomedical applications of biosynthesized AgNPs and a total collection of 224 documents were found, sourced from articles, reviews, book chapters, conference papers and reviews. AgNPs provides an excellent, dependable, and effective solution for seven major concerns: as antibacterial, antiviral, anticancer, bone healing, bone cement, dental applications and wound healing. In recent years, AgNPs have been employed in biomedical sector due to their antibacterial, antiviral and anticancer properties. This review discussed on the types of synthesis, how AgNPs are characterized and their applications in biomedical field.

Influence of glucose, sucrose, and dextran coatings on the stability and toxicity of silver nanoparticles

Aqueous colloids, consisting of 15-30 nm-sized silver nanoparticles (Ag NPs), were prepared using the reducing and stabilizing abilities of glucose, sucrose, and dextran. The long-term stability of coated Ag NPs increases from glucose over sucrose to dextran, i.e., with the increase of the molecular weight of carbohydrate molecules. The density functional theory (DFT) calculations of the partial atomic (Mulliken) charges and adsorption energies are applied to explain the enhanced stability of coated Ag NPs. All coated Ag NPs have a significantly broader concentration range of nontoxic behavior toward pre-osteoblast cells than bare Ag NPs prepared using sodium borohydride. The carbohydrate-coated Ag NPs display the same level of toxic ability against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria as bare Ag NPs. The differences in toxicity mechanism of the coated and bare Ag NPs are a consequence of the absence and presence of co-occurring Ag+ ions in examined dispersion, respectively.

Synthesis, purification and characterization of Plectonema derived AgNPs with elucidation of the role of protein in nanoparticle stabilization

Driven by the need to biosynthesize alternate biomedical agents to prevent and treat infection, silver nanoparticles have surfaced as a promising avenue. Cyanobacteria-derived nanomaterial synthesis is of substantive interest as it offers an eco-friendly, cost-effective, sustainable, and biocompatible route for further development. In the present study optimal conditions for synthesis of silver nanoparticles (AgNPs) were 1 : 9 v/v [cell extract: AgNO₃ (1 mM)], pH 7.4, and 30 °C reaction temperatures. Synthesis of nanoparticles was monitored by UV-vis spectrophotometry and the maximum absorbance was observed at a wavelength of 420 nm. SEM with EDX analysis confirmed 96.85% silver by weight which revealed the purity of AgNPs. TEM & XRD analysis exhibited a particle size of ∼12 nm with crystalline nature. FTIR analysis confirmed the presence of possible biomolecules involved in the synthesis and stabilization of AgNPs. Decapping of AgNPs followed by SDS-PAGE, LCMS and MALDI TOF analysis elucidates the proteinaceous nature of the capping and stabilizing agent. Cyanobacterial-derived capped AgNPs showed more cytotoxicicity towards a non-small cell lung cancer (A549) cell line, free radical scavenger and an antimicrobial than de-capped AgNPs. In addition they showed significant synergistic characteristics with antibiotics and fungicides. The test revealed that the capped AgNPs were biocompatible with good anti-inflammatory properties. The blend of antimicrobial and biocompatible properties, coupled with their intrinsic “green” and facile synthesis, made these biogenic nanoparticles particularly attractive for future applications in nanomedicine.

Illuminating the role of protein on the surface of cyanobacterial derived capped, decapped AgNPs and its biomedical application.

Biosynthesis and Characterization of Extracellular Silver Nanoparticles from Streptomyces aizuneusis: Antimicrobial, Anti Larval, and Anticancer Activities

The ability of microorganisms to reduce inorganic metals has launched an exciting eco-friendly approach towards developing green nanotechnology. Thus, the synthesis of metal nanoparticles through a biological approach is an important aspect of current nanotechnology. In this study, Streptomyces aizuneusis ATCC 14921 gave the small particle of silver nanoparticles (AgNPs) a size of 38.45 nm, with 1.342 optical density. AgNPs produced by Streptomyces aizuneusis were characterized by means of UV-VIS spectroscopy and transmission electron microscopy (TEM). The UV-Vis spectrum of the aqueous solution containing silver ion showed a peak between 410 to 430. Moreover, the majority of nanoparticles were found to be a spherical shape with variables between 11 to 42 nm, as seen under TEM. The purity of extracted AgNPs was investigated by energy dispersive X-ray analysis (EDXA), and the identification of the possible biomolecules responsible for the reduction of Ag+ ions by the cell filtrate was carried out by Fourier Transform Infrared spectrum (FTIR). High antimicrobial activities were observed by AgNPs at a low concentration of 0.01 ppm, however, no deleterious effect of AgNPs was observed on the development and occurrence of Drosophila melanogaster phenotype. The highest reduction in the viability of the human lung carcinoma and normal cells was attained at 0.2 AgNPs ppm.

Pharmacological properties of biogenically synthesized silver nanoparticles using endophyte Bacillus cereus extract of Berberis lyceum against oxidative stress and pathogenic multidrug-resistant bacteria

The emergence of multidrug resistance in pathogenic bacteria limits the utilization of available antibiotics. The development of alternate options to treat infectious diseases is the need of the day.The present study was aimed to synthesize, characterize and evaluate the bioactive properties of silver nanoparticles. Endophytic bacterium Bacillus cereus (MT193718) isolated from Berberis lycium was used to synthesize biocompatible silver nanoparticles. Antibacterial properties of AgNPs were evaluated against clinically isolated multidrug-resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. AgNPs indicated significant antibacterial activity against S. aureus and K. pneumoniae fwith a zone of inhibition of 17 and 18 mm at a concentration of 1000 µg/ mL with minimum inhibitory concentration of 15.6 and 62.5 µg/mL respectively. Significant antioxidant activity with an IC50 value of 9.5 µg/mL was recorded. Biosynthesized AgNPs were found compatible with red blood cells at a concentration of 31.5 µg/ml with no clumping of erythrocytes. The study suggested that AgNPs synthesized by the endophytic bacterium Bacillus cereus are biologically active and can be used as antioxidant and antibacterial agents against drug-resistant bacteria.

Marine organisms: Pioneer natural sources of polysaccharides/proteins for green synthesis of nanoparticles and their potential applications

Current innovations in the marine bionanotechnology arena are supporting and stimulating developments in other fields, including nanomedicine, pharmaceuticals, sensors, environmental trends, food, and agriculture aspects. Many oceanic creatures, particularly algae, plants, bacteria, yeast, fungi, cyanobacteria, actinomyces, invertebrates, animals and sponges can survive under extreme circumstances. They can biogenerate a broad spectrum of phytochemicals/metabolites, including proteins, peptides, alkaloids, flavonoids, polyphenols, carbohydrate polymers, polysaccharides, sulfated polysaccharides, polysaccharide-protein complexes such as carrageenan, fucoidanase, fucoidan, carboxymethyl cellulose, poly-γ-glutamic acid, sugar residues with proteins, melanin, haemocyanin, etc). These products exhibit exclusive advantages that offer pioneering roles in the eco-friendly fabrication of several nanoparticles (NPs) i.e., Ag, Au, Ru, Fe₂O₃, Cobalt (III) Oxide (Co₂O₃), ZnO and Ag@AgCl within a single phase. Importantly, marine organisms can biosynthesize NPs in two modes, namely extracellular and intracellular. Biosynthesized NPs can be characterized using various methodologies among them, ultraviolet-visible spectroscopy, fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Taken together, this review focuses on the green synthesis of metallic, metallic oxides and nonmetallic NPs utilizing extracts/derivatives from marine organisms based on eco-friendly green biogenic procedures. Moreover, significant attention is given to the medicinal and industrial importance of such marine organisms mediated NPs.

Biogenic Silver Nanoparticles: What We Know and What Do We Need to Know?

Nanobiotechnology is considered to be one of the fastest emerging fields. It is still a relatively new and exciting area of research with considerable potential for development. Among the inorganic nanomaterials, biogenically synthesized silver nanoparticles (bio-AgNPs) have been frequently used due to their unique physicochemical properties that result not only from their shape and size but also from surface coatings of natural origin. These properties determine antibacterial, antifungal, antiprotozoal, anticancer, anti-inflammatory, and many more activities of bio-AgNPs. This review provides the current state of knowledge on the methods and mechanisms of biogenic synthesis of silver nanoparticles as well as their potential applications in different fields such as medicine, food, agriculture, and industries.