Formation of Variously Shaped Gold Nanoparticles by Anabaena laxa

Apoptotic Induction by Biosynthesized Gold Nanoparticles Using Phormidesmis communis Strain AB_11_10 against Osteosarcoma Cancer

Phormidesmis communis strain AB_11_10 was isolated and identified using microscopy and 16s rRNA sequencing, and its phytochemical constituents were determined using liquid chromatography-quadrupole time-of-flight mass spectrometry. The isolate had a segmented filamentous shape with a blue-green color. Many biomolecules, including organic compounds, amino acids, and fatty acids, were detected. P. communis strain AB_11_10 was used to synthesize gold nanoparticles (Ph-AuNPs) by adjusting the optimum reaction conditions. The concentration, algal/precursor ratio, temperature, reaction time, and pH significantly influenced the synthesis of the Ph-AuNPs. Mixing 1 mL of 0.5 mM of HAuCl4 with 1 mL of algal extract and exposing the mixture to 100 °C for 30 min at pH 5.6 were the optimum conditions for the biosynthesis of Ph-AuNPs at a wavelength of 524.5 nm. The Ph-AuNPs were characterized using TEM, SEM, EDX, and mapping Zeta sizer and FTIR. The Ph-AuNPs had quasi-spherical to triangular shapes with an average diameter of 9.6 ± 4.3 nm. Ph-AuNPs composed of 76.10 ± 3.14% of Au and trace amounts of carbon and oxygen were detected, indicating that the P. communis strain AB_11_10 successfully synthesized Ph-AuNPs. The hydrodynamic diameter of the Ph-AuNPs was 28.5 nm, and their potential charge was -17.7 mV. O-H, N-H, C=C, N-O, C-H, and C-O were coated onto the surfaces of the Ph-AuNPs. These groups correspond to algal phytochemicals, which may have been the main reducing and stabilizing substances during the Ph-AuNP synthesis. The therapeutic activity of the Ph-AuNPs against osteosarcoma cancers was examined in MG-63 and SAOS-2 cell lines, while their biocompatibility was tested against Vero cell lines using a sulforhodamine B assay. The Ph-AuNPs had potent antitumor activity against the MG-63 and SAOS-2 cells, with a low toxicity toward Vero cells. Flow cytometry and cell cycle arrest analyses revealed that the Ph-AuNPs enhanced the apoptotic pathway and arrested the cell cycle in the MG-63 and SAOS-2 cells. P. communis strain AB_11_10 provides a new source to synthesize small, stable, and biocompatible AuNPs that act as apoptotic enhancers in osteosarcoma.

Time-Dependent Size and Shape Evolution of Gold and Europium Nanoparticles from a Bioproducing Microorganism, a Cyanobacterium: A Digitally Supported High-Resolution Image Analysis

Herein, the particle size distributions (PSDs) and shape analysis of in vivo bioproduced particles from aqueous Au³⁺ and Eu³⁺ solutions by the cyanobacterium Anabaena sp. are examined in detail at the nanoscale. Generally, biosynthesis is affected by numerous parameters. Therefore, it is challenging to find the key set points for generating tailored nanoparticles (NPs). PSDs and shape analysis of the Au and Eu-NPs were performed with ImageJ using high-resolution transmission electron microscopy (HR-TEM) images. As the HR-TEM image analysis reflects only a fraction of the detected NPs within the cells, additional PSDs of the complete cell were performed to determine the NP count and to evaluate the different accuracies. Furthermore, local PSDs were carried out at five randomly selected locations within a single cell to identify local hotspots or agglomerations. The PSDs show that particle size depends mainly on contact time, while the particle shape is hardly affected. The particles formed are distributed quite evenly within the cells. HR-PSDs for Au-NPs show an average equivalent circular diameter (ECD) of 8.4 nm (24 h) and 7.2 nm (51 h). In contrast, Eu-NPs preferably exhibit an average ECD of 10.6 nm (10 h) and 12.3 nm (244 h). Au-NPs are classified predominantly as "very round" with an average reciprocal aspect ratio (RAR) of ~0.9 and a Feret major axis ratio (FMR) of ~1.17. Eu-NPs mainly belong to the "rounded" class with a smaller RAR of ~0.6 and a FMR of ~1.3. These results show that an increase in contact time is not accompanied by an average particle growth for Au-NPs, but by a doubling of the particle number. Anabaena sp. is capable of biosorbing and bioreducing dissolved Au³⁺ and Eu³⁺ ions from aqueous solutions, generating nano-sized Au and Eu particles, respectively. Therefore, it is a low-cost, non-toxic and effective candidate for a rapid recovery of these sought-after metals via the bioproduction of NPs with defined sizes and shapes, providing a high potential for scale-up.

Biomedical Applications of Biosynthesized Gold Nanoparticles from Cyanobacteria: an Overview

Recently there had been a great interest in biologically synthesized nanoparticles (NPs) as potential therapeutic agents. The shortcomings of conventional non-biological synthesis methods such as generation of toxic byproducts, energy consumptions, and involved cost have shifted the attention towards green syntheses of NPs. Among noble metal NPs, gold nanoparticles (AuNPs) are the most extensively used ones, owing to the unique physicochemical properties. AuNPs have potential therapeutic applications, as those are synthesized with biomolecules as reducing and stabilizing agent(s). The green method of AuNP synthesis is simple, eco-friendly, non-toxic, and cost-effective with the use of renewable energy sources. Among all taxa, cyanobacteria have attracted considerable attention as nano-biofactories, due to cellular uptake of heavy metals from the environment. The cellular bioactive pigments, enzymes, and polysaccharides acted as reducing and coating agents during the process of biosynthesis. However, cyanobacteria-mediated AuNPs have potential biomedical applications, namely, targeted drug delivery, cancer treatment, gene therapy, antimicrobial agent, biosensors, and imaging.

Antimicrobial, antibiofilm potential, and anti-quorum sensing activity of silver nanoparticles synthesized from Cyanobacteria Oscillatoria princeps

Cyanobacteria are among the beneficial and environmentally friendly natural candidates used in the biosynthesis of nanoparticles, with their ability to accumulate heavy metals from their environment, thanks to their biologically active compounds. In the current study, an aqueous extract of Oscillatoria princeps fresh biomass was used for the green synthesis of AgNPs. UV-vis spectrum, Fourier transforms infrared, scanning electron microscopy, and energy-dispersive spectroscopy were used to validate and characterize biosynthesized of OSC-AgNPs. The biosynthesis of AgNPs was visually verified in terms of the change in the color of the AgNO₃ solution from yellowish brown to brown colors from 72 h onwards. An absorption peak of approximately 420 nm was detected in the UV-vis spectrum, corresponding to the plasmon resonance of AgNPs. FT-IR analysis showed the presence of free amino groups in addition to sulfur-containing amino acid derivatives that act as stabilizing agents. SEM images detected the roughly spherical shape of OSC-AgNPs with an average size of 38 nm. The pathogens tested were all susceptible to OSC-AgNPs showing varying antimicrobial effects on pathogenic microorganisms. E. coli and C. albicans displayed the maximum susceptibility, with zones of inhibition of 14.6 and 13.8 mm at 3-mM concentration, respectively, while B. cereus had the lowest zone of inhibition (10.6 mm) at 3-mM OSC-AgN0₃ concentration. In conclusion, AgNPs synthesized from Oscillatoria princeps inhibit biofilm formation, suggesting that AgNPs may be a promising candidate for the prevention and treatment of biofilm-associated infections caused by bacteria and yeasts.

Cyanobacteria as biochemical energy source for the synthesis of inorganic nanoparticles, mechanism and potential applications: a review

Green synthesis of nanoparticles (NPs) has gained great concern among researchers due to their unique properties, excellent applications and efficient route of synthesis. From the last decades, the number biologicals such as plants, fungus, bacteria, yeast, algae, and cyanobacteria and their products are using by various researchers for the synthesis of different NPs. However, the pillar of green chemistry keeps touching new heights to improve the performance. This review paper unveils almost recent cyanobacteria-assisted greener NP synthesis technique, characterization and application. The enormous potency of cyanobacteria in NP synthesis (silver, gold, copper, zinc, palladium, titanium, cadmium sulfide, and selenium) and significance of reducing enzymes were summarized. The extracellular and intracellular entity such as metabolites, enzyme, protein, pigments in cyanobacteria play a significant role in the conversion of metal ions to metal NPs with unique properties discussed briefly. The green synthesis of nanomaterials is valuable because of their cost-effective, nontoxic and eco-friendly prospects as well as the potential application metal NPs such as antibacterial, antifungal, anticancerous, catalytic, drug delivery, bioimaging, nanopesticide, nanofertilizer, sensing properties, etc. Therefore, in the present review, we have systematically discussed the mechanisms of synthesis and applications of cyanobacteria-assisted green synthesis of NPs.

Isolation, biosynthesis and antimicrobial activity of gold nanoparticles produced with extracts of Anabaena spiroides

Multidrug-resistant (MDR) pathogenic bacteria have become dangerous in bringing sporadic outbreaks in public health and nosocomial spreads from the addition of antibacterials/antibiotics continually. Obviously, the pharmacy world is in search of antibacterials that would be invincible by the evolved bacteria. Green synthesis of gold-nanoparticles (AuNps) was focused on the use of aqueous chloroauric acid (HAuCl₄) and cell-free aqueous extract of the N₂-fixing cyanobacterium (blue-green alga) Anabaena spiroides collected from a brackish-water, Bay of Bengal at Puri, Odisha; green-synthesized AuNps could be used as antibacterials against MDR bacteria. The synthesized AuNps were subjected to the following characterizations, UV-Vis spectrophotometry, SEM-EDX, XRD and ART-FTIR analysis. An absorption peak at 538 nm by UV-Vis spectrophotometry and the FTIR analysis confirmed the presence of AuNps. A. spiroides-AuNps were monitored for antibacterial activities against MDR pathogenic bacterial strains isolated from clinical samples, namely, Klebsiella oxytoca, MRSA and Streptococcus pyogenes, in vitro; the individual antibiograms of those bacteria were known. The recorded MIC dose values were 25, 20 and 30 mg A. spiroides-AuNps (As-AuNps) against K. oxytoca, MRSA and S. pyogenes, in vitro, respectively. Thus, As-AuNps bear promises as possible antibacterials, in future.

Green and Cost-Effective Synthesis of Metallic Nanoparticles by Algae: Safe Methods for Translational Medicine

Metal nanoparticles (NPs) have received much attention for potential applications in medicine (mainly in oncology, radiology and infectiology), due to their intriguing chemical, electronical, catalytical, and optical properties such as surface plasmon resonance (SPR) effect. They also offer ease in controlled synthesis and surface modification (e.g., tailored properties conferred by capping/protecting agents including N-, P-, COOH-, SH-containing molecules and polymers such as thiol, disulfide, ammonium, amine, and multidentate carboxylate), which allows (i) tuning their size and shape (e.g., star-shaped and/or branched) (ii) improving their stability, monodispersity, chemical miscibility, and activity, (iii) avoiding their aggregation and oxidation over time, (iv) increasing their yield and purity. The bottom-up approach, where the metal ions are reduced in the NPs grown in the presence of capping ligands, has been widely used compared to the top-down approach. Besides the physical and chemical synthesis methods, the biological method is gaining much consideration. Indeed, several drawbacks have been reported for the synthesis of NPs via physical (e.g., irradiation, ultrasonication) and chemical (e.g., electrochemisty, reduction by chemicals such as trisodium citrate or ascorbic acid) methods (e.g., cost, and/ortoxicity due to use of hazardous solvents, low production rate, use of huge amount of energy). However, (organic or inorganic) eco-friendly NPs synthesis exhibits a sustainable, safe, and economical solution. Thereby, a relatively new trend for fast and valuable NPs synthesis from (live or dead) algae (i.e., microalgae, macroalgae and cyanobacteria) has been observed, especially because of its massive presence on the Earth's crust and their unique properties (e.g., capacity to accumulate and reduce metallic ions, fast propagation). This article discusses the algal-mediated synthesis methods (either intracellularly or extracellularly) of inorganic NPs with special emphasis on the noblest metals, i.e., silver (Ag)- and gold (Au)-derived NPs. The key factors (e.g., pH, temperature, reaction time) that affect their biosynthesis process, stability, size, and shape are highlighted. Eventually, underlying molecular mechanisms, nanotoxicity and examples of major biomedical applications of these algal-derived NPs are presented.

Cyanobacteria - A Promising Platform in Green Nanotechnology: A Review on Nanoparticles Fabrication and Their Prospective Applications

Green synthesis of nanoparticles (NPs) is a global ecofriendly method to develop and produce nanomaterials with unique biological, physical, and chemical properties. Recently, attention has shifted toward biological synthesis, owing to the disadvantages of physical and chemical synthesis, which include toxic yields, time and energy consumption, and high cost. Many natural sources are used in green fabrication processes, including yeasts, plants, fungi, actinomycetes, algae, and cyanobacteria. Cyanobacteria are among the most beneficial natural candidates used in the biosynthesis of NPs, due to their ability to accumulate heavy metals from their environment. They also contain a variety of bioactive compounds, such as pigments and enzymes, that may act as reducing and stabilizing agents. Cyanobacteria-mediated NPs have potential antibacterial, antifungal, antialgal, anticancer, and photocatalytic activities. The present review paper highlights the characteristics and applications in various fields of NPs produced by cyanobacteria-mediated synthesis.

In Vivo Biosynthesis of Inorganic Nanomaterials Using Eukaryotes-A Review

Bionanotechnology, the use of biological resources to produce novel, valuable nanomaterials, has witnessed tremendous developments over the past two decades. This eco-friendly and sustainable approach enables the synthesis of numerous, diverse types of useful nanomaterials for many medical, commercial, and scientific applications. Countless reviews describing the biosynthesis of nanomaterials have been published. However, to the best of our knowledge, no review has been exclusively focused on the in vivo biosynthesis of inorganic nanomaterials. Therefore, the present review is dedicated to filling this gap by describing the many different facets of the in vivo biosynthesis of nanoparticles (NPs) using living eukaryotic cells and organisms-more specifically, live plants and living biomass of several species of microalgae, yeast, fungus, mammalian cells, and animals. It also highlights the strengths and weaknesses of the synthesis methodologies and the NP characteristics, bio-applications, and proposed synthesis mechanisms. This comprehensive review also brings attention to enabling a better understanding between the living organisms themselves and the synthesis conditions that allow their exploitation as nanobiotechnological production platforms as these might serve as a robust resource to boost and expand the bio-production and use of desirable, functional inorganic nanomaterials.

Cyanobacteria as Nanogold Factories: Chemical and Anti-Myocardial Infarction Properties of Gold Nanoparticles Synthesized by Lyngbya majuscula

To the best of our knowledge, cyanobacterial strains from the Arabian Gulf have never been investigated with respect to their potential for nanoparticle production. Lyngbya majuscula was isolated from the AlOqair area, Al-Ahsa Government, Eastern Province, Kingdom of Saudi Arabia. The cyanobacterium was initially incubated with 1500 mg/mL of HAuCl₄ for two days. The blue-green strain turned purple, which indicated the intracellular formation of gold nanoparticles. Prolonged incubation for over two months triggered the extracellular production of nanogold particles. UV-visible spectroscopy measurements indicated the presence of a resonance plasmon band at ~535 nm, whereas electron microscopy scanning indicated the presence of gold nanoparticles with an average diameter of 41.7 ± 0.2 nm. The antioxidant and anti-myocardial infarction activities of the cyanobacterial extract, the gold nanoparticle solution, and a combination of both were investigated in animal models. Isoproterenol (100 mg/kg, SC (sub cutaneous)) was injected into experimental rats for three days to induce a state of myocardial infarction; then the animals were given cyanobacterial extract (200 mg/kg/day, IP (intra peritoneal)), gold nanoparticles (200 mg/kg/day, IP), ora mixture of both for 14 days. Cardiac biomarkers, electrocardiogram (ECG), blood pressure, and antioxidant enzymes were determined as indicators of myocardial infarction. The results showed that isoproterenol elevates ST and QT segments and increases heart rate and serum activities of creatine phosphokinase (CPK), creatine kinase-myocardial bound (CP-MB), and cardiac troponin T (cTnT). It also reduces heart tissue content of glutathione peroxidase (GRx) and superoxide dismutase (SOD), and the arterial pressure indices of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP). Gold nanoparticles alone or in combination with cyanobacterial extract produced an inhibitory effect on isoproterenol-induced changes in serum cardiac injury markers, ECG, arterial pressure indices, and antioxidant capabilities of the heart.