Seaweeds: A resource for marine bionanotechnology

Bioactive nanoparticles derived from marine brown seaweeds and their biological applications: a review

The biosynthesis of novel nanoparticles with varied morphologies, which has good implications for their biological capabilities, has attracted increasing attention in the field of nanotechnology. Bioactive compounds present in the extract of fungi, bacteria, plants and algae are responsible for nanoparticle synthesis. In comparison to other biological resources, brown seaweeds can also be useful to convert metal ions to metal nanoparticles because of the presence of richer bioactive chemicals. Carbohydrates, proteins, polysaccharides, vitamins, enzymes, pigments, and secondary metabolites in brown seaweeds act as natural reducing, capping, and stabilizing agents in the nanoparticle's synthesis. There are around 2000 species of seaweed that dominate marine resources, but only a few have been reported for nanoparticle synthesis. The presence of bioactive chemicals in the biosynthesized metal nanoparticles confers biological activity. The biosynthesized metal and non-metal nanoparticles from brown seaweeds possess different biological activities because of their different physiochemical properties. Compared with terrestrial resources, marine resources are not much explored for nanoparticle synthesis. To confirm their morphology, characterization methods are used, such as absorption spectrophotometer, X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscope, and transmission electron microscopy. This review attempts to include the vital role of brown seaweed in the synthesis of metal and non-metal nanoparticles, as well as the method of synthesis and biological applications such as anticancer, antibacterial, antioxidant, anti-diabetic, and other functions.

Fucoidan, a brown seaweed polysaccharide in nanodrug delivery

Fucoidan-a sulfated marine seaweed obtained from brown algae-has raised considerable interest in the scientific community over the last decade as it possesses a wide range of biological activities such as antioxidant, antiviral, anti-inflammatory, anticoagulant, antithrombotic, anticarcinogenic, and immunoregulatory. This polysaccharide finds application as a drug delivery vehicle due to its non-cytotoxicity, biocompatibility, and biodegradability. Besides, nano biomedical systems have used this marine alga for diagnostic and therapeutic purposes. Fucoidan has been extensively studied for use in regenerative medicines, in wound healing, and for sustained drug delivery due to its large biodiversity, cost-effectiveness, and mild procedures for extraction and purification. However, the main concern that limits its application is the variance in its batch-to-batch extraction owing to species type, harvesting, and climatic factors. The current review encloses a compendious overview of the origin, chemical structure, and physicochemical and biological properties of fucoidan and its significant role in nanodrug delivery systems. Special emphasis is given to the recent advances in the use of native/modified fucoidan, its combination with chitosan and metal ions for nanodrug delivery applications, especially in cancer treatment. Additionally, use of fucoidan in human clinical trials as a complementary therapeutic agent is also reviewed.

Aconitum lycoctonum L. (Ranunculaceae) mediated biogenic synthesis of silver nanoparticles as potential antioxidant, anti-inflammatory, antimicrobial and antidiabetic agents

In this study, a polar extract of Aconitum lycoctonum L. was used for the synthesis of silver nanoparticles (AgNPs), followed by their characterization using different techniques and evaluation of their potential as antioxidants, amylase inhibitors, anti-inflammatory and antibacterial agents. The formation of AgNPs was detected by a color change, from transparent to dark brown, within 15 min and a surface resonance peak at 460 nm in the UV-visible spectrum. The FTIR spectra confirmed the involvement of various biomolecules in the synthesis of AgNPs. The average diameter of these spherical AgNPs was 67 nm, as shown by the scanning electron micrograph. The inhibition zones showed that the synthesized nanoparticles inhibited the growth of Gram-positive and negative bacteria. FRAP and DPPH assays were used to demonstrate the antioxidant potential of AgNPs. The highest value of FRAP (50.47% AAE/mL) was detected at a concentration of 90 ppm and a DPPH scavenging activity of 69.63% GAE was detected at a concentration of 20 µg/mL of the synthesized AgNPs. 500 µg/mL of the synthesized AgNPs were quite efficient in causing 91.78% denaturation of ovalbumin. The AgNPs mediated by A. lycoctonum also showed an inhibitory effect on α-amylase. Therefore, AgNPs synthesized from A. lycoctonum may serve as potential candidates for antibacterial, antioxidant, anti-inflammatory, and antidiabetic agents.

Extraction, Modification and Biomedical Application of Agarose Hydrogels: A Review

Numerous compounds present in the ocean are contributing to the development of the biomedical field. Agarose, a polysaccharide derived from marine red algae, plays a vital role in biomedical applications because of its reversible temperature-sensitive gelling behavior, excellent mechanical properties, and high biological activity. Natural agarose hydrogel has a single structural composition that prevents it from adapting to complex biological environments. Therefore, agarose can be developed into different forms through physical, biological, and chemical modifications, enabling it to perform optimally in different environments. Agarose biomaterials are being increasingly used for isolation, purification, drug delivery, and tissue engineering, but most are still far from clinical approval. This review classifies and discusses the preparation, modification, and biomedical applications of agarose, focusing on its applications in isolation and purification, wound dressings, drug delivery, tissue engineering, and 3D printing. In addition, it attempts to address the opportunities and challenges associated with the future development of agarose-based biomaterials in the biomedical field. It should help to rationalize the selection of the most suitable functionalized agarose hydrogels for specific applications in the biomedical industry.

Ultrastrong, Thermally Stable, and Food-Safe Seaweed-Based Structural Material for Tableware

Widely used disposable plastic tableware is usually buried or directly discharged into the natural environment after using, which poses potential threats to the natural environment and human health. To solve this problem, nondegradable plastic tableware needs to be replaced by tableware composed of biodegradable structural materials with both food safety and the excellent mechanical and thermal properties. Here, a food-safe sargassum cellulose nanofiber (SCNF) is extracted from common seaweed in an efficient and low energy consuming way under mild reaction conditions. Then, by assembling the SCNF into a dense bulk material, a strong sargassum cellulose nanofiber structural material (SCNSM) with high strength (283 MPa) and high thermal stability (>160 °C) can be prepared. The SCNSM also possesses good machinability, which can be processed into tableware with different shapes, e.g., knives and forks. The overall performance of the SCNSM-based tableware is better than commercial plastic, wood-based, and poly(lactic acid) tableware, which shows great application potential in the tableware field.

Biosorption and adsorption isotherm of chromium (VI) ions in aqueous solution using soil bacteria Bacillus amyloliquefaciens

This study looked at the development of effective biosorbents to recover the most toxic elements from industrial water. B. amyloliquefaciens was isolated from marine soils showing extreme resistance to Chromium (Cr(VI)) ions. During the 60 min of contact time, 79.90% Cr(VI) was adsorbed from the aqueous solution. The impact of important factors such as biomass concentration, pH of the medium, and initial metal ions concentration on biosorption rate was also examined. The desorption study indicated that 1 M HCl (91.24%) was superior to 0.5 M HCl (74.81%), 1 M NaOH (64.96%), and distilled water (3.66%). Based on the Langmuir model, the maximum adsorption capacity of the bio-absorbent was determined to be 48.44 mg/g. The absorption mechanism was identified as monolayer, and 1/n from the Freundlich model falls within 1, thus indicating favorable adsorption. Based on the findings of the present study, the soil bacterium B. amyloliquefaciens was found to be the best alternative and could be used to develop strategies for managing existing environmental pollution through biosorption.

Synthesis of silver nanoparticles from red and green parts of the pistachio hulls and their various in-vitro biological activities

In this study, synthesis of silver nanoparticles (AgNPs) was carried out utilizing the red and green parts of the pistachio hulls then their several biological activities were investigated. The DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) activities of the AgNPs synthesized from red pistachio hulls extracts (PhR-AgNPs) and green pistachio hulls extracts (PhG-AgNPs) were investigated. The DPPH scavenging capability at 200 mg/L concentration of PhR-AgNPs was around 93.01% however PhG-AgNPs displayed 91.00%. The synthesized PhR-AgNPs and PhG-AgNPs acted on the E. coli plasmid DNA, causing its complete degradation and exhibiting effective chemical nuclease activity. Furthermore, PhR-AgNPs and PhG-AgNPs showed quite good antimicrobial activity against the studied strains with a range of the minimum inhibition concentration (MIC) of 8-16 mg/L. Moreover, it was observed that both pistachio hulls coated with AgNPs were highly effective in inhibiting the biofilm generation studied strains. Moreover, PhR-AgNP and PhG-AgNP displayed a completely inhibition effect on cellular viability of E. coli with 100% at 125 mg/L.

Synthesis and Antioxidant Activity of Silver Nanoparticles Using the Odontonema strictum Leaf Extract

The aqueous extract of the leaves of Odontonema strictum (OSM) is used in folk medicine for its antihypertensive properties, and it contains a wide range of secondary metabolites, mostly polyphenols such as verbascoside and isoverbascoside, which could play a major role in the preparation of silver nanoparticles. In this study, we aimed to prepare AgNPs for the first time using the OSM leaf extract (OSM-AgNPs) to investigate their free radical-scavenging potency against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H₂O₂). Dynamic light scattering (DLS), UV/Vis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) were used to characterize the OSM-AgNPs. With a size around 100 nm and a ζ-potential of −41.1 mV, OSM-AgNPs showed a good stability and a better colloidal property due to electrostatic repulsion and the dispersity. The strong absorption peak at 3 keV in the EDX spectra indicated that silver was the major constituent. Additionally, the existence of silver atoms was confirmed by the Ag 3d_5/2 peak around 367 eV in the XPS spectra. IC₅₀ values of 116 μg/mL and 4.4 μg/mL were obtained for the scavenging activities of DPPH and H₂O₂, respectively. The synthetic OSM-AgNPs can be further exploited as potential antioxidant agents.

Green synthesis of plasmonic nanoparticles using Sargassum ilicifolium and application in photocatalytic degradation of cationic dyes

In the present work, a green synthetic method for the preparation of extremely stable silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using Sargassum ilicifolium has been demonstrated. Thus produced nanoparticles were characterized by UV-Visible (UV-Vis) spectroscopy, Fourier Transform InfraRed spectroscopy (FT-IR), Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential analyses. The average size of Ag and Au NPs was 27.9 and 9.36 nm respectively from TEM, which was further substantiated by XRD data. Zeta potential values of -42.2 mV and -28.3 mV for Ag and Au NPs respectively suggested that the nanoparticles were negatively charged and highly stable. AgNPs showed desirable bactericidal activity towards Enterobacter species, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Proteus species. The photocatalytic behaviour of AgNPs was studied to degrade malachite green (MG) and methylene blue (MB) in aqueous medium. In MG, 82.9% degradation was achieved in 180 min of light exposure and the pseudo first order rate constant was 7.2 × 10-3 min-1. In MB, almost 100% of the dye was degraded in the same period and the pseudo first order rate constant calculated was 7.5 × 10-3 min-1. The bio-derived AgNPs are hence promising materials for treating effluent from dyeing industries and water purification.

Prospects of algae-based green synthesis of nanoparticles for environmental applications

Green synthesis of nanoparticles (NPs) has emerged as an eco-friendly alternative to produce nanomaterials with diverse physical, chemical, and biological characteristics. Previously used, physical and chemical methods involve the production of toxic byproducts, costly instrumentation, and energy-intensive experimental processes thereby, limiting their applicability. Biogenic synthesis of nanoparticles has come forward as a potential alternative, providing an eco-friendly, cost-effective, and energy-efficient approach for the synthesis of a diverse range of NPs. Several biological entities are employed in the biosynthesis of NPs including bacteria, fungi, and algae. However, the distinguishing characteristics of microalgae and cyanobacteria make them promising candidates for NPs synthesis because of their higher growth rate, substantially higher rate of sequestering CO₂, hyperaccumulation of heavy metals, absence of toxic byproducts, minimum energy input, and employment of biomolecules (pigments and enzymes) as reducing and capping agents. Algal extract, being a natural reducing and capping agent, serves as a living cell factory for the efficient green synthesis of nanoparticles. Physiological and biological methods allow algal cells to uptake heavy metals and utilize them as nutrient source to generate biomass by regulating their metabolic processes. Despite their enormous potential, studies on the microalgae-based synthesis of nanoparticles for the removal of toxic pollutants from wastewater remained an unexplored research area in the literature. This review was aimed to summarize the recent advancements and prospects in the algae-based synthesis of nanoparticles for environmental applications particularly treating the wastewater.

Exploring Dose-Dependent Cytotoxicity Profile of Gracilaria edulis-Mediated Green Synthesized Silver Nanoparticles against MDA-MB-231 Breast Carcinoma

Green-based synthesis of metal nanoparticles using marine seaweeds is a rapidly growing technology that is finding a variety of new applications. In the present study, the aqueous extract of a marine seaweed, Gracilaria edulis, was employed for the synthesis of metallic nanoparticles without using any reducing and stabilizing chemical agents. The visual color change and validation through UV-Vis spectroscopy provided an initial confirmation regarding the Gracilaria edulis-mediated green synthesized silver nanoparticles. The dynamic light scattering studies and high-resolution transmission electron microscopy pictographs exhibited that the synthesized Gracilaria edulis-derived silver nanoparticles were roughly spherical in shape having an average size of 62.72 ± 0.25 nm and surface zeta potential of -15.6 ± 6.73 mV. The structural motifs and chemically functional groups associated with the Gracilaria edulis-derived silver nanoparticles were observed through X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopy. Further, the synthesized nanoparticles were further screened for their antioxidant properties through DPPH, hydroxyl radical, ABTS, and nitric oxide radical scavenging assays. The phycosynthesized nanoparticles exhibited dose-dependent cytotoxicity against MDA-MB-231 breast carcinoma cells having IC₅₀ value of 344.27 ± 2.56 μg/mL. Additionally, the nanoparticles also exhibited zone of inhibition against pathogenic strains of Bacillus licheniformis (MTCC 7425), Salmonella typhimurium (MTCC 3216), Vibrio cholerae (MTCC 3904), Escherichia coli (MTCC 1098), Staphylococcus epidermidis (MTCC 3615), and Shigella dysenteriae (MTCC9543). Hence, this investigation explores the reducing and stabilizing capabilities of marine sea weed Gracilaria edulis for synthesizing silver nanoparticles in a cost-effective approach with potential anticancer and antimicrobial activity. The nanoparticles synthesized through green method may be explored for their potential utility in food preservative film industry, biomedical, and pharmaceutical industries.

Anticancer and Antimicrobial Activity of Red Sea Seaweeds Extracts-Mediated Gold Nanoparticles

Biosynthesis of gold nanoparticles (AuNPs) is emerging as a better alternative to traditional chemical-based techniques. During this study, extracts of different marine algae species Ulva rigida (green algae), Cystoseira myrica (brown Algae), and Gracilaria foliifera (red Algae) were utilized as reducing and capping agents to synthesize AuNPs. AuNPs capped by U. rigida, C. myrica, and G. foliifera were confirmed by the appearance of surface plasmonic bands at 528, 540, and 543 nm, respectively. Transmission electron microscopy revealed mostly spherical shapes of AuNPs having a size of about 9 nm, 11 nm, and 13 nm for C. myrica, and G. foliifera extracts, respectively. Fourier transform-infrared spectroscopy (FTIR) illustrated the major chemical constituents of U. rigida, C. myrica, and G. foliifera. LC50 values of the biosynthesized AuNPs against Artemia salina nauplii were calculated at a range of concentrations (5-188 μg ml−1) after 16 to 24h. AuNPs concentration-dependent lethality was noted and U. rigida extracts-mediated AuNPs presented the lowest cytotoxicity. The biosynthesized AuNPs exhibited significant anticancer activity (86.83%) against MCF-7 cell lines (human breast adenocarcinoma cell lines) at 188 µg/ml concentration. G. foliifera demonstrated the highest anticancer value (92.13%) followed by C. myrica (89.82%), and U. rigida (86.83%), respectively. The AuNPs synthesized by different algal extracts showed variable antimicrobial activity against the tested pathogenic microorganisms. AuNPs of U. rigida extracts showed significant antimicrobial activity against dermatophytic fungi Trichosporon cataneum (30 mm) followed by Trichophyton mantigrophytes (25 mm). Furthermore, it also exhibited mild activity against Escherichia coli (17 mm), Cryptococcus neoformans (15 mm), Candida albicans (13 mm), and Staphylococcus aureus (11mm), respectively whereas no effects were observed against Bacillus cereus. To conclude, AuNPs can be effectively synthesized by marine algal species, and particularly U. rigida extracts could be effective reducing agents for the green AuNPs synthesis. These AuNPs could potentially serve as efficient alternative anticancer agents against human breast adenocarcinoma and anti-dermatophytes associated with skin infections.

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.

Biosynthesis of zinc oxide nanoparticles using Phoenix dactylifera and their effect on biomass and phytochemical compounds in Juniperus procera

Biosynthesized nanoparticles have played vital role recently, as suggested to be alternative to physical and chemical methods. In this study, biosynthesis of zinc oxide nanoparticles (ZnO NPs) were carried out using leaf extracts of Phoenix dactylifera L. and Zinc nitrate. The effect of ZnO nanoparticles on biomass and biochemical parameters was investigated. Biosynthesized ZnO nanostructure was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and Fourier transform infrared spectroscopy (FTIR). Which resulted in spherical shape with size ranging between 16 to 35 nm of Biosynthesized ZnO nanoparticles and UV absorption beak at 370.5 nm with clear peaks of functional groups. The impact of different concentrations (0.0 mg/L, 80 mg/L and 160 mg/L) of biosynthesized ZnO nanoparticles on biomass and bioactive compounds production of Juniperus procera in vitro was investigated. The results showed that, biosynthesized ZnO NPs (80 mg/L and 160 mg/L) concentrations were boosted the growth of J. Procera with significantly compared to non-treated plants in vitro. The highest concentration (160 mg/L) of ZnO NPs was enhanced the growth of plant at beginning period, one month later shoots became yellow and callus turned to be brownish. Moreover, the influence of ZnO NPs on phytochemical compounds in callus of Juniperus procera was examined using GC-MS analysis. The differences among treatments were recoded. Overall, zinc oxide nanoparticles substantially improved the growth of shoots and callus with increasing of biochemical parameters such as chlorophyll a, total phenolic and flavonoids contents, besides the total protein and, SOD, CAT and APX activity. ZnO NPs might be induced some phytochemical compounds as well as inhibit.

Exploring the therapeutic potential of Hibiscus rosa sinensis synthesized cobalt oxide (Co3O4-NPs) and magnesium oxide nanoparticles (MgO-NPs)

Herein, we present a green, economic and ecofriendly protocol for synthesis of cobalt oxide (Co3O4-NPs) and magnesium oxide nanoparticles (MgO-NPs) for multifaceted biomedical applications. In the study, a simple aqueous leaf extract of Hibiscus rosa sinensis, was employed for the facile one pot synthesis of Co3O4-NPs and MgO-NPs. The well characterized NPs were explored for multiple biomedical applications including bactericidal activity against urinary tract infection (UTI) isolates, leishmaniasis, larvicidal, antidiabetic antioxidant and biocompatibility studies. Our results showed that both the NPs were highly active against multidrug resistant UTI isolates as compared to traditional antibiotics and induced significant zone of inhibition against Proteus Vulgaris, Pseudomonas Aurigenosa and E.coli. The NPs, in particular Co3O4-NPs also showed significant larvicidal activity against the Aedes Aegypti, the mosquitoes involve in the transmission of Dengue fever. Similarly, excellent leishmanicidal activity was also observed against both the promastigote and amastigote forms of the parasite. Furthermore, the particles also exhibited considerable antidiabetic activity by inhibiting α-amylase and α-glucosidase enzymes. The biosynthesized NPs were found to be excellent antioxidant and biocompatible nanomaterials. Owing to ecofriendly synthesis, non-toxic and biocompatible nature, the Hibiscus rosa sinensis synthesized Co3O4-NPs and MgO-NPs can be exploited as potential candidates for multiple biomedical applications.

Seaweed bioactive compounds: Promising and safe inputs for the green synthesis of metal nanoparticles in the food industry

Scientific research on developing and characterizing eco-friendly metal nanoparticles (NPs) is an active area experiencing currently a systematic and continuous growth. A variety of physical, chemical and more recently biological methods can be used for the synthesis of metal nanoparticles. Among them, reports supporting the potential use of algae in the NPs green synthesis, contribute with only a minor proportion, although seaweed was demonstrated to perform as a successful reducing and stabilizing agent. Thus, the first part of the present review depicts the up-to-date information on the use of algae extracts for the synthesis of metal nanoparticles, including a deep discussion of the certain advantages as well as some limitations of this synthesis route. In the second part, the available characterization techniques to unravel their inherent properties such as specific size, shape, composition, morphology and dispersibility are comprehensively described, to finally focus on the factors affecting their applications, bioactivity, potential toxic impact on living organisms and incorporation into food matrices or food packaging, as well as future prospects. The present article identifies the key knowledge gap in a systematic way highlighting the critical next steps in the green synthesis of metal NPs mediated by algae.

Bio-Catalytic Activity of Novel Mentha arvensis Intervened Biocompatible Magnesium Oxide Nanomaterials

In the present study Mentha arvensis medaited Magnesium oxide nanoparticles were synthesized by novel green route followed by advanced characterization via XRD, FTIR, UV, SEM, TEM, DLS and TGA. The mean grain size of 32.4 nm and crystallite fcc morphology were confirmed by X-ray diffractive analysis. Scanning and Transmission electron microscopy analysis revealed the spherical and elliptical morphologies of the biosynthesized nanoparticles. Particle surface charge of −16.1 mV were determined by zeta potential and zeta size of 30–120 nm via dynamic light scattering method. Fourier transform spectroscopic analysis revealed the possible involvement of functional groups in the plant extract in reduction of Mg2+ ions to Mg0. Furthermore, the antioxidant, anti-Alzheimer, anti-cancer, and anti-H. pylori activities were performed. The results revealed that MgO-NPs has significant anti-H. pyloric potential by giving ZOI of 17.19 ± 0.83 mm against Helicobacter felis followed by Helicobacter suis. MgO-NPs inhibited protein kinase enzyme up to 12.44 ± 0.72% at 5 mg/mL and thus showed eminent anticancer activity. Significant free radicals scavenging and hemocompatability was also shown by MgO-NPs. MgO-NPs also displayed good inhibition potential against Hela cell lines with maximum inhibition of 49.49 ± 1.18 at 400 µg/mL. Owing to ecofriendly synthesis, non-toxic and biocompatible nature, Mentha arvensis synthesized MgO-NPs can be used as potent antimicrobial agent in therapeutic applications.

Functional Properties of Antimicrobial Neem Leaves Extract Based Macroalgae Biofilms for Potential Use as Active Dry Packaging Applications

Antimicrobial irradiated seaweed–neem biocomposite films were synthesized in this study. The storage functional properties of the films were investigated. Characterization of the prepared films was conducted using SEM, FT-IR, contact angle, and antimicrobial test. The macroscopic and microscopic including the analysis of the functional group and the gas chromatography-mass spectrometry test revealed the main active constituents present in the neem extract, which was used an essential component of the fabricated films. Neem leaves’ extracts with 5% w/w concentration were incorporated into the matrix of seaweed biopolymer and the seaweed–neem bio-composite film were irradiated with different dosages of gamma radiation (0.5, 1, 1.5, and 2 kGy). The tensile, thermal, and the antimicrobial properties of the films were studied. The results revealed that the irradiated films exhibited improved functional properties compared to the control film at 1.5 kGy radiation dosage. The tensile strength, tensile modulus, and toughness exhibited by the films increased, while the elongation of the irradiated bio-composite film decreased compared to the control film. The morphology of the irradiated films demonstrated a smoother surface compared to the control and provided surface intermolecular interaction of the neem–seaweed matrix. The film indicated an optimum storage stability under ambient conditions and demonstrated no significant changes in the visual appearance. However, an increase in the moisture content was exhibited by the film, and the hydrophobic properties was retained until nine months of the storage period. The study of the films antimicrobial activities against Staphylococcus aureus (SA), and Bacillus subtilis (BS) indicated improved resistance to bacterial activities after the incorporation of neem leaves extract and gamma irradiation. The fabricated irradiated seaweed–neem bio-composite film could be used as an excellent sustainable packaging material due to its effective storage stability.

Cyanobacteria-From the Oceans to the Potential Biotechnological and Biomedical Applications

Cyanobacteria are photosynthetic prokaryotic organisms which represent a significant source of novel, bioactive, secondary metabolites, and they are also considered an abundant source of bioactive compounds/drugs, such as dolastatin, cryptophycin 1, curacin toyocamycin, phytoalexin, cyanovirin-N and phycocyanin. Some of these compounds have displayed promising results in successful Phase I, II, III and IV clinical trials. Additionally, the cyanobacterial compounds applied to medical research have demonstrated an exciting future with great potential to be developed into new medicines. Most of these compounds have exhibited strong pharmacological activities, including neurotoxicity, cytotoxicity and antiviral activity against HCMV, HSV-1, HHV-6 and HIV-1, so these metabolites could be promising candidates for COVID-19 treatment. Therefore, the effective large-scale production of natural marine products through synthesis is important for resolving the existing issues associated with chemical isolation, including small yields, and may be necessary to better investigate their biological activities. Herein, we highlight the total synthesized and stereochemical determinations of the cyanobacterial bioactive compounds. Furthermore, this review primarily focuses on the biotechnological applications of cyanobacteria, including applications as cosmetics, food supplements, and the nanobiotechnological applications of cyanobacterial bioactive compounds in potential medicinal applications for various human diseases are discussed.

Deciphering and engineering photosynthetic cyanobacteria for heavy metal bioremediation

Environmental pollution caused by heavy metals has received worldwide attentions due to their ubiquity, poor degradability and easy bioaccumulation in host cells. As one potential solution, photosynthetic cyanobacteria have been considered as promising remediation chassis and widely applied in various bioremediation processes of heavy-metals. Meanwhile, deciphering resistant mechanisms and constructing tolerant chassis towards heavy metals could greatly contribute to the successful application of the cyanobacteria-based bioremediation in the future. In this review, first we summarized recent application of cyanobacteria in heavy metals bioremediation using either live or dead cells. Second, resistant mechanisms and strategies for enhancing cyanobacterial bioremediation of heavy metals were discussed. Finally, potential challenges and perspectives for improving bioremediation of heavy metals by cyanobacteria were presented.

Evaluation of the Antioxidant Capacities of Antarctic Macroalgae and Their Use for Nanoparticles Production

Macroalgae are sources of bioactive compounds that are interesting from both a chemical and a medical point of view. Although their use in biomedicine has increased significantly in recent years, tests conducted to date have been mostly related to species from temperate latitudes, with the potential application of Antarctic biodiversity being minor. The wide variety of algae species present on Antarctic coastal areas can be a source of new antioxidants. Bearing this in mind, the brown macroalgae Desmarestia antarctica (DA) and the red Iridaea cordata (IC) were selected for the preparation of aqueous extracts with the aim of analyzing their antioxidant activity. This analysis was performed by determining reducing power, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Furthermore, both extracts were employed to synthesize gold and silver nanoparticles. The nanomaterials were fully characterized by means of UV-Visible spectroscopy, transmission electron microscopy, Z potential measurements, and Fourier transform infrared spectroscopy, which confirmed the formation of stable, spherical nanoparticles with mean diameters of 13.7 ± 3.1 and 17.5 ± 3.7 nm for Ag@DA and Ag@IC and 12.6 ± 1.9 and 12.3 ± 1.6 nm for Au@DA and Au@IC. Antioxidant assays were performed after the synthesis of the nanomaterials to evaluate their possible synergistic effect with the extracts. The results suggest that polysaccharides and proteins may play a key role in the process of reduction and stabilization. Finally, for the sake of comparison, the results obtained for the Antarctic macroalgae Desmarestia menziesii and Palmaria decipiens have also been considered in the present work.

Green synthesis of silver nanoparticles using plant extracts and their antimicrobial activities: a review of recent literature

Synthesis of metal nanoparticles using plant extracts is one of the most simple, convenient, economical, and environmentally friendly methods that mitigate the involvement of toxic chemicals. Hence, in recent years, several eco-friendly processes for the rapid synthesis of silver nanoparticles have been reported using aqueous extracts of plant parts such as the leaf, bark, roots, etc. This review summarizes and elaborates the new findings in this research domain of the green synthesis of silver nanoparticles (AgNPs) using different plant extracts and their potential applications as antimicrobial agents covering the literature since 2015. While highlighting the recently used different plants for the synthesis of highly efficient antimicrobial green AgNPs, we aim to provide a systematic in-depth discussion on the possible influence of the phytochemicals and their concentrations in the plants extracts, extraction solvent, and extraction temperature, as well as reaction temperature, pH, reaction time, and concentration of precursor on the size, shape and stability of the produced AgNPs. Exhaustive details of the plausible mechanism of the interaction of AgNPs with the cell wall of microbes, leading to cell death, and high antimicrobial activities have also been elaborated. The shape and size-dependent antimicrobial activities of the biogenic AgNPs and the enhanced antimicrobial activities by synergetic interaction of AgNPs with known commercial antibiotic drugs have also been comprehensively detailed.

Macroalgae as a Source of Valuable Antimicrobial Compounds: Extraction and Applications

In the last few decades, attention on new natural antimicrobial compounds has arisen due to a change in consumer preferences and the increase in the number of resistant microorganisms. Macroalgae play a special role in the pursuit of new active molecules as they have been traditionally consumed and are known for their chemical and nutritional composition and their biological properties, including antimicrobial activity. Among the bioactive molecules of algae, proteins and peptides, polysaccharides, polyphenols, polyunsaturated fatty acids and pigments can be highlighted. However, for the complete obtaining and incorporation of these molecules, it is essential to achieve easy, profitable and sustainable recovery of these compounds. For this purpose, novel liquid-liquid and solid-liquid extraction techniques have been studied, such as supercritical, ultrasound, microwave, enzymatic, high pressure, accelerated solvent and intensity pulsed electric fields extraction techniques. Moreover, different applications have been proposed for these compounds, such as preservatives in the food or cosmetic industries, as antibiotics in the pharmaceutical industry, as antibiofilm, antifouling, coating in active packaging, prebiotics or in nanoparticles. This review presents the main antimicrobial potential of macroalgae, their specific bioactive compounds and novel green extraction technologies to efficiently extract them, with emphasis on the antibacterial and antifungal data and their applications.

Efficiency of the Green Synthesized Nanoparticles as New Tools in Cancer Therapy: Insights on Plant-Based Bioengineered Nanoparticles, Biophysical Properties, and Anticancer Roles

The aim of this work is to review the current knowledge on the efficiency of plant-based synthesized nanoparticles in medical field, particularly in the prevention, diagnosis, and therapy of cancer. For this, we examine the advantages of nanotechnological tools. Besides, a particular attention was given to understand the mechanism by which plant-based bioengineered nanoparticles can interact with components of cancerous cells. Green biosynthesized nanoparticles seem to be novel tool for prognostic biomarkers for cancer diagnosis and drug delivery in tumor cells. They can act either by leading to the damage of tumor cells, or by the protection of healthy cells, via mechanisms involving the specific properties of nanoparticles themselves and the antioxidative and antitumor properties found in plants. However, special attention should be given to the choice of plant species, extracts, and the toxic dose of some phytocompounds during the biosynthesis process. An increase in metal or trace element release from metal and metal oxide biosynthesized nanoparticles can lead to greater oxidative stress, which is associated with higher risk of cancer. Hence, plant-based nanosystems should be more developed to increase their specific targeting of the cancerous cells, in order to preserve the healthy ones.

Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics

Antibiotics used to treat bacterial infections can become ineffective over time or result in the emergence of antibiotic resistant pathogens. With the advent of nanotechnology, silver nanoparticles (AgNPs) have gained significant attention as a therapeutic agent due to the well-known antimicrobial properties of silver. However, there are concerns and limited literature on the potential cytotoxicity of nanoparticles at effective antimicrobial concentrations. AgNPs prepared from silver nitrate with glucose reduction were characterized by surface plasmon resonance, dynamic light scattering, zeta potential analysis and transmission electron microscopy. The cytotoxicity of AgNPs towards human gingival fibroblasts over 7 days was determined using cell proliferation assays and confocal microscopy. AgNP MIC and antibacterial effects alone and in combination with 11 antibiotics were determined against a panel of nine microbial species including gram-positive and gram-negative bacterial species. AgNPs concentrations ≤ 1 μg/mL were non-cytotoxic but also showed no antibacterial effects. However, when combined with each of eleven antibiotics, the biocompatible concentration of AgNPs (1 μg/mL) resulted in significant inhibition of bacterial growth for multiple bacterial species that were resistant to either the antibiotics or AgNPs alone. This study presents a promising strategy with further testing in vivo, to develop novel antimicrobial agents and strategies to confront emerging antimicrobial resistance.

Banana Peel-Derived Dendrite-Shaped Au Nanomaterials with Dual Inhibition Toward Tumor Growth and Migration

Purpose

In order to prepare functional Au nanoparticles with low toxicity and high antitumor properties, we have used fruit waste (banana peel) to synthesize a new dendrite-shaped gold nanoparticle and used it for the treatment of tumors.

Methods

Dendrite-shaped gold nanoparticle (Au-dendrite) was synthesized through a facile hydrothermal process. The banana peel was used as both the reducing agent and the protective agent for reducing chloroauric acid to obtain Au-dendrite. The safety assessment of the Au-dendrite was conducted by H&E staining of the mouse’s eyelid skin and CCK-8 assay. The antitumor effects were evaluated through in vitro tumor cytotoxicity experiments and in vivo treatment of animal tumors.

Results

In this work, a new type of gold nanomaterial (Au-dendrite) was synthesized by using a common agricultural waste (banana peel) through a facile hydrothermal process without any extra chemical reducing agent or protective agent. Subsequent experiments showed that, compared with some classical Au nanomaterials, the as-synthesized gold nanocomposites have superior biocompatibility and impressive characteristics of dual inhibition toward tumor growth and migration.

Conclusion

We successfully synthesized a dendrite-shaped gold nanocomposite which was derived from a common agricultural waste (banana peel). A facile and environmentally friendly synthetic process was proposed accordingly without regular chemical additives. The as-prepared Au-dendrite nanocomposites not only had better biocompatibility than some classical gold nanoparticles but also exhibited unique advantages in tumor inhibition.

New Prospects for Modified Algae in Heavy Metal Adsorption

Heavy metal pollution is one of the most pervasive environmental problems globally. Novel finely tuned algae have been proposed as a means to improve the efficacy and selectivity of heavy metal biosorption. This article reviews current research on selective algal heavy metal adsorption and critically discusses the performance of novel biosorbents. We emphasize emerging state-of-the-art techniques that customize algae for enhanced performance and selectivity, particularly molecular and chemical extraction techniques as well as nanoparticle (NP) synthesis approaches. The mechanisms and processes for developing novel algal biosorbents are also presented. Finally, we discuss the applications, challenges, and future prospects for modified algae in heavy metal biosorption.

Continuous Flow Copper Laser Ablation Synthesis of Copper(I and II) Oxide Nanoparticles in Water

Copper(I) oxide (Cu2O) nanoparticles (NPs) are selectively prepared in high yields under continuous flow in a vortex fluidic device (VFD), involving irradiation of a copper rod using a pulsed laser operating at 1064 nm and 600 mJ. The plasma plume generated inside a glass tube (20 mm O.D.), which is rapidly rotating (7.5 k rpm), reacts with the enclosed air in the microfluidic platform, with then high mass transfer of material into the dynamic thin film of water passing up the tube. The average size of the generated Cu2ONPs is 14 nm, and they are converted to copper(II) oxide (CuO) nanoparticles with an average diameter of 11 nm by heating the as-prepared solution of Cu2ONPs in air at 50 °C for 10 h.

Green nanotechnology: a review on green synthesis of silver nanoparticles - an ecofriendly approach

Background: Nanotechnology explores a variety of promising approaches in the area of material sciences on a molecular level, and silver nanoparticles (AgNPs) are of leading interest in the present scenario. This review is a comprehensive contribution in the field of green synthesis, characterization, and biological activities of AgNPs using different biological sources. Methods: Biosynthesis of AgNPs can be accomplished by physical, chemical, and green synthesis; however, synthesis via biological precursors has shown remarkable outcomes. In available reported data, these entities are used as reducing agents where the synthesized NPs are characterized by ultraviolet-visible and Fourier-transform infrared spectra and X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results: Modulation of metals to a nanoscale drastically changes their chemical, physical, and optical properties, and is exploited further via antibacterial, antifungal, anticancer, antioxidant, and cardioprotective activities. Results showed excellent growth inhibition of the microorganism. Conclusion: Novel outcomes of green synthesis in the field of nanotechnology are appreciable where the synthesis and design of NPs have proven potential outcomes in diverse fields. The study of green synthesis can be extended to conduct the in silco and in vitro research to confirm these findings.

Algae-based metallic nanoparticles: Synthesis, characterization and applications

Nanomaterials (NMs) tailored via conventional physicochemical routes play havoc with the environment that has led to the evolution of competent green routes for the actualization of a circular economy on an industrial-scale. Algae belonging to the class Cyanophyceae, Chlorophyceae, Phaeophyceae and Rhodophyceae have been harnessed as nano-machineries through intracellular and extracellular synthesis of gold (Au), silver (Ag) and several other metallic nanoparticles. Algae are an appealing platform for the production of diverse NMs, primarily due to the presence of bioactive compounds such as pigments and antioxidants in their cell extracts that act as biocompatible reductants. Chlorella spp. and Sargassum spp. have been extensively explored for the synthesis of nanoparticles having antimicrobial properties, which can potentially substitute conventional antibiotics. Characterization of nanoparticles (NPs) synthesised from algae has been done using advanced spectroscopic, diffractographic and microscopic techniques such as UV-Vis FT-IR, DLS, XPS, XRD, SEM, TEM, AFM, HR-TEM, and EDAX. The present paper reviews the information available on algae-mediated biosynthesis of various NPs, their characterization and applications in different domains.

Anticancer, antimicrobial and photocatalytic activities of green synthesized magnesium oxide nanoparticles (MgONPs) using aqueous extract of Sargassum wightii

A rapid and ecofriendly fabrication of metal oxide nanoparticles using biogenic sources is the current trend being used to replace the toxic chemical method. The present study was carried out to synthesize magnesium oxide nanoparticles (MgONPs) using the marine brown algae Sargassum wighitii as the reducing and capping agent. The as-prepared MgONPs were characterized by spectroscopic and microscopic analyses. UV-visible spectrum of the MgONPs showed a sharp absorption peak at 322 nm. X- ray diffraction analysis illustrated that the MgONPs were crystalline in nature with a face-centered cubic structure. Presence of magnesium and oxygen were further confirmed by EDX profile. FTIR analysis showed the presence of functional groups specific for sulfated polysaccharides, which might be responsible for the synthesis of MgONPs. Zeta potential and dynamic light scattering analysis illustrated that the MgONPs were highly stable at 19.8 mV with an average size of 68.06 nm. MgONPs showed potent antibacterial activity and antifungal activities against human pathogens. Photocatalytic activity of MgONPs was witnessed by the quick degradation of the organic dye methylene blue on exposure to both sunlight and UV irradiation. MgONPs showed significant cytotoxicity against the lung cancer cell lines A549 in a dose dependent manner with the IC50 value of 37.5 ± 0.34 μg/ml. Safety evaluation using peripheral blood mononuclear cells (PBMCs) illustrated the MgONPs to be non-toxic in nature. Overall, the results concluded that the MgONPs generated using marine algae have exhibited scope for multifaceted biological applications.

Mycosynthesis of Size-Controlled Silver Nanoparticles through Optimization of Process Variables by Response Surface Methodology

The present study was carried out to reduce the size of silver nanoparticles (AgNPs) by optimizing physico-chemical conditions of the Aspergillus fumigatus BTCB10 growth based on central composite design (CCD) through response surface methodology (RSM). Variables such as a concentration of silver nitrate (mM), NaCl (%) and the wet weight of biomass (g) were controlled to produce spherical, monodispersed particles of 33.23 nm size, observing 78.7% reduction in size as compared to the initially obtained size that was equal to 356 nm. The obtained AgNPs exhibited negative zeta potential of -9.91 mV with a peak at 420 nm in the UV-Vis range whereas Fourier Transform Infrared (FT-IR) analysis identified O-H, C = C, C ≡ C, C-Br and C-Cl groups attached as capping agents. After conducting RSM experiments, a high nitrate reductase activity value of 179.15 nmol/h/ml was obtained; thus indicating a likely correlation between enzyme production and AgNPs synthesis. The F-value (significant at 3.91), non-significant lack of fit and determination coefficient (R2 = 0.7786) is representative of the good relation between the predicted values of response. We conclude that CCD is an effective tool in obtaining significant results of high quality and efficiency.

The present study was carried out to reduce the size of silver nanoparticles (AgNPs) by optimizing physico-chemical conditions of the Aspergillus fumigatus BTCB10 growth based on central composite design (CCD) through response surface methodology (RSM). Variables such as a concentration of silver nitrate (mM), NaCl (%) and the wet weight of biomass (g) were controlled to produce spherical, monodispersed particles of 33.23 nm size, observing 78.7% reduction in size as compared to the initially obtained size that was equal to 356 nm. The obtained AgNPs exhibited negative zeta potential of –9.91 mV with a peak at 420 nm in the UV-Vis range whereas Fourier Transform Infrared (FT-IR) analysis identified O–H, C = C, C ≡ C, C–Br and C–Cl groups attached as capping agents. After conducting RSM experiments, a high nitrate reductase activity value of 179.15 nmol/h/ml was obtained; thus indicating a likely correlation between enzyme production and AgNPs synthesis. The F-value (significant at 3.91), non-significant lack of fit and determination coefficient (R2 = 0.7786) is representative of the good relation between the predicted values of response. We conclude that CCD is an effective tool in obtaining significant results of high quality and efficiency.

Phyto-mediated synthesis of silver nanoparticles using fucoidan isolated from Spatoglossum asperum and assessment of antibacterial activities

The present study was aimed to investigate the antibacterial efficacy of fucoidan mediated silver nanoparticles (Fu-AgNPs) synthesized from Spatoglossum asperum. The synthesized Fu-AgNPs were characterized by UV-visible, Field emission - scanning electron microscope (FE-SEM), Tranmission electron microscope (TEM), X-ray diffraction (XRD), Selected area electron diffraction (SAED) pattern, Energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FT-IR), Dynamic light scattering (DLS) and Zeta potential analysis. The UV-visible spectrum of Fu-AgNPs exhibited a characteristic surface plasmon resonance (SPR) peak at 440 nm. The electron microscopic results revealed that the nanoparticles were spherical to oval in shape and are found to be 20 to 46 nm. Altogether the X-ray diffraction analysis showed that the Fu-AgNPs were crystalline in nature. The FT-IR spectrum confirmed the existence of CC stretching vibration of aromatic compounds and sulfated groups of fucoidan plays a major role in the synthesis of Fu-AgNPs. The biosynthesized Fu-AgNPs shows potential antibacterial activity against Klebsiella pneumoniae in agar bioassay, disk diffusion, reactive oxygen species, protein leakage and confocal laser scanning microscopy assays. Furthermore, Artemia toxicity assay results showed less mortality (3.3 ± 0.8%) even at higher concentration of Fu-AgNPs. Therefore, Fu-AgNPs can be effectively used as an antibacterial agent in the pharmaceutical fields.

Developments of Cyanobacteria for Nano-Marine Drugs: Relevance of Nanoformulations in Cancer Therapies

Current trends in the application of nanomaterials are emerging in the nano-biotechnological sector for development of medicines. Cyanobacteria (blue-green algae) are photosynthetic prokaryotes that have applications to human health and numerous biological activities as dietary supplements. Cyanobacteria produce biologically active and chemically diverse compounds such as cyclic peptides, lipopeptides, fatty acid amides, alkaloids, and saccharides. More than 50% of marine cyanobacteria are potentially exploitable for the extraction of bioactive substances, which are effective in killing cancer cells by inducing apoptotic death. The current review emphasizes that not even 10% of microalgal bioactive components have reached commercialized platforms due to difficulties related to solubility. Considering these factors, they should be considered as a potential source of natural products for drug discovery and drug delivery approaches. Nanoformulations employing a wide variety of nanoparticles and their polymerized forms could be an emerging approach to the development of new cancer drugs. This review highlights recent research on microalgae-based medicines or compounds as well as their biomedical applications. This review further discusses the facts, limitations, and commercial market trends related to the use of microalgae for industrial and medicinal purposes.

ROS-mediated cytotoxic activity of ZnO and CeO2 nanoparticles synthesized using the Rubia cordifolia L. leaf extract on MG-63 human osteosarcoma cell lines

In the present scenario, the synthesis and characterization of zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles (NPs) through biological routes using green reducing agents are quite interesting to explore various biomedical and pharmaceutical applications, particularly for the treatment of cancer. This study was focused on the phytosynthesis of ZnO and CeO2 NPs using the leaf extract of Rubia cordifolia L. The active principles present in the plant extract were liable for rapid reduction of Zn and Ce ions to metallic nanocrystals. ZnO and CeO2 NPs were characterized by UV-visible spectroscopy, X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDAX), and photoluminescence (PL) techniques. ZnO and CeO2 NPs were partially agglomerated with a net-like structure. Biomedical activities of ZnO and CeO2 NPs were tested against MG-63 human osteosarcoma cells using MTT and reactive oxygen species (ROS) quantification assays. In treated cells, loss of cell membrane integrity, oxidative stress, and apoptosis was observed and it is well correlated with cellular damage immediately after induction. Overall, this study shed light on the anti-cancer potential of ZnO and CeO2 NPs on MG-63 human osteosarcoma cells through differential ROS production pathways, describing the potential role of greener synthesis.

An enhancement of antimicrobial efficacy of biogenic and ceftriaxone-conjugated silver nanoparticles: green approach

Of the various methods explored for the synthesis of nanoparticles, biogenesis of silver nanoparticles (AgNPs) received great attention due to their versatile properties. In this report, Daucus carota extract was used for the synthesis of AgNPs and ceftriaxone was conjugated with AgNPs to enhance their antimicrobial efficacy. The conjugated and unconjugated AgNPs were characterized by adopting UV-Vis spectroscopy, FTIR, AFM, DLS, and TEM, which revealed the SPR peak at 420 nm and spherical shaped nanoparticles of 20 nm size, respectively. The antimicrobial efficacies of the unconjugated AgNPs and ceftriaxone-conjugated AgNPs were tested against ceftriaxone-resistant human pathogens, Bacillus cereus, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The ceftriaxone-conjugated AgNPs showed high inhibitory action (23 mm) than the unconjugated AgNPs (18 mm) at the concentration of 50 μg/mL. Both the unconjugated and ceftriaxone-conjugated AgNPs were found to be non-toxic on EAC cells at 50 μg/mL. The dose-dependent cytotoxic activities were observed on increasing the concentration of the AgNPs. The ceftriaxone-conjugated AgNPs showed high activity than the unconjugated AgNPs. The enhanced activity could be useful to treat ceftriaxone-resistant human pathogens.

New insights on the green synthesis of metallic nanoparticles using plant and waste biomaterials: current knowledge, their agricultural and environmental applications

Nanotechnology is a rapidly growing scientific field and has attracted a great interest over the last few years because of its abundant applications. Green nanotechnology is a multidisciplinary field that has emerged as a rapidly developing research area, serving as an important technique that emphasize on making the procedure which are clean, non-hazardous, and especially environmentally friendly, in contrast with chemical and physical methods currently employed for nanosynthesis. The biogenic routes could be termed green as these do not involve the use of highly toxic chemicals or elevated energy inputs during the synthesis. Differences in the bio-reducing agents employed for nanosynthesis can lead to the production of nanoparticles (NPs) having distinct shapes, sizes, and bioactivity. The exquitiveness of the green fabricated NPs have capacitated their potential applications in various sectors such as biomedicine, pharmacology, food science, agriculture, and environmental engineering. The present review summarizes current knowledge on various biogenic synthesis methods, relying on plants, waste biomass, and biopolymers and their reducing and stabilizing agents to fabricate nanomaterials. The main emphasis has been given on the current status and future challenges related to the wide-scale fabrication of nanoparticles for environmental remediation, pathogenicity, and agricultural applications.

Biogenic synthesis of gold nanoparticles from Terminalia arjuna bark extract: assessment of safety aspects and neuroprotective potential via antioxidant, anticholinesterase, and antiamyloidogenic effects

The development of neuroprotective drugs through eco-friendly production routes is a major challenge for current pharmacology. The present study was carried out to synthesize gold nanoparticles (AuNPs) through biogenic route using ethanolic bark extract of Terminalia arjuna, a plant of high interest in Asian traditional medicine, and to evaluate its neuroprotective effects. The synthesized AuNPs were characterized by UV-Vis spectroscopy, FTIR spectroscopy, XRD, FESEM, EDX, HRTEM, DLS, and zeta potential analyses. UV-Vis spectroscopy showed a characteristics SPR absorption band at 536 nm specific for AuNPs. XRD, TEM, and FESEM analyses revealed the formation of face-centered cubic crystalline, spherical and triangular shaped AuNPs, with size ranging between 20 and 50 nm. DLS and ZP analysis illustrated that the average size of AuNPs was 30 nm, which was found to be stable at 45 mv. The neuroprotective potential of AuNPs was evaluated by assessing its antioxidant, cholinesterase inhibitory, and antiamyloidogenic activities. AuNPs showed dose-dependant inhibition of acetylcholinesterase and butyrylcholinesterase with IC₅₀ value of 4.25 ± 0.02 and 5.05 ± 0.02 μg/ml, respectively. In vitro antioxidant assays illustrated that AuNPs exhibited the highest reducing power and DPPH radical scavenging activity. In addition, AuNPs also efficiently suppressed the fibrillation of Aβ and destabilized the preformed mature fibrils. Results of toxicity studies in PBMC and adult zebra fish illustrated that AuNPs are non-toxic and biocompatible. Overall, our results highlighted the AuNPs promising potential in terms of antioxidant, anticholinesterase, antiamyloidogenic effects, and non-lethality allowing us to propose these nanomaterials as a suitable candidate for the development of drugs helpful in the treatment of neurodegenerative disorders like Alzheimer's disease. Graphical abstract ᅟ.

Macroalgae Extracts From Antarctica Have Antimicrobial and Anticancer Potential

Background: Macroalgae are sources of bioactive compounds due to the large number of secondary metabolites they synthesize. The Antarctica region is characterized by extreme weather conditions and abundant aggregations of macroalgae. However, current knowledge on their biodiversity and their potential for bio-prospecting is still fledging. This study evaluates the antimicrobial and cytotoxic activity of different extracts of four macroalgae (Cystosphaera jacquinotii, Iridaea cordata, Himantothallus grandifolius, and Pyropia endiviifolia) from the Antarctic region against cancer and non-cancer cell lines.

Methods: The antimicrobial activity of macroalgae was evaluated by the broth microdilution method. Extracts were assessed against Staphylococcus aureus ATCC 19095, Enterococcus faecalis ATCC 4083, Escherichia coli ATCC29214, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 62342, and the clinical isolates from the human oral cavity, namely, C. albicans (3), C. parapsilosis, C. glabrata, C. lipolytica, and C. famata. Cytotoxicity against human epidermoid carcinoma (A-431) and mouse embryonic fibroblast (NIH/3T3) cell lines was evaluated with MTT colorimetric assay.

Results: An ethyl acetate extract of H. grandifolius showed noticeable antifungal activity against all fungal strains tested, including fluconazole-resistant samples. Cytotoxicity investigation with a cancer cell line revealed that the ethyl acetate extract of I. cordata was highly cytotoxic against A-431 cancer cell line, increasing the inhibitory ratio to 91.1 and 95.6% after 24 and 48 h exposure, respectively, for a concentration of 500 μg mL⁻¹. Most of the algal extracts tested showed little or no cytotoxicity against fibroblasts.

Conclusion: Data suggest that macroalgae extracts from Antarctica may represent a source of therapeutic agents.

HIGHLIGHTS

Different macroalgae samples from Antarctica were collected and the lyophilized biomass of each macroalgae was extracted sequentially with different solvents

The antimicrobial and anticancer potential of macroalgae extracts were evaluated

Ethyl acetate extract of H. grandifolius showed noticeable antifungal activity against all the fungal strains tested, including fluconazole-resistant samples

Ethyl acetate extract of I. cordata was highly cytotoxic against the A-431 cancer cell line

Most of the algal extracts tested showed little or no cytotoxicity against normal cell lines