Algae have long been exploited commercially and industrially as food, feed, additives, cosmetics, pharmaceuticals, and fertilizer, but now the trend is shifting towards the algae-mediated green synthesis of nanoparticles (NPs). This trend is increasing day by day, as algae are a rich source of secondary metabolites, easy to cultivate, have fast growth, and are scalable. In recent era, green synthesis of NPs has gained widespread attention as a safe, simple, sustainable, cost-effective, and eco-friendly protocol. The secondary metabolites from algae reduce, cap, and stabilize the metal precursors to form metal, metal oxide, or bimetallic NPs. The NPs synthesis could either be intracellular or extracellular depending on the location of NPs synthesis and reducing agents. Among the diverse range of algae, the most widely investigated algae for the biosynthesis of NPs documented are brown, red, blue-green, micro and macro green algae. Due to the biocompatibility, safety and unique physico-chemical properties of NPs, the algal biosynthesized NPs have also been studied for their biomedical applications, which include anti-bacterial, anti-fungal, anti-cancerous, anti-fouling, bioremediation, and biosensing activities. In this review, the rationale behind the algal-mediated biosynthesis of metallic, metallic oxide, and bimetallic NPs from various algae have been reviewed. Furthermore, an insight into the mechanism of biosynthesis of NPs from algae and their biomedical applications has been reviewed critically.

An Overview of the Algae-Mediated Biosynthesis of Nanoparticles and Their Biomedical Applications

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the recent outbreak of coronavirus 2019 (COVID-19). Although nearly two decades have passed since the emergence of pandemics such as SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), no effective drug against the CoV family has yet been approved, so there is a need to find newer therapeutic targets. Currently, simultaneous research across the globe is being performed to discover efficient vaccines or drugs, including both conventional therapies used to treat previous similar diseases and emerging therapies like nanomedicine. Nanomedicine has already proven its value through its application drug delivery and nanosensors in other diseases. Nanomedicine and its components can play an important role in various stages of prevention, diagnosis, treatment, vaccination, and research related to COVID-19. Nano-based antimicrobial technology can be integrated into personal equipment for the greater safety of healthcare workers and people. Various nanomaterials such as quantum dots can be used as biosensors to diagnose COVID-19. Nanotechnology offers benefits from the use of nanosystems, such as liposomes, polymeric and lipid nanoparticles, metallic nanoparticles, and micelles, for drug encapsulation, and facilitates the improvement of pharmacological drug properties. Antiviral functions for nanoparticles can target the binding, entry, replication, and budding of COVID-19. The toxicity-related inorganic nanoparticles are one of the limiting factors of its use that should be further investigated and modified. In this review, we are going to discuss nanomedicine options for COVID-19 management, similar applications for related viral diseases, and their gap of knowledge.

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Nanomedicine for COVID-19: the role of nanotechnology in the treatment and diagnosis of COVID-19.

Sustainable solutions on fabricating and using a face mask to block the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread during this coronavirus pandemic of 2019 (COVID-19) are required as society is directed by the World Health Organization (WHO) toward wearing it, resulting in an increasingly huge demand with over 4 000 000 000 masks used per day globally. Herein, various new mask technologies and advanced materials are reviewed to deal with critical shortages, cross-infection, and secondary transmission risk of masks. A number of countries have used cloth masks and 3D-printed masks as substitutes, whose filtration efficiencies can be improved by using nanofibers or mixing other polymers into them. Since 2020, researchers continue to improve the performance of masks by adding various functionalities, for example using metal nanoparticles and herbal extracts to inactivate pathogens, using graphene to make masks photothermal and superhydrophobic, and using triboelectric nanogenerator (TENG) to prolong mask lifetime. The recent advances in material technology have led to the development of antimicrobial coatings, which are introduced in this review. When incorporated into masks, these advanced materials and technologies can aid in the prevention of secondary transmission of the virus.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202102189

Masks for COVID-19.

Background: Nanotechnology is the branch of science and technology, which deals with the production of substances in size less than100nm scale as nanoparticles. Nanoparticles are studied as building blocks of the next generation of technology with applications in different disciplines. Currently biological species like algae are in great use for the nanoparticles synthesis. Algae are ecological and economically important eukaryotic, photosynthetic organism of the kingdom Protista. As like true plants, algae are not differentiated into root, stem and leaves but similar to lower plants for example Mosses, liverworts, etc. Aims: In the present study we use the extract of green alga Botryococcus braunii for the synthesis of copper and silver nanoparticles. Methods: Green alga was collected from Udaisagar Lake Udaipur (Rajasthan, India) and isolated by serial dilution method and grown on Chu-13 nutrient medium. The characterization of alga synthesized copper and silver nanoparticles was carried out by using UVVis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron spectroscopy (SEM). Green synthesized nanoparticles were toxic against bacteria and fungus. Expected findings: FT-IR measurements showed all functional groups having control over reduction and stabilization of the nanoparticles. X-ray diffraction pattern revealed that the particles were crystalline in nature with face-centred cubic (FCC) geometry. SEM micrographs have shown the morphology of biogenically synthesized metal nanoparticles. Further these biosynthesized nanoparticles were found to be highly toxic against two Gram negative bacterial strains Pseudomonas aeruginosa (MTCC 441), and Escherichia coli (MTCC 442), two Gram positive bacterial strains Klebsiella pneumoniae (MTCC 109) and Staphylococcus aureus (MTCC 96) and a fungal strain Fusarium oxysporum (MTCC 2087).

https://www.longdom.org/open-access/biogenic-synthesis-of-copper-and-silver-nanoparticles-using-green-alga-botrycoccus-braunii-and-its-antimicrobial-activit.pdf

Biogenic synthesis of copper and silver nanoparticles using Green Alga Botrycoccus braunii and its antimicrobial activity

In the recent times, nanomaterials have emerged in the field of biology, medicine, electronics, and agriculture due to their immense applications. Owing to their nanoscale sizes, they present large surface/volume ratio, characteristic structures, and similar dimensions to biomolecules resulting in unique properties for biomedical applications. The chemical and physical methods to synthesize nanoparticles have their own limitations which can be overcome using biological methods for the synthesis. Moreover, through the biogenic synthesis route, the usage of microorganisms has offered a reliable, sustainable, safe, and environmental friendly technique for nanosynthesis. Bacterial, algal, fungal, and yeast cells are known to transport metals from their environment and convert them to elemental nanoparticle forms which are either accumulated or secreted. Additionally, robust nanocarriers have also been developed using viruses. In order to prevent aggregation and promote stabilization of the nanoparticles, capping agents are often secreted during biosynthesis. Microbial nanoparticles find biomedical applications in rapid diagnostics, imaging, biopharmaceuticals, drug delivery systems, antimicrobials, biomaterials for tissue regeneration as well as biosensors. The major challenges in therapeutic applications of microbial nanoparticles include biocompatibility, bioavailability, stability, degradation in the gastro-intestinal tract, and immune response. Thus, the current review article is focused on the microbe-mediated synthesis of various nanoparticles, the different microbial strains explored for such synthesis along with their current and future biomedical applications.

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Microbial Nano-Factories: Synthesis and Biomedical Applications.

As therapeutic antiviral agents, biological nanoparticles can fight the drug-resistant types of viruses helping the antiviral drug development. In this study, two blue-green algal strains; Oscillat...

Antiviral activity of algae biosynthesized silver and gold nanoparticles against Herps Simplex (HSV-1) virus in vitro using cell-line culture technique.

This work aims to assess the cytotoxicity of silver oxide and gold nanoparticles on two cancer cell cultures, human colon CaCo-2, and cervical HeLa cancer cells. Silver oxide and gold nanoparticles were synthesized using the isolated microalgae Oscillatoria sp. and Spirulina platensis. Different characterization tools (UV–Vis spectrum, XRD diffraction, TEM photography, FTIR spectroscopy, and Zeta-potential) had been used to confirm the resulted nanoparticles. Thereafter, the resulted silver oxide and gold nanoparticles were assessed as anticancer agents against human colon cancer (CaCo-2), cervical cancer (HeLa), and normal cells (WISH). The effective interaction of Oscillatoria sp. mediated Ag2O|AgO-NPs and S. platensis mediated Au-NPs against the normal human cells (WISH) and the cancer cells (CaCo-2 and HeLa), as IC50 of Ag2O|AgO-NPs recorded 147.77, 252.83, and 286.74 μg/ml for WISH, CaCo-2, and HeLa cells, respectively. IC50 for Au-NPs recorded 307.31, 311.00, and 382.90 μg/ml for WISH, CaCo-2, and HeLa cells, respectively. The safety limit against HeLa reached 98.61% by 3.906 μg/ml of Ag2O|AgO-NPs, and it recorded 93.13% by 15.625 μg/ml against CaCo-2, while the results of WISH was 51.29 % by 125.00 μg/ml. Concerning the anticancer effect of Au-NPs, the safety limit recorded 92.47% by 3.906 μg/ml against CaCo-2, while HeLa reached 93.43% by 15.625 μg/ml and WISH was 99.62% by 62.500 μg/ml. The cytotoxicity results revealed that both Oscillatoria sp. mediated Ag2O|AgO-NPs and S. platensis mediated Au-NPs caused the reduction of the colon (CaCo-2) and cervical cancer cell lines. Although the low concentrations of silver oxide nanoparticles 3.906 and 15.625 μg/ml showed the safety limit effect against HeLa and CaCo-2, they revealed no hazard on WISH cells. In conclusion, algal silver oxides and gold nanoparticles exhibited effective anticancer activities against cancer cells as a green nanotechnology application.

Assessment of the in vitro anticancer activities of cyanobacteria mediated silver oxide and gold nanoparticles in human colon CaCo-2 and cervical HeLa cells

The efficient role of algae as green factories for nanotechnology and their vital applications.

Recently, green nanotechnology is considered a more suitable and safer tool for medical applications due to its nature reductants with low toxicity and low eco-hazard. The micro-algal biomass was used for the nanoparticles biosynthesis, depending on using whole algal cell cultivation. During the current study, cyanobacteria Oscillatoria sp. and Spirulina platensis exhibited their ability to synthesize silver oxide (Ag2O|AgO-NPs) and gold nanoparticles (Au-NPs), respectively. The characterization results confirmed the formation of Oscillatoria sp.-mediated silver oxide nanoparticles (O.Ag2O|AgO-NPs) and S. platensis-mediated gold nanoparticles (S.Au-NPs). Three different methods had been examined, (i) culture-free cells (secondary metabolites), (ii) algal aqueous extract, and (iii) whole cells cultivation (in vivo). UV–Vis spectroscopy confirmed the biosynthesized O.Ag-NPs at 438 nm, while S.Au-NPs reached 545 nm by whole cells cultivation technique. TEM scanning indicated the formation of spherical-shaped O.Ag2O|AgO-NPs with an average size ranged between 10.49 and 45.81 nm. S.Au-NPs also were detected in triangular, pentagonal, and slightly spherical shapes with an average size of 15.49–55.08 nm. Both O.Ag2O|AgO-NPs, and S.Au-NPs demonstrated antibacterial and antifungal properties against Gram-positive and Gram-negative bacteria. S.Au-NPs were more effective than O.Ag2O|AgO-NPs, which recorded high significant MIC results against Bacillus subtilis ATCC 19659 (1.95 μg/ml), Salmonella typhi ATCC14028 (3.90 μg/ml), and Candida tropicalis ATCC 1380 (1.1 μg/ml) after 24 h treatment, comparing with the control. It is concluded that O.Ag2O|AgO-NPs and S.Au-NPs have efficient antibacterial and antifungal activities.

Evaluation of antimicrobial activities of blue-green algae-mediated silver and gold nanoparticles

SPIRULINA has drawn attention throughout the last decades. It is an essential source of valuable products, such as proteins, phycobilins, carotenoids, phenolics, and unsaturated fatty acids. These products had been used in medicine, pharmaceutical, and agriculture. In this study, the effect of different growth media on Spirulina platensis was studied after the cultivation at optimum growth conditions; continuous light intensity (60μmol photons m-2s-1), temperature (25±3oC), and pH (9.0 ± 0.2). The growth was estimated through 42 days by optical density (OD), cell counting (CC), and chlorophyll contents. The results showed that Kuhl’s medium was the optimum for S. platensis with the highest results, i.e.: (OD), (CC) and Chlorophyll content increased 11.57 times, 19.55 times, and 22.66 times of the initial record, respectively. KNO3 showed the best nitrogen source for S. platensis, where the different parameters of growth elevated to 3.56 times OD, 7.33 times CC, and 1.91 total chlorophyll more than their corresponding control.

https://ejbo.journals.ekb.eg/article_112649_6605ef6f4796a9320dac53412ef629cd.pdf

Hanaa H. Morsi

Papers

Antiviral activity of algae biosynthesized silver and gold nanoparticles against Herps Simplex (HSV-1) virus in vitro using cell-line culture technique.

Assessment of the in vitro anticancer activities of cyanobacteria mediated silver oxide and gold nanoparticles in human colon CaCo-2 and cervical HeLa cells

The efficient role of algae as green factories for nanotechnology and their vital applications.

Evaluation of antimicrobial activities of blue-green algae-mediated silver and gold nanoparticles

Growth Enhancement of Spirulina platensis through Optimization of Media and Nitrogen Sources