Biosynthesis of Metal and Metal Oxide Nanoparticles

A Review on Bioflocculant-Synthesized Copper Nanoparticles: Characterization and Application in Wastewater Treatment

Copper nanoparticles (CuNPs) are tiny materials with special features such as high electric conductivity, catalytic activity, antimicrobial activity, and optical activity. Published reports demonstrate their utilization in various fields, including biomedical, agricultural, environmental, wastewater treatment, and sensor fields. CuNPs can be produced utilizing traditional procedures; nevertheless, such procedures have restrictions like excessive consumption of energy, low production yields, and the utilization of detrimental substances. Thus, the adoption of environmentally approachable "green" approaches for copper nanoparticle synthesis is gaining popularity. These approaches involve employing plants, bacteria, and fungi. Nonetheless, there is a scarcity of data regarding the application of microbial bioflocculants in the synthesis of copper NPs. Therefore, this review emphasizes copper NP production using microbial flocculants, which offer economic benefits and are sustainable and harmless. The review also provides a characterization of the synthesized copper nanoparticles, employing numerous analytical tools to determine their compositional, morphological, and topographical features. It focuses on scientific advances from January 2015 to December 2023 and emphasizes the use of synthesized copper NPs in wastewater treatment.

Exploring the Potential of Nickel Oxide Nanoparticles Synthesized from Dictyota bartayresiana and its Biological Applications

The present study validates the impact of nickel oxide nanoparticles (NiONPs) biosynthesized from the brown seaweed Dictyota bartayresiana (DB) and its biological applications. The phytochemicals analyzed in the seaweed extract served as a reducing, capping or stabilizing agent in the formation of nanoparticles. UV visible spectrum of nickel oxide nanoparticles synthesized from DB (DB-NiONPs) represented a prominent peak at 392 nm which validates its formation. Fourier Transmission Infrared Spectroscopy (FT-IR) showcased the presence of functional groups in the biomolecules which aids in the stabilization of DB-NiONPs. The X-ray diffractometry (XRD) revealed the crystalline nature of DB-NiONPs and the particle size was calculated as 18.26 nm. The Scanning electron microscope (SEM) illustrates the irregularly shaped DB-NiONPs and the desired elements were depicted in energy dispersive X-ray (EDX) spectrum which confirms the purity of DB-NiONPs. The DB-NiONPs efficiently decolorised the Black B133 (BB133) dye to 86% in 25 min. The data of adsorption studies well fitted into Langmuir isotherm and pseudo-second order kinetic model. The thermodynamic study substantiated the spontaneous, feasible and endothermic process of adsorption. DB-NiONPs revealed enhanced antimicrobial, larvicidal and nematicidal activities against the selected microbes, larva of Culex pipens and juveniles of Meloidogyne incognita respectively. The phytotoxicity studies revealed the DB-NiONPs had a positive impact on the germination and growth of green gram seedlings.

A narrative review on application of metal and metal oxide nanoparticles in endodontics

The distinct physicochemical and biological characteristics of metal and metal oxide nanoparticles have attracted considerable interest in various branches of dentistry as potential solutions to the problems associated with conventional dental treatments and to promote human health. Many scientists have been interested in nanoparticles for endodontic applications in the last several decades. Endodontic treatment is more likely to be successful when metal and metal oxide nanoparticles are used. Endodontic therapies often make use of nanoparticles made of metals and metal oxides. The effect of nano metals and metal oxide in endodontic treatments has not been published or is not widely available in the literature. Therefore, this paper aims to review recent studies on the development and application of some important metal and metal oxide nanoparticles such as silver and silver oxide, zinc oxide, zirconium oxide, magnesium oxide, titanium dioxide and other metal oxide nanoparticles in endodontic therapeutic procedures.

Carbon Nanodot-Microbe-Plant Nexus in Agroecosystem and Antimicrobial Applications

The intensive applications of nanomaterials in the agroecosystem led to the creation of several environmental problems. More efforts are needed to discover new insights in the nanomaterial-microbe-plant nexus. This relationship has several dimensions, which may include the transport of nanomaterials to different plant organs, the nanotoxicity to soil microbes and plants, and different possible regulations. This review focuses on the challenges and prospects of the nanomaterial-microbe-plant nexus under agroecosystem conditions. The previous nano-forms were selected in this study because of the rare, published articles on such nanomaterials. Under the study's nexus, more insights on the carbon nanodot-microbe-plant nexus were discussed along with the role of the new frontier in nano-tellurium-microbe nexus. Transport of nanomaterials to different plant organs under possible applications, and translocation of these nanoparticles besides their expected nanotoxicity to soil microbes will be also reported in the current study. Nanotoxicity to soil microbes and plants was investigated by taking account of morpho-physiological, molecular, and biochemical concerns. This study highlights the regulations of nanotoxicity with a focus on risk and challenges at the ecological level and their risks to human health, along with the scientific and organizational levels. This study opens many windows in such studies nexus which are needed in the near future.

Emerging approaches of utilizing trees to produce advanced structural and functional materials

The global number of trees is approximately 3 trillion, covering 31% of the land area. Trees are considered a cheap, abundant, renewable, and environmentally friendly feedstock for producing advanced structural and functional materials toward a widespread application in sustainable energy and environment. In this highlight, we reveal the structure and composition of wood, leaves, and tree extracts, and then highlight the strategies to control their hierarchical structures and properties. Moreover, we provide an up-to-date overview of their emerging applications in sustainable buildings, ionic nanofluidics, batteries, capacitors, solar cells, environmental remediation, biodegradable packaging, and nanomaterial synthesis. Finally, we outline the challenges and opportunities in valorizing trees for creating a sustainable future.

Sustainable synthesis of bionanomaterials using non-native plant extracts for maintaining ecological balance: A computational bibliography analysis

Biological approaches via biomolecular extracts of bacteria, fungi, or plants have recently been introduced as an alternative approach to synthesizing less or nontoxic nanomaterials, compared to conventional physical and chemical approaches. Among these biological methods, plant-mediated approaches (phytosynthesis) are reported to be highly beneficial for large-scale, nontoxic nanomaterial synthesis. However, plant-mediated synthesis of nanomaterials using native plant extract can lead to bioprospecting issues and deforestation challenges. On the other hand, non-native or invasive plants are non-indigenous to a particular geographic location that can grow and spread rapidly, ultimately disrupting the local and endogenous plant communities or ecosystems. Thus, controlling or eradicating these non-native plants before they damage the ecosystem is necessary. Even though mechanical, chemical, and biological approaches are available to control non-native plants, all these methods possess certain limitations, such as environmental toxicity, disturbance in the nutrient cycle, and loss of genetic integrity. Therefore, non-native plants were recently proposed as a novel sustainable source of phytochemicals for preparing nanomaterials via green chemistry, mainly metallic nanoparticles, as an alternative to native, agriculture-based, or medicinal plants. This work aims to cover a literature gap on plant-mediated bionanomaterial synthesis with an overview and bibliography analysis of non-native plants via novel data mining and advanced visualization tools. In addition, the potential of non-native plants as a sustainable, green chemistry-based alternative for bionanomaterial preparation for maintaining ecological balance, the mechanism of formation via phytochemicals, and their possible applications to promote their control and spread were also discussed. The bibliography analysis revealed that only an average of 4 articles have been published in the last 10 years (2013-2023) on non-native/invasive plants for nanomaterial synthesis, which shows the significance of this article.

Facile green synthesis of a novel NiO and its catalytic effect on methylene blue photocatalytic reduction and sodium borohydride hydrolysis

NiO nanoparticles were synthesized from pine cone extract by green synthesis method, which is a simple, cost-effective, environmentally friendly and sustainable method. The particle size of NiO nanoparticles was determined to be in the range of 10-25 nm by X-diffraction differential and transmission electron microscope analysis, and the bandgap energy of NiO nanoparticles was determined to be 2.66 eV. The catalytic effect of NiO nanoparticles in both microwave-assisted sodium borohydride hydrolysis and photocatalytic reduction of methylene blue was examined and it was determined that they had a high catalytic effect in both applications. It was determined that the hydrogen production rate in sodium borohydride hydrolysis was 1135 mL/g/min. The activation energy of sodium borohydride hydrolysis is 29.69 kJ/mol and 29.59 kJ/mol for the nth-order and Langmuir Hinshelwood kinetic models, respectively. In the photocatalytic reduction of methylene blue with NaBH4, it was determined that the reduction did not occur in the absence of a catalyst, but in the presence of the catalyst, the reduction occurred 98% in 3 min. It was determined that NiO nanoparticles were used five times in the photocatalytic reduction of methylene blue and the reduction efficiency for the fifth time was 93%. It was determined that the photocatalytic reduction of methylene blue was pseudo-first order and the rate constant was 1.63 s-1. It was determined that NiO nanoparticles synthesized by the environmentally friendly green synthesis method can be used as catalysts for two different applications.

Multifaceted chemical and bioactive features of Ag@TiO2 and Ag@SeO2 core/shell nanoparticles biosynthesized using Beta vulgaris L. extract

Due to increasing concerns about environmental impact and toxicity, developing green and sustainable methods for nanoparticle synthesis is attracting significant interest. This work reports the successful green synthesis of silver (Ag), silver-titanium dioxide (Ag@TiO2), and silver-selenium dioxide (Ag@SeO2) nanoparticles (NPs) using Beta vulgaris L. extract. Characterization by XRD, SEM, TEM, and EDX confirmed the successful formation of uniformly distributed spherical NPs with controlled size (25 ± 4.9 nm) and desired elemental composition. All synthesized NPs and the B. vulgaris extract exhibited potent free radical scavenging activity, indicating significant antioxidant potential. However, Ag@SeO2 displayed lower hemocompatibility compared to other NPs, while Ag@SeO2 and the extract demonstrated reduced inflammation in a carrageenan-induced paw edema animal model. Interestingly, Ag@TiO2 and Ag@SeO2 exhibited strong antifungal activity against Rhizoctonia solani and Sclerotia sclerotium, as evidenced by TEM and FTIR analyses. Generally, the findings suggest that B. vulgaris-derived NPs possess diverse biological activities with potential applications in various fields such as medicine and agriculture. Ag@TiO2 and Ag@SeO2, in particular, warrant further investigation for their potential as novel bioactive agents.

Ginger (Zingiber officinale)-Mediated Green Synthesis of Silver-Doped Tin Oxide Nanoparticles and Evaluation of Its Antimicrobial Activity

Green synthesis of nanoparticles using plant extract is a novel development that has gained significant attention because of its low cost, nontoxicity, and environmental friendliness. In the present study, silver-doped stannic oxide (Ag-doped SnO2) nanoparticle was synthesized by an eco-friendly green synthesis method. The synthesized samples were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), and their antimicrobial activities were assessed against two bacteria Escherichia coli (E. coli) and Staphylococcus aureus (S. aurus) and two fungi Fusarium oxysporum (F. oxysporum) and Fusarium graminearum (F. graminearum) by using the disk diffusion method. Ag-doped SnO2 nanoparticles show a strong and broad absorption from UV-vis spectra when compared to pure SnO2 nanoparticles. FTIR spectral analysis revealed that the peak at 505.69 cm-1 was assigned to Sn-O and O-Sn-O stretching vibration of SnO2 nanoparticles. XRD analysis confirmed the formation of a tetragonal rutile structure with average particle size ranging from 10 to 17 nm. The antimicrobial result indicates that the Ag-doped SnO2 revealed significant antimicrobial activity against both bacterial and fungi strains with the zone of inhibition of 29 ± 0.54, 27 ± 0.05, 17 ± 0.05, and 15 ± 0.05 mm for S. aureus, E. coli, F. oxysporum , and F. graminearum, respectively. Thus, the studies suggested that Ag-doped SnO2 nanoparticles exhibit good activity against both Gram-negative and Gram-positive bacteria and fungi. This is because doping SnO2 nanoparticles with metallic elements such as Ag has been used to enhance their performance, confirming them as a good candidate for antimicrobial agents and the development of future therapeutic agents.

Review on fate, transport, toxicity and health risk of nanoparticles in natural ecosystems: Emerging challenges in the modern age and solutions toward a sustainable environment

In today's era, nanoparticles (NPs) have become an integral part of human life, finding extensive applications in various fields of science, pharmacy, medicine, industry, electronics, and communication. The increasing popularity of NP usage worldwide is a testament to their tremendous potential. However, the widespread deployment of NPs unavoidably leads to their release into the environmental matrices, resulting in persistence in ecosystems and bioaccumulation in organisms. Understanding the environmental behavior of NPs poses a significant challenge due to their nanoscale size. Given the current environmental releases of NPs, known negative consequences, and the limited knowledge available for risk management, comprehending the toxicity of NPs in ecosystems is both awaiting and crucial. The present review aims to unravel the potential environmental influences of nano-scaled materials, and provides in-depth inferences of the current knowledge and understanding in this field. The review comprehensively summarizes the sources, fate, transport, toxicity, health risks, and remediation solutions associated with NP pollution in aquatic and soil ecosystems. Furthermore, it addresses the knowledge gaps and outlines further investigation priorities for the sustainable control of NP pollution in these environments. By gaining a holistic understanding of these aspects, we can work toward ensuring the responsible and sustainable use of NPs in today's fast-growing world.

Camellia sinensis Assisted Synthesis of Copper Oxide Nanoparticles (CuONPs) and Assessment of Its Antioxidant Activity and Zebrafish Embryonic Toxicology Evaluation

BACKGROUND

- Camellia sinensis, or oolong tea, is a partially fermented version of tea used in Asian countries. The remarkable reduction activity of the tea extract can potentially be used for synthesizing nanoparticles. Recently, Camellia sinensis has gained popularity for the formulation of some metal nanoparticles. Aim To formulate green synthesis of copper oxide nanoparticles (CuONPs) mediated by Camellia sinensis (oolong tea) and assess its cytotoxicity and antioxidant properties. Materials & Methods Oolong tea extract is prepared and added to CuSO4 solution to synthesize CuO nanoparticles (CuONPs). The centrifugation pellet of CuONPs is collected and subjected to DPPH (2,2 - diphenyl -1- picrylhydrazyl hydrate) and H2O2 assays. The cytotoxicity screening is performed using zebrafish embryos. Results The reducing activity of oolong tea successfully synthesizes the copper nanoparticles. High values are obtained in DPPH (63% inhibition at 10µL concentration, 73% inhibition at 20µL, 80% at 30µL, 85% at 40µL and 90% at 50µL concentrations) and H2O2 (50% inhibition at 10µL concentration, 65% at 20µL, 68% at 30µL, 75% at 40µL and 80% at 50µL concentrations) assays. There are no morphological deformities in the zebrafish and no loss of cell viability or delayed hatching at low concentrations (below 4-8 µL), as shown by the viable embryos with no morphological deformities. Conclusion The study has evidenced high antioxidant activity and minimal cytotoxicity of CuO nanoparticles produced using Camellia sinensis, thus proving it to be a good biomaterial for a wide range of biological applications.

Biofabrication of Acer palmatum-Mediated Multifunctional CuO Nanoparticles for Dye Removal, Antibacterial-Antifungal Activity, and Molecular Docking

Copper oxide nanoparticles (CuONPs) are used in many fields from electronics to medicine due to their multifunctionality, and therefore, their production with environmentally friendly methods is a current issue. In this study, biofabricated CuONPs were obtained by using the leaf extract of Acer palmatum plant originating from the Far East to enlighten the characteristics of the novel nanoparticles differentiating from those existing in the literature. Multifunctional nature of the CuONPs was evaluated by the antibacterial, antifungal, and decolorative applications and also by performing molecular docking analysis. The fabricated CuONPs were characterized using ultraviolet-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and dynamic light scattering (DLS). The absorbance seen at 270 nm in the SPR band obtained by UV-vis spectroscopy proved the presence of CuONPs, while the 602, 560, and 540 cm-1 vibrations obtained in the FT-IR spectroscopy indicated the same result. SEM images proved that the nanoparticles were in spherical form with sizes ranging from 140 to 225 nm. The result of DLS analysis showed that the average particle size was 229 nm in diameter, and CuONPs had monodisperse systems (polydispersity index, 0.184). The dye removal potency of CuONPs was also investigated by using remazol brilliant blue R (RBBR) and napthol blue black (NBB). Decolorizations (74 and 86%) of RBBR and NBB were obtained in 90 min at 50 °C, respectively. The strong antibacterial properties of the synthesized CuONPs were observed on both Gram (-) and Gram (+) bacterial strains by disk diffusion and optical analyses, and their antifungal activity was close to that of Amphotericin B, which was applied as a positive control. Molecular docking analysis was performed with Escherichia coli dihydrofolate reductase and Staphylococcus aureus DNA Gyrase B to analyze the antibacterial mechanisms of CuONP and observed that they exhibit good interactions with their targets with binding energies of -12.562 and -8.797 kcal/mol, respectively. Our findings suggested that CuONPs are crucial in the mechanisms of folate metabolism and DNA replication associated with bacterial proliferation. This work will provide significant guidance for the biofabrication of CuONPs and their medical and industrial applications.

Enhanced alpha-amylase inhibition activity of amine-terminated PAMAM dendrimer stabilized pure copper-doped magnesium oxide nanoparticles

The present work aims to prepare copper-doped MgO nanoparticles via a sol-gel approach and study their antidiabetic alpha-amylase inhibition activity with undoped MgO nanoparticles. The ability of G5 amine-terminated polyamidoamine (PAMAM) dendrimer for the controlled release of copper-doped MgO nanoparticles to exhibit alpha-amylase inhibition activity was also evaluated. The synthesis of MgO nanoparticles via sol-gel approach and optimization of calcination temperature and time has led to the formation of nanoparticles with different shapes (spherical, hexagonal, and rod-shaped) and a polydispersity in size ranging from 10 to 100 nm with periclase crystalline phase. The presence of copper ions in the MgO nanoparticles has altered their crystallite size, eventually modifying their size, morphology, and surface charge. The efficiency of dendrimer to stabilize spherical copper-doped MgO nanoparticles (ca. 30 %) is higher than in other samples, which was confirmed by UV-Visible, DLS, FTIR, and TEM analysis. The amylase inhibition assay emphasized that the dendrimer nanoparticles stabilization has led to the prolonged enzyme inhibition ability of MgO and copper-doped MgO nanoparticles for up to 24 h.

A comprehensive review on potential applications of metallic nanoparticles as antifungal therapies to combat human fungal diseases

Human pathogenic fungi are responsible for causing a range of infection types including mucosal, skin, and invasive infections. Life-threatening and invasive fungal infections (FIs) are responsible for mortality and morbidity, especially for individuals with compromised immune function. The number of currently available therapeutic agents against invasive FIs is limited compared to that against bacterial infections. In addition, the increased mortality and morbidity caused by FIs are linked to the limited number of available antifungal agents, antifungal resistance, and the increased toxicity of these agents. Currently available antifungal agents have several drawbacks in efficiency, efficacy, toxicity, activity spectrum, and selectivity. It has already been demonstrated with numerous metallic nanoparticles (MNPs) that these nanoparticles can serve as an effective and alternative solution as fungicidal agents. MNPs have great potential owing to their intrinsic antifungal properties and potential to deliver antifungal drugs. For instance, gold nanoparticles (AuNPs) have the capacity to disturb mitochondrial calcium homeostasis induced AuNP-mediated cell death in Candida albicans. In addition, both copper nanoparticles and copper oxide nanoparticles exerted significant suppressive properties against pathogenic fungi. Silver nanoparticles showed strong antifungal properties against numerous pathogenic fungi, such as Stachybotrys chartarum, Mortierella alpina, Chaetomium globosum, A. fumigatus, Cladosporium cladosporioides, Penicillium brevicompactum, Trichophyton rubrum, C. tropicalis, and C. albicans. Iron oxide nanoparticles showed potent antifungal activities against A. niger and P. chrysogenum. It has also been reported that zinc oxide nanoparticles can significantly inhibit fungal growth. These NPs have already exerted potent antifungal properties against a number of pathogenic fungal species including Candida, Aspergillus, Fusarium, and many others. Several strategies are currently used for the research and development of antifungal NPs including chemical modification of NPs and combination with the available drugs. This review has comprehensively presented the current and innovative antifungal approach using MNPs. Moreover, different types of MNPs, their physicochemical characteristics, and production techniques have been summarized in this review.

A critical review on the biosynthesis, properties, applications and future outlook of green MnO2 nanoparticles

MnO2 nanoparticles have played a vital role in biomedical, catalysis, electrochemical and energy storage fields, but requiring toxic chemicals in the fabrication intercepts their applications. There is an increasing demand for biosynthesis of MnO2 nanoparticles using green sources such as plant species in accordance with the purposes of environmental mitigation and production cost reduction. Here, we review recent advancements on the use of natural compounds such as polyphenols, reducing sugars, quercetins, etc. Extracted directly from low-cost and available plants for biogenic synthesis of MnO2 nanoparticles. Role of these phytochemicals and formation mechanism of bio-medicated MnO2 nanoparticles are shed light on. MnO2 nanoparticles own small particle size, high crystallinity, diverse morphology, high surface area and stability. Thanks to higher biocompatibility, bio-mediated synthesized MnO2 nanoparticles exhibited better antibacterial, antifungal, and anticancer activity than chemically synthesized ones. In terms of wastewater treatment and energy storage, they also served as efficient adsorbents and catalyst. Moreover, several aspects of limitation and future outlook of bio-mediated MnO2 nanoparticles in the fields are analyzed. It is expected that the present work not only expands systematic understandings of synthesis methods, properties and applications MnO2 nanoparticles but also pave the way for the nanotechnology revolution in combination with green chemistry and sustainable development.

Zn nutrients-loaded chitosan nanocomposites and their efficacy as nanopriming agents for maize (Zea mays) seeds

Recent breakthroughs in agro-inputs research have led to the development of nanomaterials that can promote precision agriculture and better environmental security. The agricultural sector is increasingly facing the negative impacts of changing climates due to various stress conditions. To curb this scenario, economical and low-risk practices such as decreasing fertilizer inputs and seed priming have been promoted. In the current study, the H. odoratissimum aqueous extract was used to nucleate the Zn ionic species and grow the zinc oxide nanoparticles (ZnO NPs). The developed nanocomposites and their ionic zinc precursor were then integrated into tripolyphosphate (TPP)-crosslinked chitosan (CS/TPP) nanostructures by ionic gelation. Advanced physicochemical characterization techniques (SEM, EDS, TEM, DLS, FTIR, TGA, and XPS) were exploited to report the morphology, hydrodynamic size, surface charge, and structural organization of the developed nanomaterials. These revealed positively charged particles with hydrodynamic size in the 149-257 nm range. The NPs were used as priming agents for Zea mays seeds. At 0.04%, the ZnO-loaded CS/TPP NPs achieved higher root and shoot elongation in 10-day old seedlings compared to other treatments. The pristine CS/TPP NPs, Zn(II)-laden CS/TPP NPs, and ZnO-loaded CS/TPP NPs at 0.01% significantly promoted the early seedling development of seeds under salt stress. This represents the first report showing ZnO integrated chitosan nanocomposites as an auspicious nanopriming agent for stimulating the seed germination of maize. The study envisages offering perspectives on utilizing green nanotechnology to improve the early seedling development of maize. Furthermore, it has the potential to contribute towards UN SDG 2, thus addressing the threats to global food insecurity and doubling agricultural productivity by 2030.

Genetic effects of chemically and biosynthesized titanium dioxide nanoparticles in vitro and in vivo of female rats and their fetuses

With the increase in nanoparticles (NPs) products on the market, the possibility of animal and human exposure to these materials will increase. The smaller size of NPs facilitates their entrance through placental barriers and allows them to accumulate in embryonic tissue, where they can then be a source of different developmental malformations. Several toxicity studies with chemically synthesized titanium dioxide NPs (CTiO2 NPs) have been recently carried out; although there is insufficient data on exposure to biosynthesized titanium dioxide NPs (BTiO2 NPs) during pregnancy, the study aimed to evaluate the ability of an eco-friendly biosynthesis technique using garlic extract against maternal and fetal genotoxicities, which could result from repeated exposure to TiO2 NPs during gestation days (GD) 6-19. A total of fifty pregnant rats were divided into five groups (n = 10) and gavaged CTiO2 NPs and BTiO2 NPs at 100 and 300 mg/kg/day concentrations. Pregnant rats on GD 20 were anesthetized, uterine horns were removed, and then embryotoxicity was performed. The kidneys of the mothers and fetuses in each group were collected and then maintained in a frozen condition. Our results showed that garlic extract can be used as a reducing agent for the formation of TiO2 NPs. Moreover, BTiO2 NPs showed less toxic potential than CTiO2 NPs in HepG2 cells. Both chemically and biosynthesized TiO2 NP-induced genetic variation in the 16S rRNA sequences of mother groups compared to the control group. In conclusion, the genetic effects of the 16S rRNA sequence induced by chemically synthesized TiO2 NPs were greater than those of biosynthesized TiO2 NPs. However, there were no differences between the control group and the embryo-treated groups with chemically and biologically synthesized TiO2 NPs.

Impact of Diverse Parameters on the Physicochemical Characteristics of Green-Synthesized Zinc Oxide-Copper Oxide Nanocomposites Derived from an Aqueous Extract of Garcinia mangostana L. Leaf

Compared to conventional metal oxide nanoparticles, metal oxide nanocomposites have demonstrated significantly enhanced efficiency in various applications. In this study, we aimed to synthesize zinc oxide-copper oxide nanocomposites (ZnO-CuO NCs) using a green synthesis approach. The synthesis involved mixing 4 g of Zn(NO3)2·6H2O with different concentrations of mangosteen (G. mangostana) leaf extract (0.02, 0.03, 0.04 and 0.05 g/mL) and 2 or 4 g of Cu(NO3)2·3H2O, followed by calcination at temperatures of 300, 400 and 500 °C. The synthesized ZnO-CuO NCs were characterized using various techniques, including a UV-Visible spectrometer (UV-Vis), photoluminescence (PL) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis and Field Emission Scanning Electron Microscope (FE-SEM) with an Energy Dispersive X-ray (EDX) analyzer. Based on the results of this study, the optical, structural and morphological properties of ZnO-CuO NCs were found to be influenced by the concentration of the mangosteen leaf extract, the calcination temperature and the amount of Cu(NO3)2·3H2O used. Among the tested conditions, ZnO-CuO NCs derived from 0.05 g/mL of mangosteen leaf extract, 4 g of Zn(NO3)2·6H2O and 2 g of Cu(NO3)2·3H2O, calcinated at 500 °C exhibited the following characteristics: the lowest energy bandgap (2.57 eV), well-defined Zn-O and Cu-O bands, the smallest particle size of 39.10 nm with highest surface area-to-volume ratio and crystalline size of 18.17 nm. In conclusion, we successfully synthesized ZnO-CuO NCs using a green synthesis approach with mangosteen leaf extract. The properties of the nanocomposites were significantly influenced by the concentration of the plant extract, the calcination temperature and the amount of precursor used. These findings provide valuable insights for researchers seeking innovative methods for the production and utilization of nanocomposite materials.

Novel Concepts for Graphene-Based Nanomaterials Synthesis for Phenol Removal from Palm Oil Mill Effluent (POME)

In recent years, the global population has increased significantly, resulting in elevated levels of pollution in waterways. Organic pollutants are a major source of water pollution in various parts of the world, with phenolic compounds being the most common hazardous pollutant. These compounds are released from industrial effluents, such as palm oil milling effluent (POME), and cause several environmental issues. Adsorption is known to be an efficient method for mitigating water contaminants, with the ability to eliminate phenolic contaminants even at low concentrations. Carbon-based materials have been reported to be effective composite adsorbents for phenol removal due to their excellent surface features and impressive sorption capability. However, the development of novel sorbents with higher specific sorption capabilities and faster contaminant removal rates is necessary. Graphene possesses exceptionally attractive chemical, thermal, mechanical, and optical properties, including higher chemical stability, thermal conductivity, current density, optical transmittance, and surface area. The unique features of graphene and its derivatives have gained significant attention in the application of sorbents for water decontamination. Recently, the emergence of graphene-based adsorbents with large surface areas and active surfaces has been proposed as a potential alternative to conventional sorbents. The aim of this article is to discuss novel synthesis approaches for producing graphene-based nanomaterials for the adsorptive uptake of organic pollutants from water, with a special focus on phenols associated with POME. Furthermore, this article explores adsorptive properties, experimental parameters for nanomaterial synthesis, isotherms and kinetic models, mechanisms of nanomaterial formation, and the ability of graphene-based materials as adsorbents of specific contaminants.

Recapitulating Antioxidant and Antibacterial Compounds into a Package for Tissue Regeneration: Dual Function Materials with Synergistic Effect

Oxidative damage and infection can prevent or delay tissue repair. Moreover, infection reinforces reactive oxygen species (ROS) formation, which makes the wound's condition even worse. Therefore, the need for antioxidant and antibacterial agents is felt for tissue regeneration. There are emerging up-and-coming biomaterials that recapitulate both properties into a package, offering an effective solution to turn the wound back into a healing state. In this article, the principles of antioxidant and antibacterial activity are summarized. The review starts with biological aspects, getting the readers to familiarize themselves with tissue barriers against infection. This is followed by the chemistry and mechanism of action of antioxidant and antibacterial materials (dual function). Eventually, the outlook and challenges are underlined to provide where the dual-function biomaterials are and where they are going in the future. It is expected that the present article inspires the designing of dual-function biomaterials to more advanced levels by providing the fundamentals and comparative points of view and paving the clinical way for these materials.

Nanobiotechnological approaches in anticoagulant therapy: The role of bioengineered silver and gold nanomaterials

Nanotechnology is a novel area that has exhibited various remarkable applications, mostly in medicine and industry, due to the unique properties coming with the nanoscale size. One of the notable medical uses of nanomaterials (NMs) that attracted enormous attention recently is their significant anticoagulant activity, preventing or reducing coagulation of blood, decreasing the risk of strokes, heart attacks, and other serious conditions. Despite successful in vitro experiments, in vivo analyses are yet to be confirmed and further research is required to fully prove the safety and efficacy of nanoparticles (NPs) and to introduce them as valid alternatives to conventional ineffective anticoagulants with various shortcomings and side-effects. NMs can be synthesized through two main routes, i.e., the bottom-up route as a more preferable method, and the top-down route. In numerous studies, biological fabrication of NPs, especially metal NPs, is highly suggested given its eco-friendly approach, in which different resources can be employed such as plants, fungi, bacteria, and algae. This review discusses the green synthesis and characterization of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) as two of the most useful metal NPs, and also their alloys in different studies focussing on their anticoagulant potential. Challenges and alternative approaches to the use of these NPs as anticoagulants have also been highlighted.

Protective role of iron oxide nanocomposites on disease index, and biochemical resistance indicators against Fusarium oxysporum induced-cucumber wilt disease: In vitro, and in vivo studies

Recently nanocomposites have become a super-growth inducers as well as vital antifungal agents, which enhance plant growth and suppress plant diseases. A new strategy regarding the fabrication of humic acid (H) and boron (B) conjugated Fe₂O₃ nanocomposites was performed. Fe₂O₃ NP-B and Fe₂O₃ NP-H were synthesized in the presence of gamma-rays (as a direct reducing agent). Gamma-rays provoked reduction of metal ions due to the liberated reducing electrons, (e^-_aq), in aqueous solutions which can be considered as direct reduction. Antifungal potential against Fusarium oxysporum, the causative agent of wilt disease in cucumber was determined. Disease index percent, metabolic resistance indicators in cucumber plant as response to promotion of systemic resistance (SR) were recorded. Results illustrated that both Fe₂O₃ NPs-B and Fe₂O₃ NPs-H had antifungal activity against F. oxysporum in vitro as well as in vivo. Results revealed that minimum inhibitory concentrations of Fe₂O₃ NPs-B and Fe₂O₃ NPs-H were 0.25 and 0.125 mM, respectively. Application of Fe₂O₃ NPs-B (0.25 mM) and Fe₂O₃ NPs-H (0.125 mM) appeared highly reduced the cucumber wilt disease symptoms incidence caused by F. oxysporum, and recorded disease severity by 83.33%. Fe₂O₃ NPs-B was the best treatment reducing disease indexes by 20.83% and gave highly protection against wilt disease by 75.0% and came next Fe₂O₃ NPs-H which reduced disease indexes by 25% and gave 69.99% protection against disease. Fe₂O₃ NPs-B and Fe₂O₃ NPs-H treatments improved morphological traits, photosynthetic pigments, osmolytes, total phenol and antioxidant enzymes activities in both infected and non-infected plants. The beneficial effects of the Fe₂O₃ NPs-B and Fe₂O₃ NPs-H were extended to increase not only the total phenol, and total soluble protein content but also the activities of peroxidase (POD), and polyphenol oxidase (PPO) enzymes of the healthy and infected cucumber plants in comparison with control.

Synthesis, applications, toxicity and toxicity mechanisms of silver nanoparticles: A review

Silver nanoparticles (AgNPs) have become one of the most popular objects of study for the past few decades. The ability to design AgNPs through different synthetic methods according to the application area and desired features is their advantage in many applications. Green synthesis of silver nanoparticles has become one of the most potential synthesis methods. Because of their strong antibacterial activity, AgNPs have been used in a wide range of applications, such as food packaging and medical products and devices. With the increasing application of AgNPs, it is becoming necessary for a better understanding of the toxicity of AgNPs and their potential mechanism of toxicity. In the review, we first describe the synthetic methods of AgNPs. The application of AgNPs in the field is then briefly described. The toxicity of AgNPs and their potential toxicity mechanisms are discussed.

Dynamic Light Scattering: A Powerful Tool for In Situ Nanoparticle Sizing

Due to surface effects and quantum size effects, nanomaterials have properties that are vastly different from those of bulk materials due to surface effects. The particle size distribution plays an important role in chemical and physical properties. The measurement and control of this parameter are crucial for nanomaterial synthesis. Dynamic light scattering (DLS) is a fast and non-invasive tool used to measure particle size, size distribution and stability in solutions or suspensions during nanomaterial preparation. In this review, we focus on the in situ sizing of nanomaterial preparation in the form of colloids, especially for metal oxide nanoparticles (MONs). The measuring principle, including an overview of sizing techniques, advantages and limitations and theories of DLS were first discussed. The instrument design was then investigated. Ex-situ and in situ configuration of DLS, sample preparations, measurement conditions and reaction cell design for in situ configuration were studied. The MONs preparation monitored by DLS was presented, taking into consideration both ex situ and in situ configuration.

Biosynthesis of Metal and Metal Oxide Nanoparticles Using Microbial Cultures: Mechanisms, Antimicrobial Activity and Applications to Cultural Heritage

Nanoparticles (1 to 100 nm) have unique physical and chemical properties, which makes them suitable for application in a vast range of scientific and technological fields. In particular, metal nanoparticle (MNPs) research has been showing promising antimicrobial activities, paving the way for new applications. However, despite some research into their antimicrobial potential, the antimicrobial mechanisms are still not well determined. Nanoparticles' biosynthesis, using plant extracts or microorganisms, has shown promising results as green alternatives to chemical synthesis; however, the knowledge regarding the mechanisms behind it is neither abundant nor consensual. In this review, findings from studies on the antimicrobial and biosynthesis mechanisms of MNPs were compiled and evidence-based mechanisms proposed. The first revealed the importance of enzymatic disturbance by internalized metal ions, while the second illustrated the role of reducing and negatively charged molecules. Additionally, the main results from recent studies (2018-2022) on the biosynthesis of MNPs using microorganisms were summarized and analyzed, evidencing a prevalence of research on silver nanoparticles synthesized using bacteria aiming toward testing their antimicrobial potential. Finally, a synopsis of studies on MNPs applied to cultural heritage materials showed potential for their future use in preservation.

Larvicidal and pupicidal activity of phyto-synthesized zinc oxide nanoparticles against dengue vector aedes aegypti

This study aimed to assess the phyto-synthesizing potential of Tarenna asiatica methanol leaf extract as well as its larvicidal and pupicidal potential against Aedes aegypti larvae. According to the findings of this study, the methanol leaf extract of T. asiatica has the potential to synthesize zinc oxide nanoparticles from zinc acetate dehydrate. Standard analytical techniques such as UV-visible spectrophotometer, Fourier-transform infrared spectroscopy, X-ray Diffraction analysis, Scanning Electron Microscope, and Energy Dispersive X-Ray were used to characterize the phyto-synthesized nanoparticles. The zinc oxide nanoparticles synthesized ranged in size from 22.35 to 31.27 nm and was spherical in shape. These nanoparticles demonstrated excellent larvicidal activity against Aedes aegypti larvae in the second, third, and fourth in stars, as well as significant pupicidal activity. These findings suggest that the methanol leaf extract of T. asiatica synthesized zinc oxide nanoparticles, which could be used to develop mosquito repellents.

Bacillus spp. as Bioagents: Uses and Application for Sustainable Agriculture

Food security will be a substantial issue in the near future due to the expeditiously growing global population. The current trend in the agriculture industry entails the extravagant use of synthesized pesticides and fertilizers, making sustainability a difficult challenge. Land degradation, lower production, and vulnerability to both abiotic and biotic stresses are problems caused by the usage of these pesticides and fertilizers. The major goal of sustainable agriculture is to ameliorate productivity and reduce pests and disease prevalence to such a degree that prevents large-scale damage to crops. Agriculture is a composite interrelation among plants, microbes, and soil. Plant microbes play a major role in growth promotion and improve soil fertility as well. Bacillus spp. produces an extensive range of bio-chemicals that assist in plant disease control, promote plant development, and make them suitable for agricultural uses. Bacillus spp. support plant growth by N fixation, P and K solubilization, and phytohormone synthesis, in addition to being the most propitious biocontrol agent. Moreover, Bacilli excrete extracellular metabolites, including antibiotics, lytic enzymes, and siderophores, and demonstrate antagonistic activity against phytopathogens. Bacillus spp. boosts plant resistance toward pathogens by inducing systemic resistance (ISR). The most effective microbial insecticide against insects and pests in agriculture is Bacillus thuringiensis (Bt). Additionally, the incorporation of toxin genes in genetically modified crops increases resistance to insects and pests. There is a constant increase in the identified Bacillus species as potential biocontrol agents. Moreover, they have been involved in the biosynthesis of metallic nanoparticles. The main objective of this review article is to display the uses and application of Bacillus specie as a promising biopesticide in sustainable agriculture. Bacillus spp. strains that are antagonistic and promote plant yield attributes could be valuable in developing novel formulations to lead the way toward sustainable agriculture.

An Evaluation of the Biocatalyst for the Synthesis and Application of Zinc Oxide Nanoparticles for Water Remediation—A Review

Global water scarcity is threatening the lives of humans, and it is exacerbated by the contamination of water, which occurs because of increased industrialization and soaring population density. The available conventional physical and chemical water treatment techniques are hazardous to living organisms and are not environmentally friendly, as toxic chemical elements are used during these processes. Nanotechnology has presented a possible way in which to solve these issues by using unique materials with desirable properties. Zinc oxide nanoparticles (ZnO NPs) can be used effectively and efficiently for water treatment, along with other nanotechnologies. Owing to rising concerns regarding the environmental unfriendliness and toxicity of nanomaterials, ZnO NPs have recently been synthesized through biologically available and replenishable sources using a green chemistry or green synthesis protocol. The green-synthesized ZnO NPs are less toxic, more eco-friendly, and more biocompatible than other chemically and physically synthesized materials. In this article, the biogenic synthesis and characterization techniques of ZnO NPs using plants, bacteria, fungi, algae, and biological derivatives are reviewed and discussed. The applications of the biologically prepared ZnO NPs, when used for water treatment, are outlined. Additionally, their mechanisms of action, such as the photocatalytic degradation of dyes, the production of reactive oxygen species (ROS), the generation of compounds such as hydrogen peroxide and superoxide, Zn2+ release to degrade microbes, as well as their adsorbent properties with regard to heavy metals and other contaminants in water bodies, are explained. Furthermore, challenges facing the green synthesis of these nanomaterials are outlined. Future research should focus on how nanomaterials should reach the commercialization stage, and suggestions as to how this ought to be achieved are presented.

Plasma-Assisted Synthesis of Surfactant-Free and D-Fructose-Coated Gold Nanoparticles for Multiple Applications

The excellent optical properties of gold nanoparticles (AuNPs) make them promising for numerous applications. Herein, we present a facile synthesis of both surfactant-free (SF-AuNPs) and non-toxic D-fructose (DF)-coated gold nanoparticles (DF-AuNPs) via the plasma-liquid interactions (PLIs) method. Moreover, we demonstrate that both SF-AuNPs and DF-AuNPs are potential candidates for trace detection via surface-enhanced Raman scattering (SERS) and catalytic degradation of toxic dyes. However, SF-AuNPs have superior SERS and catalytic performance compared to the DF-AuNPs due to their surfactant-free nature. Moreover, SF-AuNPs have also been shown to quench the fluorescence of analyte molecules, making their SERS-based trace detection more efficient. In particular, SERS enhancement of rhodamine 6G (R6G) and catalytic reduction of a toxic dye methylene blue (MB) have been explored.

Retrospective analysis of the key molecules involved in the green synthesis of nanoparticles

Emerging nanotechnology leads to success in synthesizing and applying nanoparticles (NPs) using the green-chemistry approach. NPs synthesized using naturally derived materials are a potential alternative to chemical and physical methods because they are simple, cost-effective, eco-friendly, and lower the possibility of hazardous residues being released into the environment. Furthermore, NPs synthesized using the green synthesis approach are stable and biocompatible. However, because natural extracts contain a diverse spectrum of bioactive components, it is difficult to pinpoint the specific component involved in NP formation. Furthermore, the bioactive component contained in the extract changes based on a number of environmental factors; therefore, several studies began with the synthesis of NPs using a pure compound isolated from diverse natural sources. Hence, the present review paper makes an effort to retrospectively analyze the key compounds of the extracts which are responsible for the synthesis of the NPs. The analysis was carried out based on the physicochemical characteristics and biological activities of NPs synthesized from either the extract or the pure compounds. These pure-compound-based NPs were studied for their antimicrobial, antibiofilm, anti-inflammatory, anticancer, and antioxidant properties. In addition, the present review also describes progress in the study of pure compound-based numerous biological activities and the underlying mechanisms of action.

Effect of Currently Available Nanoparticle Synthesis Routes on Their Biocompatibility with Fibroblast Cell Lines

Nanotechnology has acquired significance in dental applications, but its safety regarding human health is still questionable due to the chemicals utilized during various synthesis procedures. Titanium nanoparticles were produced by three novel routes, including Bacillus subtilis, Cassia fistula and hydrothermal heating, and then characterized for shape, phase state, size, surface roughness, elemental composition, texture and morphology by SEM, TEM, XRD, AFM, DRS, DLS and FTIR. These novel titanium nanoparticles were tested for cytotoxicity through the MTT assay. L929 mouse fibroblast cells were used to test the cytotoxicity of the prepared titanium nanoparticles. Cell suspension of 10% DMEM with 1 × 104 cells was seeded in a 96-well plate and incubated. Titanium nanoparticles were used in a 1 mg/mL concentration. Control (water) and titanium nanoparticles stock solutions were prepared with 28 microliters of MTT dye and poured into each well, incubated at 37 °C for 2 h. Readings were recorded on day 1, day 15, day 31, day 41 and day 51. The results concluded that titanium nanoparticles produced by Bacillus subtilis remained non-cytotoxic because cell viability was >90%. Titanium nanoparticles produced by Cassia fistula revealed mild cytotoxicity on day 1, day 15 and day 31 because cell viability was 60−90%, while moderate cytotoxicity was found at day 41 and day 51, as cell viability was 30−60%. Titanium nanoparticles produced by hydrothermal heating depicted mild cytotoxicity on day 1 and day 15; moderate cytotoxicity on day 31; and severe cytotoxicity on day 41 and day 51 because cell viability was less than 30% (p < 0.001). The current study concluded that novel titanium nanoparticles prepared by Bacillus subtilis were the safest, more sustainable and most biocompatible for future restorative nano-dentistry purposes.

SmMnO3-decorated ZnO in a hexane-water interface for enhancing visible light-driven photocatalytic degradation of malachite green

Malachite green (MG) contributes to water contamination because its accumulation adversely impacts aquatic systems. For the first time, we prepare a high photoresponse of ZnO/SmMnO₃ heterojunction via a high-speed stirring method at the nonpolar-polar interface assisted by Alstonia scholaris leaves extract (ASLE) as natural hydrolyzing and stabilizing agents. The heterojunction formation boosts the photocatalytic activity of ZnO up to 91.74% under visible light irradiation. Photoluminescence analysis confirmed that modification with SmMnO₃ increases the separation of photogenerated charges and plummets the recombination rates of electron-holes, which induces high photodegradation of MG. With 3 mg of catalyst, the %TOC removal efficiency for MG degradation over ZnO/SmMnO₃ was found to be 53.09%, which is higher than that over ZnO. The kinetics model for the photocatalytic reaction was a pseudo-first-order with excellent stability in four consecutive cycles with no structural change. The radical trapping experiment suggests that h⁺ was the major species in the MG photodegradation reaction. Additionally, morphology and elemental analyses clearly present the formation of ZnO/SmMnO₃ heterojunction without any impurities. The current research demonstrates a simple and advanced technique to design heterojunction photocatalyst at the interface of hexane-water.

Nanoparticle and Nanostructure Synthesis and Controlled Growth Methods

Nanomaterials are materials with one or more nanoscale dimensions (internal or external) (i.e., 1 to 100 nm). The nanomaterial shape, size, porosity, surface chemistry, and composition are controlled at the nanoscale, and this offers interesting properties compared with bulk materials. This review describes how nanomaterials are classified, their fabrication, functionalization techniques, and growth-controlled mechanisms. First, the history of nanomaterials is summarized and then the different classification methods, based on their dimensionality (0-3D), composition (carbon, inorganic, organic, and hybrids), origin (natural, incidental, engineered, bioinspired), crystal phase (single phase, multiphase), and dispersion state (dispersed or aggregated), are presented. Then, the synthesis methods are discussed and classified in function of the starting material (bottom-up and top-down), reaction phase (gas, plasma, liquid, and solid), and nature of the dispersing forces (mechanical, physical, chemical, physicochemical, and biological). Finally, the challenges in synthesizing nanomaterials for research and commercial use are highlighted.

Green synthesis and characterization of zinc oxide nanoparticles using bush tea (Athrixia phylicoides DC) natural extract: assessment of the synthesis process

Background: Nanoparticles are globally synthesized for their antimicrobial, anti-inflammatory, wound healing, catalytic, magnetic, optical, and electronic properties that have put them at the forefront of a wide variety of studies. Among them, zinc oxide (ZnO) has received much consideration due to its technological and medicinal applications. In this study, we report on the synthesis process of ZnO nanoparticles using Athrixia phylicoides DC natural extract as a reducing agent.   Methods: Liquid chromatography–mass spectrometry (LC-MS) was used to identify the compounds responsible for the synthesis of ZnO nanoparticles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized through X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).   Results: LC-MS results showed that different flavonoids and polyphenols, as well as Coumarin, an aromatic compound, reacted with the precursor to form ZnO nanoparticles. XRD and UV-Vis analysis confirmed the synthesis of ZnO nanoparticles, with a spherical shape showed in SEM images. The quasi-spherical ZnO crystals had an average crystallite size of 24 nm. EDS and FTIR analysis confirmed that the powders were pure with no other phase or impurity.   Conclusions: This study successfully demonstrated that the natural plant extract of A. phylicoides DC. can be used in the bio-reduction of zinc nitrate hexahydrate to prepare pure ZnO nanoparticles, thus, extending the use of this plant to an industrial level.

Nanotechnological interventions of the microbiome as a next-generation antimicrobial therapy

The rise of antimicrobial resistance (AMR) impacts public health due to the diminished potency of existing antibiotics. The microbiome plays an important role in the host's immune system activity and shows the history of exposure to antimicrobials and its manipulation in combating antimicrobial resistance. Advancements in gene technologies, DNA sequencing, and computational biology have emerged as powerful platforms to better understand the relationship between animals and microorganisms (MOs). The past few years have witnessed an increase in the use of nanotechnology, both in industry and in academia, as tools to tackle antimicrobial resistance. New strategies of microbiome manipulation have been developed, such as the use of prebiotics, probiotics, peptides, antibodies, an appropriate diet, phage therapy, and the use of various nanotechnological techniques. Owing to the research outcomes, targeted delivery of antimicrobials with some modifications with nanoparticles can lead to the destruction of resistant microbial cells. In addition, nanoparticles have been studied for their potential antimicrobial effects both in vitro and in vivo. In this review, we highlight key opportunistic areas for applying nanotechnologies with the aim of manipulating the microbiome for the treatment of antimicrobial resistance. Besides providing a detailed review on various nanomaterials, technologies, opportunities, technical needs, and potential approaches for the manipulation of the microbiome to address these challenges, we discuss future challenges and our perspective.

Green Synthesis of Metal Oxides Semiconductors for Gas Sensing Applications

During recent decades, metal oxide semiconductors (MOS) have sparked more attention in various applications and industries due to their excellent sensing characteristics, thermal stability, abundance, and ease of synthesis. They are reliable and accurate for measuring and monitoring environmentally important toxic gases, such as NO₂, NO, N₂O, H₂S, CO, NH₃, CH₄, SO₂, and CO₂. Compared to other sensing technologies, MOS sensors are lightweight, relatively inexpensive, robust, and have high material sensitivity with fast response times. Green nanotechnology is a developing branch of nanotechnology and aims to decrease the negative effects of the production and application of nanomaterials. For this purpose, organic solvents and chemical reagents are not used to prepare metal nanoparticles. On the contrary, the synthesis of metal or metal oxide nanoparticles is done by microorganisms, either from plant extracts or fungi, yeast, algae, and bacteria. Thus, this review aims at illustrating the possible green synthesis of different metal oxides such as ZnO, TiO₂, CeO₂, SnO₂, In₂O₃, CuO, NiO, WO_3, and Fe₃O₄, as well as metallic nanoparticles doping.

Smart nanomaterials for cancer diagnosis and treatment

Innovations in nanomedicine has guided the improved outcomes for cancer diagnosis and therapy. However, frequent use of nanomaterials remains challenging due to specific limitations like non-targeted distribution causing low signal-to-noise ratio for diagnostics, complex fabrication, reduced-biocompatibility, decreased photostability, and systemic toxicity of nanomaterials within the body. Thus, better nanomaterial-systems with controlled physicochemical and biological properties, form the need of the hour. In this context, smart nanomaterials serve as promising solution, as they can be activated under specific exogenous or endogenous stimuli such as pH, temperature, enzymes, or a particular biological molecule. The properties of smart nanomaterials make them ideal candidates for various applications like biosensors, controlled drug release, and treatment of various diseases. Recently, smart nanomaterial-based cancer theranostic approaches have been developed, and they are displaying better selectivity and sensitivity with reduced side-effects in comparison to conventional methods. In cancer therapy, the smart nanomaterials-system only activates in response to tumor microenvironment (TME) and remains in deactivated state in normal cells, which further reduces the side-effects and systemic toxicities. Thus, the present review aims to describe the stimulus-based classification of smart nanomaterials, tumor microenvironment-responsive behaviour, and their up-to-date applications in cancer theranostics. Besides, present review addresses the development of various smart nanomaterials and their advantages for diagnosing and treating cancer. Here, we also discuss about the drug targeting and sustained drug release from nanocarriers, and different types of nanomaterials which have been engineered for this intent. Additionally, the present challenges and prospects of nanomaterials in effective cancer diagnosis and therapeutics have been discussed.

Mycosynthesis, Characterization, and Mosquitocidal Activity of Silver Nanoparticles Fabricated by Aspergillus niger Strain

Herein, silver nanoparticles (Ag-NPs) were synthesized using an environmentally friendly approach by harnessing the metabolites of Aspergillus niger F2. The successful formation of Ag-NPs was checked by a color change to yellowish-brown, followed by UV-Vis spectroscopy, Fourier transforms infrared (FT-IR), Transmission electron microscopy (TEM), and X-ray diffraction (XRD). Data showed the successful formation of crystalline Ag-NPs with a spherical shape at the maximum surface plasmon resonance of 420 nm with a size range of 3–13 nm. The Ag-NPs showed high toxicity against I, II, III, and IV instar larvae and pupae of Aedes aegypti with LC50 and LC90 values of 12.4–22.9 ppm and 22.4–41.4 ppm, respectively under laboratory conditions. The field assay exhibited the highest reduction in larval density due to treatment with Ag-NPs (10× LC50) with values of 59.6%, 74.7%, and 100% after 24, 48, and 72 h, respectively. The exposure of A. aegypti adults to the vapor of burning Ag-NPs-based coils caused a reduction of unfed individuals with a percentage of 81.6 ± 0.5% compared with the positive control, pyrethrin-based coils (86.1 ± 1.1%). The ovicidal activity of biosynthesized Ag-NPs caused the hatching of the eggs with percentages of 50.1 ± 0.9, 33.5 ± 1.1, 22.9 ± 1.1, and 13.7 ± 1.2% for concentrations of 5, 10, 15, and 20 ppm, whereas Ag-NPs at a concentration of 25 and 30 ppm caused complete egg mortality (100%). The obtained data confirmed the applicability of biosynthesized Ag-NPs to the biocontrol of A. aegypti at low concentrations.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment. Nanomaterials produced by green synthesis approaches can offer additional benefits, including reduced energy inputs and lower production costs than traditional synthesis, which bodes well for commercial-scale production. The biomolecules and phytochemicals extracted from microbes and plants, respectively, are active compounds that function as reducing and stabilizing agents for the green synthesis of nanoparticles. Microorganisms, such as bacteria, yeasts, fungi, and algae, have been used in nanomaterials' biological synthesis for some time. Furthermore, the use of plants or plant extracts for metal and metal-based hybrid nanoparticle synthesis represents a novel green synthesis approach that has attracted significant research interest. This review discusses various biosynthesis approaches via microbes and plants for the green preparation of metal and metal oxide nanoparticles and provides insights into the molecular aspects of the synthesis mechanisms and biomedical applications. The use of agriculture waste as a potential bioresource for nanoparticle synthesis and biomedical applications of biosynthesized nanoparticles is also discussed.

Effect of calcination temperature on morphology and phase transformation of MnO2 nanoparticles: A step towards green synthesis for reactive dye adsorption

Green synthesis of manganese oxide nanoparticles (NPs) was carried out by sol-gel method using Acacia Concinna fruit extract for removal of reactive dye. The effect of calcination temperature on its morphology was investigated. α-MnO₂ and Mn₃O₄ NPs were synthesized at 400 °C and 900 °C respectively and were characterized by PXRD, SEM, TEM, FTIR, BET, Raman and TGA. As-synthesized MnO₂ NPs were investigated for the adsorption of Reactive Blue 21 (RB-21) dye. The effect of pH, adsorbent dose, agitation speed, initial dye concentration and temperature on dye removal was explored. pH_pzc was calculated from zeta potential study showing positive surface charge below pH 3.18 resulting in electrostatic force of attraction between adsorbate and adsorbent. Both linear and non-linear regression approaches were utilised for the fitting of kinetic models and adsorption isotherms. Adsorption data follows a pseudo second order kinetics and fits well with the Freundlich isotherm model. Thermodynamic parameters such as ΔH^o, ΔS^o and ΔG^o were determined. The dye removal efficiency, in case of MnO₂ NPs at pH 3.0 was obtained to be 98% whereas for Mn₃O₄, no such dye adsorption was observed. The mechanism of adsorption was studied theoretically confirming π-π interaction and H-bonding between the MnO₂ and RB dye molecules.