Sustainable green synthesis of Hedychium coronarium leaf extract-stabilized silver nanoparticles and their applications: colorimetric sensing of Sn2+ and Hg2+ and antifungal and antimicrobial properties

Hedychium coronarium (Hc) (commonly known as Gulbakawali) leaf extract was used for the stable and sustainable green synthesis of silver nanoparticles (Hc-AgNPs), which were biodegradable and non-toxic. Hedychium coronarium leaf extract was used as a reducing agent to stabilize the Hc-AgNPs by converting Ag+ to Ag0 without adding any capping agent. It demonstrated stability for up to six months, and no agglomeration was observed. The Hc-AgNPs were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), ultraviolet-visible spectrophotometry, and fluorescence spectroscopy analysis. The UV-visible spectrum supported the formation of stable Hc-AgNPs by displaying a strong surface plasmon resonance (SPR) peak at 440 nm. FT-IR spectra showed the functional groups present in the leaf extract of Hedychium coronarium, which was the primary source of secondary metabolites attached to Ag0. XRD analysis revealed a distinct 2θ peak of Hc-AgNPs at 38.15°, indicating a face-centred cubic structure with a crystallite size of 22.6 ± 1 nm at the (111) plane. Moreover, TEM demonstrated the spherical morphology of the Hc-AgNPs with an average particle size of 22.42 ± 1 nm. The photophysical characteristics of the Hc-AgNPs, as highlighted by their UV-vis and fluorescence characteristics, revealed their semiconducting nature with an impressive band gap (E g) value of 3.78 eV. Fascinatingly, the fluorescence activity of Hc-AgNPs at 504 nm showed a broad emission band corresponding to the absorption band at 251 nm. We performed the selective colorimetric sensing of Sn2+ metal ions using Hc-AgNPs, which demonstrated a detection limit of 10-3 M, suggesting their potential as very good solid biosensors. Interestingly, the Hc-AgNPs showed antifungal activity, which has not been reported before. Specifically, the results showed that the Hc-AgNPs had a higher fungitoxicity effect against Aspergillus flavus (59.58 ± 3.68) than against Fusarium oxysporum (57.93 ± 4.18). The antibacterial activity of the Hc-AgNPs was evaluated against three Gram-negative phytopathogenic bacteria: Xanthomonas oryzae (X. oryzae), Ralstonia solanacearum (R. solanacearum), and Erwinia carotovora (E. carotovora), showing effective inhibition zones of 16.33 ± 0.57, 15.33 ± 0.57, and 14.33 ± 0.57 mm, respectively. These results indicate that the Hc-AgNPs could inhibit these phytopathogenic bacteria with varying degrees of effectiveness in the order of X. oryzae > R. solanacearum > E. carotovora.

Recent applications of coinage metal nanoparticles passivated with salicylaldehyde and salicylaldehyde-based Schiff bases

Salicylaldehyde (SD) and its derivatives are effective precursors for generating coinage metal (gold, silver, and copper) nanoparticles (NPs). These NPs have a variety of potential environmental applications, such as in water purification and sensing, and those arising from their antibacterial activity. The use of SD and its derivatives for synthesizing coinage NPs is attractive due to several factors. First, SD is a relatively inexpensive and readily available starting material. Second, the synthetic procedures are typically simple and can be carried out under mild conditions. Finally, the resulting NPs can be tailored to have specific properties, such as size, shape, and surface functionality, by varying the reaction conditions. In an alkaline solution, the phenolate form of SD was converted to its quinone form, while ionic coinage metal salts were converted to zero-valent nanoparticles. The capping in situ produced quinone of coinage metal nanoparticles generated metal-enhanced fluorescence under suitable experimental conditions. The formation of iminic bonds during the formation of Schiff bases altered the properties (especially metal-enhanced fluorescence) and applications.

Highly fluorescent quinone-capped silver hydrosol for environmental remediation and sensing applications

A metal-enhanced fluorescence was achieved from in situ-generated Ag0 nanoparticles in the proximity of 2-hydroxy benzaldehyde (2HB). Such nanoparticles eliminated methyl blue (MB) dye from water exclusively in the presence of Zn2+ and were proven to be an efficient adsorbent for environmental remediation (maximum uptake capacity 1065 mg·g-1). Ag was zero valent in the absorbent, while Zn2+ was in Zn(OH)2 form. Fe3+ brought back MB in the aqueous medium due to the strong interaction of MB with Fe3+ and the regeneration of blue color helped to design a selective and sensitive Fe3+ sensing platform colorimetrically (linear detection range 10-4-10-6 M; linear detection limit 10-6 M). The silver nanoparticle-induced metal-enhanced fluorescence was quenched efficiently with MB. Pb2+ restored the quenched fluorescence by removing MB from the proximity of the metalized surface of silver, and Pb2+ sensing was performed fluorometrically (linear detection range; 10-5-5 × 10-8 M limit of detection 5 × 10-8 M). Iron and lead were also estimated in a variety of natural water sources, including rainfall, drinking water from taps, and water from the Ganga River via spiking method.

Antifungal activity of copper oxide nanoparticles derived from Zizyphus spina leaf extract against Fusarium root rot disease in tomato plants

Incorporating green chemistry concepts into nanotechnology is an important focus area in nanoscience. The demand for green metal oxide nanoparticle production has grown in recent years. The beneficial effects of using nanoparticles in agriculture have already been established. Here, we highlight some potential antifungal properties of Zizyphus spina leaf extract-derived copper oxide nanoparticles (CuO-Zs-NPs), produced with a spherical shape and defined a 13-30 nm particle size. Three different dosages of CuO-Zs-NPs were utilized and showed promising antifungal efficacy in vitro and in vivo against the selected fungal strain of F. solani causes tomato root rot disease, which was molecularly identified with accession number (OP824846). In vivo  results indicated that, for all CuO-Zs-NPs concentrations, a significant reduction in Fusarium root rot disease occurred between 72.0 to 88.6% compared to 80.5% disease severity in the infected control. Although treatments with either the chemical fungicide (Kocide 2000) showed a better disease reduction and incidence with (18.33% and 6.67%) values, respectively, than CuO-Zs-NPs at conc. 50 mg/l, however CuO-Zs-NPs at 250 mg/l conc. showed the highest disease reduction (9.17 ± 2.89%) and lowest disease incidence (4.17 ± 3.80%). On the other hand, CuO-Zs-NPs at varied values elevated the beneficial effects of tomato seedling vigor at the initial stages and plant growth development compared to either treatment with the commercial fungicide or Trichoderma Biocide. Additionally, CuO-Zs-NPs treatments introduced beneficial results for tomato seedling development, with a significant increase in chlorophyll pigments and enzymatic activity for CuO-Zs-NPs treatments. Additionally, treatment with low concentrations of CuO-Zs-NPs led to a rise in the number of mature pollen grains compared to the immature ones.  however the data showed that CuO-Zs-NPs have a unique antifungal mechanism against F. solani, they  subsequently imply that CuO-Zs-NPs might be a useful environmentally friendly controlling agent for the Fusarium root rot disease that affects tomato plants.

Green synthesis of gold and silver nanoparticles using crude extract of Aconitum violaceum and evaluation of their antibacterial, antioxidant and photocatalytic activities

Green synthesis of metal nanoparticles (NPs) has received extensive attention over other conventional approaches due to their non-toxic nature and more biocompatibility. Herein we report gold and silver NPs (AuNPs@AV and AgNPs@AV) prepared by employing a green approach using crude extract of Aconitum violaceum Jacquem. ex Stapf. The synthesized NPs were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX), X-ray Diffraction (XRD), UV/Visible spectroscopy, Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Zeta Potential. Morphological analysis showed spherical and triangular shapes of the NPs with average size of <100 nm. The AuNPs@AV and AgNPs@AV exhibited effective antibacterial activities, with minimum inhibitory concentrations (MICs) of 95 and 70 μg/mL against Lactobacillus acidophilus (L. acidophilus) and 90 and 65 μg/mL against Escherichia coli (E. coli), respectively. Strong antioxidant effect of AuNPs@AV and AgNPs@AV were reported against DPPH radical and PTIO within range of IC50 values; 161-80 μg/ml as compared to the standard (23-11 μg/mL) respectively. Moreover, the AuNPs@AV and AgNPs@AV showed efficient photocatalytic activity and degraded 89.88% and 93.7% methylene blue (MB) dye under UV light, respectively.

Colorimetric sensor based on biogenic nanomaterials for high sensitive detection of hydrogen peroxide and multi-metals

Hydrogen peroxide (H2O2) and heavy metals, which are among the wastes of the industrial sector, become a threat to living things and the environment above certain concentrations. Therefore, the detection of both H2O2 and heavy metals with simple, low-cost, and fast analytical methods has gained great importance. The use of nanoparticles in colorimetric sensor technology for the detection of these analytes provides great advantages. In recent years, green synthesis of nanomaterials with products that can be considered biowaste is among the popular topics. In this study, silver/silver chloride nanoparticles (Ag@AgCl NPs) were synthesized using the green synthesis method as an eco-friendly and cheap method, the green algae extract was used as a reducing agent. The characterization of Ag@AgCl nanoparticles and green algae extract was carried out with several techniques such as Transmission Electron Microscopy (TEM), UV-Visible spectrometry (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction patterns (XRD) methods were used for characterization. According to TEM analysis, the Ag@AgCl NPs typically spherical in form and range in size from 4 to 10 nm, and UV-vis showed the formation of surface plasmon resonance (SPR) of the Ag@AgCl between 400 and 450 nm. In addition, its activity as a colorimetric sensor for hydrogen peroxide (H2O2) and multi-metal detection was evaluated. Interestingly, Ag/AgCl NPs caused different color formations for 3 metals simultaneously in the sensor study for heavy metal detection, and Fe3+, Cu2+, and Cr6+ ions were detected. The R2 values for H2O2, Fe3+, Cu2+, and Cr6+ were 0.9360, 0.9961, 0.9787, and 0.9625 the limit of detection (LOD) was 43.75, 1.69, 3.18, and 5.05 ppb (ng/mL), respectively. It was determined that Ag@AgCl NPs have the potential to be used as a colorimetric sensor for the detection of H2O2 and heavy metals from wastewater.

Structural characterization, antioxidant and anti-uropathogenic potential of biogenic silver nanoparticles using brown seaweed Turbinaria ornata

Alternative treatment strategies for urinary tract infections (UTIs) are becoming more necessary due to increasing drug resistance patterns in uropathogens. Nanoparticle-based therapeutics is emerging as a way to treat UTIs. In the present study, using Turbinaria ornata extract, silver nanoparticles (AgNPs) were synthesized, characterized, and their anti-uropathogenic activity was evaluated. The stability and formation of synthesized To-AgNPs were confirmed by UV-visible spectroscopy, FTIR, XRD, SEM, and DLS. An FTIR spectrum confirmed the presence of seaweed functional groups in To-AgNPs, a XRD analysis confirmed their crystalline nature, and SEM imaging confirmed their spherical nature with an average size of 73.98 nm with diameters ranging from 64.67 to 81.28 nm. This was confirmed by TEM results. DLS determined that the cumulant hydrodynamic diameter of To-AgNPs was 128.3 nm with a PdI of 0.313 and the zeta potential value were found to be -63.3 mV which indicates the To-AgNPs are negatively charged and more stable. DPPH assays were used to assess the antioxidant activity of biosynthesized To-AgNPs, while an agar well diffusion method was used to test the antibacterial activity against uropathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Klebsiella pneumoniae. The To-AgNPs showed the highest susceptibility to S. aureus (15.75 ± 0.35 mm) and E. coli (15 ± 0.7 mm) with MIC values of 0.0625 and 0.125 mg/ml, respectively in macro broth dilution method and observed considerable membrane damage under CLSM and SEM. To-AgNPs displayed stronger antioxidant and antimicrobial activity, suggesting they may be developed as a new class of antimicrobial agents for treating UTIs.

Biosynthesis of Silver Nanoparticles Utilizing Leaf Extract of Trigonella foenum-graecum L. for Catalytic Dyes Degradation and Colorimetric Sensing of Fe3+/Hg2

The aqueous Trigonella foenum-graecum L. leaf extract belonging to variety HM 444 was used as reducing agent for silver nanoparticles (AgNPs) synthesis. UV-Visible spectroscopy, Particle size analyser (PSA), Field emission scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (FESEM-EDX) and High-resolution transmission electron microscopy (HRTEM) were used to characterize AgNPs. Selected area electron diffraction (SAED) confirmed the formation of metallic Ag. Fourier Transform Infrared Spectroscopy (FTIR) was done to find out the possible phytochemicals responsible for stabilization and capping of the AgNPs. The produced AgNPs had an average particle size of 21 nm, were spherical in shape, and monodispersed. It showed catalytic degradation of Methylene blue (96.57%, 0.1665 ± 0.03 min^-1), Methyl orange (71.45%, 0.1054 ± 0.002 min^-1), and Rhodamine B (92.72%, 0.2004 ± 0.01 min^-1). The produced AgNPs were excellent solid bio-based sensors because they were very sensitive to Hg²⁺ and Fe³⁺ metal ions with a detection limit of 11.17 µM and 195.24 µM, respectively. From the results obtained, it was suggested that aqueous leaf extract demonstrated a versatile and cost-effective method and should be utilized in future as green technology for the fabrication of nanoparticles.

A critical review on the bio-mediated green synthesis and multiple applications of magnesium oxide nanoparticles

Nowadays, advancements in nanotechnology have efficiently solved many global problems, such as environmental pollution, climate change, and infectious diseases. Nano-scaled materials have played a central role in this evolution. Chemical synthesis of nanomaterials, however, required hazardous chemicals, unsafe, eco-unfriendly, and cost-ineffective, calling for green synthesis methods. Here, we review the green synthesis of MgO nanoparticles and their applications in biochemical, environmental remediation, catalysis, and energy production. Green MgO nanoparticles can be safely produced using biomolecules extracted from plants, fungus, bacteria, algae, and lichens. They exhibited fascinating and unique properties in morphology, surface area, particle size, and stabilization. Green MgO nanoparticles served as excellent antimicrobial agents, adsorbents, colorimetric sensors, and had enormous potential in biomedical therapies against cancers, oxidants, diseases, and the sensing detection of dopamine. In addition, green MgO nanoparticles are of great interests in plant pathogens, phytoremediation, plant cell and organ culture, and seed germination in the agricultural sector. This review also highlighted recent advances in using green MgO nanoparticles as nanocatalysts, nano-fertilizers, and nano-pesticides. Thanks to many emerging applications, green MgO nanoparticles can become a promising platform for future studies.

Biogenic Synthesis of Carboxymethyl Cashew Gum Modified Gold Nanoparticles and its Sensitive and Selective Calorimetric Detection of Hg2+ Ions and Catalytic Reduction of Methyl Red

In the present study, we have successfully synthesized and characterized carboxy methyl cashew gum modified gold nanoparticles (CMCG-AuNPs) via a microwave-assisted method and used as a calorimetric probe for selective detection of Hg²⁺ ions as well as catalytic reduction of methyl red in an aqueous medium. The effect of different parameters including concentration and irradiation time on the formation of CMCG-AuNPs was also investigated. The presence of strong surface plasmon resonance (SPR) peak in the visible region indicated the formation of AuNPs. The characterization techniques were identified the interaction between the CMCG and AuNPs with estimation of size and morphology. The face centred cubic (FCC) crystal structure was identified by using XRD and supporting with SAED pattern. TEM images of CMCG-AuNPs were exhibited as polydispersed with spherical in shape and the average particle size was 12 ± 3 nm. The synthesized CMCG-AuNPs were utilized to sensing Hg²⁺ ions in an aqueous medium, the presence of Hg²⁺ ions selectively among other metal ions, the CMCG-AuNPs were aggregated by changing the color from wine red to purple blue accompanied by change in the position of SPR peak and intensity. It was observed as a strong linear relationship based on the change in intensity, the limit of detection was determined to be 0.277 nM. The catalytic activity was also examined for the reduction of methyl red (MR) in the presence of CMCG-AuNPs was completed within 12 min and followed pseudo-first order kinetics with a rate constant of 0.261 min^-1. From the obtained results, the synthesized CMCG-AuNPs were useful for detection of heavy metal ions as well as toxic pollutants degradation via a green method, and utilized sensing, environmental, and biomedical application in future.

Photocatalytic Activity Induced by Metal Nanoparticles Synthesized by Sustainable Approaches: A Comprehensive Review

Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Among many techniques that are employed toward the production of nanoparticles, synthesis using green technologies is the simplest and environment friendly. Nanoparticles produced from plant extracts have become a very popular subject of study in recent decades due to their diverse advantages such as low-cost synthesis, product stability, and ecofriendly protocols. These merits have prompted the development of nanoparticles from a variety of sources, including bacteria, fungi, algae, proteins, enzymes, etc., allowing for large-scale production with minimal contamination. However, nanoparticles obtained from plant extracts and phytochemicals exhibit greater reduction and stabilization and hence have proven the diversity of properties, like catalyst/photocatalyst, magnetic, antibacterial, cytotoxicity, circulating tumor deoxy ribo nucleic acid (CT-DNA) binding, gas sensing, etc. In the current scenario, nanoparticles can also play a critical role in cleaning wastewater and making it viable for a variety of operations. Nano-sized photocatalysts have a great scope toward the removal of large pollutants like organic dyes, heavy metals, and pesticides in an eco-friendly and sustainable manner from industrial effluents. Thus, in this review article, we discuss the synthesis of several metal nanoparticles using diverse plant extracts, as well as their characterization via techniques like UV–vis (ultraviolet–visible), XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), FTIR (Fourier transform infrared spectroscopy), etc., and catalytic activity on various hazardous systems.

Ag@CDs nanohybrid: Fabrication, design of a multi-mode chemosensory probe for selective Fe3+ detection and logic gate operation

In this study, we propose a unique use of silver-carbon dot nanohybrid (Ag@CDs) with an average size of 16 nm as a multi-mode sensor for the selective detection of Fe³⁺ and the construction of logic gates based on these unique detection properties. The Ag NPs exhibit colourimetric sensing and fluorescence quenching in response to Fe³⁺ in the concentration range of 10-100 ppm, with the carbon dots acting as the fluorescent entity. Surprisingly, the nanohybrid was shown to have excellent sensitivity to Fe³⁺, resulting in aggregation and formation of yellowish-brown clumps. When the reaction mixture was treated with Fe³⁺, there was a discernible change in the colour of the assay mixture and fluorescence quenching. That is, the Ag@CDs acted as a calorimetric and fluorescence multi-mode sensor. Even in interfering groups in the natural river water sample, the produced nanohybrid displayed good selectivity towards Fe³⁺, with a minimum LOD of 0.76 ppm. Further, we constructed an advanced logic system, IMP-OR gate, by using additional inputs - ascorbic acid and urea.

Metallic and Metal Oxides Nanoparticles for Sensing Food Pathogens—An Overview of Recent Findings and Future Prospects

Nowadays, special importance is given to quality control and food safety. Food quality currently creates significant problems for the industry and implicitly for consumers and society. The effects materialize in economic losses, alterations of the quality and organoleptic properties of the commercial products, and, last but not least, they constitute risk factors for the consumer’s health. In this context, the development of analytical systems for the rapid determination of the sanitary quality of food products by detecting possible pathogenic microorganisms (such as Escherichia coli or Salmonella due to the important digestive disorders that they can cause in many consumers) is of major importance. Using efficient and environmentally friendly detection systems for identification of various pathogens that modify food matrices and turn them into food waste faster will also improve agri-food quality throughout the food chain. This paper reviews the use of metal nanoparticles used to obtain bio nanosensors for the purpose mentioned above. Metallic nanoparticles (Au, Ag, etc.) and their oxides can be synthesized by several methods, such as chemical, physical, physico-chemical, and biological, each bringing advantages and disadvantages in their use for developing nanosensors. In the “green chemistry” approach, a particular importance is given to the metal nanoparticles obtained by phytosynthesis. This method can lead to the development of good quality nanoparticles, at the same time being able to use secondary metabolites from vegetal wastes, as such providing a circular economy character. Considering these aspects, the use of phytosynthesized nanoparticles in other biosensing applications is also presented as a glimpse of their potential, which should be further explored.

Natural and Engineered Nanomaterials for the Identification of Heavy Metal Ions—A Review

In recent years, there has been much interest in developing advanced and innovative approaches for sensing applications in various fields, including agriculture and environmental remediation. The development of novel sensors for detecting heavy metals using nanomaterials has emerged as a rapidly developing research area due to its high availability and sustainability. This review emphasized the naturally derived and engineered nanomaterials that have the potential to be applied as sensing reagents to interact with metal ions or as reducing and stabilizing agents to synthesize metallic nanoparticles for the detection of heavy metal ions. This review also focused on the recent advancement of nanotechnology-based detection methods using naturally derived and engineered materials, with a summary of their sensitivity and selectivity towards heavy metals. This review paper covers the pros and cons of sensing applications with recent research published from 2015 to 2022.

Biogenic biocompatible silver nanoparticles: a promising antibacterial agent

The biogenic synthesis of silver nanoparticles (AgNPs) are gaining attention because they are eco-friendly, non-hazardous, economical and devoid of the drawbacks of physicochemical processes. Biogenic approaches for synthesizing nanoparticles (NPs) using plant leaves, seeds, bark, stems, fruits, roots and flowers are highly cost-effective compared to other methods. Silver (Ag) has been used since ancient times, but biogenic AgNPs have only been made in the last few decades. They have been employed primarily in the food and pharmaceutical industries as antimicrobials and antioxidants. Recent studies have confirmed that many molecules present in different bacteria, including Escherichia coli, Staphylococcus aureus, Citrobacter koseri, Bacillus cereus, Salmonella typhi, Klebsipneumoniaoniae, Vibrio parahaemolyticus, Pseudomonas Aeruginosa, are bound to the AgNPs and can be inhibited using multifaceted mechanisms like AgNPs inter inside the cells, free radicals, ROS generation and modulate transduction pathways. Recent breakthroughs in nanobiotechnology-based therapeutics have opened up new possibilities for fighting microorganisms. Thus, in particular, biogenic AgNPs as powerful antibacterial agents have gained much interest. Surface charge, colloidal state, shape, concentration and size are the most critical physicochemical characteristics that determine the antibacterial potential of AgNPs. Based on this review, it can be stated that AgNPs could be made better in terms of their potency, durability, accuracy, biosecurity and compatibility.

Comparison and Advanced Antimicrobial Strategies of Silver and Copper Nanodrug-Loaded Glass Ionomer Cement against Dental Caries Microbes

Caries lesions during cement repairs are a severe issue, and developing a unique antimicrobial restorative biomaterial can help to reduce necrotic lesion recurrence. As a result, Thymus vulgaris extract was used to biosynthesize copper nanoparticles (TVE-CuNPs) exhibiting different characteristics (TVE). Along with TVE-CuNPs, commercial silver nanoparticles (AgNPs) and metronidazole were combined with glass ionomer cement (GIC) to test its antibacterial efficacy and compressive strength. FTIR, XRD, UV-Vis spectrophotometry, and TEM were applied to characterize the TVE-CuNPs. Additionally, AgNPs and TVE-CuNPs were also combined with metronidazole and GIC. The modified GIC samples were divided into six groups, where groups 1 and 2 included conventional GIC and GIC with 1.5% metromidazole, respectively; group 3 had GIC with 0.5% TVE-CuNPs, while group 4 had 0.5% TVE-CuNPs with metronidazole in 1.5%; group 5 had GIC with 0.5% AgNPs, and group 6 had 0.5% AgNPs with metronidazole at 1.5%. An antimicrobial test was performed against Staphylococcus aureus (S. aureus) and Streptococcus mutans (S. mutans) by the disc diffusion method and the modified direct contact test (MDCT). GIC groups 4 and 6 demonstrated a greater antimicrobial efficiency against the two tested strains than the other groups. In GIC groups 4 and 6, the combination of GIC with two antimicrobial agents, 1.5% metronidazole and 0.5% TVE-CuNPs or AgNPs, enhanced the antimicrobial efficiency when compared to that of the other groups with or without a single agent. GIC group specimens combined with nanosilver and nanocopper had similar mean compressive strengths when compared to the other GIC groups. Finally, the better antimicrobial efficacy of GIC boosted by metronidazole and the tested nanoparticles against the tested strains may be relevant for the future creation of more efficient and modified restorations to reduce dental caries lesions.

Therapeutic potential of biogenic and optimized silver nanoparticles using Rubia cordifolia L. leaf extract

Rubia cordifolia L. is a widely used traditional medicine in the Indian sub-continent and Eastern Asia. In the present study, the aqueous leaf extract of the R. Cordifolia was used to fabricate silver nanoparticles (RC@AgNPs), following a green synthesis approach. Effect of temperature (60 °C), pH (8), as well the concentration of leaf extract (2 ml) and silver nitrate (2 mM) were optimized for the synthesis of stable RC@AgNPs. The phytofabrication of nanosilver was validated by UV–visible spectral analysis, which displayed a distinctive surface plasmon resonance peak at 432 nm. The effective functional molecules as capping and stabilizing agents, and responsible for the conversion of Ag⁺ to nanosilver (Ag⁰) were identified using the FTIR spectra. The spherical RC@AgNPs with an average size of ~ 20.98 nm, crystalline nature, and 61% elemental composition were revealed by TEM, SEM, XRD, and. EDX. Biogenic RC@AgNPs displayed a remarkable anticancer activity against B16F10 (melanoma) and A431 (carcinoma) cell lines with respective IC₅₀ of 36.63 and 54.09 µg/mL, respectively. Besides, RC@AgNPs showed strong antifungal activity against aflatoxigenic Aspergillus flavus, DNA-binding properties, and DPPH and ABTS free radical inhibition. The presented research provides a potential therapeutic agent to be utilized in various biomedical applications.

Antioxidant, Antibacterial, and Anti-diabetic Activity of Green Synthesized Copper Nanoparticles of Cocculus hirsutus (Menispermaceae)

The emergence of new technologies has led to the discovery of the biological properties of nanoparticles through green approach. In the present investigation, we report the potential antibacterial, antioxidant, and anti-diabetic properties of copper nanoparticle (CuNPs) synthesized by reducing 3 mM copper acetate solution with aqueous leaf extract of Cocculus hirsutus. A colour change from deep brown to dark greenish brown indicated the formation of copper nanoparticles. The so-formed CuNPs were characterized by employing UV spectroscopy, FTIR, SEM, and EDX analyses which described sheet-like structure morphology having typical size of 63.46 nm. Later, the synthesized CuNPs efficiency was evaluated against bacterial pathogens, and was found highly toxic to B. subtilis and S. aureus strains. The synthesized CuNPs were examined through H₂O₂ and PMA assays which demonstrated the highest free radical scavenging activity. Besides, the resulted CuNPs revealed the higher anti-diabetic efficacy in both the [Formula: see text]-amylase and [Formula: see text] -glucosidase inhibition assays (64.5% ± 0.11 and 68.5% ± 0.11, respectively). Finally, our findings report that C. hirsutus can be exploited as a source for green synthesis of CuNPs, having potent in vitro antioxidant, antibacterial, and anti-diabetic properties.

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

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

Hg(II) sensing, catalytic, antioxidant, antimicrobial, and anticancer potential of Garcinia mangostana and α-mangostin mediated silver nanoparticles

This study reports synthesis of Garcinia mangostana fruit pericarp (unwanted waste material) and α-mangostin mediated silver nanoparticles (AgNPs). These AgNPs were efficiently produced using 1:10 (extract and salt) ratio under stirring and heating, which was confirmed by surface plasmon resonance (SPR) band in UV-Visible spectroscopic analysis, and size of 73-91 nm determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The synthesized AgNPs were used for Hg(II) detection in tap water, where the limits of detection and quantification were 2.6 μM and 8.9 μM, respectively. Furthermore, the subject AgNPs showed promising catalytic activity in the reduction of dyes and food colours including Congo red (CR), methylene blue (MB), malachite green (MG), methyl orange (MO), para-nitrophenol (PNP), rhodamine B (RdB), zarda yellow (ZY), deep green (DG), and bright red (BR). The synthesized AgNPs were also evaluated for their antioxidant, antimicrobial, and anticancer properties, where α-mangostin and its nanoparticles (Mang-AgNPs) exhibited promising IC₅₀ values of 14.1 and 13.5 μg/mL, respectively against DU-145 cell line validated by in silico molecular docking study. This study is the first report highlighting the application of AgNPs of G. mangostana fruit pericarp extracts, and α-mangostin in Hg(II) detection, dyes degradation, and anticancer potential against DU-145. Finding of this study suggested the suitability of AgNPs as promising solid biosensor in Hg(II) metal detection, dyes reduction, and target in anticancer drug development.

A review on plant-mediated synthesis of silver nanoparticles, their characterization and applications

For decades, silver has been used as a non-toxic inorganic antimicrobial agent. Silver has a lot of potential in a variety of biological/chemical applications, particularly in the form of nanoparticles (NPs). Eco-friendly synthesis approach for NPs are becoming more common in nanobiotechnology, and the demand for biological synthesis methods is growing, with the goal of eliminating hazardous and polluting agents. Cultures of bacteria, fungi, and algae, plant extracts, and other biomaterials are commonly used for NP synthesis in the ‘green synthesis’ process. Plant-based green synthesis is a simple, fast, dependable, cost-effective, environmentally sustainable, and one-step method that has a significant advantage over microbial synthesis due to the lengthy process of microbial isolation and pure culture maintenance. In this report, we focussed on phytosynthesis of silver nanoparticles (AgNPs) and their characterization using various techniques such as spectroscopy (UV–vis, FTIR), microscopy (TEM, SEM), X-Ray diffraction (XRD), and other particle analysis. The potential applications of AgNPs in a variety of biological and chemical fields are discussed.

Cytotoxic, Antimitotic, DNA Binding, Photocatalytic, H2O2 Sensing, and Antioxidant Properties of Biofabricated Silver Nanoparticles Using Leaf Extract of Bryophyllum pinnatum (Lam.) Oken

Bryophyllum pinnatum is a perennial herb traditionally used in ethnomedicine. In the present report, silver nanoparticles (AgNPs) were synthesized using B. pinnatum leaf extract. BP-AgNPs were confirmed following UV-Vis spectroscopy with SPR peak at 412 nm and further characterized by FTIR, XRD, SEM-EDX, and TEM. Microscopic images confirmed the spherical shape and ~15 nm average size of nanostructures. BP-AgNPs were evaluated for photocatalytic degradation of hazardous dyes (methylene blue and Rhodamine-B) and showed their complete reduction within 100 and 110 min., respectively. BP-AgNPs have emerged as a unique SPR-based novel sensor for the detection of H2O2, which may deliver exciting prospects in clinical and industrial areas. DPPH and ABTS free radical scavenging activity were studied with respective IC50 values of 89 and 259 μg/mL. A strong intercalating interaction of CT-DNA with BP-AgNPs was investigated. Observed chromosomal abnormalities confirm the antimitotic potential of BP-AgNPs in the meristematic root tip. The cytotoxicity of BP-AgNPs against B16F10 (melanoma cell line) and A431 (squamous cell carcinoma cell line), was assessed with respective IC50 values of 59.5 and 96.61 μg/ml after 24 h of treatment. The presented green synthetic approach provides a novel and new door for environmental, industrial, and biomedical applications.

Distinctive detection of Fe2+ and Fe3+ by biosurfactant capped silver nanoparticles via naked eye colorimetric sensing

Distinctive detection of Fe²⁺ and Fe³⁺via naked eye colorimetic sensing.

Green synthesis of copper nanoparticles using leaf extract of Ageratum houstonianum Mill. and study of their photocatalytic and antibacterial activities

The novel copper nanoparticles (CuNPs) were synthesized using aqueous leaf extract of Ageratum houstonianum Mill. (AHLE). The green synthesized AH-CuNPs have a useful dye degradation property in the existence of daylight. The photocatalytic activity of AH-CuNPs was evaluated against an azo dye congo red (CR), whereas, same NPs displayed no effect on other dyes. The CR was completely degraded within 2 h, and the reaction rate was followed by pseudo-first-order kinetics, and the rate constant was recorded 3.1 × 10−4 s−1, (R2 = 0.9359). Antibacterial activity of green synthesized AH-CuNPs was studied against gram-negative bacterium Escherichia coli (MTCC no. 40), and a significant growth inhibition was recorded with 12.43 ± 0.233 mm zone of inhibition. The AH-CuNPs were characterized through UV-visible spectroscopy, XRD, SEM, FT-IR, TEM, and zeta particle size analyzer. Ageratum houstonianum mediated green synthesized copper nanoparticles (AH-CuNPs) were cubic, hexagonal, and rectangular in shape, with average size of ∼80 nm. The optical band gap was 4.5 eV, which was investigated using UV-visible spectroscopy, and the band gap value revealed that AH-CuNPs were semiconductor materials.

New Dual-Functional and Reusable Bimetallic Y2ZnO4 Nanocatalyst for Organic Transformation under Microwave/Green Conditions

A novel bimetallic and reusable Y₂ZnO₄ nanocatalyst was synthesized by a simple coprecipitation method. The prepared nanocatalyst exhibited dual catalytic activity and was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The average crystallite and grain sizes were found to be 17 ± 1 and 10 ± 2 nm, respectively. On the one hand, the catalytic activity of the nanocatalyst was studied for the Knoevenagel condensation reaction of aromatic aldehydes with active methylene compounds, such as ethyl cyanoacetate and malononitrile, under microwave irradiation and solvent-free conditions. On the other hand, the nanoparticles also showed faster photocatalytic activity against methyl orange (MO) compared to other dyes. The nanocatalyst was easily recoverable by a simple filtration method and was recycled without any significant loss of catalytic activity. The advantages of this nanocatalyst were a simple workup procedure, high reaction yields, solvent-free conditions, reusability, and a short reaction time under green reaction conditions.

Green synthesis of copper nanoparticles from an extract of Jatropha curcas leaves: characterization, optical properties, CT-DNA binding and photocatalytic activity

The green synthesis of copper nanoparticles (CuNPs) using a leaf extract from Jatropha curcas (JC) has been documented in our present research work.