No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Microwave-assisted phytogenic Ag/Ag2O/ZnO nanocomposite as a replacement of Ag/Ag2O and ZnO nanoparticles: A comparative antioxidant study
Abstract
A biogenic approach, particularly plant-mediated synthesis, is currently regarded as the sustainable approach for
synthesizing nanomaterials (NMs). The present investigation concentrates on the green fabrication of Ag/Ag2O
nanoparticles (NPs), ZnO NPs, and Ag/Ag2O/ZnO nanocomposites (NCs) via microwave irradiation using Murusi
peel (MP) and Kew peel (KP) aqueous extracts and comparatively determine their antioxidant potentials. The
synthesis parameters of Ag/Ag2O NPs, ZnO NPs, and Ag/Ag2O/ZnO NCs were optimized and characterized using
different analytical techniques. Surface plasmon resonance peaks appeared at 448–450 nm, 350–370 nm, and
400–500 nm for Ag/Ag2O NPs, ZnO NPs, and Ag/Ag2O/ZnO NCs, respectively. The scanning electron microscopic
images of both peel-mediated Ag/Ag2O NPs depicted quasi-spherical shapes aggregating on the flakeshaped
ZnO surface, leading to the Ag/Ag2O/ZnO NCs formation. Transition electron microscopic analysis
revealed the average particle sizes of MP and KP-mediated Ag/Ag2O NPs, ZnO NPs, and Ag/Ag2O/ZnO NCs as
13.58±1.32 nm, and 36.79±1.24 nm, 13.00±1.26 nm, and 10.28±1.25 nm, 28.37±1.39 nm, and 11.21±1.06
nm, respectively. X-ray diffraction analysis confirmed the synthesis of pure crystalline structures with a hexagonal
wurtzite structure for ZnO and a face-centered structure for Ag and Ag2O during the formation of Ag/
Ag2O/ZnO NCs. According to the research findings, MP and KP-mediated Ag/Ag2O/ZnO NCs displayed an
enhanced free radical scavenging effect for DPPH (2,2-diphenyl-1-picrylhydrazyl) assay with IC50 values of 54.13
±0.53 ppm and 51.41±1.27 ppm, respectively. At higher concentrations, the NCs exhibited a greater radical
scavenging potential for ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) assay, with the IC50 values
for MP and KP-mediated as 72.28±0.83 ppm and 65.78±1.29 ppm, respectively. Similarly, for the FRAP (Ferric
reducing antioxidant power) assay, MP and KP-mediated Ag/Ag2O/ZnO NCs demonstrated a higher antioxidant
potential, expressed in terms of ascorbic acid equivalents (AE), which were 46±0.7 (AE) mg/1 g and 50±1.1 (AE)
mg/1 g, respectively. To the best of our knowledge, this study remains the first comparative analysis of synergistically
enhanced antioxidant potential of the agro-waste mediated Ag/Ag2O/ZnO NCs with their respective
NPs counterparts, Ag/Ag2O NPs and ZnO NPs. These research findings pave the path for sustainably utilizing
these NMs in biomedical applications.
... Qualitative analysis was conducted to identify the active phytoconstituents in aqueous extracts of PPulp and PSprt. Standard procedures for phytochemical screening were followed as described in previously published literature [13]. Carbohydrates were identified using Molisch's test while reducing sugars were detected using Benedict's and Fehling's tests. ...
... The Ag/Ag 2 O NPs, ZnO NPs, and Ag/Ag 2 O/ZnO NCs were prepared based on the procedure mentioned previously [13], with minor adjustments on the relative concentrations of the metal reagents and plant extracts, as well as the mixing ratios. For both NPs, the effects of varying 2 ]. 2H 2 O) by volume and subsequently pH of the medium was adjusted to 12 by adding 2 M NaOH solution. ...
... The phytogenic NMs and the aqueous plant extracts were tested for their scavenging activity by DPPH assay with slight modifications [13]. From each sample (10,20,40,60,80, and 100 μg/mL), 1.5 mL was mixed with 3 mL of methanolic solution containing DPPH radicals (3.2 mg/mL) and incubated for 20 min. ...
Purpose
This study presents a green approach for synthesizing silver and zinc-based nanoparticles (NPs)/nanocomposites (NCs) utilizing aqueous extracts of palmyra palm (Borassus flabellifer) sprouts and mature fruit pulp.
Methods
The formation of nanomaterial (NM) was confirmed with several characterization techniques. Plant extracts and plant-derived Ag/Ag2O NPs, ZnO NPs, and Ag/Ag2O/ZnO NCs were analyzed to determine their efficacies as antioxidant, anti-inflammatory, and antibacterial agents with standard biological assays.
Results
Under optimized conditions, pulp and sprout-mediated Ag/Ag2O NPs, ZnO NPs, and Ag/Ag2O/ZnO NCs exhibited surface plasmon resonance peaks at 436–438 nm, 350–354 nm, and 350–450 nm, respectively. SEM imaging revealed of quasi-spherical Ag/Ag2O NPs, hexagonal rod-shaped ZnO NPs, and both morphologies arranged into the formation of Ag/Ag2O/ZnO NCs. The average sizes of all biogenic NMs were between 11 and 120 nm. Ag and Ag2O were of face-centered cubic symmetries alongside hexagonal wurtzite ZnO crystallinities. Sprout-mediated Ag/Ag2O/ZnO NCs revealed superior antioxidant potential, (IC50 of 48 ppm for DPPH and 87 ppm for ABTS assays, 74 mg AAE/1 g for FRAP assay). Sprout-mediated Ag/Ag2O NPs demonstrated significantly high (p ≤ 0.05) anti-inflammatory properties, (IC50; 414 ppm for protein denaturation inhibition and 438 ppm for HRBC membrane stabilization assay). The sprout-mediated Ag/Ag2O NPs exhibited the maximum growth inhibition zones (19 mm against E. coli and 17 mm against S. aureus).
Conclusion
To the best of our knowledge, this study remains the first comparative report on the anti-inflammatory and antibacterial activities of Ag/Ag2O/ZnO NCs and their NP counterparts. The biological activities were size, morphology, and dose-dependent, and the synergistic combination of plant polyphenolics and NMs enhanced bioactivities.
Graphical Abstract
... At the maximum concentration of 1,000 μg/mL, the synthesized Ag/ Ag 2 O (CE) had better antioxidant activity of 69.91%, whereas ZnO (CE) exhibited higher DPPH activity of 52.138% at 1,000 μg/mL. ZnO/Ag/Ag 2 O (CE) showed the highest radical scavenging activity of 86.554% at 1,000 μg/mL (Aththanayaka et al., 2023). Antioxidant activity increased with the concentration of the tested samples in the DPPH assay (Awan et al., 2023). ...
... Peng, Y. et al. (2022) demonstrated the preparation of cellulose/chitosan/Ag/Ag 2 O/ZnO nanocomposites through synthetic methods, evaluating their efficacy against E. coli and S. aureus bacterial strains (Peng et al., 2022). Aththanayaka, S. et al. (2023) outlined a synthetic approach for synthesizing Ag/ Ag 2 O/ZnO nanocomposites utilizing Murusi peel and Kew peel, showcasing promising antioxidant activity through DPPH radical scavenging assays (Aththanayaka et al., 2023). Hezam, ...
... Peng, Y. et al. (2022) demonstrated the preparation of cellulose/chitosan/Ag/Ag 2 O/ZnO nanocomposites through synthetic methods, evaluating their efficacy against E. coli and S. aureus bacterial strains (Peng et al., 2022). Aththanayaka, S. et al. (2023) outlined a synthetic approach for synthesizing Ag/ Ag 2 O/ZnO nanocomposites utilizing Murusi peel and Kew peel, showcasing promising antioxidant activity through DPPH radical scavenging assays (Aththanayaka et al., 2023). Hezam, ...
Plant extract-mediated fabrication of metal nanocomposites is used in cell proliferation inhibition and topical wound treatment, demonstrating significant effectiveness. Salvia hispanica L. (chia) seed extract (CE) is used as the reaction medium for the green fabrication of ecofriendly ZnO(CE) nanoparticles (NPs) and Ag/Ag2O(CE) and ZnO/Ag/Ag2O(CE) nanocomposites. The resultant nanoparticles and nanocomposite materials were characterized using UV–visible, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) techniques. In the context of antioxidant studies, ZnO/Ag/Ag2O(CE) exhibited 57% reducing power and 86% 2,2, diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. All three materials showed strong antibacterial activity against Staphylococcus aureus (S. aureus), Escherichia coli (E.coli), and Bacillus subtilis (B. subtilis) bacterial strains. Additionally, ZnO(CE), Ag/Ag2O(CE), and ZnO/Ag/Ag2O(CE) also revealed 64.47%, 42.56%, and 75.27% in vitro Michigan Cancer Foundation-7 (MCF7) cancer cell line inhibition, respectively, at a concentration of 100 μg/mL. Selectively, the most effective composite material, ZnO/Ag/Ag2O(CE), was used to evaluate in vivo wound healing potential in rat models. The study revealed 96% wound closure in 10 days, which was quite rapid healing compared to wound healing using clinically available ointment. Therefore, in conclusion, the ZnO/Ag/Ag2O(CE) nanocomposite material could be considered for further testing and formulation as a good anticancer and wound healing agent.
... Consequently, this method significantly boosts the photocatalytic efficiency of ZnO, rendering it an even more effective photocatalyst for wastewater treatment. Silver is a versatile metal widely utilized in various fields, including chemistry, medicine, and catalysis, owing to its status as both a transition metal and a precious metal (Abouelela et al., 2024;Aththanayaka et al., 2023;Balu et al., 2023;Gündoğdu et al., 2024;Karim et al., 2024;Li et al., 2024;Liu et al., 2023b;Tong et al., 2024;Yang et al., 2024). ...
... The doping of Ag onto ZnO proved instrumental in improving the photo response, effectively suppressing the recombination of electron-hole pairs. This enhancement is attributed to the presence of Ag + acting as an electron capture, facilitating the rapid transfer of charge carriers, and promoting the generation of reactive radicals (Aththanayaka et al., 2023;Liu et al., 2023aLiu et al., , 2023bTong et al., 2024;Vaiano et al., 2019). ...
... These findings underscore the production of reactive radicals, including ⋅ OH, h + , and ⋅ O 2 − , during the photocatalysis reaction. Furthermore, it was observed that ⋅ O 2 − exerted the most significant influence on the degradation of M-CF, followed by h + and ⋅ OH radicals (Aththanayaka et al., 2023;Liu et al., 2023aLiu et al., , 2023bTong et al., 2024;Vaiano et al., 2019;Yang et al., 2024). ...
Micropollutants, such as caffeine (M-CF), pose a significant threat to ecosystems and human health through water and food sources. The utilization of metal oxide-based photocatalysts has proven to be an effective treatment method for the removal of organic pollutants. This study explores the efficacy of Ag-doped ZnO (Ag/ZnO) for removing M-CF from wastewater. The characterization of Ag/ZnO underscores the crucial role of band gap energy in the photocatalytic degradation process. This parameter influences the separation of electrons and holes (e⁻/h⁺) and the generation of reactive radicals. Under solar light, Ag/ZnO demonstrated markedly superior photocatalytic activity, achieving an impressive degradation efficiency of approximately 93.4%, in stark contrast to the 53.2% occurred by ZnO. Moreover, Ag/ZnO exhibited a remarkable degradation efficiency of M-CF in wastewater, reaching 83.5%. A key advantage of Ag/ZnO lies in its potential for recovery and reuse in subsequent treatments, contributing to a reduction in operational costs for industrial wastewater treatment. Impressively, even after five cycles, Ag/ZnO maintained a noteworthy photodegradation rate of M-CF at 78.6%. These results strongly suggest that Ag/ZnO presents a promising solution for the removal of micropollutants in wastewater, with potential scalability for industrial and large-scale applications.
... @AA NC can be attributed to several factors. Firstly, AA is a wellknown antioxidant, and its incorporation likely enhances the overall radical-scavenging ability of the nanocomposite [95,96]. The presence of AA introduces additional hydroxyl groups, which can effectively interact with and neutralize free radicals, thereby improving antioxidant activity [97]. ...
This study presents the synthesis and characterization of iron oxide nanocomposites (Fe₃O₄/Fe₂O₃ NC) functionalized with ascorbic acid (Fe₃O₄/Fe₂O₃@AA NC) for enhanced photocatalytic and antioxidant activities. The nanocomposites were synthesized using a modified co-precipitation method and characterized by UV-visible spectroscopy, FTIR, XRD, and SEM. The photocatalytic degradation of Brilliant Cresyl Blue (BCB) and amoxicillin (AMX) under sunlight irradiation was evaluated. Results showed a remarkable degradation efficiency of 99.2% for BCB and 99.1% for AMX using Fe₃O₄/Fe₂O₃@AA NC, compared to 97% and 95% with Fe₃O₄/Fe₂O₃ NC. The rate constants for the degradation of BCB were 0.041 min⁻¹ for Fe₃O₄/Fe₂O₃@AA NC and 0.031 min⁻¹ for Fe₃O₄/Fe₂O₃ NC, while for AMX, they were 0.035 min⁻¹ and 0.025 min⁻¹, respectively. Additionally, the antioxidant activity of Fe₃O₄/Fe₂O₃@AA NC was significantly higher, ranging from 45% to 95.25%, compared to 41.8% to 79.6% for Fe₃O₄/Fe₂O₃ NC. These findings suggest that ascorbic acid functionalization significantly enhances the photocatalytic and antioxidant properties of iron oxide nanocomposites.
Graphical Abstract
... The superior performance of Fe 3 O 4 /Fe 2 O 3 @AA NC can be attributed to several factors. Firstly, AA is a wellknown antioxidant, and its incorporation likely enhances the overall radical-scavenging ability of the nanocomposite [95,96]. The presence of AA introduces additional hydroxyl groups, which can effectively interact with and neutralize free radicals, thereby improving antioxidant activity [97]. ...
In this study, α-Fe2O3/Fe3O4 nanocomposite (NC) coated with polyethylene glycol were synthesized via hydrothermal synthesis, achieving uniform particle formation and controlled crystallinity. Characterization using Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV–Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDAX) confirmed the physical attributes and homogeneity of the nanocomposite. Polyethylene glycol-coated α-Fe2O3/Fe3O4 showed a reduced crystalline size of 19.13 nm compared to 22.93 nm for uncoated nanoparticles. Optical band gap measurements revealed values of 4.64 electron volts for polyethylene glycol, 1.98 electron volts for α-Fe2O3/Fe3O4 NC, and 3.18 electron volts for α-Fe2O3/Fe3O4@polyethylene glycol nanocomposites, indicating both insulating and semiconducting behaviors. The photocatalytic performance of the polyethylene glycol-coated α-Fe2O3/Fe3O4 was demonstrated by a 99.4% degradation of Brilliant Cresyl Blue (BCB) dye within 120 minutes at a concentration of 5 milligrams per milliliter, with a pseudo-first-order rate constant of 0.02047 per minute. Furthermore, the nanocomposites exhibited strong recyclability and reusability, making them viable candidates for environmental remediation. The study underscores the potential of α-Fe2O3/Fe3O4 NC in applications such as water treatment and antioxidant therapies.
... Silver and silver oxide nanoparticles are known for their unique properties, being used in numerous fields including electrochemistry and electronics (they improve the efficiency and functionality of devices), catalysis (their ability to oxidize makes them valuable for various chemical reactions and industrial processes), energy storage systems and renewable energy (sensors, photovoltaic cells), and optics (integral switching devices and optical data storage systems). In the medical and pharmaceutical field, they can be functionalized to attach to specific biological molecules, chemotherapy, and antibiotic treatment, and in cosmetics, their beneficial properties are used in skin care products [41][42][43][44][45][46]. ...
This study presents the phytosynthesis of silver-based nanoparticles using tomato flower waste extracts for the first time in the literature. The determination of total polyphenolic and flavonoid contents in the extracts showed high gallic acid equivalents (6436–8802 mg GAE/kg dm) and high quercetin equivalents (378–633 mg QE/kg dm), respectively, dependent on the extraction method. By the Ultra Performance Liquid Chromatography technique, 14 polyphenolic compounds were identified and quantified in the tomato flower waste extracts. The abundant phenolic compounds were caffeic acid (36,902–32,217 mg/kg) and chlorogenic acid (1640–1728 mg/kg), and the abundant flavonoid compounds were catechin (292–251 mg/kg) and luteolin (246–108 mg/kg). Transmission electron microscopy of the nanoparticles revealed a particle size range of 14–40 nm. Fourier Transform infrared spectroscopy and X-ray diffraction studies confirmed the phytosynthesis of the silver/silver oxide nanoparticles. These findings hold significant results for the antibacterial and antitumoral potential applications of the obtained nanoparticles, opening new areas for research and development and inspiring further exploration. The impact of this research on the field of metallic nanoparticle phytosynthesis is substantial, as it introduces a novel approach and could lead to significant advancements in the field.
... The ethanol extract obtained from the bark of D. ovoideum (DOEB) was subjected to phytochemical analysis using standard methods (Yadav et al., 2014;Aththanayaka et al., 2023). The experiments were conducted to determine the presence of phenols, flavonoids, tannins, saponins, terpenoids, and steroids. ...
The present study aimed to investigate the biological activities of the ethanol extract of the bark of Dialium ovoideum Thwaites (DOEB), which is an endemic plant of Sri Lanka with various medicinal values. A powdered bark sample was subjected to soxhlet extraction using ethanol followed by solvent evaporation to obtain the bark extract. The phytochemical screening performed on DOEB revealed the presence of phenols, flavonoids, tannins, saponins, terpenoids and steroids. The total phenolic and flavonoid contents of the DOEB were measured as 233.4±22.7 mg GAE/g and 198.1±24.5 mg QE/g, respectively. The antioxidant activity of DOEB showed an EC 50 of 68.5±6.3 µg/mL for the DPPH free radical scavenging assay and a significant (p<0.05) reductive potential compared to the ascorbic acid for the FRAP assay with a percentage reductive potential ranging from 5.7±0.8 to 79.2±2.2% across concentrations of 12.5 to 400 µg/mL. The modified L-DOPA method revealed the anti-tyrosinase activity of DOEB which is expressed as the IC 50 of 1298.3±36.2 µg/mL. The human red blood cell stabilization assay by heat hemolysis resulted in an IC 50 of 425.7±9.3 µg/mL. The agar-well diffusion assay was conducted to assess the anti-microbial activities against the Staphylococus aureus, Escherichia coli, Klebsiella pneumoniae bacterial strains and the fungus, Candida albicans. The results exhibited that DOEB inhibited the growth of all three bacteria and fungi in different concentrations. Functional groups analysis of DOEB by FT-IR spectroscopy revealed the presence of alcohols, carboxylic acids, alkanes, alkenes, aliphatic esters, carbonyl and aromatic compounds. This study showed that DOEB has promising bioactivities based on the assays conducted which has a high potential to isolate bioactive compounds. Hence, DOEB may be employed as a prospective candidate in the food and pharmaceutical industries.
Introduction: Ageratum conyzoides L., commonly known as Goat Weed, has long been utilized in traditional medicine for its therapeutic properties. This study aims to scientifically validate these claims and explore the potential applications of the plant in nanotechnology. Methods: In this experimental study, the biochemical profile of A. conyzoides was assessed using standard analytical techniques. Phytochemical analyses, including the alkaline reagent test, Hager's test, foam test, and Liebermann's test, were performed on the extract following established methods, all indicating its medicinal potential and strong antioxidant activity. Antioxidant properties were evaluated through DPPH and NO radical scavenging assays, as well as the Ferric Reducing Antioxidant Power (FRAP) assay. Nanoparticles of A. conyzoides were characterized using UV-Vis spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). Results: Phytochemical analysis revealed the presence of flavonoids, alkaloids, tannins, saponins, and phenolic compounds, all contributing to its medicinal potential and strong antioxidant activity. Toxicological evaluations, including acute and sub-acute toxicity tests, as well as hematological and white blood cell analyses of treated Wistar rats, confirmed a positive and favorable safety profile for the extract. The results also demonstrated that the aqueous extract of A. conyzoides exhibited significant antimicrobial activity against a variety of pathogenic bacteria and fungi. Additionally, the extract facilitated the green synthesis of silver, copper, and zinc nanoparticles. Conclusion: The results support the traditional medicinal use of A. conyzoides for treating various ailments, such as wounds and inflammation. Furthermore, the plant shows promising potential in natural antimicrobial applications, nanomedicine, and drug development.
Biogenic metallic nanoparticles (BMNPs) are nanostructure materials synthesized through biological processes that have gained significant attention due to their small size and high surface area-to-volume ratio. BMNPs have several advantages over chemically synthesized ones due to their eco-friendly synthesis regimen, sustainability, biocompatibility, and diverse multifarious biomedical applications. Moreover, the superior cytocompatibility and stability due to the capping layer over metallic nanoparticles (MNPs), reduces the like hood of toxicity and side effects, making them a safer alternative to traditional drug delivery methods. Among several promising applications of BMNPs, their antibacterial activity, analytical sensing of heavy metals, and their roles in food preservations have been widely explored. In addition, to drug delivery and imaging, BMNPs have also been investigated for therapeutic activity such as antimicrobial efficacy against the skin and soft tissue nosocomial pathogens and targeting cancer cells in cancer therapy. The present review bestows several characterization techniques involved with MNPs and compressive aspects of the biogenic synthesis of MNPs using agricultural and biological materials, which reduces the cost of synthesis and minimizes the use of hazardous chemicals. The review also focuses on the multifold applications of BMNPs including biomedical, analytical, preservation of food, and in other consumable goods with toxicological aspects.
The biosynthesis of algal-based zinc oxide (ZnO) nanoparticles has shown several ad-
vantages over traditional physico-chemical methods, such as lower cost, less toxicity, and greater
sustainability. In the current study, bioactive molecules present in Spirogyra hyalina extract were
exploited for the biofabrication and capping of ZnO NPs, using zinc acetate dihydrate and zinc nitrate
hexahydrate as precursors. The newly biosynthesized ZnO NPs were characterized for structural and
optical changes through UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray
diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy
(EDX). A color change in the reaction mixture from light yellow to white indicated the successful
biofabrication of ZnO NPs. The UV-Vis absorption spectrum peaks at 358 nm (from zinc acetate)
and 363 nm (from zinc nitrate) of ZnO NPs confirmed that optical changes were caused by a blue
shift near the band edges. The extremely crystalline and hexagonal Wurtzite structure of ZnO NPs
was confirmed by XRD. The involvement of bioactive metabolites from algae in the bioreduction
and capping of NPs was demonstrated by FTIR investigation. The SEM results revealed spherical-
shaped ZnO NPs. In addition to this, the antibacterial and antioxidant activity of the ZnO NPs was
investigated. ZnO NPs showed remarkable antibacterial efficacy against both Gram-positive and
Gram-negative bacteria. The DPPH test revealed the strong antioxidant activity of ZnO NPs.
Biogenic metallic nanoparticles (BMNPs) are nanostructure materials synthesized through biological processes that have gained significant attention due to their small size and high surface area-to-volume ratio. BMNPs have several advantages over chemically synthesized ones due to their eco-friendly synthesis regimen, sustainability, biocompatibility, and diverse multifarious biomedical applications. Moreover, the superior cytocompatibility and stability due to the capping layer over metallic nanoparticles (MNPs), reduces the like hood of toxicity and side effects, making them a safer alternative to traditional drug delivery methods. Among several promising applications of BMNPs, their antibacterial activity, analytical sensing of heavy metals, and their roles in food preservations have been widely explored. In addition, to drug delivery and imaging, BMNPs have also been investigated for therapeutic activity such as antimicrobial efficacy against the skin and soft tissue nosocomial pathogens and targeting cancer cells in cancer therapy. The present review bestows several characterization techniques involved with MNPs and compressive aspects of the biogenic synthesis of MNPs using agricultural and biological materials, which reduces the cost of synthesis and minimizes the use of hazardous chemicals. The review also focuses on the multifold applications of BMNPs including biomedical, analytical, preservation of food, and in other consumable goods with toxicological aspects.
Nanotechnology deals with the production and usage of material with nanoscale dimension. Nanoscale dimension provides nanoparticles a large surface area to volume ratio and thus very specific proper- ties. Zinc oxide nanoparticles (ZnO NPs) had been in recent studies due to its large bandwidth and high exciton binding energy and it has potential applications like antibacterial, antifungal, anti-diabetic, anti- inflammatory, wound healing, antioxidant and optic properties. Due to the large rate of toxic chemicals and extreme environment employed in the physical and chemical production of these NPs, green methods employing the use of plants, fungus, bacteria, and algae have been adopted. This review is a comprehen- sive study of the synthesis and characterization methods used for the green synthesis of ZnO NPs using different biological sources.
In this work, Ag–ZnO nanocomposites were prepared by a green synthesis route using aqueous leaf extract of Tetradenia riperia and investigated for antibacterial activity against Escherichia coli and Staphylococcus aureus. To optimize the synthesis of the Ag–ZnO, the effects of precursor concentrations, pH, and temperatures were studied. The Ag–ZnO nanocomposites were characterized by XRD, ATR-FTIR, FESEM, and TEM. Results show that the concentration of 8% Ag, the temperature of 80 °C, and a pH of 7–8 were optimal for the synthesis of Ag–ZnO nanocomposites. The XRD analysis showed the decrease in particle size of Ag–ZnO from 23.6 to 14.8 nm with an increase in Ag concentrations, which was further supported by FESEM analysis. TEM image of 8% Ag provides more information on the coexistence of Ag on ZnO where an average particle size of 14.8 nm was determined. The ATR-FTIR analysis confirmed the presence of phenolic compounds, which work as reducing and stabilizing agents. The antimicrobial activity results show that Ag–ZnO nanocomposite demonstrated a higher antimicrobial potency on E. coli than on S. aureus. Therefore, Tetradenia riperia leaf extract is a viable route for the synthesis of Ag–ZnO nanocomposites to be used for various applications, including water disinfection.
In this work, a simple and green synthesis procedure for phytofabrication Zinc oxide-silver supported biochar nanocomposite (Ag/ZnO@BC) via Persicaria salicifolia biomass is investigated for the first time to uphold numerous green chemistry such as less hazardous chemical syntheses. XRD technique showed the crystal structure of the phytosynthesized Ag/ZnO@BC, whereas UV–visible spectroscopy, FT-IR, SEM, EDX, TEM, and XPS analyses indicated the successful biosynthesis of the nanocomposite. Testing the photocatalytic potential of this novel nanocomposite in the removal of TC under different conditions unraveled its powerful photodegradation efficiency that reached 70.3% under the optimum reaction conditions: TC concentration; 50 ppm, pH; 6, a dose of Ag/ZnO@BC; 0.01 g, temperature; 25 °C, and H2O2 concentration; 100 mM. The reusability of Ag/ZnO@BC was evident as it reached 53% after six cycles of regeneration. Ag/ZnO@BC was also shown to be a potent antimicrobial agent against Klebsiella pneumonia as well as a promising antioxidant material. Therefore, the current work presented a novel nanocomposite that could be efficiently employed in various environmental and medical applications.
The vastness of metal-based nanoparticles has continued to arouse much research interest, which has led to the extensive search and discovery of new materials with varying compositions, synthetic methods, and applications. Depending on applications, many synthetic methods have been used to prepare these materials, which have found applications in different areas, including biology. However, the prominent nature of the associated toxicity and environmental concerns involved in most of these conventional methods have limited their continuous usage due to the desire for more clean, reliable, eco-friendly, and biologically appropriate approaches. Plant-mediated synthetic approaches for metal nanoparticles have emerged to circumvent the often-associated disadvantages with the conventional synthetic routes, using bioresources that act as a scaffold by effectively reducing and stabilizing these materials, whilst making them biocompatible for biological cells. This capacity by plants to intrinsically utilize their organic processes to reorganize inorganic metal ions into nanoparticles has thus led to extensive studies into this area of biochemical synthesis and analysis. In this review, we examined the use of several plant extracts as a mediating agent for the synthesis
of different metal-based nanoparticles (MNPs). Furthermore, the associated biological properties, which have been suggested to emanate from the influence of the diverse metabolites found in these plants, were also reviewed.
The present study is focused on the synthesis of silver nanoparticles (AgNPs) utilizing endophytic fungus Talaromyces purpureogenus , isolated from Taxus baccata Linn. Extracellular extract of Talaromyces purpureogenus has shown occurrence of secondary metabolites viz. terpenoids and phenols. Gas chromatography-mass spectroscopy analysis showed the presence of 16 compounds. Techniques like Ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering, field emission gun scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction were employed to characterize the synthesized AgNPs. UV–Vis spectroscopy showed sharp peaks at 380–470 nm which indicates the presence of metallic silver. FTIR analysis showed the presence of various functional groups like phenols, hydroxyl groups, and primary amines. In DLS, Z-average size and PdI of synthesized AgNPs were 240.2 r.nm and 0.720 respectively, with zeta potential − 19.6 mV. In FEG-SEM and HRTEM the spherical AgNPs showed diameter in the range of 30–60 nm. In EDS analysis the weight percent of Ag is 67.26% and atomic percent is 43.13%. From XRD analysis the size of AgNPs was found to be 49.3 nm with face-centered cubic crystalline nature of fungal synthesized AgNPs. These nanoparticles have shown significant antibacterial activity against tested strains viz. Listeria monocytogenes (13 ± 0.29 mm), Escherichia coli (17 ± 0.14 mm), Shigella dysenteriae (18 ± 0.21 mm) and Salmonella typhi (14 ± 0.13 mm). These synthesized AgNPs have shown effective free radical scavenging activity against 2,2′-diphenyl-1-picrylhydrazyl. The present study showed that the endophytic fungus Talaromyces purpureogenus can be used as a prominent source to synthesize AgNPs by using biological, ecofriendly, and in a non-toxic way accompanied by antibacterial and antioxidant properties which further can reduce the harvesting pressure faced by Taxus baccata.
Graphical Abstract
Nanotechnology is an interdisciplinary area of research taking advantage of core techniques used in various disciplines like chemistry, engineering, physics and biological sciences, and leading to the development of novel strategies to manipulate minute particles resulting in the production of nanoparticles (NPs). These NPs may be defined as particles with at least one dimension ranging from 1–100 nm. Nanotechnology deals with the synthesis, development and applications of a variety of NPs. These NPs are generally produced via laborious and hazard-prone physical and chemical methods. According to the safety-by-design principle, during the last decade a large array of safe, facile, cost effective, reproducible and scalable green synthesis approaches of NPs have been developed. Among these green biological methods, plant-based biosynthesis of NPs is considered a gold technique due to easy availability and the diverse nature of plants. The poten-tial of plant extracts to produce NPs that have definite size and shape, as well as composition, is of great importance. Moreover, the great diversity of phytochemicals readily available in plant ex-tracts can be utilized in this green approach as the natural stabilizing and reducing agents for the biosynthesis of NPs. Plant-derived NPs are also prone to present less harmful side effects to the human population as compared to chemically synthesized NPs, and exhibit high biological po-tential with applications in various domains such as in agriculture, in food science and technol-ogy, in bioengineering, in cosmetics or in nanomedicine and human health protection. Recently, NPs have also emerged as a novel effective elicitor in plant in vitro systems with the ability to enhance the synthesis of bioactive secondary metabolites, thus further increasing the potential applications spectra of plant-based NPs. This special issue provides an overview of recent methods for the production and characterization of the green plant-based nanoparticles, their applications as well as future directions.
Pineapple waste accounts for a significant part of waste accumulated in landfill which will further contribute to the release of greenhouse gases. With the rising pineapple demands worldwide, the abundance of pineapple waste and its disposal techniques are a major concern. Exploiting the pineapple waste into valuable products could be the most sustainable way of managing these residues due to their useful properties and compositions. In this review, we concentrated on producing useful products from on-farm pineapple waste and processing waste. Bioenergy is the most suitable option for green energy to encounter the increasing demand for renewable energy and promotes sustainable development for agricultural waste. The presence of protease enzyme in pineapple waste makes it a suitable raw material for bromelain production. The high cellulose content present in pineapple waste has a potential for the production of cellulose nanocrystals, biodegradable packaging and bio-adsorbent, and can potentially be applied in the polymer, food and textile industries. Other than that, it is also a suitable substrate for the production of wine, vinegar and organic acid due to its high sugar content, especially from the peel wastes. The potentials of bioenergy production through biofuels (bioethanol, biobutanol and biodiesel) and biogas (biomethane and biohydrogen) were also assessed. The commercial use of pineapples is also highlighted. Despite the opportunities, future perspectives and challenges concerning pineapple waste utilisation to value-added goods were also addressed. Pineapple waste conversions have shown to reduce waste generation, and the products derived from the conversion would support the waste-to-wealth concept.
Processing pineapple industry produces huge amounts of waste thus contributing to worsen the global environmental problem. Valorising pineapple waste through further processing until it is transformed into valuable products using environmentally friendly techniques is both, a challenge, and an opportunity. The aim of this review is to characterize and highlight the phytochemical constituents of pineapple peel, their biological activity, and to evaluate the
current state-of-art for the utilization of pineapple waste from the processing industry for obtaining pharmaceuticals, food, and beverages, biocombustibles, biodegradable fibers, and other different usage. Pineapple residues are rich in many bioactive compounds such as ferulic acid, vitamin A and C as
antioxidant, and containing alkaloids, flavonoids, saponins, tannins, cardiac glycoside, steroids, triterpenoids and phytosterols may provide a good source of several beneficial properties, as well as bromelain that showed significant anticancer activity. Also, pineapple processing residues contain important volatile compounds used as aroma enhancing products and have high potential to produce value-added natural essences. Pineapple peels can be used as non-pharmacological therapeutical in the form of processed food and instant drinks; its potent natural antimicrobial properties may be applied for food conservation and as potential leads to discover new drugs to control some infectious microbial. Pineapple waste is a promising source of metabolites for therapeutics, functional foods, and cosmeceutical applications.
In recent years, biosynthesized zinc oxide nanoparticles (ZnO NPs) have been gaining importance due to their unique properties and tremendous applications. This study aimed to fabricate ZnO NPs by using extracts from various parts of the traditional medicinal plant Heliotropium indicum (H. indicum) and evaluate their photocatalytic activity. Further, their potential in photoluminescence and fluorescence resonance energy transfer (FRET) was assessed. The Ultraviolet-Visible spectrum exhibited a hypsochromic shifted absorption band between 350–380 nm. Transmission electron microscopy (TEM) analysis revealed spherical NPs, while X-ray diffraction (XRD) data revealed wurtzite, hexagonal and crystalline nature. The TEM and XRD consistently determined an average particle size range from 19 to 53 nm. The photocatalytic degradation reaches a maximum of 95% for biogenic ZnO NPs by monitoring spectrophotometrically the degradation of methylene blue dye (λmax = 662.8 nm) under solar irradiation. Photoluminescence analysis revealed differentiated spectra with high-intensity emission peaks for biogenic ZnO NPs compared with chemically synthesized ZnO NPs. Eventually, the highest efficiency of FRET (80%) was found in ZnO NPs synthesized from the leaves. This remains the first report highlighting the multifunctional ZnO NPs capabilities mediated by using H. indicum, which could lead to important potential environmental and biomedical applications.
Pineapple peel still contains an important amount of phenolic compounds and vitamins with valuable antioxidant activity. In this way, the aim of this study was the recovery of the bioactive compounds from pineapple peel using environmentally friendly and low-cost techniques, envisaging their application in food products. From the solid-liquid extraction conditions tested, the one delivering an extract with higher total phenolic content and antioxidant capacity was a single extraction step with a solvent-pineapple peel ratio of 1:1 (w/w) for 25 min at ambient temperature, using ethanol-water (80–20%) as a solvent. The resulting extract revealed a total phenolic content value of 11.10 ± 0.01 mg gallic acid equivalent (GAE)/g dry extract, antioxidant activity of 91.79 ± 1.98 µmol Trolox/g dry extract by the DPPH method, and 174.50 ± 9.98 µmol Trolox/g dry extract by the FRAP method. The antioxidant rich extract was subjected to stabilization by the spray drying process at 150 °C of inlet air temperature using maltodextrin (5% w/w) as an encapsulating agent. The results showed that the antioxidant capacity of the encapsulated compounds was maintained after encapsulation. The loaded microparticles obtained, which consist of a bioactive powder, present a great potential to be incorporated in food products or to produce bioactive packaging systems.
Phytochemical screening of ten different locally available plant parts was done in methanol extract. Tannin, quinine, terpenoid, flavonoid, steroid, alkaloid, cardiac glycoside, glycoside, volatile oils, etc were the phytoconstituents found in plants. The study of the effect of phytoconstituents in the germination of Pisum sativum seeds revealed that the phytoconstituents present in plant extracts showed the cytotoxic effect in living cells i.e. in germinating Pisum sativum seeds. The phytoconstituents present in the plant extract showed an effect on cell proliferation and growth. Hence these plants could be used to develop drugs against cancer cells and also may be effective against microbes and bacteria
In this study, Ag/AgO NPs were synthesized by Crocus sativus L Extract in a single step biosynthesis. It acts as an agent to reduce and cap. Nanoparticles were characterized by UV–Visible spectra, X-ray diffraction (XRD). The Plasmon resonance surface (Ag / AgO NPs) of the as-prepared surface showed a Plasmon resonance at 410 nm. The XRD pattern showed Ag and AgO peaks. The mean crystalline size of Ag is 28.25 nm and 26.21 nm for AgO. Electron microscope field emission scanning (FESEM) was used to study the morphology of the Ag/AgO NPs. The biological test results demonstrated the effect of silver nanoparticles on different types of a bacterium: gram-positive, gram-negative, as different inhibitors for each type were registered and the impact of silver material on bacteria inhibition was shown.
Green synthesis is one of the most valuable and emerging methods for the synthesis of nanoparticles (NPs) nowadays, presenting imperative biological benefits, reduced process time, cost-effectiveness, and environmental benefits, as an alternative to physical and chemical processes. Silver, a noble metal, possess unique properties and potential applications in medicine, requiring the search for novel and suitable tools for its production due to the growing demand. The exploration of plants diversity can be used towards rapid and single-step preparatory methods for various NPs, maintaining the green principle over conventional ones, an important aspect for medical applications. Plants contain bio-organics components, which usually play multiple roles as reducing, capping as well as stabilizing agents for metal compounds into silver nanoparticles (AgNPs). The stability of these NPs is governed by certain parameters, which influence stability and bioavailability. In this perspective, this review aims to provide a comprehensive view to understand the possible induced mechanism, current scenario and future prospects for the bio-inspired synthesis of AgNPs.
Herein, a facile green synthesis route was reported for the synthesis of Ag–ZnO nanocomposites using potato residue by simple and cost effective combustion route and investigated the photocatalytic degradation of methylene blue (MB) dye. In the preparation potato extract functioned as a biogenic reducing as well as stabilizing agent for the reduction of Ag + , thus eliminating the need for conventional reducing/stabilizing agents. Ag–ZnO nanocomposites with different Ag mass fractions ranging from 2 to 10% were characterized by using XRD, FT-IR, XPS, SEM, TEM, and UV–Vis spectroscopy. XRD analysis revealed that the as prepared Ag–ZnO nanocomposites possessed high crystallinity with hexagonal wurtzite structure. TEM and SEM images showed that the Ag–ZnO nanocomposites in size ranging from 15 to 25 nm have been obtained, and the particle size was found to increase with the increase in percentage of Ag. FTIR results confirmed the characteristics band of ZnO along with the Ag bands. XPS analysis revealed a pair of doublet with peaks corresponding to Ag and a singlet with peaks corresponding to ZnO. With the increase of concentration of Ag in ZnO, the intensity of NBE emission in the PL spectra was observed to be decrease, resulted to the high photocatalytic activity. Photocatalytic properties of Ag–ZnO nanocomposites evaluated against the MB dye under visible-light irradiation showed superior photodegradation of ~ 96% within 80 min for 2% Ag–ZnO nanocomposites. The apparent reaction rate constant for 2% Ag–ZnO nanocomposites was higher than that of other nanocomposites, which proved to be the best photocatalyst for the maximum degradation of MB. Furthermore, various functional parameters such as dosing, reaction medium, concentration variation were performed on it for better understanding. The enhancement in photocatalytic degradation might be due to the presence of Ag nanoparticles on the surface of ZnO by minimizing the recombination of photo induced charge carriers in the nanocomposites.
Nanoparticle synthesis using microorganisms and plants by green synthesis technology is biologically safe, cost-effective, and environment-friendly. Plants and microorganisms have established the power to devour and accumulate inorganic metal ions from their neighboring niche. The biological entities are known to synthesize nanoparticles both extra and intracellularly. The capability of a living system to utilize its intrinsic organic chemistry processes in remodeling inorganic metal ions into nanoparticles has opened up an undiscovered area of biochemical analysis. Nanotechnology in conjunction with biology gives rise to an advanced area of nanobiotechnology that involves living entities of both prokaryotic and eukaryotic origin, such as algae, cyanobacteria, actinomycetes, bacteria, viruses, yeasts, fungi, and plants. Every biological system varies in its capabilities to supply metallic nanoparticles. However, not all biological organisms can produce nanoparticles due to their enzymatic activities and intrinsic metabolic processes. Therefore, biological entities or their extracts are used for the green synthesis of metallic nanoparticles through bio-reduction of metallic particles leading to the synthesis of nanoparticles. These biosynthesized metallic nanoparticles have a range of unlimited pharmaceutical applications including delivery of drugs or genes, detection of pathogens or proteins, and tissue engineering. The effective delivery of drugs and tissue engineering through the use of nanotechnology exhibited vital contributions in translational research related to the pharmaceutical products and their applications. Collectively, this review covers the green synthesis of nanoparticles by using various biological systems as well as their applications.
The present investigation reports a comparative study of direct Sunlight and UV irradiation driven silver nanoparticles (AgNPs) synthesized from water extracts of seasonal fruit wastes of Garcinia mangostana L. (fruit rind and seed), and Nephelium lappaceum L. (peel and seed). Synthesized NPs were characterized using Ultraviolet–Visible spectrophotometry, Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), and Energy-dispersive spectroscopy (EDX). As per the SEM and TEM images, synthesized NPs appeared to be spherical, with a UV absorbance range of 400–440 nm. FTIR spectra demonstrated peaks at 3268–3290 cm⁻¹, 2347–2363 cm⁻¹, 2099–2103 cm⁻¹, and 1635–1639 cm⁻¹ for fruit waste extracts, with low intensity for AgNPs. The particle size of AgNPs vary from 12.1–31.3 nm, as observed from the TEM, and the EDX spectra confirmed the purity of the AgNPs. The quenching ability of biogenic AgNPs was evaluated using Rhodamine B dye under Fluorescence spectrophotometry. As per the results, all biogenic AgNPs behaved as quenchers. The highest fluorescence quenching activity was observed in AgNPs synthesized via G. mangostana peel extract and N. lappaceum seed extract. The photocatalytic activity of the NPs was measured by the degradation of Methylene Blue dye under Sunlight. Among all four, AgNPs synthesized via N. lappaceum seed extract act as an effective photocatalyst, and the degradation efficiency was recorded as 95% with 22 min of Half-life. Thus, this study proposes that the synthesized biogenic AgNPs behave as an ideal material for dye degradation and fluorescence quenching.
Fruit peels have a diverse range of phytochemicals including carotenoids, vitamins, dietary fibres, and phenolic compounds, some with remarkable antioxidant properties. Nevertheless, the comprehensive screening and characterization of the complex array of phenolic compounds in different fruit peels is limited. This study aimed to determine the polyphenol content and their antioxidant potential in twenty different fruit peel samples in an ethanolic extraction, including their comprehensive characterization and quantification using the LC-MS/MS and HPLC. The obtained results showed that the mango peel exhibited the highest phenolic content for TPC (27.51 ± 0.63 mg GAE/g) and TFC (1.75 ± 0.08 mg QE/g), while the TTC (9.01 ± 0.20 mg CE/g) was slightly higher in the avocado peel than mango peel (8.99 ± 0.13 mg CE/g). In terms of antioxidant potential, the grapefruit peel had the highest radical scavenging capacities for the DPPH (9.17 ± 0.19 mg AAE/g), ABTS (10.79 ± 0.56 mg AAE/g), ferric reducing capacity in FRAB (9.22 ± 0.25 mg AA/g), and total antioxidant capacity, TAC (8.77 ± 0.34 mg AAE/g) compared to other fruit peel samples. The application of LC-ESI-QTOF-MS/MS tentatively identified and characterized a total of 176 phenolics, including phenolic acids (49), flavonoids (86), lignans (11), stilbene (5) and other polyphenols (25) in all twenty peel samples. From HPLC-PDA quantification, the mango peel sample showed significantly higher phenolic content, particularly for phenolic acids (gallic acid, 14.5 ± 0.4 mg/g) and flavonoids (quercetin, 11.9 ± 0.4 mg/g), as compared to other fruit peel samples. These results highlight the importance of fruit peels as a potential source of polyphenols. This study provides supportive information for the utilization of different phenolic rich fruit peels as ingredients in food, feed, and nutraceutical products.
Nanotechnology is an emerging science with a wide array of applications involving the synthesis and manipulation of materials with dimensions in the range of 1–100 nm. Nanotechnological applications include diverse fields such as pharmaceuticals, medicine, the environment, food processing and agriculture. Regarding the latter, applications are mainly focused on plant growth and crop protection against plagues and diseases. In recent years, the biogenic reduction of elements such as Ag, Au, Cu, Cd, Al, Se, Zn, Ce, Ti and Fe with plant extracts has become one of the most accepted techniques for obtaining nanoparticles (NPs), as it is considered an ecological and cost‐effective process without the use of chemical contaminants. The objective of this work was to review NPs synthesized by green chemistry using vegetable extracts, as well as their use as antimicrobial agents against phytopathogenic fungi and bacteria. Given the need for alternatives to control and integrate management of phytopathogens, this review is relevant to agriculture, although this technology is barely exploited in this field. © 2020 Society of Chemical Industry
In the present study, biogenic synthesized zinc oxide (ZnO) nanoparticles using as a nano-priming agent for enhancing seed germination and seedling growth parameters of maize (Zea mays) were determined. The results of the present study carried out in paper roll towel method shown that ZnO nano-primed seeds @ 100 mg/L showed highest improved seed germination rate and seedling parameters viz., shoot length (13.0 cm), shoot width (3.4 mm); root length (20.7 cm), root width (1.0 mm); leaf length (60 mm), width (16.0 mm); vigor index (2931.9) and dry matter production (5.33 gm) than ionic control (zinc acetate) and normal control (hydro-priming). In addition, HR-SEM analysis reveals the absorption of ZnO nanoparticles on the endosperm regions of seed. Taken together, the aforementioned results also showed that the use of ZnO nanoparticles could alleviate zinc deficiency and improved the agronomical characters of maize seedling.
In the present article, the nanoparticles of Ananas comosus (pineapple) extract were prepared by an effective way considering the environment and cost to be efficient. The nanoparticles were prepared by bioreduction method. Characterization of the sythesized nanoparticles were done by UV-visble, FTIR and SEM methods. At 420 nm, an absorption peak was found. The nature of the peak was broad which indicates that increase in time broaden the peak that in-turn indicates that the synthesized nanoparticles were polydispersed. The synthesized nanoparticles were stabilized and the capping of the same were done by the biomolecules present which was characterized using FTIR spectra. It also proved that capping material in the extract was the sole reason for the bioreduction process.
Phytofabrication of Zinc Oxide nanoparticles (ZnO–NPs) through Nephelium lappaceum L. and Garcinia mangostana L. plants' wastes were achieved as an environmentally friendly method of synthesizing nanoparticles. Biogenic ZnO–NPs were characterized by Ultra Violet Visible (UV–vis) spectrophotometry, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Energy Dispersive Energy (EDX ), and Fourier Transform Infrared spectroscopy (FTIR). UV- Visible absorption of ZnO–NPs indicated a characteristic absorption band at 362–368 nm region. The synthesized nanoparticles were flower in shape, as shown by the SEM images, and they were further elucidated by the TEM images. ZnO-NP synthesized via Rambutan Peel Extract (RPE), Rambutan Seed Extract (RSE), Mangosteen Peel Extract (MPE) and Mangosteen Seed Extract (MSE) showed the average particle size of 29 nm–184 nm, 86 nm–260 nm, 92 nm–247 nm, and 233 nm–334 nm respectively. FTIR spectra demonstrated peaks at 3269–3500 cm−1, 2308–2361 cm−1, 2103–2110 cm−1 and 1630–1640 cm−1, 586–632 cm−1 for the plant extracts, whereas an additional peak appeared within the range of 458–499 cm−1 in ZnO–NPs spectra. The photocatalytic activity of the synthesized ZnO–NPs was measured by the degradation of Methylene Blue under sunlight. The highest degradation of Methylene Blue dye was detected in ZnO—NPs synthesized using the seed extract of Nephelium lappaceum L., where a Half-life of 78 min and 97% degradation efficiency at 150 min time frame was observed. The ZnO–NPs were identified to possess fluorescence quenching ability of Rhodamine B. The highest quenching ability was recorded in ZnO–NPs synthesized via Garcinia mangostana L. seed. The Photoluminescence study showed that the intensity of spectral lines of biogenic ZnO–NPs were higher compared with the chemically synthesized ZnO–NPs.
The development of new nanomaterials with high biomedical performance and low toxicity is essential to obtain more efficient therapy and precise diagnostic tools and devices. Recently, scientists often face issues of balancing between positive therapeutic effects of metal oxide nanoparticles and their toxic side effects. In this review, considering metal oxide nanoparticles as important technological and biomedical materials, the authors provide a comprehensive review of researches on metal oxide nanoparticles, their nanoscale physicochemical properties, defining specific applications in the various fields of nanomedicine. Authors discuss the recent development of metal oxide nanoparticles that were employed as biomedical materials in tissue therapy, immunotherapy, diagnosis, dentistry, regenerative medicine, wound healing and biosensing platforms. Besides, their antimicrobial, antifungal, antiviral properties along with biotoxicology were debated in detail. The significant breakthroughs in the field of nanobiomedicine have emerged in areas and numbers predicting tremendous application potential and enormous market value for metal oxide nanoparticles.
Even though the photocatalytic processes are a good technology for treatment of toxic organic pollutants, the majority of current photocatalysts cannot utilize sunlight sufficiently to realize the decomposition of these organic pollutants. As stated by various researchers, metal oxide nanoparticles have a significant photocatalytic performance under visible light source. Among various chemical and physical methods used to synthesize nanostructured silver oxide, green synthetic route is a cheaper and environmental friendly method. To confirm the optimum production of Ag2O NPs, effect of pH, extract concentration, metal ion concentration, and contact time were optimized. The structure, morphology, crystallinity, size, purity, elemental composition, and optical properties of obtained Ag2O NPs were characterized by different techniques, such as scanning electron microscopy (SEM), transmission electron microscope (HRTEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and UV-visible spectrophotometer accordingly as revealed by our literature review. The photocatalytic performance of the synthesized nanocrystalline Ag2O by photocatalytic degradation of organic dyes under visible light irradiation has been discussed thoroughly in this review. Many past studies revealed that organic dyes and pollutants are decomposed completely by green synthesized Ag2O NPs under irradiation of visible light.
Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag–Au alloy, [email protected] core–shell, and [email protected] core–shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination of optical constants of Au–Ag alloys reported in the literature. Although both Au–Ag core–shell and alloy nanoparticles exhibit an intermediary optical response between that of pure Ag and Au nanoparticles, there are noticeable differences in the spectral characteristics. Also, the effect of the bimetallic constitution in anisotropic nanoparticles is starkly different from that in spherical nanoparticles due to the absence of Au interband transitions in the former case. In general, the improved chemical stability of Ag nanoparticles by incorporation of Au comes with a cost of reduction in plasmonic enhancement, also applicable to anisotropic nanoparticles with a weaker effect. A photothermal heat transfer study confirms that increased absorption by the incorporation of Au in spherical Ag nanoparticles also results in an increased steady-state temperature. On the other hand, anisotropic nanoparticles are inherently better absorbers and hence better photothermal sources, and their photothermal properties are apparently not strongly affected by the incorporation of one metal in the other. This study of the optical/spectral and photothermal characteristics of bimetallic Au–Ag alloy versus core–shell nanoparticles provides detailed physical insight for development of new taylor-made plasmonic nanostructures.
The quest to synthesize nanomaterials with improved properties, but less undesirable effects on the environment necessitated this research. Zinc Oxide (ZnO) nanoparticles and zinc oxide–silver (ZnO–Ag), zinc oxide–copper (ZnO–Cu) nanocomposites were synthesized with pure eco-friendly dye extracted from Bridelia ferruginea, zinc acetate (Zn(CH3COO)2) as host, copper acetate (Cu (CH3COO)2), and silver nitrate (AgNO3) as dopant precursors. Phytochemical screening of dyes showed high, presence of phenols and terpenoids. The nanomaterials were characterized by Fourier-transform infrared, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy and ultraviolet–visible spectroscopy. The results showed the capping agents in the dyes were responsible for reducing the bulk materials. The crystallinity of the nanomaterials were found to be 19.02, 18.98 and 18.90 nm for the ZnO, ZnO–Ag and ZnO–Cu nanoparticles respectively. The ZnO nanoparticles were flakelike in shape, whereas the Cu and Ag doped particles were spherical. An optical bandgap of 4.73 eV was recorded for the dye and 3.24 eV for the ZnO nanoparticles. This was narrowed to 3.18 and 3.13 eV by silver and copper dopant respectively. These results showed the nanoparticles as a potential agent for photovoltaics and other optical applications.
Background:
Caralluma europaea (C. europaea) is a medicinal plant used in Moroccan popular medicine. Objective of the Study. The present work was aimed at identifying the chemical composition and the antioxidant and antiproliferative activities of hydroethanolic and bioactive compound classes of C. europaea) is a medicinal plant used in Moroccan popular medicine. Materials and Methods. The chemical composition was analyzed using HPLC. The antioxidant power was determined using both DPPH and FRAP assays. The antiproliferative activity was effectuated against cancerous cells using WST-1.
Results:
The chemical analysis showed the presence of bioactive constituents such as quercetin, myricetin, and hesperetin. The polyphenol and flavonoid contents were estimated at 51.42 mg GA/g and 20.06 mg EQ/g, respectively. The EC50 values of FRAP assay of hydroethanolic, flavonoid, saponin, and mucilage extracts were 5.196 mg/ml, 4.537 mg/ml, 3.05 mg/ml, and 6.02 mg/ml, respectively. The obtained IC50 values with the DPPH test were 1.628 mg/ml, 1.05 mg/ml, 1.94 mg/ml, and 9.674 mg/ml, respectively. Regarding MDA-MB-231, saponins were highly effective even with the lowest concentration (15.62 μg/ml). The flavonoids decreased the cell viability with IC50 values of 43.62 ± 0.06 μg/ml). The flavonoids decreased the cell viability with IC50 values of 43.62 ± 0.06 μg/ml). The flavonoids decreased the cell viability with IC50 values of 43.62 ± 0.06 .
Conclusion:
The present results suggest that C. europaea) is a medicinal plant used in Moroccan popular medicine.
Process food industry in Sri Lanka has been expanded with the open economy, increase of population, technological
development, and the modern lifestyle of people. Meantime, disposal of solid food waste from such industries has
become one of the major environmental issues in the country. Although fruits are the leading food waste type
generates globally, literature for fruit wastes (FW) generate in Sri Lankan fruit manufacturing industries (FMI) is
scanty. Therefore, the objectives of this study were to investigate the types and amounts of FW generates in FMI,
waste management practices currently employing in FMI, issues and challenges associated with the implementation
of sustainable waste management practices and potentials of reuse and recycle the FW instead of disposal. The
study was carried out as a qualitative study using the five leading FMI in Sri Lanka and the data were collected
through a questionnaire survey, personal interviews, focused group discussions and personal observations.
Gathered data demonstrated that annual fruit wastage of FMI is around 35 to 60%. Pineapple leftovers found to
be the leading FW type generates in local FMI. Out of studied industries, only one FMI recycle and reuse the FW
by composting and for others FW is a profit loss since they hire a third party to dispose the waste. As such, there
is a great potential to reuse and recycle the FW generate in Sri Lankan FMI. However, financial restriction, lack
of affordable technologies, difficulty in finding workers and lands, and public protest against the development of
waste processing areas were identified as manger issues in the attempt of reuse and recycling the waste
The greener way of producing silver nanoparticles is the easiest, cheapest and most efficient way of producing large-scale nanoparticles that have no adverse effect on the environment. The nanosynthesis using various methodologies and the biological synthesis of silver nanoparticles have been discussed in detail. Plant extracts have been known to be competent for the extracellular biosynthesis of silver nanoparticles suggested by the various publications. Further, effects of various sources and methods on nanoparticle synthesis have been examined. Additionally, the impact of conditions such as dark, light, heating, boiling, sonication, autoclave on the size and shape of colloidal nanoparticles has been analyzed. Moreover, effects of specific parameters such as leaf extract concentration, AgNO3, reaction temperature, pH, light and stirring time for nanoparticle synthesis are discussed, and the impact of silver nanoparticles on plant physiology has examined.
A simple, eco-friendly, and biomimetic approach using Thymus vulgaris (T. vulgaris) leaf extract was developed for the formation of ZnO-Ag nanocomposites (NCs) without employing any stabilizer and a chemical surfactant. T. vulgaris leaf extract was used for the first time, in a novel approach, for green fabrication of ZnO-Ag NCs as a size based reducing agent via the hydrothermal method in a single step. Presence of phenols in T. vulgaris leaf extract has served as both reducing and capping agents that play a critical role in the production of ZnO-Ag NCs. The effect of silver nitrate concentration in the formation of ZnO-Ag NCs was studied. The in-vitro Antimicrobial activity of NCs displayed high antimicrobial potency on selective gram negative and positive foodborne pathogens. Antioxidant activity of ZnO-Ag NCs was evaluated via (2,2-diphenyl-1-picrylhydrazyl) DPPH method. Photocatalytic performance of ZnO-Ag NCs was appraised by degradation of phenol under natural sunlight, which exhibited efficient photocatalytic activity on phenol. Cytotoxicity of the NCs was evaluated using the haemolysis assay. Results of this study reveal that T. vulgaris leaf extract, containing phytochemicals, possess reducing property for ZnO-Ag NCs fabrication and the obtained ZnO-Ag NCs could be employed effectively for biological applications in food science. Therefore, the present study offers a promising way to achieve high-efficiency photocatalysis based on the hybrid structure of semiconductor/metal.
Nanotechnology is a developing branch of pharmaceutical sciences wherein the particles extend in nanosizes and turn out to be more responsive when contrasted with their unique counter parts. In the past numerous years, the utilization of synthetic concoctions and physical strategies were in mould; however, the acknowledgment of their toxic impacts on human well-being and condition influenced serious world view for the researchers. Presently, green synthesis is the watch word for the combination of nanoparticles (NPs) by plants or their metabolites. This innovation is particularly compensating as far as decreasing the poisonous quality caused by the conventionally integrated NPs. In this review, we cover the perspectives by which metal particles can be integrated from green methods in the perspective of green methods utilized in the NPs combination. In the green strategies, plant metabolites and natural substances are utilized to orchestrate the NPs for the pharmaceutical and other applications. Some characterization methods are also reviewed along with applications of NPs.
Nanoparticles (NPs) have been synthesized by various methods like physical, chemical and biological methods. Physical and chemical methods are costly and toxic to the environment. So there is an emerging need for production of nanoparticles using nontoxic, eco-friendly and reliable methods to expand their applications in agriculture field. Best option to achieve this goal is the use of biological entities such as microorganisms and plant extracts to synthesize nanoparticles. The main focus of this review is to compile the studies of synthesis of nanoparticles using “eco-friendly nano-factories” i.e., plant extract and microorganisms. Agriculture is an area where new technologies are often applied to improve the yield of crops. Plant diseases are one of the major factors that affect crop productivity. The problem with disease management lies with the detection of the exact stage of prevention. The employment of nanoparticles in agriculture field with some beneficial effects to the crops will be promising step toward nano-revolution in agriculture field. This review also summarizes antimicrobial activity of nanoparticles, their influence on the plant growth parameters and their role in plant pathogenicity.
A rapid phytosynthesis of silver nanoparticles (AgNPs) using an extract from the aerial parts of Asphodelus aestivus Brot. was investigated in this study. Ultraviolet–visible spectroscopy, fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and zeta potential (ZP) were used to characterize the formation of silver nanoparticles (AgNPs). The antioxidant properties of these AgNPs were evaluated using DPPH, ABTS⁺ and hydrogen peroxide scavenging assays. The synthesized AgNPs were noticed through visual color change from yellow to gray brown. The UV–Vis spectrum exhibited an absorption band at around 440 nm, which is a characteristic band for Ag. FT-IR measurement was carried out to identify the possible biomolecules responsible for capping and reducing agent for the Ag nanoparticles synthesized by A. aestivus aqueous extract. XRD results showed peaks at (200), (111), (110), (120), (330) and (210), which confirmed the presence of AgNPs with mono clinic crystals. The TEM image of silver nanoparticles shown that the morphology of silver nanoparticles was predominantly spherical. It could be concluded that A. aestivus extract can be used efficiently in the production of potential antioxidant AgNPs for commercial application.
Indonesia is a large pineapple (Ananas comosus) producing country. Food industries in Indonesia processed this fruit for new products and further resulted wastes of which cause an environmental problems. Approximately, one pineapple fruit total weight is 400 gr of which 60 g is of peel wastes. In order to reduce such pineapple peel wastes (PPW), processing to a valuable product using an environmentally friendly technique is indispensable. PPW contained phenolic compound, ferulic acid, and vitamin A and C as antioxidant. This study aimed to PPW using ethanol and water as well as to analyze its chemical properties. Both dried and fresh PPW were extracted using mixtures of ethanol and water with various concentrations ranging from 15 to 95% (v/v) at room temperature for 24 h. The chemical properties, such as antioxidant activity, total phenolic content (Gallic acid equivalent/GAE), and total sugar content were determined. The results showed that the range of Inhibition Concentration (IC)50 value as antioxidant activity of extracts from dried and fresh PPW were in the range of 0.8±0.05 to 1.3±0.09 mg.mL⁻¹ and 0.25±0.01 to 0.59±0.01 mg.mL⁻¹, respectively, with the highest antioxidant activity was in water extract. The highest of total phenolic content of 0.9 mg.g⁻¹ GAE, was also found in water extract.
Nanotechnology deals with the production and usage of material with nanoscale dimension. Nanoscale dimension provides nanoparticles a large surface area to volume ratio and thus very specific properties. Zinc oxide nanoparticles (ZnO NPs) had been in recent studies due to its large bandwidth and high exciton binding energy and it has potential applications like antibacterial, antifungal, anti-diabetic, anti-inflammatory, wound healing, antioxidant and optic properties. Due to the large rate of toxic chemicals and extreme environment employed in the physical and chemical production of these NPs, green methods employing the use of plants, fungus, bacteria, and algae have been adopted. This review is a comprehensive study of the synthesis and characterization methods used for the green synthesis of ZnO NPs using different biological sources.
The aim of this study was to evaluate the antioxidant activity, screening the phytogenic chemical compounds, and to assess the alkaloids present in the E. intermedia to prove its uses in Pakistani folk medicines for the treatment of asthma and bronchitis. Antioxidant activity was analyzed by using 2,2-diphenyl-1-picryl-hydrazyl-hydrate assay. Standard methods were used for the identification of cardiac glycosides, phenolic compounds, flavonoids, anthraquinones, and alkaloids. High performance liquid chromatography (HPLC) was used for quantitative purpose of ephedrine alkaloids in E. intermedia . The quantitative separation was confirmed on Shimadzu 10AVP column (Shampack) of internal diameter (id) 3.0 mm and 50 mm in length. The extract of the solute in flow rate of 1 ml/min at the wavelength 210 nm and methanolic extract showed the antioxidant activity and powerful oxygen free radicals scavenging activities and the IC50 for the E. intermedia plant was near to the reference standard ascorbic acid. The HPLC method was useful for the quantitative purpose of ephedrine (E) and pseudoephedrine (PE) used for 45 samples of one species collected from central habitat in three districts (Ziarat, Shairani, and Kalat) of Balochistan. Results showed that average alkaloid substance in E. intermedia was as follows: PE (0.209%, 0.238%, and 0.22%) and E (0.0538%, 0.0666%, and 0.0514%).
The present study reports the comparative analysis for the synthesis of zinc oxide nano particles by precipitation techniques using different zinc precursors. The synthesized nano particles were characterized by X-ray diffractometry (XRD), energy dispersive X-ray analysis and scanning electron microscopy (SEM) analysis for their sizes, shapes and arrangement. SEM has been studied for the samples before as well as after calcination to know the effect of temperature on structural behaviours. The XRD pattern shows the purity of synthesized zinc oxide nano particles and using Debye–Scherrer equation, the average crystal size of synthesized nanoparticles was calculated. The results have been discussed in the light of variation of morphological structures of different samples. Apart from this, the band gap energies of the synthesized particles have also been calculated from UV–visible spectrophotometric analysis, which is quite appreciable with the reported results.
Photoactivated antibacterial activity is a very promising strategy to fight bacteria without inducing bacterial resistance. This contribution combines the photodynamic and photothermal properties along with plasmonic effect in a single nanocomposite to effectively kill bacteria. Plasmonic Ag/p-Ag2O/n-ZnO heterojunction nanocomposites with well-defined morphologies are synthesized via solution combustion using glycine and Thymus vulgaris extract as fuels. Ag/Ag2O/ZnO shows excellent photothermal conversion behavior under 600 nm light illumination. ESR analysis confirms the production of reactive species (ROS) under 600 nm. Ag acts as a plasmonic material enhancing the light absorption in the visible region. FT-IR confirms the presence of Thymus vulgaris-related function groups on the surface of the prepared nanocomposite which also contribute to enhancing the antibacterial activity. Ag/Ag2O/ZnO shows promising antibacterial activity under 600 nm illumination against Enterococcus faecalis. Moreover, the nanocomposite shows excellent antibacterial activity against C. albicans and S. epidermidis in the dark. The efficient bacterial killing under 600 nm light illumination is attributed to the synergetic effects among photothermal, photodynamic, and plasmonic effects. The antibacterial activity in the dark is due to the intrinsic antibacterial activity of Ag, ZnO, and Ag2O along with Thymus vulgaris plant extract. Cytotoxicity of Ag/Ag2O/ZnO on Huh-7 human liver cancer cells line is also investigated and the IC50 values calculated are 112.9 and 313 μg/mL for the Ag/Ag2O/ZnO samples prepared using 3 ml (3AgZn) and 7 ml AgNO3 (7AgZn), respectively.
Nanoscale materials are primarily synthesized by utilizing several physiochemical methodologies; however, with inevitable negative consequences, such as environmental pollution, high energy consumption, high cost, and potential health problems. Hence, in recent years, several efforts have been made to identify reliable and environmentally friendly synthetic strategies for synthesizing nanocomposites (NCs). Amongst, the plant-mediated synthesis has been identified as an alternative as plant extracts are used rather than the industrial chemical agents and harsh operational conditions to reduce metal ions which provide significant benefits in terms of cost-effectiveness, decreased toxicity, and abundancies of raw materials. Further, plant-derived biofunctionalized NCs are currently being used successfully in several applications, including environmental remediation, biomedical applications, agricultural and food industries, and engineering, due to their obvious beneficial properties. The use of plant-derived NCs in the field of nanotechnology has paved the way for sustainable synthesis as well as opened up new opportunities for innovation and commercialization in a wide range of industries. Hence, this review describes the advantages of the plant-derived NCs to the nanotechnology field, as well as an overview of the three types of matrix NCs, their synthesis, properties, and various potential applications. Further, this review article may facilitate future research and development on plant-derived NCs in touched and untouched areas of science.
In recent years, the green synthesis of nanoparticles has been the most explored area of research due to the need for eco-friendly, simple and non-toxic ways for synthesizing the nanoparticles with less waste production. In this paper, the synthesis of Ag–ZnO nanocomposite via hydrothermal method using neem leaf extracts in different solvents i.e., water and ethanol is studied. The characterization of thus prepared Ag–ZnO nanocomposites was done using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Fourier Transform Infrared spectroscopy (FTIR) and Photoluminescence (PL) to examine the structural, morphological and optical properties of the prepared nanocomposites. The I–V characteristics of the samples are also studied to determine their electrical properties. The decrease in bandgap and linear plot of I–V characterization of Ag–ZnO nanocomposite make it a suitable candidate for applications in various fields like solar cells, gas sensing, biosensors, photoanodes, photocatalysis and anti-bacterial applications etc.
In the present study, biological synthesis of Ag-ZnO nanocomposites was performed using hydroalcoholic extract of fenugreek leaves. Metal/semiconductor oxide nanocomposites are excellent owing to their optical, electrical, magnetic, and chemical properties that are not detected in single individual constituents. The synthesized Ag-ZnO nanocomposites were investigated through the use of methods such as FTIR, UV vis DRS, SEM-EDX, TEM, XRD, zeta potential analysis, and DLS. The synthesized Ag-ZnO nanocomposites had an average particle size of about 75 nm and a zeta potential of −37.5 mV. The XRD results confirmed that Ag was successfully introduced into the Ag-ZnO nanocomposites via a hydrothermal method. The antimicrobial and antifungal activities of Ag-ZnO nanocomposites were evaluated by agar well diffusion method against three microbial and fungal strains; it was found that the Ag-ZnO nanocomposites were toxic against all the tested microbial and fungal strains. Ag-ZnO nanocomposites was observed to have significant antioxidant activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) free radicals. The Ag-ZnO nanocomposites exhibited excellent photocatalytic activity and stability against the degradation of malachite green under visible light irradiation. The study successfully applied a simple and eco-friendly method for synthesizing efficient multifunctional Ag-ZnO nanocomposites using green synthetic approach.
Cubic Cu2−xSe nanocrystals (NCs) exhibit a strong localized surface plasmon resonance (LSPR) absorption in the near-infrared (NIR) region, in which the LSPR wavelength and stability are significant for the NIR-region applications in photo-thermal therapy and photoacoustic imaging. Herein, we have systematically studied the effects of surface ligands with varying the feeding ratio of oleylamine (OM) to oleic acid (OA) on LSPR behavior and stabilization of Cu2−xSe NCs, which were synthesized by using a typical hot-injection method. The LSPR wavelength of the as-obtained Cu2−xSe NCs could be tuned from 1260 to 1030 nm with an increase of the feeding ratio of OM to OA. Furthermore, these Cu2−xSe NCs showed different LSPR stability with varying feeding ratios of OM to OA. For the Cu2−xSe NCs synthesized in the presence of only OM, the LSPR could keep stable basically after exposure to air for 60 days. However, in the feeding ratio of OM to OA of 7:3 and 5:5 cases, the LSPR extinction spectra showed an obvious blue-shift in the wavelength. The characterized results indicated the different surface ligands had significant effects on the LSPR behavior and stabilization, and the LSPR change was in good agreement with the calculated results based on the Mie-Drude model. This work provides a new research idea for tuning the LSPR behavior of copper chalcogenide NCs.
Pineapple contains many bioactive compounds and nutraceutical values which are good for human health. Processing pineapple in industries leaves a lot of wastes which can cause serious environmental problems. Pineapple waste is a by-product of the pineapple processing industry and it consists of residual pulp, peels and skin. Studies on the content of phenolic and the antioxidant activities in wastes of fruits have been emerging for the past years due to the concern on sustainable environment. In this study, the phenolic compound was extracted from pineapple wastes (namely skin) by using MAE (Microwave-Assisted Extraction). The aims of the present paper are to determine the phenolic compound and antioxidant activity of pineapple waste and to find the optimum condition at 250 W microwave power by using MAE with the temperature varied at 30 °C, 60 °C, 90 °C and 120 °C. The phenolic content was measured by using the Folin-Ciocalteu reagent. For the antioxidant activity, the analysis was done by using DPPH (2,2'-diphenyl-1-picrylhydrazyl) radical scavenging assay. The optimum condition for the extraction was found at 30 °C using deionised water as a solvent. At this optimum condition, the value of the phenolic content was achieved at the highest value, 206.46 mg GAE/g dry weight whereas the EC50, DPPH value was obtained at the lowest value, 13.65 mg/mL. From this research, it is proved that the pineapple skin is one of the good sources of antioxidant phenolic and serves as the best candidate to be a potential source of natural antioxidant for food and nutraceutical application.
A facile and green synthesis of the Ag/ZnO nanocomposite by extract of Valeriana officinalis L. root in the absence of any stabiliser or surfactant has been reported in this work. The green synthesised Ag/ZnO nanocomposite was characterised by Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), elemental mapping, Fourier-Transform infrared (FT-IR), X-ray diffraction analysis (XRD) and UV-Vis spectroscopy. According to SEM and TEM images, the Ag and ZnO particles are spherical with diameters of less than 20 and 40-50 nm, respectively. The Ag NPs/ZnO nanocomposite proved to be an effective catalyst in the reduction of various dyes including methyl orange (MO), Congo red (CR) and methylene blue (MB) in the presence of NaBH4 in aqueous media at ambient temperature. A maximum degradation (100%) of dyes was performed using Ag/ZnO nanocomposite. The extraordinary performance of the prepared Ag/ZnO nanocomposite is attributed to the synergetic effect induced by both ZnO and Ag NPs in the catalytic degradation of organic dyes. The catalyst could be reused and recovered several times with no significant loss of catalytic activity.
Nanotechnology is emerging as an important area of research with its tremendous applications in all fields of science,
engineering, medicine, pharmacy, etc. It involves the materials and their applications having one dimension
in the range of 1–100 nm. Generally, various techniques are used for syntheses of nanoparticles (NPs) viz. laser
ablation, chemical reduction, milling, sputtering, etc. These conventional techniques e.g. chemical reduction
method, in which various hazardous chemicals are used for the synthesis of NPs later become liable for innumerable
health risks due to their toxicity and endangering serious concerns for environment, while other approaches
are expensive, need high energy for the synthesis of NPs. However, biogenic synthesis method to produce NPs is
eco-friendly and free of chemical contaminants for biological applications where purity is of concerns. In biological
method, different biological entities such as extract, enzymes or proteins of a natural product are used to
reduce and stabilised formation of NPs. The nature of these biological entities also influence the structure,
shape, size and morphology of synthesized NPs. In this review, biogenic synthesis of zinc oxide (ZnO) NPs,
procedures of syntheses, mechanism of formation and their various applications have been discussed. Various
entities such as proteins, enzymes, phytochemicals, etc. available in the natural reductants are responsible for
synthesis of ZnO NPs.