Effect of biosynthesis of ZnO nanoparticles via Cucurbita seed extract on Culex tritaeniorhynchus mosquito larvae with its biological applications

Withania coagulans-mediated green synthesis of silver nanoparticles: characterization and assessment of their phytochemical, antioxidant, toxicity, and antimicrobial activities

BACKGROUND

In this study, we report the biofabrication of silver nanoparticles (Ag-NPs) using aqueous leaf extracts of Withania coagulans, which act as both reducing and capping agents. The goal was to synthesize and characterize the silver nanoparticles and evaluate their biological properties.

RESULTS

The silver nanoparticles were characterized by multiple techniques including UV-visible spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), zeta potential, dynamic light scattering (DLS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). A surface plasmon resonance peak was observed at 420 nm, and the XRD pattern indicated highly crystalline Ag-NPs with a crystallite size of 39.76 nm. SEM and HRTEM revealed irregular morphology with an average particle diameter of 26.63 nm. Zeta potential of -21.4 mV indicated relatively stable nanoparticles. FTIR spectra displayed significant peaks at 3269, 2921, 1628, 1513, and 1385 cm⁻1. Thermal stability was confirmed via TGA and DSC. Bioassays including total phenolics, total flavonoids, ferric reducing antioxidant power, and DPPH assays showed higher antioxidant potential in Ag-NPs compared to extracts, though phenolic and flavonoid content was lower. Biocompatibility tests such as hemolysis (IC₅₀ = 141.466 μg/mL) and brine shrimp lethality assay (IC₅₀ = 721.76 μg/mL) indicated moderate cytotoxicity. Phytotoxicity assays revealed higher toxicity of Ag-NPs against radish compared to control. Significant antibacterial activity was observed against Klebsiella pneumoniae and Salmonella typhi (29 ± 0.01 mm and 28 ± 1.00 mm inhibition zones at 25 μg/mL, respectively).

CONCLUSIONS

The Withania coagulans leaf-extract-mediated silver nanoparticles exhibit remarkable antioxidant, phytochemical, and antimicrobial properties, suggesting potential for commercial applications in various biomedical and agricultural fields.

Ecofriendly synthesis characterization and biological activities of Eruca sativa mediated silver oxide nanoparticles

One of the popular subjects of millennia is the synthesis of nanostructures, their applications in numerous fields, and their interaction with various biological systems, making them appealing for drug delivery systems, and diagnostic and therapeutic agents. In this study, silver oxide nanoparticles were synthesized using E. sativa (ES) aqueous extract. The biosynthesis was followed via UV-vis spectroscopy by analysis, FTIR, XRD, TEM, and Zeta potential to further analyze the synthesized nanoparticles. Furthermore, the biosynthesized silver oxide nanoparticles (Ag2ONPs) were checked through various biological activities. The antioxidative potential was assessed by performing a DPPH radical scavenging assay, total reducing power assay, and total antioxidant capacity assay. Antimicrobial potential was observed against various bacterial and fungal strains. Likewise, Artemia salina (brine shrimps) was used to study cytotoxicity, while VERO and HEK-293 cell lines were applied to check the biocompatibility of synthesized NPs. Anticancer potential was evaluated against the Hep-2 cells by utilizing an MTT assay. A mean crystallite ~ 50 nm size is evidenced by TEM analysis. Notable antimicrobial activity was detected with various bacterial and fungal strains with maximum ZOI by B. subtilis was 18.5 ± 2.36 mm at 1000 µg/mL and A. niger reveals a minimum ZOP of 16 ± 1.7 mm at 1000 µg/mL respectively. A dose-dependent response was observed in biological evaluation against A. salina (LC50: 12.21 µg/mL), DPPH (IC50: 62.36 µg/mL), VERO cell line (IC50: 43.11 µg/mL), HEK-293 cell line (IC50: 26.56 µg/mL), and Hep-2 cell line (IC50: 9.97 µg/mL). The multifaceted attributes of ES-Ag2ONPs encompassing antimicrobial, antioxidant, cytotoxic, and anticancer properties render them a versatile platform in drug delivery and biomedical horizons. However, detailed investigation and clinical trials will undoubtedly provide translational applications in diverse fields.

Bioinspired multifunctional silver nanoparticles by Smilax Chenensis and their enhanced biomedical and catalytic applications

Currently, Nano-materials have been explored for their abundant biomedical applications. In the present study the green synthesized (SC-AgNPs) by root extract of Smilax Chenensis have been characterized by UV-visible spectroscopy revealed SPR peak at 432 nm and FT-IR data reveals that the bioactive components of root extract have been actively involved in the reduction and stabilization of SC-AgNPs. TEM and AFM results revealed that SC-AgNPs were roughly spherical in shape. Further, the particle size of SC-AgNPs was also carried out by Dynamic Light Scattering method by aqueous colloidal solution and the results reveals that the SC-AgNPs are poly-dispersed in nature with an average size 45.6 nm with a Z average of 39.5 nm. The stability of colloidal SC-AgNPs was further confirmed by negative zeta potential value of - 21.0 mV. The SC-AgNPs showed good antibacterial activity against both gram -ve and gram + ve bacteria, whereas, SC-AgNPs coupled with antibiotic reveals excellent and enhanced antibacterial activity. The gram -ve E.coli and gram + ve S.aureus revealed highest zone of inhibition when compared to other two bacterial species. So, SC-AgNPs coupled with antibiotics can be excellent alternative to treat antibiotic resistant bacteria. The SC-AgNPs also reveals excellent antioxidant activity among them DPPH method revealed superior activity with an IC50 value76.22. The SC-AgNPs also reveals superior anticancer activity against MDA-MB-231 with IC50 value of 33.98 µg/mL and photo-catalytic activity the optical density of reduced from 1.861 to 0.135 OD within 30 min. The green SC-AgNPs detected to have multiple therapeutic applications.

Potential biological applications of environment friendly synthesized iron oxide nanoparticles using Sageretia thea root extract

The green synthesis of Iron oxide nanoparticles (IONPs) has shown numerous advantages over conventional physical and chemical synthesis methods as these methods non-ecofriendly and uses toxic chemicals and complicated equipments. In present study, Iron oxide nanoparticles (IONPs) were created using simple, sustainable, eco-friendly and green chemistry protocol. The roots of novel medicinal plant Sageretia thea was used as a bio-template for the preparation of IONPs. Further, the synthesis of IONPs was confirmed using different analytical tools like UV-Vis, FT-IR, XRD, EDX, and SEM. The average sizes of (NPs) were found to be 16.04 nm. Further, asynthesized IONPs were evaluated for several biological potentials including antibacterial, antifungal Anti-radical potentials (DPPH) and cytotoxicity assays. Antibacterial potencies were investigated using bacterial strains (in the concentration range of 1000-31.25 µg/mL) revealing significant antibacterial potentials. ABA and SAU was reported to be least susceptible while KPN was observed to be most susceptible strain in bactericidal studies. Further, different fungal strains were used to investigate the antifungal potentials of IONPs (in the concentration range of 1000-31.25 µg/mL) and revealed strong antifungal potencies against different pathogenic strains. Furthermore, MRA, FA and ANI were most susceptible and ABA was least susceptible in fungicidal examination. Significant cytotoxicity potential was examined using brine shrimps cytotoxicity assay, thus revealing the cytotoxic potential of asynthesized IONPs. The IC50 for S. thea based IONPs was recorded as 33.85 µg/mL. Strong anti-radical potentials (DPPH) assay was performed to evaluate the ROS scavenging potential of S.T@IONPs. The highest scavenging potential was noted as 78.06%, TRP as 81.92% and TAC as 84% on maximum concentration of 200 µg/mL. In summary, our experimental results concluded, that asynthesized IONPs have strong antibacterial, antifungal, DPPH scavenging and cytotoxic potentials and can be used in different biological applications. In nutshell, our as-prepared nanoparticles have shown potential bioactivities and we recommend, different other in vitro and in vivo biological and bioactivities to further analyze the biological potentials.

Green synthesis of selenium nanoparticles from Cassia javanica flowers extract and their medical and agricultural applications

Nanostructured materials are advantageous within numerous fields of medicine owing to their intriguing qualities, which include their size, reactive surface, bioactivity, potential for modification, and optical characteristics. Cassia javanica flower extract was used as a chelating agent in an environmentally friendly process to create SeNPs FTIR, XRD, and TEM, SAED were utilized to analyze and characterize the synthesized. The findings showed that the MIC of Se NPs against B. subtilis and S. aureus was 500 µg/ml. Conversely, the MIC for P. aeruginosa, E. coli, and C. albicans were 125, 250, and 62.5 µg/ml, respectively. Hence, SeNPs considerably reduced the activity; the inhibition peaked at 77.6% at 250 µg/ml to reach 49.04% at 7.8 µg/ml. Which showed the greatest suppression of MRSA biofilm formation without affecting bacterial growth. SeNPs showed an intriguing antioxidant capacity, achieving an IC50 of 53.34 µg/ml. This study looked how soaking seeds before sowing them with Se NPs at 50, 100, and 200 ppm affected the plants' development in different parameters, as well as their yield of Vicia faba L. The growth conditions were effectively increased by soaking application of various quantities of Se NPs. The highest values of dry weight/pod (g), number of seeds/plant, weight of 100 seeds (g), and number of pods/plant were caused by high concentrations of Se NPs, by 28.43, 89.60, 18.20, and 94.11%, respectively.

Anticancer, antimicrobial and antioxidant activity of CuO-ZnO bimetallic nanoparticles: green synthesised from Eryngium foetidum leaf extract

In the present study, green synthetic pathway was adapted to synthesize CuO-ZnO bimetallic nanoparticles (BNPs) using Eryngium foetidum leaf extract and their anti-cancer activity against MCF7 breast cancer cell lines, anti-microbial activity and in vitro anti-oxidant activity were evaluated. Various bio-active compounds present in leaf extract were responsible for the reduction of CuO-ZnO NPs from respective Cu2+ and Zn2+ metal precursors. In the present study, the involvement of bio-active compounds present in E. foetidum extract before and after green synthesis of BNPs were evaluated for the first time. Rod-shaped and spherical structural morphology of synthesized BNPs were revealed by using FESEM, TEM, and XRD analysis with particle size ranged from 7 to 23 nm with an average size of 16.49 nm. The distribution of Cu and Zn were confirmed by elemental mapping. The green synthesized CuO-ZnO NPs showed significant cytotoxic effect with the inhibition rate 89.20 ± 0.03% at concentration of 500 μg/mL. Again, good antioxidant activity with IC50; 0.253 mg/mL and antimicrobial activity of BNPs were also evaluated with the increasing order of MIC; E. coli (7.81 μg/mL) < B. subtilis (62.5 μg/mL) < S. aureus (31.25 μg/mL).

Biogenic synthesis, characterization, and in vitro biological investigation of silver oxide nanoparticles (AgONPs) using Rhynchosia capitata

The current research aimed to study the green synthesis of silver oxide nanoparticles (AgONPs) using Rhynchosia capitata (RC) aqueous extract as a potent reducing and stabilizing agent. The obtained RC-AgONPs were characterized using UV, FT-IR, XRD, DLS, SEM, and EDX to investigate the morphology, size, and elemental composition. The size of the RC-AgONPs was found to be ~ 21.66 nm and an almost uniform distribution was executed by XRD analysis. In vitro studies were performed to reveal biological potential. The AgONPs exhibited efficient DPPH free radical scavenging potential (71.3%), reducing power (63.8 ± 1.77%), and total antioxidant capacity (88.5 ± 4.8%) to estimate their antioxidative power. Antibacterial and antifungal potentials were evaluated using the disc diffusion method against various bacterial and fungal strains, and the zones of inhibition (ZOI) were determined. A brine shrimp cytotoxicity assay was conducted to measure the cytotoxicity potential (LC50: 2.26 μg/mL). In addition, biocompatibility tests were performed to evaluate the biocompatible nature of RC-AgONPs using red blood cells, HEK, and VERO cell lines (< 200 μg/mL). An alpha-amylase inhibition assay was carried out with 67.6% inhibition. Moreover, In vitro, anticancer activity was performed against Hep-2 liver cancer cell lines, and an LC50 value of 45.94 μg/mL was achieved. Overall, the present study has demonstrated that the utilization of R. capitata extract for the biosynthesis of AgONPs offers a cost-effective, eco-friendly, and forthright alternative to traditional approaches for silver nanoparticle synthesis. The RC-AgONPs obtained exhibited significant bioactive properties, positioning them as promising candidates for diverse applications in the spheres of medicine and beyond.

Biogenic fabrication and enhanced photocatalytic degradation of tetracycline by bio structured ZnO nanoparticles

ABSTRACTZinc oxide nanoparticles (ZnO NPs) were synthesized using Zinc Nitrate as precursor salt, and plant leaves extracts from Azadirachta indica (Common name: Neem), Cymbopogan citratus (Common name: Lemongrass), and Mangifera indica (Common name: Mango), as both chelating and reducing agents for the synthesis of ZnO NPs by a simple cost-effective and eco-friendly green method. The biosynthesized ZnO NPs were well characterized by various methods. XRD pattern revealed a hexagonal wurtzite phase of ZnO, with no other impurity peaks present revealing XRD crystalline sizes of 13.94-16.37 nm calculated using Scherrer equation. The XPS confirmed the presence of Zn, O, and C, and the carbon peaks are almost in agreement with peaks observed by FT-IR. TEM showed the different ZnO with spherical shapes and some aggregations. BET surface area gave 24.98, 21.62, and 22.72 m²/g, respectively for ZnO-AI, ZnO-Cyc, and ZnO-MI, while BJH pore volume and average pore diameter were estimated to be 0.217 cc/g, 0.209 cc/g, 0.211 cc/g, and 2.132 nm, 2.025 nm, and 2.100 nm respectively for ZnO-AI, ZnO-Cyc, and ZnO-MI.Furthermore, the bio-synthesized ZnO NPs were evaluated for their catalytic and photocatalytic performance in the degradation of aqueous tetracycline (TC). The biosynthesized ZnO NPs exhibit good photodegradation efficiency for TC in varying degrees with ZnO-AI > ZnO-MI > ZnO-Cyc. Optimum operational parameters for TC degradation using the ZnO-AI were established, and maximum degradation efficiency of 84.8% was obtained. In addition, the catalyst can also be regenerated and reused up to three cycles, with the third cycle still achieving greater than 80% TC degradation.

Nanoantioxidant Materials: Nanoengineering Inspired by Nature

Oxidants are very active compounds that can cause damage to biological systems under specific environmental conditions. One effective way to counterbalance these adverse effects is the use of anti-oxidants. At low concentrations, an antioxidant is defined as a compound that can delay, control, or prevent an oxidative process. Antioxidants exist in plants, soil, and minerals; therefore, nature is a rich source of natural antioxidants, such as tocopherols and polyphenols. In nature, antioxidants perform in tandem with their bio-environment, which may tune their activity and protect them from degradation. In vitro use of antioxidants, i.e., out of their biomatrix, may encounter several drawbacks, such as auto-oxidation and polymerization. Artificial nanoantioxidants can be developed via surface modification of a nanoparticle with an antioxidant that can be either natural or synthetic, directly mimicking a natural antioxidant system. In this direction, state-of-the-art nanotechnology has been extensively incorporated to overcome inherent drawbacks encountered in vitro use of antioxidants, i.e., out of their biomatrix, and facilitate the production and use of antioxidants on a larger scale. Biomimetic nanoengineering has been adopted to optimize bio-medical antioxidant systems to improve stability, control release, enhance targeted administration, and overcome toxicity and biocompatibility issues. Focusing on biotechnological sciences, this review highlights the importance of nanoengineering in developing effective antioxidant structures and comparing the effectiveness of different nanoengineering methods. Additionally, this study gathers and clarifies the different antioxidant mechanisms reported in the literature and provides a clear picture of the existing evaluation methods, which can provide vital insights into bio-medical applications.

Nano-bioremediation of textile industry wastewater using immobilized CuO-NPs myco-synthesized by a novel Cu-resistant Fusarium oxysporum OSF18

Currently, bionanotechnologies are attracting great interest due to their promising results and potential benefits on many aspects of life. In this study, the objectives was to biosynthesis CuO-NPs using cell-free extract(s) of copper-resistant fungi and use them in bioremediation of textile industry wastewater. Out of 18 copper-resistant fungal isolates, the novel fungus strain Fusarium oxysporum OSF18 was selected for this purpose. This strain showed a high efficiency in extracellular reducing copper ions to their nano-form. The myco-synthesized CuO-NPs were characterized using UV-Vis spectroscopy, HRTEM, FTIR, and XRD and were found to be spherical nanocrystals with the size range of 21-47 nm. The bio-synthesized CuO-NPs showed promising antimicrobial activity as well as high efficiency in removing heavy metals and textile dye from industrial wastewater. The myco-synthesized CuO-NPs immobilized in alginate beads exhibited superior microbial disinfection (99.995%), heavy metals removal (93, 55, and 30 % for Pb, Cr, and Ni, respectively), and dye decolorization (90%). Such results represent a promising step to produce an eco-friendly, cost-effective, and easy-to handle tool for the bioremediation of textile industry wastewater.

Nanoparticles: A Potential and Effective Method to Control Insect-Borne Diseases

Insects act as vectors to carry a wide range of bacteria and viruses that can cause multiple vector-borne diseases in humans. Diseases such as dengue fever, epidemic encephalitis B, and epidemic typhus, which pose serious risks to humans, can be transmitted by insects. Due to the absence of effective vaccines for most arbovirus, insect control was the main strategy for vector-borne diseases control. However, the rise of drug resistance in the vectors brings a great challenge to the prevention and control of vector-borne diseases. Therefore, finding an eco-friendly method for vector control is essential to combat vector-borne diseases. Nanomaterials with the ability to resist insects and deliver drugs offer new opportunities to increase agent efficacy compared with traditional agents, and the application of nanoagents has expanded the field of vector-borne disease control. Up to now, the reviews of nanomaterials mainly focus on biomedicines, and the control of insect-borne diseases has always been a neglected field. In this study, we analyzed 425 works of the literature about different nanoparticles applied on vectors in PubMed around keywords, such as"nanoparticles against insect," "NPs against insect," and "metal nanoparticles against insect." Through these articles, we focus on the application and development of nanoparticles (NPs) for vector control, discussing the lethal mechanism of NPs to vectors, which can explore the prospect of applying nanotechnology in the prevention and control of vectors.

Green Synthesis of Zinc Oxide Nanocrystals Utilizing Origanum majorana Leaf Extract and Their Synergistic Patterns with Colistin against Multidrug-Resistant Bacterial Strains

There is a crucial necessity for the formulation of efficient antimicrobial agents owing to the increasing prevalence of hospital-acquired bacterial infections triggered by multidrug-resistant microbes that result in significant deaths and illnesses around the world. Hence, the current investigation examined the antibacterial proficiency of zinc oxide nanoparticles formulated utilizing the green route against bacterial strains that were resistant to multiple drugs. In addition, the synergistic antibacterial action of ZnO nanoparticles (ZnO NPs) combined with colistin was investigated against the tested microbial strains to determine the efficiency of the bioinspired ZnO nanoparticles in boosting the antibacterial proficiency of colistin antibiotic. Incidentally, the bioinspired ZnO nanoparticles were synthesized using water extract of Origanum majorana leaves and these nanomaterials were physicochemically characterized using different analytical techniques. The bioactivity of the synthesized nanomaterials against multidrug-resistant bacterial strains was appraised using the agar diffusion method. The biogenic ZnO NPs at a concentration of 100 μg/disk revealed a compelling antimicrobial efficacy against the tested strains, expressing the maximum antimicrobial action against Escherichia coli strain with clear zone diameter of 38.16 ± 0.18 mm. The remarkable antibacterial proficiency might be accredited to the tiny particle size of the bioformulated ZnO NPs of 12.467 ± 1.36 nm. The net charge of ZnO nanomaterials was −14.8 mV while XRD analysis confirmed their hexagonal wurtzite structure. Furthermore, the bioformulated ZnO NPs showed a promising synergistic potency with colistin demonstrating respective synergism proportions of 91.05, 79.07, 75.04, 75.25, 56.28 and 10.60% against E. coli, Klebsiella pneumoniae, Acinetobacter baumannii, Salmonella typhimurium, Enterobacter cloacae, and Pseudomonas aeruginosa, respectively. In conclusion, the water extract of O. majorana leaves mediated green formulation of zinc oxide nanoparticles with unique physicochemical characteristics and effective antibacterial proficiency against the examined drug-resistant bacterial strains. These nanomaterials could be used in the synthesis of effective antibacterial coatings to control hospital acquired infections caused by multidrug-resistant bacterial pathogens.

Green synthesis of ionic liquid mediated neodymium oxide nanoparticles via Couroupita guianensis abul leaves extract with its biological applications

Bio-nanoparticles have created a new era of rapid, harmless and nontoxic drugs for various biomedical applications. The nanoparticles (NPs) of rare earth metal oxides attract researcher's attention due to their excellent chemical and physical properties that exhibit potential activity against disease causing pathogens. Couroupita guianensis (C. guianensis) abul is a medicinal plant whose leaves are effectively used for the synthesis of neodymium oxide (Nd₂O₃) NPs. The 1-butyl 3-methyl imidazolium tetrafluoroborate (BMIM BF₄) ionic liquid is used as a stabilizing agent to get better the morphology and biological properties of Nd₂O₃ NPs. 1-Butene, 4,4-diethoxy-2-methyl is the main compound in C. guianensis abul leaves extract was confirmed by GCMS analysis. The structure of synthesized Nd₂O₃ (without ionic liquid) and Nd₂O₃-IL (with ionic liquid) NPs is identified by powder X-ray diffraction (PXRD). The vibrations of the different functional groups were investigated by Fourier-transform infrared (FTIR) and Raman spectroscopy. In UV-Vis spectra, the optical absorption was identified to be 210 and 221nm of Nd₂O₃ and Nd₂O₃-IL samples and the PL spectrum provides blue and green emission peaks at 386 and 554 nm. The X-ray photoelectron spectroscopy (XPS) and DLS spectra illustrate the electronic configuration and particle size of the synthesized Nd₂O₃-IL NPs. The morphology, surface nature and lattice spacing were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The purity and weight percentage of the compound presented can be identified by the energy-dispersive X-ray spectroscopy (EDX). The biomedical properties such as antibacterial, antioxidant, antidiabetic, anti-inflammatory and anticancer activities were investigated. Finally, the overall biocompatible studies reveal that the ionic liquid assisted Nd₂O₃ NPs can be considered as a potential drug for pharmaceutical and biomedical applications.

Effect of green synthesized ZnO nanoparticles using Paspalum scrobiculatum grains extract in biological applications

In this report, ZnO nanoparticles were biosynthesized using Paspalum scrobiculatum grains extract for the first time. GC-MS analysis explicated that diethyl phthalate was the major phytocompound with 94.09% in aqueous extract. ZnO nanoparticles formation was confirmed by various physicochemical analyses. HR-TEM images showed the hexagonal, rectangular shaped nanoparticles in 15-30 nm size. The antioxidant, anti-inflammatory, and anti-diabetic analyses showed the effective bioactivity of ZnO nanoparticles in 80 μg/ml concentration with 95.36%, 94.08%, and 91.96%, respectively. The morphological and tissue changes witnessed in larvicidal and insecticidal activities against Culex tritaeniorhynchus and Tribolium castaneum revealed the efficient nature of ZnO nanoparticles in 100 ppm at 48 h and 100 μg/kg at 72 h, respectively. The morphological changes in antibacterial activity demonstrated the bactericidal nature of ZnO nanoparticles against Salmonella typhi and Staphylococcus aureus in 150 μg/ml concentration. The morphological observations in anticancer activity against HepG2 liver cancer cells showed the potent drug features of ZnO nanoparticles in 100 μg/ml concentration with 97.18% of cytotoxicity. The ZnO nanoparticles showed no toxicity against HDF normal cells in lower concentrations and it explicated the biocompatible features of nanoparticles. The Vigna radiata plant growth was efficiently promoted by low (60 ppm) concentration of nanoparticles. The ZnO nanoparticles divulged effective degradation of IPA, EDTA, BQ, and DPBF in 75%, 45%, 55%, and 80% through ROS formation, respectively. Thus, the synthesized ZnO nanoparticles are biocompatible and inexpensive material compared to the traditional one and can be utilized as an efficient material in biological fields.

Nanoantioxidants: Pioneer Types, Advantages, Limitations, and Future Insights

Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.

Green Synthesis of Zinc Oxide Nanoparticles (ZnO-NPs) by Pseudomonas aeruginosa and Their Activity against Pathogenic Microbes and Common House Mosquito, Culex pipiens

The synthesis of nanoparticles by green approaches is gaining unique importance due to its low cost, biocompatibility, high productivity, and purity, and being environmentally friendly. Herein, biomass filtrate of Pseudomonas aeruginosa isolated from mangrove rhizosphere sediment was used for the biosynthesis of zinc oxide nanoparticles (ZnO-NPs). The bacterial isolate was identified based on morphological, physiological, and 16S rRNA. The bio-fabricated ZnO-NPs were characterized using color change, UV-visible spectroscopy, FT-IR, TEM, and XRD analyses. In the current study, spherical and crystalline nature ZnO-NPs were successfully formed at a maximum SPR (surface plasmon resonance) of 380 nm. The bioactivities of fabricated ZnO-NPs including antibacterial, anti-candida, and larvicidal efficacy were investigated. Data analysis showed that these bioactivities were concentration-dependent. The green-synthesized ZnO-NPs exhibited high efficacy against pathogenic Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and unicellular fungi (Candida albicans) with inhibition zones of (12.33 ± 0.9 and 29.3 ± 0.3 mm), (19.3 ± 0.3 and 11.7 ± 0.3 mm), and (22.3 ± 0.3 mm), respectively, at 200 ppm. The MIC value was detected as 50 ppm for E. coli, B. subtilis, and C. albicans, and 200 ppm for S. aureus and P. aeruginosa with zones of inhibition ranging between 11.7 ± 0.3-14.6 ± 0.6 mm. Moreover, the biosynthesized ZnO-NPs showed high mortality for Culex pipiens with percentages of 100 ± 0.0% at 200 ppm after 24 h as compared with zinc acetate (44.3 ± 3.3%) at the same concentration and the same time.

Comparative efficacy of biogenic zinc oxide nanoparticles synthesized by Pseudochrobactrum sp. C5 and chemically synthesized zinc oxide nanoparticles for catalytic degradation of dyes and wastewater treatment

Discharge of untreated textile wastewaters loaded with dyes is not only contaminating the soil and water resources but also posing a threat to the health and socioeconomic life of the people. Hence, there is a need to devise the strategies for effective treatment of such wastewaters. The present study reports the catalytic potential of biogenic ZnO nanoparticles (ZnO NPs) synthesized by using a bacterial strain Pseudochrobactrum sp. C5 for degradation of dyes and wastewater treatment. The catalytic potential of the biogenic ZnO NPs for degradation of dyes and wastewater treatment was also compared with that of the chemically synthesized ones. The characterization of the biogenic ZnO NPs through FT-IR, XRD, and field emission scanning electron microscopy (FESEM) indicated that these are granular agglomerated particles having a size range of 90-110 nm and zeta potential of -27.41 mV. These catalytic NPs had resulted into almost complete (> 90%) decolorization of various dyes including the methanol blue and reactive black 5. These NPs also resulted into a significant reduction in COD, TDS, EC, pH, and color of two real wastewaters spiked with reactive black 5 and reactive red 120. The findings of this study suggest that the biosynthesized ZnO NPs might serve as a potential green solution for treatment of dye-loaded textile wastewaters.

An Astragalus membranaceus based eco-friendly biomimetic synthesis approach of ZnO nanoflowers with an excellent antibacterial, antioxidant and electrochemical sensing effect

Nowadays featuring outstanding eco-friendliness, the phytochemical fabrication method of nanostructures is very popular. Here, we propose to utilize the Astragalus membranaceus extract as the reducing and capping agent to stabilize the metal and to avoid the aggregations of nanoparticles during ZnO nanoflowers synthesis procedure. As a result, the whole fabrication procedure was highly efficient and cost-effective without requiring a special environment of high pressure or elevated temperature and without chemical hazards used or produced. After the fabrication, detailed characterization about material morphology and crystal structure was carried out, including scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscope (FTIR). Moreover, the ZnO nanoflowers demonstrated distinctive antibacterial, antioxidant and electrochemical sensing effect. Specifically, ZnO nanoflowers had an antibacterial inhibition zone of 19(±0.7) and 15(±0.8) mm in diameter against the concentration of 50 μL (1 mg/mL) Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which is greatly improved compared to the reference drug (Kanamycin). Besides, antioxidant activity was also tested using H₂O₂ free radical scavenging assay and 60% 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition of 0.5 mg/mL was reported. Finally, controlled by the diffusion process during the charge transfer procedure, 4-nitorphenol was dramatically reduced and a limit of detection of 0.08 μM by ZnO nanoflowers modified electrode was observed during the cyclic voltammetry (CV) experiment. Because the phenolic compounds originating from Astragalus membranaceus helped to facilitate the electron transfer, the limit of detection was lower compared to other materials, such as copper oxide nanoparticles (Cu₂O-NPs), silicon dioxide/silver nanoparticles (SiO₂/Ag-NPs), zinc oxide nanoparticles (ZnO-NPs), activated carbon (AC) and cobalt oxide nanocubes (Co₃O₄). Therefore, featuring easy operation, low-cost and eco-friendliness, our proposed ZnO nanoflowers fabrication method will have a great potential in biomedical and electro-catalytic fields.