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Metal oxide nanoparticles (NPs) have gained attention in biomedicine due to their broad spectrum of applications, such as targeted drug delivery, their use as antibacterial agents or in cancer treatments. In particular, zinc oxide nanoparticles (ZnO NPs) have become one of the most popular metal oxide NPs in biomedical applications. The present study describes for the first time the biogenic synthesis of rod shaped ZnO NPs using C. annuum L. var. grossum (L.) Sendt) extract as a capping agent. The purified C. annum-based zinc oxide nanorods (Ca-ZnO NRs) were characterized by different physico-chemical techniques. UV–vis spectroscopy depicted the absorbance peak at 372 nm. The size of nanorods ranges between 70 and 80 nm as revealed by FE-TEM micrographs and the mean size was 72 nm. Ca-ZnO NRs exhibited antibacterial activity in a dose-dependent manner and a greater activity was observed against S. enterica. Ca-ZnO NRs have shown antioxidant activity (91%) at 100 μg ml−1 when compared to the standard (ascorbic acid) (98%). A significant inhibition of bovine serum albumin (BSA) protein denaturation evidenced their anti-inflammatory property. Further, Ca-ZnO NRs showed hemolysis of red blood cells (RBC) (~ 3%) (up to 3 μg ml−1) which is much lesser than permissible limit.

In the present study, phytochemical analysis, synthesis and characterization of zinc oxide nanoparticles (NG-ZnO NPs) from neem gum as a capping agent. GC–MS analysis confirms the phytochemical oxadiazol-2yl-benzothiazole-(21.5%) on the synthesized ZnO nanoparticles. Various sophisticated analytical instrumentations characterized the morphological and crystalline behaviour of NG-ZnO NPs. The analytical results confirm the spherical crystals of NG-ZnO NPs in size range of 60–80 nm size. The NG-ZnO NPs shown significantly efficient antibacterial and antibiofilm activity against P. aeruginosa at 100 µg/mL. Further, in vitro study on human liver cancer cell line (Hep G2) indicated significantly inhibited the cell proliferation at 100 µg/mL in 24 h. Also, NG-ZnO NPs have also shown potent mosquito larvicidal activity on C. quinquefasciatus at 100 µg/mL. Based on findings, it is recommended that neem gum capped ZnO NPs is potential nano biomedical agents to be used in new drug formulations.

Bio-molecule assisted synthesis of nanoparticles using protein templates and the self-assembly of the bio-molecules together with small peptides, denatured protein, and DNA is a new advancement. Specific interactions with nanoparticles ultimately dictate the size and crystallinity of the nanomaterials and the formation of nanoparticles using protein for structural integrity. Here, we are using protein-based synthesis method for preparing highly crystalline ZnONPs. Crustin(Cr)-capped ZnONPs were synthesized and confirmed by Ultraviolet-vis spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), Raman, X-ray diffraction (XRD), High-resolution transmission electron microscopy (HR-TEM), and Zeta potential analysis. UV–Vis spectrum revealed the preliminary confirmation of the Cr-ZnONPs. By using XRD patterns, confirmed the crystalline structure of Cr-ZnONPs. In addition, TEM analysis revealed that the particle size measurements are within the 50 nm range. Further, Cr-ZnONPs tested against different Gram-negative and Gram-positive bacteria at 50 µg/mL. The great potential of the antibacterial and biofilm control ability of Cr-ZnONPs at 50 µg/mL was observed. Moreover, the control of thrush infective fungal Candida albicans cells and eco-toxicological analysis of Cr-ZnONPs showed that no increase in toxicity up to 100 µg/L was observed in Ceriodaphnia cornuta. Overall, Cr-ZnONPs can be used for potential photocatalytic, antibacterial, antifungal and antibiofilm applications.

In this study, silver nanoparticle was green synthesized using the leaf extract of Solanum nigrum (Sn-AgNPs) and bio-physically characterized by UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HR-TEM), Zeta potential analysis and Energy dispersive X-ray (EDX) analysis. The ecotoxicity of silver nanoparticle (Sn-AgNPs) were tested against both invertebrate (Ceriodaphnia cornuta and Paramecium sp.) and vertebrate aquatic animal models (Guppy fish, Poecilia reticulata) in comparison with bare silver nitrate. Sn-AgNPs were observed to be less toxic than ionic silver (silver nitrate). The ecotoxicity levels of Sn-AgNPs were found to be varied between tested organisms. Sn-AgNPs caused 100% mortality of freshwater crustacean, C. cornuta at 50 µg mL−1. At concentration below 50 µg mL−1 (10–30 µg mL−1), abnormality in the swimming behavior of C. cornuta was noticed. The ingestion and accumulation of Sn-AgNPs in the intestine of C. cornuta neonates were visualized under light and confocal laser scanning microscopic images. The ecotoxicity of Sn-AgNPs to the freshwater protozoan ciliate, Paramecium sp. showed that 30 µg mL−1 were lethal and produced 100% mortality at the same concentration. The study concludes that Sn-AgNPs was less toxic to both invertebrate and vertebrate models compared to ionic silver nitrate.

Cynara scolymus leaves were used in the green synthesis of zinc oxide nanoparticles (ZnO NPs). ZnO NPs was confirmed by the formation of a white precipitate. UV–visible spectroscopy results showed a strong absorbance peak at 371 nm. The use of SEM confirmed the spherical shape of the nanoparticles, which had an average size of 65.9 nm. The nanoparticle zinc (80.17%) and oxygen (19.83%) composition was confirmed using energy-dispersive X-ray analysis (EDXA). X-ray power diffraction (XRD) spectra confirmed the crystalline nature of the nanoparticles. We found 0.5% hemolysis following the addition of 100 μg/ml of ZnO NPs. A MIC study found that bacteria were more susceptible to ZnO NPs relative to fungi. The ZnO NPs photocatalytic degradation activity was assessed using methyl violet and malachite green, which exhibited 94.3% degradation after 120 min of UV exposure and 89.5% degradation after 120 min of UV exposure, respectively. Using human breast cancer cell line (MCF 7) and Vero cells, we found half maximal IC50 values of 65.31 μg/μl and 957.85 μg/μl, respectively, following antiproliferative assays. Thus, green synthesized ZnO NPs were found to possess hemolytic, antimicrobial, photocatalytic, and antiproliferative activities, and as such could be used in the development of novel drugs.

Silver nanoparticles have been widely used to treat bacterial infections on wounds. Chitosan is a natural polymer having good biocompatibility and biodegradability. Chitosan have antibacterial effects and are largely used in healthcare practices to cure wounds. In this scenario, an attempt was made to biologically synthesize AgNPs using the chitosan extracted from shrimp shell waste. The synthesized Ch-AgNPs exhibited strong UV absorption spectra at 404 nm. XRD spectrum confirmed the presence of nanocrystals with an average crystallite size of 26 nm. HR-TEM images have shown spherical shaped particles with the size ranging between 10 and 50 nm. Ch-AgNPs exhibited antibacterial activity in a dose-dependent manner and greater activity was observed against P. aeruginosa. The zone of inhibition against P. aeruginosa was 10, 15 and 20 mm at 25, 50 and 100 µg mL−1, respectively. The zone of inhibition against MRSA was 8, 15 and 18 mm at 25, 50 and 100 µg mL−1 respectively. Ch-AgNPs effectively inhibited the biofilm of MRSA and P. aeruginosa at 100 µg mL−1. In addition, Ch-AgNPs coated band-aid cloth showed greater antibacterial activity compared to uncoated band-aid cloth. Furthermore, Ch-AgNPs exhibited anticoagulant activity by inhibiting the coagulation of human blood for 24 h.

Lycopersicon esculentum leaf-extract was utilized in the synthesis of zinc-oxide nanoparticles (Le-ZnO-NPs) using zinc acetate as the precursor. The synthesized ZnO-NPs were attested by the detection of a notable absorption peak at 343 nm, appearing in UV–Vis spectra due to surface-plasmon-resonance. The XRD-spectrum recorded at 2θ values coincides with that of lattice planes. HR-TEM results revealed that Le-ZnO-NPs exhibited a crystalline structure with hexagonal wurtzite shape (10–50 nm size). The effectiveness of inhibition of the microbial biofilms of Proteus vulgaris, Enterococcus faecalis and Candida albicans was analyzed at a concentration of 100 µg ml−1. Moreover, Le-ZnO-NPs showed a significant range of anti-coagulant activity, in contrast to commercial anti-coagulant (heparin). Cytotoxicity studies showed that Le-ZnO-NPs (100 µg ml−1) are non-toxic to murine macrophage cells, but toxic to human cervical cancer (HeLa) cells. Indeed, a reduction in the viability of HeLa-cells and a notable variation in the apoptotic cell structure were apparent.

Recently, marine bio-products have provided a new insight on biomaterials for pharmaceutical applications. Herein, the use of adhesive protein in the fabrication of bio-inspired nanomaterials noted to the possible realization of vital biomedical applications. This study illustrates the biosynthesize ZnO nanoparticles (ZnO NPs) using adhesive protein from sea anemone Stichodactyla haddoni (ShAp). ShAp-ZnO NPs were characterized via SDS-PAGE, UV–Visible, XRD, FTIR, TEM and SAED. The molecular weight of the adhesive protein was determined by SDS-PAGE to be between 36 and 42 kDa. The UV–Vis peak of ShAp-ZnO NPs was revealed at 210 nm while XRD exhibited the crystalline nature of ShAp-ZnO NPs. FTIR revealed that functional group of ShAp-ZnO NPs, which exhibited peaks at 3441.31–1073.36 cm−1. HR-TEM revealed that ShAp-ZnO NPs obtained structure were hexagonal with 10 nm diameter. The antioxidant properties of ShAp, zinc acetate, and ShAp-ZnO NPs were noted at 100 µg/mL. Further, microscopic analysis demonstrated that 50 µg/mL of ShAp, zinc acetate, and ShAp-ZnO NPs efficiently repressed the biofilm formation of both Gram(+) and Gram(−) bacteria. In addition, maximal larvicidal effects were noticed at 100 µg/mL of ShAp-ZnO NPs against the 3rd instar of Aedes aegypti. Overall, the ShAp-ZnO NPs could have entomological and pharmaceutical applications.

The green synthesis of pesticides and antibiotics is gaining increasing importance nowadays. We fabricated Euphorbia rothiana-capped Ag nanoparticles (Er-AgNPs), testing their antibiofilm and growth inhibition potential on various microbial pathogens. We evaluated the toxicity of E. rothiana-capped Ag nanoparticles on larvae of the Zika virus vector Aedes aegypti, shedding light on histological changes post-exposure to the plant leaf extract and Er-AgNPs. Nanoparticles were characterized by UV–Vis, and FTIR spectroscopy, XRD and TEM. Light microscopy showed the greatest inhibition of biofilm formation in Gram positive and Gram-negative bacteria post-treatment with E. rothiana-capped Ag nanoparticles at 75 μg/ml. Confocal microscopy confirmed the biofilm interruption and disintegration post-treatment with nanoparticles at 75 μg/ml. E. rothiana extract and Er-AgNPs showed 100% larvicidal activity on A.aegypti at 50 and 8 mg/L, respectively. AgNO3 led to 100% mortality of A. aegypti larvae at 40 mg/L after 48 h. Stereomicroscopic and histopathological analysis reported tissue damages and loss of cuticular parts in mosquito larvae.

Our understanding of nanoparticle toxicity and fate in the aquatic environment is still patchy. In the present study, the toxicity of silver nanoparticles coated by Camellia sinensis (Cs) leaf extract metabolites (Cs-AgNPs) was investigated in comparison with C. sinensis leaf extract and AgNO3 on a micro-crustacean, Ceriodaphnia cornuta, and a fish Poecilia reticulata. 100% mortality of C. cornuta was observed post-exposure to AgNO3 (40 µg/ml) if compared to the Cs leaf extract and Cs-AgNPs, showing 30 and 56% mortality at the same concentration, respectively. In P. reticulata 100% mortality was observed testing AgNO3 and Cs-AgNPs post-exposure to 1 and 30 µg/ml, respectively. Light microscopy and CLSM images showed the accumulation of nanoparticles in the intestine of C. cornuta treated with Cs-AgNPs at 40 µg/ml. In addition, histological observations confirmed the abnormal tissue texture in nanoparticle-exposed P. reticulata, if compared to control fishes. Furthermore, C. cornuta and P. reticulata treated with Cs-AgNPs showed DNA damages compared to the control. Overall, these findings indicated relevant limits about the employ of silver-based pesticides in the environment, and also pointed out the Cs-AgNPs were less toxic to C. cornuta and P. reticulata if compared to silver ions.

Recently, the green synthesis of silver nanoparticles gained increasing attention due to interesting properties for optical, antimicrobial and pest control applications. However, their toxicity against micro-crustaceans and fishes has been scarcely explored, while most of the research efforts focused on mosquito control with the green-synthesized nanocomposites. In this study, we investigated the toxic effects of AgNO3, Cissus quadrangularis (Cq)-synthesized AgNPs and Cq extract in two different study models, the larvae of Poecilia reticulata fishes and adults of the micro-crustacean Ceriodaphnia cornuta. In both species, AgNO3 and Cq-AgNPs showed high mortality rates even if tested at very low doses. Molecular analysis revealed high DNA damages induced by Cq-AgNPs on both aquatic organisms. Furthermore, light microscopy studies evidenced lesions in the gills and vacuolization in the gills and in the abdomen of P. reticulata larvae. Overall, our research pointed out that the exposure of aquatic organisms to AgNO3 or green-fabricated AgNPs can damage fishes and crustaceans, posing noteworthy risks to the aquatic ecosystems.