Musibau A. Azeez

Biogenic synthesis of silver nanoparticles using a pod extract of Cola nitida: Antibacterial and antioxidant activities and application as a paint additive

Abstract This work reports the biogenic synthesis of silver nanoparticles (AgNPs) using the pod extract of Cola nitida, the evaluation of their antibacterial and antioxidant activities, and their application as an antimicrobial additive in paint. The AgNPs were characterized with UV–Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The AgNP solution was dark brown with a maximum absorbance occurring at 431.5 nm. The FTIR spectrum showed strong peaks at 3336.85, 2073.48, and 1639.49 cm−1, indicating that proteins acted as the capping and stabilization agents in the synthesis of the AgNPs. The AgNPs were spherical, with sizes ranging from 12 to 80 nm. Energy dispersive X-ray (EDX) analysis showed that silver was the prominent metal present, while the selected area electron diffraction pattern conformed to the face-centred cubic phase and crystalline nature of AgNPs. At various concentrations between 50 and 150 μg/ml, the AgNPs showed strong inhibition of the growth of multidrug resistant strains of Klebsiella granulomatis, Pseudomonas aeruginosa, and Escherichia coli. In addition, at 5 μg/ml, the AgNPs completely inhibited the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, A. flavus and A. fumigatus in a paint-AgNP admixture. The AgNPs exhibited a potent antioxidant activity with an IC50 of 43.98 μg/ml against 2,2-diphenyl-1-picrylhydrazyl and a ferric ion reduction of 13.62–49.96% at concentrations of 20–100 μg/ml. This study has demonstrated the biogenic synthesis of AgNPs that have potent antimicrobial and antioxidant activities and potential biomedical and industrial applications. To the best of our knowledge, this work is the first to use the pod extract of C. nitida for the green synthesis of nanoparticles.

Biomedical and Catalytic Applications of Gold and Silver-Gold Alloy Nanoparticles Biosynthesized Using Cell-Free Extract of Bacillus Safensis LAU 13: Antifungal, Dye Degradation, Anti-Coagulant and Thrombolytic Activities

This study investigated the green biosynthesis of gold (Au) and silver-gold alloy (Ag-Au) nanoparticles using cell-free extract of Bacillus safensis LAU 13 strain (GenBank accession No: KJ461434). The biosynthesized AuNPs and Ag-AuNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Evaluation of the antifungal activities, degradation of malachite green, anti-coagulation of blood, and thrombolysis of human blood clot by the biosynthesized nanoparticles were investigated. The AuNPs and Ag-AuNPs had maximum absorbance at 561 and 545 nm, respectively. The FTIR peaks at 3318, 2378, 2114, 1998, 1636, 1287, 446, 421 cm-1 for AuNPs; and 3310, 2345, 2203, 2033, 1636, 1273, 502, 453, 424 cm-1 for Ag-AuNPs indicated that proteins were the capping and stabilization molecules in the biosynthesized nanoparticles. The particles were fairly spherical in shape with size of 10-45 nm for AuNPs and 13-80 nm for Ag-AuNPs. Moreover, energy dispersive X-ray analysis of AuNPs revealed gold as the most prominent metal in the AuNPs solution, while silver and gold were the most prominent in the case of Ag-AuNPs. Selected area electron diffraction showed the biosynthesized nanoparticles as crystal structures with ring shape pattern. AuNPs and Ag-AuNPs displayed growth inhibitions of 66.67-90.78% against strains of Aspergillus fumigatus and A. niger at concentration of 200 μg/ml, and remarkable degradation (> 90%) of malachite green after 48 h. Furthermore, the nanoparticles prevented coagulation of blood, and also completely dissolved blood clots, indicating the biomedical potential of AuNPs and Ag-AuNPs in the management of blood coagulation disorders. This is the first report of the synthesis of AuNPs and Ag-AuNPs using a strain of B. safensis for biomedical and catalytic applications.

Phytosynthesis of silver nanoparticles (AgNPs) using miracle fruit plant (Synsepalum dulcificum) for antimicrobial, catalytic, anticoagulant, and thrombolytic applications

Abstract In the present work, we report the phytosynthesis of AgNPs mediated by leaf and seed extracts of Synsepalum dulcificum. The extracts catalyzed the formation of brown colloidal AgNPs, which stabilized in 10 min. The leaf and seed AgNPs yielded surface plasmon resonance at 440 and 438.5 nm, respectively. Prominent peaks at 3408, 2357, 2089, and 1639 cm−1 were recorded for leaf AgNPs, whereas 3404, 2368, 2081, and 1641 cm−1 were revealed for seed-mediated AgNPs from Fourier transform infrared data. These showed the involvement of phenolic compounds and proteins in the phytosynthesis. The particles were fairly spherical and crystalline in nature having size of 4–26 nm, with prominence of silver in the colloidal solutions. The particles inhibited the growth of drug-resistant strains of Pseudomonas aeruginosa and Klebsiella granulomatis with zone of inhibition of 11–24 mm. Also, the phytosynthesized AgNPs completely inhibited the growth of Aspergillus flavus and Aspergillus niger. In addition, by using 20 μg/ml of AgNPs, malachite green was degraded by approximately 80% in 24 h. Similarly, the particles displayed blood anticoagulant activities as well as achieved thrombolysis. The AgNPs can be explored for biomedical and catalytic applications. The report is the first on the eco-friendly synthesis of nanoparticles by S. dulcificum.

Enterococcus species for the one-pot biofabrication of gold nanoparticles: Characterization and nanobiotechnological applications

In the current work, cell-free extracts of four strains of non-pathogenic Enterococcus species of food origin, were studied for the green synthesis of gold nanoparticles (AuNPs), and characterized by UV-Vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The AuNPs were evaluated for their Anopheles gambiae larvicidal, dye degradation, antioxidant and thrombolytic activities. The blue-black colloidal AuNPs which absorbed maximally at 549-552nm were nearly spherical in shape, and crystalline in nature with size of 8-50nm. The EDX spectra showed formation of AuNPs to the tune of 89-94%. The prominent FTIR peaks obtained at 3251-3410, 2088 and 1641-1643cm-1 alluded to the fact that proteins were involved in the biofabrication and capping of AuNPs. AuNPs degraded methylene blue and malachite green by 24.3-57.6%, and 88.85-97.36% respectively in 24h, whereas at 12h, larvicidal activities with LC50 of 21.28-42.33μg/ml were obtained. DPPH scavenging activities of 33.24-51.47% were obtained for the biosynthesized AuNPs. The AuNPs prevented coagulation of blood and also achieved 9.4-94.6% lysis of blood clot showing potential nanomedical applications. This study has presented an eco-friendly and economical synthesis of AuNPs by non-pathogenic strains of Enterococcus species for various nanobiotechnological applications.

Cytogenotoxicity potentials of cocoa pod and bean-mediated green synthesized silver nanoparticles on Allium cepa cells

Abstract Nanotechnology is a ground-breaking scientific innovation, but there are possible hazards to environment and human health. Therefore, there is a need to understand the toxic potential of nanoparticles. Cytotoxic and genotoxic effects of biogenic cocoa pod husk and cocoa bean silver nanoparticles (CPHE-AgNPs and CBE-AgNPs, respectively), and silver nitrate salts (Ags) were evaluated using the A. cepa root assay. Twenty onion bulbs were exposed to various concentrations (0.01, 0.10, 1.0, 10.0, and 100.0 μg ml–1) of AgNP and Ags solutions. Effects on cell division and chromosomes were observed at 24, 48 and 72 h, while root number and growth inhibition were evaluated at 72 h. Both biogenic AgNPs have potential to be cytotoxic with disturbances to mitotic phases. Mitotic index was less than one half the values of control for almost all concentrations throughout exposure periods. The highest concentration of both AgNPs induced complete cell arrest at both 48 and 72 h, except for Ags. Induction of chromosomal aberrations (chromosomal bridge, c-mitosis, vagrant chromosome, sticky chromosome) pointed to potential for genotoxicity. AgNPs demonstrated a clear mito-depressive effect culminating in growth inhibition of the A. cepa roots, except for 0.01 μg ml–1 of CPHE-AgNPs (p < 0.05). EC50 values showed that growth inhibition was in the order of CPHE-AgNPs>Ags>CBE-AgNPs. While indiscriminate usage of AgNPs might have an impact on the health status of exposed organisms, raising concerns, the cell arresting potential of both AgNPs can be explored in the control of growth of cancerous cells.

Fungal xylanases-mediated synthesis of silver nanoparticles for catalytic and biomedical applications

Green synthesis of nanoparticles has fuelled the use of biomaterials to synthesise a variety of metallic nanoparticles. The current study investigates the use of xylanases of Aspergillus niger L3 (NEA) and Trichoderma longibrachiatum L2 (TEA) to synthesise silver nanoparticles (AgNPs). Characterisation of AgNPs was carried out using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy, while their effectiveness as antimicrobial, antioxidant, catalytic, anticoagulant, and thrombolytic agents were determined. The colloidal AgNPs was brownish with surface plasmon resonance at 402.5 and 410 nm for NEA-AgNPs and TEA-AgNPs, respectively; while FTIR indicated that protein molecules were responsible for the capping and stabilisation of the nanoparticles. The spherical nanoparticles had size of 15.21-77.49 nm. The nanoparticles significantly inhibited the growth of tested bacteria (63.20-88.10%) and fungi (82.20-86.10%), and also scavenged DPPH (37.48-79.42%) and hydrogen peroxide (20.50-96.50%). In addition, the AgNPs degraded malachite green (78.97%) and methylene blue (25.30%). Furthermore, the AgNPs displayed excellent anticoagulant and thrombolytic activities using human blood. This study has demonstrated the potential of xylanases to synthesise AgNPs which is to the best of our knowledge the first record of such. The present study underscores the relevance of xylanases in nanobiotechnology.

Safety evaluation of green synthesized Cola nitida pod, seed and seed shell extract-mediated silver nanoparticles (AgNPs) using an Allium cepa assay

Abstract The increase in the use of nanoparticles in various fields of human endeavours calls for the need to understand the toxic potential of green synthesized nanoparticles. Cytogenotoxic potentials of green synthesized Cola pod (Cp-AgNPs), seed (Cs-AgNPs) and seed shell (Css-AgNPs) silver nanoparticles and silver nitrate salts (Ags) were evaluated using an A. cepa assay. Twenty onion bulbs were exposed to 0.01, 0.10, 1.0, 10.0, and 100.0 μg/ml AgNPs and Ags solutions. Microscopic evaluation was performed at 24, 48 and 72 h with 5000 cells per concentration scored for chromosomal aberrations, while the effects on the root growth were evaluated at 72 h. The observed dividing cells and mitotic inhibition were dose-dependent for the three AgNPs and Ags at 24, 48 and 72 h. Mitotic index obtained for 1.0, 10 and 100 μg/mL at all times of evaluation were less than half the value of the negative control, while cell arrest was only observed at 72 h at a concentration of 100 μg/mL for the three AgNPs. The chromosomal aberrations observed were c-mitosis, a chromosome bridge, a vagrant chromosome, and a sticky chromosome, which indicate the potential of AgNPs for genotoxicity. The mean root length of A. cepa treated with AgNPs showed a dose-dependent significant decrease compared to the control, indicating their inhibitory potential, but the mean root lengths were found to be lower at all concentrations compared to those treated with Ags, thus showing the attenuation of growth inhibition. The EC50 values revealed the order of growth inhibition as Ags>Cp-AgNPs>Css-AgNPs>Cs-AgNPs. The cytogenotoxic potential of the AgNPs suggests that caution should be exercised in their usage to prevent environmental pollution.

Compatibility study using hybridization procedure among Pleurotus genotypes and authentication by enzyme expression and ITSR of rDNA

Cross compatibility and authentication of hybrid genotypes among species of Pleurotus were studied using lignocellulotic enzymes production and Internal transcribed spacer (ITS) of rDNA. Schematic procedure of hyphal anastomosis hybridization between the species of Pleurotus was employed in this study. Formation of clamp connexion, changes in morphological hyphal arrangement and general increased in the enzymes production by the hybrid strains over their wild types is an evidence for the compatibility of crossed genotypes. Highest produced enzyme was manganese peroxidase by hybrid LN 97 with 3.25 Uml–1, followed by laccase with 3.06 Uml–1 obtained in LN 91 (hybrid). Lignin peroxidase was the least enzyme produced, but with better performance in hybrid LN 97 (2.75 Uml–1). Dendrogram of relationship among the genotypes revealed two major clusters. Cluster II contained singleton (LN 95), hybrid strain which totally separated from both parents. Most strains clustered away from their parents, authenticating the hybrids produced. Current study shows the Pleurotus employed for this investigation are cross compatible with high expression of heterosis in hybrid strains relative to the parents on the basis of enzymes produced. This technique could serve as a good tool in breeding programs for Pleurotus strain improvement.

Genetic Diversity Among Strains of Pleurotus species (oyster mushroom) Using Morphometric Traits Under Varied Temperature and pH

Abstract Genetic diversity in nineteen strains of Pleurotus was studied using morphometric traits and growth factors. Ability of the isolates of these strains to tolerate different ranges of temperature and pH were evaluated. Highest mycelial growth rates were obtained at 25 °C (mutants and hybrids) and 30 °C (wild type), while LAU 90 (mutant) performed satisfactorily at all evaluated temperature ranges (15-35 °C). Highest mycelial yields (dry weight) were produced by LAU 90 at different pH regimes (4.0 - 9.0), while hybrids LN 97 and LN 98 maximally produced mycelial yield at pH 5.0 and 7.0, respectively. Analysis od Principal component (PC) revealed that components of these strains accounted for 86.1% of total variations among the strains with first PC recording 44.6%. The dendrogram discriminated nineteen Pleurotus genotypes into two major genetic groups with mutants and hybrid strains in Cluster A, separated distinctly from wild parents in Cluster B, indicating genetic diversity. The expression of heterosis can be maximized by information obtained among the hybrid strains and mutant (LAU90) strain. The hybrid (LN98) strain with superior performance may be selected for adoption in commercial mushroom production.