Sunday A. Ojo

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.

Biogenic synthesis of silver nanoparticles using cell-free extract of Bacillus safensis LAU 13: antimicrobial, free radical scavenging and larvicidal activities

Abstract The cell-free extract of Bacillus safensis LAU 13 strain (GenBank accession No: KJ461434) was used for green biosynthesis of silver nanoparticles (Ag-NPs). Characterization of Ag-NPs was carried out using UV-VIS spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Evaluation of synthesized Ag-NPs as antimicrobial agents was done using multi-drug resistant clinical isolates as well as their synergistic effects when combined with some selected antibiotics. Furthermore, potential of Ag-NPs as antimicrobial additives in paint was demonstrated. The Ag-NPs have maximum absorbance at 419 nm, with peaks at 3308, 2359, 1636, and 422 cm−1, indicating that proteins were the capping and stabilisation molecules in the synthesis of Ag-NPs. The particles were spherical shaped having size of 5-95 nm, with silver as the prominent metal from the energy dispersive X-ray analysis, while selected area electron diffraction pattern agrees well with the crystalline nature and face-centred cubic phase of Ag-NPs. Inhibition of Staphylococcus aureus, Escherichia coli, Klebsiella granulomatis and Pseudomonas aeruginosa was achieved at 100 μg/mL. Improvement of activities of augmentin, ofloxacin and cefixime to the tune of 7.4-142.9% was achieved in synergistic study, while total inhibitions of P. aeruginosa, S. aureus, Aspergillus flavus and Aspergillus fumigatus were achieved in Ag-NPs-paint admixture. The Ag-NPs showed potent antioxidant and larvicidal activities with IC50 and LC50 of 15.99 and 42.19 μg/mL, respectively. The present study demonstrated that the biosynthesized Ag-NPs have potent biological activities, which can find applications in diverse areas. The report adds to the growing biotechnological relevance of B. safensis.

The emerging roles of arthropods and their metabolites in the green synthesis of metallic nanoparticles

Abstract Nanotechnology has remained relevant as a multifacet discipline, which cuts across different areas of science and technology. Several successful attempts had been documented regarding the involvement of biological materials in the green synthesis of various metal nanoparticles (MeNPs) because of their eco-friendliness, cost-effectiveness, safe handling, and ultimately less toxicity as opposed to the physical and chemical methods with their concomitant problems. Biological agents, including bacteria, fungi, algae, enzymes, plants, and their extracts, have been implicated in most cases by several authors. Moreover, nanotechnology in recent times has also made an inroad for animal species, specifically arthropods and metabolites thereof to be used as excellent candidates for the green synthesis of MeNPs. The increasing literature on the use of metabolites of arthropods for the green synthesis of nanoparticles has necessitated the need to document a review on their relevance in nanobiotechnology. The review, which represents the first of its kind, seeks to underscore the importance of arthropods in the multidisciplinary subject of nanoscience and nanotechnology.

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.

Nanomedical Applications of Nanoparticles for Blood Coagulation Disorders

Nanotechnology has evolved as a novel multidisciplinary concept of the twenty-first century, abridging gaps in materials science, engineering, life sciences and medicine, with tremendous applications in diverse areas of human endeavours. Nanoparticles, which form critical components of nanoscience and nanotechnology, have also played prominent roles in extending the frontiers of applications of the emerging discipline. The metallic nanoparticles, owing to their unique optical, surface, chemical, biological, catalytic, electronic, and resonance properties have formed an epicentre of research in recent times, with major focus on synthesis and novel applications. A new line of application that has emerged is in the delivery of quality healthcare, leading to the offshoot of a sub-discipline, nanomedicine. A major health problem confronting man is the blood coagulation disorder, which often leads to cardiovascular diseases, with the attendant high mortality worldwide. The use of conventional drugs in the treatment blood coagulation has been plagued with problems of high cost, short-lived action and adverse severe reactions. Hence, there is need to search for newer treatment regimes with improved outcomes, of which nanotechnology holds a promising future. In this review, we focus on the emerging applications of metallic nanoparticles in the management of blood coagulation disorders; notably in the prevention of clot formation, dissolution of blood clots, and in the combined role of therapeutic and diagnostic agents. The review presents a comprehensive overview on blood coagulation disorders, synthesis and applications of metallic nanoparticles, and the novel management of blood coagulation disorders using nanoplatform deliveries. Emphasis has been placed on the prospects of the use of metallic nanoparticles such as silver, gold and silver-gold alloy nanoparticles as anticoagulant, thrombolytic and theranostic agents, with evidences of excellent performances in the prevention of blood clot formation, dissolution of blood clots, and enhanced imaging of thrombus (blood clot) in vivo. The increasing appraisals of these nanoplatforms, potent action, improved biocompatibility cum absence of complications of excessive bleeding are good indicators of potential future integration in the clinical management of blood coagulation disorders. However, diligent studies are needed to be conducted to establish the long-term safety of applications of these nanomedical materials. The compendium seeks to bring to the fore, the continued relevance of nanotechnology in the twenty-first century, and its potential dynamic integration into medicare programmes.