Jamal M. Khaled

Guazuma ulmifolia bark-synthesized Ag, Au and Ag/Au alloy nanoparticles: Photocatalytic potential, DNA/protein interactions, anticancer activity and toxicity against 14 species of microbial pathogens

In the present study, we focused on a quick and green method to fabricate Ag, Au and Ag/Au alloy nanoparticles (NPs) using the bark extract of Guazuma ulmifolia L. Green synthesized metal NPs were characterized using different techniques, including UV-Vis spectroscopy, FT-IR, XRD, AFM and HR-TEM analyses. The production of Ag, Au and Ag/Au alloy NPs was observed monitoring color change from colorless to brown, followed by pink and dark brown, as confirmed by UV-Vis spectroscopy characteristic peaks at 436, 522 and 510nm, respectively. TEM shed light on the spherical shapes of NPs with size ranges of 10-15, 20-25 and 10-20nm. Biosynthesized NPs showed good catalytic activity reducing two organic dyes, 4-nitrophenol (4-NP) and Congo red (CR). UV-vis spectroscopy, fluorescence, circular dichroism spectroscopy and viscosity analyses were used to investigate the NP binding with calf thymus DNA. The binding constant of NPs with DNA calculated in UV-Vis absorption studies were 1.18×104, 1.83×104 and 2.91×104M-1, respectively, indicating that NPs were able to bind DNA with variable binding affinity: Ag/Au alloy NPs>Ag NPs>Au NPs. Ag/Au alloy NPs also showed binding activity to bovine serum albumin (BSA) over the other NPs. Ag and Ag/Au alloy NPs exhibited good antimicrobial activity on 14 species of microbial pathogens. In addition, the cytotoxic effects of Ag/Au alloy NPs were studied on human cervical cancer cells (HeLa) using MTT assay. Overall, our work showed the promising potential of bark-synthesized Ag and Ag/Au alloy NPs as cheap sources to develop novel and safer photocatalytic, antimicrobial and anticancer agents.

Green synthesis of gold nanoparticles using a cheap Sphaeranthus indicus extract: Impact on plant cells and the aquatic crustacean Artemia nauplii

The impact of green-fabricated gold nanoparticles on plant cells and non-target aquatic species is scarcely studied. In this research, we reported an environment friendly technique for the synthesis of gold nanoparticles (Au NPs) using the Sphaeranthus indicus leaf extract. The formation of the metal NPs was characterized by UV-Visible and FT-IR spectroscopy, XRD, SEM and TEM analyses. The UV-Visible spectra of Au NPs showed a surface plasmon resonance peak at 531nm. FT-IR analysis indicated functional bio-molecules associated with Au NPs formation. The crystalline nature of Au nanoparticles was confirmed by their XRD diffraction pattern. TEM revealed the spherical shape with a mean particle size of 25nm. Au NPs was tested at 0, 1, 3, 5, 7 and 10% doses in mitotic cell division assays, pollen germination experiments, and in vivo toxicity trials against the aquatic crustacean Artemia nauplii. Au NPs did not show any toxic effects on plant cells and aquatic invertebrates. Notably, Au NPs promoted mitotic cell division in Allium cepa root tip cells and germination of Gloriosa superba pollen grains. Au NPs showed no mortality on A. nauplii, all the tested animals showed 100% survivability. Therefore, these Au NPs have potential applications in the development of pollen germination media and plant tissue culture.

Facile green synthesis of zinc oxide nanoparticles using Ulva lactuca seaweed extract and evaluation of their photocatalytic, antibiofilm and insecticidal activity

The bioactivity of semiconductor nanocomplexes has been poorly studied in the field of pesticide science. In this research, the synthesis of zinc nanoparticles was accomplished through new effortless green chemistry process, using the Ulva lactuca seaweed extract as a reducing and capping agent. The production of U. lactuca-fabricated ZnO nanoparticles (Ul-ZnO Nps) was characterized by powder X-ray diffraction (XRD), UV-visible, Fourier transform infrared (FTIR) spectroscopy, selected area electron diffraction (SAED) analysis and transmission electron microscopy (TEM). The U. lactuca-fabricated ZnO NPs were tested for their photodegradative action against organic dyes, as well as for antibiofilm and larvicidal activities. The UV visible absorbance spectrum of Ul-ZnO NPs exhibited the absorbance band at 325nm and TEM highlighted average crystallite sizes of nanoparticles of 10-50nm. Methylene blue (MB) dye was efficiently corrupted under sunlight in presence of Ul-ZnO NPs. Excellent bactericidal activity was shown by the Ul-ZnO Nps on Gram positive (Bacillus licheniformis and Bacillus pumilis) and Gram negative (Escherichia coliand Proteus vulgaris) bacteria. High antibiofilm potential was noted under both dark and sunlight conditions. The impact of a single treatment with Ul-ZnO NPs on biofilm architecture was also analyzed by confocal laser scanning microscopy (CLSM) on both Gram positive and Gram negative bacteria. Moreover, Ul-ZnO NPs led to 100% mortality of Aedes aegypti fourth instar larvae at the concentration of 50μg/ml within 24h. The effects of ZnO nanoparticle-based treatment on mosquito larval morphology and histology were monitored. Overall, based on our results, we believe that the synthesis of multifunctional Ul-ZnO Nps using widely available seaweed products can be promoted as a potential eco-friendly option to chemical methods currently used for nanosynthesis of antimicrobials and insecticides.

Larvicidal activity of Blumea eriantha essential oil and its components against six mosquito species, including Zika virus vectors: the promising potential of (4E,6Z)-allo-ocimene, carvotanacetone and dodecyl acetate

The effective and environmentally sustainable control of mosquitoes is a challenge of essential importance. This is due to the fact that some invasive mosquitoes, with special reference to the Aedes genus, are particularly difficult to control, due to their high ecological plasticity. Moreover, the indiscriminate overuse of synthetic insecticides resulted in undesirable effects on human health and non-target organisms, as well as resistance development in targeted vectors. Here, the leaf essential oil (EO) extracted from a scarcely studied plant of ethno-medicinal interest, Blumea eriantha (Asteraceae), was tested on the larvae of six mosquitoes, including Zika virus vectors. The B. eriantha EO was analyzed by GC and GC-MS. The B. eriantha EO showed high toxicity against 3rd instar larvae of six important mosquito species: Anopheles stephensi (LC50=41.61 μg/ml), Aedes aegypti (LC50=44.82 μg/ml), Culex quinquefasciatus (LC50 =48.92 μg/ml), Anopheles subpictus (LC50=51.21 μg/ml), Ae. albopictus (LC50=56.33 μg/ml) and Culex tritaeniorhynchus (LC50=61.33 μg/ml). The major components found in B. eriantha EO were (4E,6Z)-allo-ocimene (12.8%), carvotanacetone (10.6%), and dodecyl acetate (8.9%). Interestingly, two of the main EO components, (4E,6Z)-allo-ocimene and carvotanacetone, achieved LC50 lower than 10 μg/ml on all tested mosquito species. The acute toxicity of B. eriantha EO and its major constituents on four aquatic predators of mosquito larval instars was limited, with LC50 ranging from 519 to 11.431 μg/ml. Overall, the larvicidal activity of (4E,6Z)-allo-ocimene and carvotanacetone far exceed most of the LC50 calculated in current literature on mosquito botanical larvicides, allowing us to propose both of them as potentially alternatives for developing eco-friendly mosquito control tools.

GC and GC/MS analysis of essential oil composition of the endemic Soqotraen Leucas virgata Balf.f. and its antimicrobial and antioxidant activities.

Leucas virgata Balf.f. (Lamiaceae) was collected from the Island Soqotra (Yemen) and its essential oil was obtained by hydrodistillation. The chemical composition of the oil was investigated by GC and GC-MS. Moreover, the essential oil was evaluated for its antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria, and one yeast species by using broth micro-dilution assay for minimum inhibitory concentrations (MIC) and antioxidant activity by measuring the scavenging activity of the DPPH radical. The investigation led to the identification of 43 constituents, representing 93.9% of the total oil. The essential oil of L. virgata was characterized by a high content of oxygenated monoterpenes (50.8%). Camphor (20.5%) exo-fenchol (3.4%), fenchon (5.4%), and borneol (3.1%) were identified as the main components. Oxygenated sesquiterpenes were found as the second major group of compounds (21.0%). β-Eudesmol (6.1%) and caryophyllene oxide (5.1%) were the major compounds among oxygenated sesquiterpenes. The results of the antimicrobial assay showed that the oil exhibited a great antibacterial activity against the tested S. aureus, B. subtilis, and E. coli. No activity was found against P. aeruginosa and C. albicans. Moreover, the DPPH-radical scavenging assay exhibited only a moderate antioxidant activity (31%) for the oil at the highest concentration tested (1 mg/mL).

Biopolymer zein-coated gold nanoparticles: Synthesis, antibacterial potential, toxicity and histopathological effects against the Zika virus vector Aedes aegypti

The control of multidrug-resistant bacteria as well as insect pests and vectors is timely and important now a days. The present study was designed to evaluate the in vitro antibacterial, antibiofilm and mosquito larvicidal effects of gold nanoparticles synthesized using the zein biopolymer (Ze-AuNPs) against Gram positive (Bacillus pumilus and Bacillus subtilis), Gram negative (Shigella sonnei and Pseudomonas aeruginosa) bacteria and third instar larvae of the dengue and Zika virus vector Aedes aegypti. The synthesized Ze-AuNPs were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The antibacterial assays testing Ze-AuNPs at 100μg/ml showed that the zones of inhibition against Gram positive species B. pumilus and B. subtilis were 13.9 and 14.2mm, respectively, while for Gram negative S. sonnei and P. aeruginosa they were 18.1 and 18.4mm, respectively. Light and confocal laser scanning microscopy (CLSM) confirmed the interruption and disintegration of bacterial biofilm post-treatment with Ze-AuNPs at 100μg/ml. In larvicidal assays on A. aegypti, HAuCl4 and Ze-AuNPs treated third instar larvae of A. aegypti showed LC50 of 26.6 and 6.81mg/L, respectively, and LC90 of 81.1 and 13.6mg/L respectively. The histopathological analysis of A. aegypti treated with Ze-AuNPs showed complete disintegration of abdominal region, particularly the midgut and caeca, with loss of lateral and caudal hairs. The stereomicroscopic visualization of A. aegypti treated with Ze-AuNPs showed the loss of upper head hair, lower head hair, antenna hair, lateral hair and caudal hair. Overall, the study concludes that Ze-AuNPs have excellent antibacterial, antibiofilm effects and has ability to control the larval populations of A. aegypti mosquitoes.

Bacterial exopolysaccharide (EPS)-coated ZnO nanoparticles showed high antibiofilm activity and larvicidal toxicity against malaria and Zika virus vectors

In this study, a novel and effective approach was performed to synthesize ZnO nanoparticles (ZnO NPs) using the exopolysaccharides (EPS) from the probiotic strain Bacillus licheniformis Dahb1. EPS acted as reducing and stabilizing agent for the formation of EPS-ZnO NPs by co-precipitation method. Structural characterization was investigated by a surface plasma resonance centered at 375nm in UV-vis spectrum. FTIR spectrum exhibited functional groups with strong absorption peak at 3814.7-420cm-1. XRD showed the crystalline nature of EPS-ZnO NPs. TEM showed that the EPS-ZnO NPs were hexagonal in shape, with size within the range of 10-100nm. The presence of Zn was confirmed by EDX analysis. Antibacterial activity of EPS-ZnO NPs was demonstrated as 100μg/ml significantly inhibited the effective growth control of Gram-negative (Pseudomonas aeruginosa and Proteus vulgaris) and Gram-positive (Bacillus subtilis and Bacillus pumilus) bacteria. Light microscopy and confocal laser scanning microscopy evidenced that the antibiofilm activity of EPS-ZnO NPs was higher against Gram-negative bacteria over Gram positive bacteria. EPS-ZnO NPs also inhibited the biofilm growth of Candida albicans at the concentration of 75μg/ml. The hemolytic test showed low cytotoxicity of EPS-ZnO NPs at 5mg/ml. In addition, EPS-ZnO NPs achieved 100% mortality against third instars mosquito larvae of Anopheles stephensi and Aedes aegypti at very low doses. Moreover, histology studies revealed the presence of damaged cells and tissues in the mid-gut of treated mosquito larvae. The multipurpose properties of EPS-ZnO NPs revealed in the present study can be further considered for pharmaceutical, parasitological and entomological applications.

Biopolymer gelatin-coated zinc oxide nanoparticles showed high antibacterial, antibiofilm and anti-angiogenic activity

The use of natural polymers in drug design plays an important role in biomedical applications. Combinations of nanoparticles (NPs) and biopolymers have been shown to be useful for many purposes. This study focused on gelatin-coated zinc oxide NPs synthesized by co-precipitation. The particles were characterized by UV-Vis spectrum, showing a main peak at 375nm. The stability and crystalline nature of the particles was evaluated by Zeta potential and X-ray diffraction analysis. Fourier transform infrared spectroscopy (FTIR) revealed the possible functional groups of Ge-ZnO NPs, with strong bands at 3851, 3447, and 2923cm-1. Moreover, transmission electron microscopy (TEM) highlighted the presence of spherically shaped Ge-ZnO NPs that were 20nm in size. Energy dispersive analysis X-ray (EDX) analysis showed that the zinc elemental content of Ge-ZnO NPs was 59.10%. The results of antibacterial activity assays revealed higher inhibition of Ge-ZnO NPs against Gram-negative Pseudomonas aeruginosa at 100μg/ml over that against Gram-positive Enterococcus faecalis. Greater inhibition of biofilm formation was observed for Gram-negative bacteria compared to Gram-positive bacteria. In addition, Ge-ZnO NPs effectively inhibited the biofilm growth of the fungus Candida albicans at 50μg/ml. Ge-ZnO NPs reduced the viability of hepatocarcinoma cancer cell lines at 100μg/ml. Moreover, in chick embryos, notable anti-angiogenesis effects were observed for Ge-ZnO NPs and zinc acetate at 50μg/ml compared to that observed testing gelatin. Overall, based on the results, Ge-ZnO NPs may be used as a novel agent for the control of biofilm-forming microbial pathogens.

Eco-friendly fabrication of Ag nanostructures using the seed extract of Pedalium murex, an ancient Indian medicinal plant: Histopathological effects on the Zika virus vector Aedes aegypti and inhibition of biofilm-forming pathogenic bacteria

The control of Zika virus mosquito vectors and well as the development of drugs in the fight against biofilm-forming microbial pathogens, are timely and important challenges in current bionanoscience. Here we focused on the eco-friendly fabrication of Ag nanostructures using the seed extract of Pedalium murex, an ancient Indian medicinal plant. Initial confirmation of Ag nanoparticles (AgNPs) production was showed by a color change from transparent to dark brown. The UV-Visible spectrum (476nm), X-ray diffraction peaks (101, 200, 220 and 311) and Fourier transform infrared spectroscopy shed light on the production of green-capped AgNPs. Morphological structure analysis using HR-TEM showed that the AgNPs were mostly hexagonal in shape with rough edges, and a size of 20-30nm. The larvicidal potential of P. murex seed extract and AgNPs fabricated using the P. murex seed extract (Pm-AgNPs) was tested on fourth instar mosquito larvae of the Zika virus vector Aedes aegypti. Maximum efficacy was achieved by Pm-AgNPs against Ae. aegypti after 24h (LC50 34.88; LC90 64.56mg/ml), if compared to the P. murex seed extract. Histopathological analyses showed severe damages to the hindgut and larval muscles in NPs-treated Ae. aegypti larvae. The sub-MIC concentrations of Pm-AgNPs exhibited significant anti-biofilm activity against Gram positive (Enterococcus faecalis, Staphylococcus aureus) and Gram negative (Shigella sonnei, Pseudomonas aeruginosa) bacterial pathogens, as showed by EPS and MTP assays. Light and CLSM microscopic studies highlighted a significant impact of P. murex seed extract and Pm-synthesized AgNPs on the surface topography and architecture of bacterial biofilm, both in Gram positive and Gram negative species. Overall, results reported here contribute to the development of reliable large-scale protocols for the green fabrication of effective mosquito larvicides and biofilm inhibitors.

Dermatophyte and non dermatophyte fungi in Riyadh City, Saudi Arabia.

Background Dermatophytes are a scientific label for a group of three genera (Microsporum, Epidermophyton and Trichophyton) of fungus that causes skin disease in animals and humans. Conventional methods for identification of these fungi are rapid and simple but are not accurate comparing to molecular methods. Objective This study aimed to isolate human pathogenic dermatophytes which cause dermatophytosis in Riyadh City, Saudi Arabia and to identify these fungi by using conventional and molecular methods. Methods The study was conducted in Medical Complex, Riyadh and King Saud University. Samples of infected skin, hairs and nails were collected from 112 patients. Diagnosis of skin infections, direct microscopic test, isolation and identification of dermatophytes by conventional and molecular methods were carried out. Results The results indicated that the tinea capitis infection had the highest prevalence among the patients (22.3%) while Tinea barbae had the lowest. In this study the identified dermatophyte isolates belong to nine species as Trichophyton violaceum, Trichophyton verrucosum, Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton schoenleinii, Trichophyton concentricum, Microsporum canis, Microsporum audouinii and Epidermophyton floccosum which cause skin infections were isolated during this study. Non dermatophyte isolates included 5 isolates from Aspergillus spp. 4 isolates from Acremonium potronii and 15 isolates from Candida spp. M. canis were the most common species (25% of isolated dermatophytes). Out of the 52 dermatophyte isolates identified by conventional methods, there were 45 isolates identified by the molecular method. Conclusions The results concluded that approximately M. canis caused a quarter of dermatophyte cases, tinea capitis infection was prevalent and the molecular method was more accurate than conventional methods.