Naheed Ahmad

Rapid synthesis of silver nanoparticles using dried medicinal plant of basil

Plants respond to heavy metal stress by metal complexation process like production of phytochelations or by other metal chelating peptides. In this paper we report the synthesis of silver nanoparticles (AgNPs) from the room dried stem and root of Ocimum sanctum. The broth of the plant is used as a reducing agent for the synthesis of Ag nanoparticles at room temperature. The reaction process was simple and was monitored by ultraviolet-visible spectroscopy (UV-vis). There was formation of highly stable silver nanoparticles in the solution. The morphology and crystalline phase of the NPs were determined from transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) spectra. Transmission Electron Microscopy studies showed that the silver nanoparticles obtained from roots and stem were of sizes 10+/-2 and 5+/-1.5 nm, respectively. The various phytochemicals present within the ocimum plant result in effective reduction of silver salts to nanoparticles but their chemical framework is also effective at wrapping around the nanoparticles to provide excellent robustness against agglomeration.

Biosynthesis of Silver Nanoparticles from Desmodium triflorum: A Novel Approach Towards Weed Utilization

A single-step environmental friendly approach is employed to synthesize silver nanoparticles. The biomolecules found in plants induce the reduction of Ag+ ions from silver nitrate to silver nanoparticles (AgNPs). UV-visible spectrum of the aqueous medium containing silver ions demonstrated a peak at 425 nm corresponding to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) showed the formation of well-dispersed silver nanoparticles in the range of 5–20 nm. X-ray diffraction (XRD) spectrum of the AgNPs exhibited 2θ values corresponding to the silver nanocrystal. The process of reduction is extracellular and fast which may lead to the development of easy biosynthesis of silver nanoparticles. Plants during glycolysis produce a large amount of H+ ions along with NAD which acts as a strong redoxing agent; this seems to be responsible for the formation of AgNPs. Water-soluble antioxidative agents like ascorbic acids further seem to be responsible for the reduction of AgNPs. These AgNPs produced show good antimicrobial activity against common pathogens.

The cag Pathogenicity Island of Helicobacter pylori Is Disrupted in the Majority of Patient Isolates from Different Human Populations

ABSTRACT The cag pathogenicity island (cag-PAI) is one of the major virulence determinants of Helicobacter pylori. The chromosomal integrity of this island or the lack thereof is speculated to play an important role in the progress of the gastroduodenal pathology caused by H. pylori. We determined the integrity of the cag-PAI by using specific flanking and internally anchored PCR primers to know the biogeographical distribution of strains carrying fully integral cag-PAI with proinflammatory behavior in vivo. Genotypes based on eight selected loci were studied in 335 isolates obtained from eight different geographic regions. The cag-PAI appeared to be disrupted in the majority of patient isolates throughout the world. Conservation of cag-PAI was highest in Japanese isolates (57.1%). However, only 18.6% of the Peruvian and 12% of the Indian isolates carried an intact cag-PAI. The integrity of cag-PAI in European and African strains was minimal. All 10 strains from Costa Rica had rearrangements. Overall, a majority of the strains of East Asian ancestry were found to have intact cag-PAI compared to strains of other descent. We also found that the cagE and cagT genes were less often rearranged (18%) than the cagA gene (27%). We attempted to relate cag-PAI rearrangement patterns to disease outcome. Deletion frequencies of cagA, cagE, and cagT genes were higher in benign cases than in isolates from severe ulcers and gastric cancer. Conversely, the cagA promoter and the left end of the cag-PAI were frequently rearranged or deleted in isolates linked to severe pathology. Analysis of the cag-PAI genotypes with a different biogeoclimatic history will contribute to our understanding of the pathogen-host interaction in health and disease.

Comparing Genomes of Helicobacter pylori Strains from the High-Altitude Desert of Ladakh, India

ABSTRACT The genomic diversity of Helicobacter pylori from the vast Indian subcontinent is largely unknown. We compared the genomes of 10 H. pylori strains from Ladakh, North India. Molecular analysis was carried out to identify rearrangements within and outside the cag pathogenicity island (cag PAI) and DNA sequence divergence in candidate genes. Analyses of virulence genes (such as the cag PAI as a whole, cagA, vacA, iceA, oipA, babB, and the plasticity cluster) revealed that H. pylori strains from Ladakh are genetically distinct and possibly less virulent than the isolates from East Asian countries, such as China and Japan. Phylogenetic analyses based on the cagA-glr motifs, enterobacterial repetitive intergenic consensus patterns, repetitive extragenic palindromic signatures, the glmM gene mutations, and several genomic markers representing fluorescent amplified fragment length polymorphisms revealed that Ladakhi strains share features of the Indo-European, as well as the East Asian, gene pools. However, the contribution of genetic features from the Indo-European gene pool was more prominent.

Biosynthesis of silver nanoparticles from biowaste pomegranate peels

NWe present a simple and eco-friendly biosynthesis of silver nanoparticles using Pomegranate peel extract as the reducing agent. The extract was challenged with AgNO3 solution for the production of silver nanoparticles (AgNPs). The reaction process was simple for the formation of highly stable silver nanoparticles at room temperature by using the biowaste of the fruit. The morphology and crystalline phase of the NPs was determined from UV-Vis spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) spectra and Fourier-Transform IR spectroscopy (FTIR). TEM studies showed that the silver nanoparticles obtained were of sizes 5 ± 1.5 nm. An effort has also been made to understand the possible involved mechanism for the biosynthesis of AgNPs. Presumably biosynthetic products or reduced cofactors play an important role in the reduction of respective salts to nanoparticles.

Ocimum Mediated Biosynthesis of Silver Nanoparticles

Currently the need for various developmental models in material sciences to develop green technologies has been reemphasized. For biodiversity rich countries like India, low investment and sustainability of biological synthesis adds to its attraction. Plants respond to heavy metal stress by metal complexation process like production of phyochelations or by other metal chelating peptides. In this paper we report the synthesis of AgNPS from the room dried stem and root of Ocimum sanctum at room temperature. The reaction process was simple for formation of highly stable silver nanoparticles. The morphology and crystalline phase of the NPs were determined from transmission electronmicroscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction(XRD) spectra. Transmission Electron Microscopy studies showed that the average silver nanoparticles obtained from roots and stem were of sizes 10 ± 2 nm and 5 ± 1.5 nm respectively.

Biomediated AgNPS from Some Ethnobotanical Weeds—Pyllanthus amarus

ABSTRACT Biomolecules found in plants such as enzymes/proteins, amino acids, polysaccharides, and vitamins induce formation of nanoparticles. In this study, plant broth of Phyllanthus amarus containing a number of secondary metabolites was selected for the formation of silver nanoparticles (AgNPs) at room temperature. The UV-visible spectrum of the aqueous medium containing silver ions demonstrated a peak at 425,356 nm corresponding to the plasmon absorbance of silver nanoparticles. High-resolution transmission electron microscopy (HRTEM) showed the formation of well-dispersed silver nanoparticles in the range of 10–20 nm. The X-ray diffraction (XRD) spectrum of the AgNPS exhibited 2θ values corresponding to the silver nanocrystal.

Biosynthesized composites of Au-Ag nanoparticles using Trapa peel extract induced ROS-mediated p53 independent apoptosis in cancer cells

Abstract The current study highlights rapid, sustainable, and cost-effective biosynthesis of silver (Ag), gold (Au) nanoparticles (NPs), and bimetallic Au-AgNPs composites using bio-waste extract of Trapa natans. Growth of the NPs was monitored spectrophotometrically and peak was observed at ∼525 nm, ∼450 nm, and ∼495 nm corresponding to Plasmon absorbance of AuNPs, AgNPs, and Au-AgNPs, respectively. Transmission electron microscopy (TEM) revealed the size of AgNPs (∼15 nm), AuNPs (∼25 nm), and Au-AgNPs (∼26–90 nm). Synthesized NPs follow the Gaussian bell curve and its crystalline nature was identified by X-ray diffraction (XRD). Furthermore, Au-AgNPs induced cytotoxicity in various cancer cells (HCT116, MDA-MB-231, and HeLa) effectively at 200 μg/mL. Au-AgNPs-exposed cancer cells exhibited apoptotic features such as nuclear condensation, mitochondrial membrane potential loss, and cleavage of casp-3 and poly (ADP-ribose) polymerase-1 (PARP). Au-AgNPs exposure enhanced reactive oxygen species (ROS) and upon inhibition of ROS, apoptosis was reduced effectively. NPs treatment killed HCT116 WT and p53 knockout cells without any significant difference. Mechanistically, Au-AgNPs derived with Trapa peel extract significantly enhance ROS which trigger p53-independent apoptosis in various cancer cells effectively. Our study explores the use of bio-waste for the green synthesis of NPs, which can be attractive candidates for cancer therapy.

Modification of Nanoclay Systems: An Approach to Explore Various Applications

Nanoclay has a great potential in various fields. Small amount of nanoclay can change the whole physical and chemical properties of polymers, paints, inks and lubricants by dispersing nanoclay layers into the polymer matrices. The flexibility of interlayer gallery of nanoclay helps in the release of drugs to the targeted place. The controlled release of drugs takes place on account of the drug incorporated within the nanoclay galleries. This makes these nanomaterials as potential materials with its application in pharmaceutical field. Organoclays, a type of nanoclay are also being utilized for waste water treatment in junction with other sorbents viz. activated carbon and alum. Organoclays have been found to be the finest material for water treatment especially when the water contains enough amounts of oil and grease or humic acid. The use of nanoclays as reinforcing agent or additives in polymers for various properties is exploited for various applications. This chapter provides an overview of nanoclays or types of nanoclays with significance on the utilization of nanoclays as the filler in polymer matrices for the synthesis/fabrication of polymer nanocomposites, drug delivery agents, viscosity modifier for coatings, inks and lubricants and nanoclays for industrial effluent as well as potable water treatment.