Sadia Nazir

Enhanced visible light photocatalytic inactivation of Escherichia coli using silver nanoparticles as photocatalyst.

The silver nanoparticles (AgNPs) were green synthesized using Cirsium arvense plant extract as a reducing and stabilizing agent, with superior photo inactivation activity against Escherichia coli (E. coli). The synthesized AgNPs had crystalline structure and were characterized by UV-vis spectroscopy, XRD, HRTEM, SEM, EDX and FT-IR. The formation of nanoparticles was observed at different pH and different plant extract concentrations and it was found that at higher pH (pH>6) and at lower concentration (10 mL), the reducing and stabilizing efficiency of plant extract was increased. The synthesized AgNPs had small size (<15 nm) and spherical shape. The AgNPs were evaluated for antibacterial activity against E. coli. Before transferring it to antibacterial activity, it was placed under visible light for 120 min. The same experiment was performed in dark as a control medium. The photo irradiated AgNPs were observed to be more effective against E. coli. The results showed, that the diameter of zone of inhibition of visible light irradiated AgNPs against E. coli was 23 (±0.5)mm and in dark was 11 (±0.4)mm.

Visible light photo catalytic inactivation of bacteria and photo degradation of methylene blue with Ag/TiO2 nanocomposite prepared by a novel method

Water purification is one of the worldwide problem and most of the conventional methods are associated with a number of drawbacks. Therefore it is the need of the day to develop new methods and materials to overcome the problem of water purification. In this research work we present a simple and green approach to synthesize silver decorated titanium dioxide (Ag/TiO2) nanocomposite with an efficient photo catalytic activities. Phytochemicals of the Cestrum nocturnum leaf extract were used to synthesize silver nanoparticles (AgNPs), Titanium dioxide (TiO2) and Ag/TiO2 nanocomposite. To confirm the formation, crystal structure, particle size and shape of green synthesized nanoparticles and nanocomposite, they were characterized by UV-visible spectroscopy (UV-vis), X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The AgNPs, TiO2 and Ag/TiO2 were evaluated for photo degradation of methylene blue (MB) and photo inhibition of Bacteria. The bio-synthesized Ag/TiO2 nanocomposite was observed to have strong catalytic activities for photo reduction of MB and photo inactivation of bacteria as compared to bare AgNPs and TiO2. In the presence of Ag/TiO2, 90% of MB was degraded only in 40min of irradiation. Alternatively the bare AgNPs and TiO2 degraded less than 30% and 80% respectively of MB even in more than 100min of irradiation. Similarly the Ag/TiO2 has very strong photo inhibition efficiency towards Escherichia coli and Pseudomonas aeruginosa. The zone of inhibition of irradiated Ag/TiO2 nanocomposites against E. coli and P. aeruginosa was 19mm and 17mm respectively which was two times higher than in dark. These promising photocatalytic activities of nanocomposite may be due to the highly decorated AgNPs over the surface of TiO2.

Sapium sebiferum leaf extract mediated synthesis of palladium nanoparticles and in vitro investigation of their bacterial and photocatalytic activities

There is a growing need to introduce eco-friendly and sustainable procedures for the synthesis of metal nanoparticles that include a mild reaction conditions, simple reaction setup, use of nontoxic medium such as water and plant extract, cost effectiveness as well as greater efficiency for biomedical and catalytic applications. For this purpose, small and highly dispersed palladium nanoparticles (PdNPs) were prepared by eco-friendly and cost effective green method using water soluble leaf extract of Sapium sebiferum as a reducing and capping agent. The formation of PdNPs was optimized at various temperatures i.e. (30°C, 60°C and 90°C) and different leaves extract (5mL and 10mL) in order to control their size and shape. The results indicated that PdNPs synthesized at 10mL leaf extract concentration and 60°C temperature have small sized (5nm) and spherical shape. The nanoparticles formation, their dispersion, size and shape were confirmed by various characterization techniques i.e. UV-Vis spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA) and Dynamic light scattering technique (DLS) analysis. The biologically synthesized PdNPs were tested for size dependent photo degradation of methylene blue and inactivation of bacteria. The PdNPs synthesized at optimized condition (10mL extract concentration and 60°C) have strong photo catalytic activity and reduced 90% methylene blue in 70min. The optimized PdNPs also showed strong bacterial inhibition against Staphylococcus aureus 29(±0.8mm), Bacillus subtilis 19(±0.6mm) and pseudomonas aeruginosa 11(±0.6mm). The results of this examination demonstrate effective applications of extremely active PdNPs.

Facile and green synthesis of phytochemicals capped platinum nanoparticles and in vitro their superior antibacterial activity

The increase in the severe infectious diseases and resistance of the majority of the bacterial pathogens to the available drug is a serious problem now a day. In order to overcome this problem it is necessary to develop new therapeutic agents which are non-toxic and more effective to inhibit these microbial pathogens. For this purpose the plant extract of highly active medicinal plant, Taraxacum laevigatum was used for the synthesis of platinum nanoparticles (PtNPs) to enhance its bio-activities. The surface plasmon resonance peak appeared at 283nm clearly represent the formation of PtNPs. The results illustrate that the bio-synthesized PtNPs were uniformly dispersed, small sized (2-7nm) and spherical in shape. The green synthesized PtNPs were characterized by UV-vis spectroscopy, XRD, TEM, SEM, EDX, DLS and FTIR. These nanoparticles were tested against gram positive bacteria (Bacillus subtilis) and gram negative bacteria (Pseudomonas aeruginosa). The bio-synthesized PtNPs were examined to be more effective against both of the bacteria. The results showed, that the zone of inhibition of PtNPs against P. aeruginosa was 15 (±0.5) mm and B. subtilis was 18 (±0.8) mm. The most significant outcome of this examination is that PtNPs exhibited strong antibacterial activity against P. aeruginosa and B. subtilis which have strong defensive system against several antibiotics.

Ultra-efficient photocatalytic deprivation of methylene blue and biological activities of biogenic silver nanoparticles

Phytosynthesis of metal nanoparticles is considered as a safe, cost-effective, and green approach. In this study, silver nanoparticles (AgNPs) were successfully synthesized using the aqueous extract of Lychee (Litchi chinensis) fruit peel and an aqueous solution of silver nitrate (AgNO3). The synthesized nanoparticles were characterized by several analytical techniques i.e. UV-Vis Spectroscopy, XRD (X-ray diffraction spectroscopy), EDX (electron dispersive X-ray), SAED (selected area electron diffraction), HRTEM (high-resolution transmission electron microscopy), and FTIR (Fourier transform infrared spectroscopy). HRTEM and XRD results indicated that the prepared AgNPs are spherical in shape, well dispersed and face centered cubic crystalline. AgNPs showed potent antibacterial properties against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The minimum inhibitory concentration (MIC) values were 125μg against E. coli and 62.5μg against both S. aureus and B. subtilis. AgNPs induce efficient cell constituent release from bacterial cells, which indicates the deterioration of cytoplasmic membrane. Moreover, antioxidant studies on the as-synthesized nanoparticles reveal efficient scavenging of the stable or harmful DPPH free radical. The cytotoxicity assay confirmed that biosynthesized AgNPs are nontoxic to normal healthy RBCs. AgNPs exhibited consistent release of Ag(+) determined by ICP-AES analysis. AgNPs exhibited extraordinary photocatalytic degradation (99.24%) of methylene blue. On the other hand, commercial silver nanoparticles have moderate biological activities against the tested bacterial strains and negligible photocatalytic degradation of methylene blue. The significant biological and photocatalytic activities of the biosynthesized silver nanoparticles are attributed to their small size, spherical morphology and high dispersion.

Antibacterial activity of biochemically capped iron oxide nanoparticles: A view towards green chemistry

A green approach to fabricate nanoparticles has been evolved as a revolutionary discipline. Eco-compatible reaction set ups, use of non-toxic materials and production of highly active biological and photocatalytic products are few benefits of this greener approach. Here, we introduce a green method to synthesize Fe oxide NPs using Punica granatum peel extract. The formation of Fe oxide NPs was optimized using different concentrations of peel extract (20mL, 40mL and 60mL) to achieve small size and better morphology. The results indicate that the FeNPs, obtained using 40mL concentration of peel extract possess the smallest size. The morphology, size and crystallinity of NPs was confirmed by implementing various techniques i.e. UV-Vis spectroscopy, X-ray diffraction, Scanning Electron Microscopy and Electron Diffraction Spectroscopy. The bio-chemicals responsible for reduction and stabilization of FeNPs were confirmed by FT-IR analysis. The biogenic FeNPs were tested for their size dependent antibacterial activity. The biogenic FeNPs prepared in 40mL extract concentrations exhibited strongest antibacterial activity against Pseudomonas aeruginosa i.e. 22 (±0.5) mm than FeNPs with 20mL and 60mL extract concentrations i.e. 18 (±0.4) mm and 14 (±0.3) mm respectively. The optimized FeNPs with 40mL peel extract are not only highly active for ROS generation but also show no hemolytic activity. Thus, FeNPs synthesized using the greener approach are found to have high antibacterial activity along with biocompatibility. This high antibacterial activity can be referred to small size and large surface area.

Biodirected synthesis of palladium nanoparticles using Phoenix dactylifera leaves extract and their size dependent biomedical and catalytic applications

The emerging microbial resistance and increased water pollution are of serious concern around the globe. In order to cope with these problems, new strategies are needed to develop less toxic and more effective nanomaterials that could arrest the microbial growth and eliminate unwanted organic pollutants from water samples. In the present contribution, we report the green synthesis of palladium nanoparticles using the aqueous extract of Phoenix dactylifera leaves. The appearance of a characteristic surface plasmon resonance peak at 278 nm confirmed the synthesis of palladium nanoparticles (UV-vis spectroscopy). The formation of the PdNPs was optimized at different temperatures (30 °C, 60 °C and 90 °C) and varying amounts of leaf extract (5 mL, 10 mL and 20 mL) in order to control their size, shape and dispersion. Average particle sizes of 13, 5, and 21 nm were observed by using the leaf concentrations of 5, 10, and 20 mL, respectively (HRTEM, DLS), with a fixed amount of PdCl2 (0.003 M) at 60 °C. The PdNPs synthesized under the optimized conditions (10 mL extract + 60 °C + 0.003 M PdCl2) were spherical in shape, small sized and uniformly distributed (HRTEM). The biologically synthesized nanoparticles were tested for their size dependent biomedical and catalytic applications. The PdNPs synthesized under optimized conditions exhibited strong catalytic activity with a complete reduction of 4-nitrophenol to 4-aminophenol in only 2 min. These nanoparticles were highly active in scavenging DPPH free radicals. The optimized palladium nanoparticles also exhibited strong antibacterial efficiency against Pseudomonas aeruginosa 26 (±0.8 mm). This high activity of PdNPs may be due to their small size, high dispersion and surface capping phytochemicals.

Longan fruit juice mediated synthesis of uniformly dispersed spherical AuNPs: cytotoxicity against human breast cancer cell line MCF-7, antioxidant and fluorescent properties

The development of a biologically glorious experimental process for the synthesis of nanoparticles is an important emerging branch of nanotechnology. Gold nanoparticles (AuNPs) can be easily synthesized, functionalized and are biocompatible. In the present work AuNPs were synthesized by an eco-friendly, fast, one-pot and green synthetic route using Longan fruit juice as a reducing, capping and stabilizing agent. The AuNPs showed surface plasmon resonance at around 555 nm. The spherical shape, fine dispersion, average size (25 nm), crystalline structure and elemental composition were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The capping and stabilizing molecules were characterized by Fourier transform infrared spectroscopy (FTIR). The AuNPs were found to be unique with respect to mono-structural morphology and greater yield as compared to other bio-synthesized AuNPs. Furthermore, the cytotoxicity of AuNPs proved to be potent agent against human breast cancer cell line MCF-7. AuNPs exhibited significant antioxidant activity and fluorescence emission. These biomaterials can be used for broad biomedical applications.

Antimicrobial and enzyme inhibitory assay of constituents of Lonicera lanceolata

The phytochemical study on the chloroform fraction of Lonicera lanceolata led to the first time isolation of four known compounds (1 to 4). The antimicrobial and enzyme inhibition assay of four compounds isolated from L. lanceolata are presented in this study. These compounds were screened against two human Gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus) and four Gramnegative ones (Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae and Klebsiella Pneumoniae) by performing Agar well diffusion method for antibacterial and antifungal activities. Minimum inhibitory concentration (MIC) was determined by Agar well dilution method. Minimum bactericidal concentration (MBC) was carried out by viable cell count method. Compound 1 showed maximum antimicrobial activities, while the other compounds also showed significant antimicrobial activities. In addition, the isolated compounds were assayed for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Moreover, the IC50 (50% inhibitory effect) values of compounds 1 and 2 against AChE were determined to be 1.99 and 1.75 μM, while the values obtained against BChE were 3.65 and 4.90 μM, respectively.