Femina Kanjirathamthadathil Saidu; Alex Joseph; Eldhose Varghese; George Vazhathara Thomas
Abstract
Metal nanoparticles incorporated conducting polymer nanocomposites have outstanding properties and potential applications in various fields and significant research has been carried out over the last two decades for the development of efficient methods for their synthesis. The current study describes ...
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Metal nanoparticles incorporated conducting polymer nanocomposites have outstanding properties and potential applications in various fields and significant research has been carried out over the last two decades for the development of efficient methods for their synthesis. The current study describes a microwave-assisted, rapid, and environmentally friendly method for depositing silver nanoparticles (AgNPs) over poly(1-naphthylamine) (PNA) using clammy cherry (Cordia Obliqua willd) extract as a reductant to create silver/nanocomposites (Gr-Ag/PNA) with varying silver contents. Thermal stability and charge transfer kinetics of PNA was significantly improved upon introducing AgNPs, as evidenced by the thermogravimetric analysis and electrochemical investigations, respectively. All prepared Gr-Ag/PNA nanocomposites could show improved catalytic activity towards the borohydride-aided reduction of 4-nitrophenol (4-NP) and the pseudo-first-order rate constants showed a direct relationship with the percent of silver incorporated over PNA. Additionally, for the first time, the Gr-Ag/PNA modified carbon paste electrode (Gr-Ag/PNA/CPE) was utilized to validate its usefulness and applicability in the electrocatalytic reduction of 4-NP. A low-cost enzymeless voltammetric 4-NP sensor based on Gr-Ag/PNA/CPE was fabricated and it showed excellent selectivity for 4-NP, as well as a strong linear response over a wide range of 4-NP concentrations (30-1000 𝜇M) and a detection limit of 6.25 𝜇M.
Bipul Sarkar; Palash Mondal
Abstract
Monitoring the levels of toxic Hg2+ metal ion in aquatic environment is important issue because this ion can have adverse effect in human health and environment. Therefore, detection of Hg2+ ion in water is very important issue for improving human health and water quality. Metallic nanoparticles such ...
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Monitoring the levels of toxic Hg2+ metal ion in aquatic environment is important issue because this ion can have adverse effect in human health and environment. Therefore, detection of Hg2+ ion in water is very important issue for improving human health and water quality. Metallic nanoparticles such as gold and silver nanoparticles (AuNPs & AgNPs) have received much attention due to their colorimetric properties as well as localized surface plasmon resonance (LSPR) properties. AuNPs and AgNPs can easily change their colour (AuNPs: Red to Pink/Blue; AgNPs: Yellow to orange/red) which is easily discriminate by visual inspection. Functionalization of AuNPs and AgNPs offers an excellent application in many scientific worlds as the choice of ligands/functionalizing groups is outmost importance for their colloidal stability and function of the nanoparticles. In this review, we have discussed the colorimetric sensors of gold and silver nanoparticles based on functionalization of organic ligands, polymers, amino acid, and proteins for the detection of Hg2+ ion in aqueous medium.
Susarla Sastry
Abstract
Nanotechnology is getting an incredible drive due to the potential of manipulating metals into their nano size particles. The synthesis and characterization of nano particles using green technology have many applications. The wet chemical techniques used presently in the synthesis of nano particles are ...
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Nanotechnology is getting an incredible drive due to the potential of manipulating metals into their nano size particles. The synthesis and characterization of nano particles using green technology have many applications. The wet chemical techniques used presently in the synthesis of nano particles are deleterious along with flammable conditions. Silver nanoparticles have the capability of killing microbes in an effective manner. This paper explains about the green technology and pollution free methodology for synthesizing silver particles at nano scale using 1mM silver nitrate solution from the extracts of Carica papaya, Emblica officianalis, Azadirachta indica and Cocos nucifera. When the silver nanoparticles are synthesized the solution turns to brownish yellow colour. The tools used in the characterisation of silver nano particles are Ultra Violet - Visible absorption Spectroscopy and Field Emission Scanning Electron Microscopy. The solutions with silver nanoparticles showed the maximum absorption at 450 nm with Ultra Violet - Visible spectroscopy. It is found that C. Papaya and E. oficianalis showed the maximum absorbance of 0.578 and 0.59 respectively at 450 nm. The average range of the produced silver nano particles are analysed to be 5 – 70 nm with FESEM and the shape is examined to be spherical.
Shirish Sadashiv Pingale; Shobha Vasant Rupanar; Manohar Chaskar
Abstract
The present study reports one step green synthesis of silver nanoparticles using Gymnema sylvestre aqueous extract at room temperature and their usage in the photodegradation of methyl orange dye. The silver nanoparticles are synthesized using an aqueous extract of stem and root of Gymnema sylvestre. ...
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The present study reports one step green synthesis of silver nanoparticles using Gymnema sylvestre aqueous extract at room temperature and their usage in the photodegradation of methyl orange dye. The silver nanoparticles are synthesized using an aqueous extract of stem and root of Gymnema sylvestre. UV-Visible spectral analysis showed absorbance peak at 430 nm with special reference to the excitation of surfaces plasmon vibration by silver nanoparticles. FT-IR analysis of nanoparticles reveals the presence of molecular functional groups such as amides, phenolic compounds, and carboxylic acid. These phytochemicals act capping and stabilizing agents for silver nanoparticles. EDAX elemental analysis shows the presence of silver as the main element in synthesized nanoparticles. The average crystalline size of silver nanoparticles was found to be 25.3 nm and 9.97 nm for Stem-AgNPs and Root-AgNPs respectively by Scherer formula. XRD patterns also suggest the occurrence of crystalline silver ions. Further, photocatalytic degradation of methyl orange was measured spectrophotometrically by using silver nanoparticles as nanocatalyst under solar light effect. The results revealed that biosynthesized silver nanoparticles using G. sylvestyre was found to be notable in degrading methyl orange dye under the influence of sunlight.
Vida Alizadeh; Bahram Golestani Eimani; Fariba Amjady
Abstract
Background and objectives: Drug resistance in bacteria is one of the important problems in the antibacterial field. Therefore, new drugs and therapeutic approaches are required to eliminate bacteria using different and novel mechanisms. Among these, the silver nanoparticles have been proposed as a substance ...
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Background and objectives: Drug resistance in bacteria is one of the important problems in the antibacterial field. Therefore, new drugs and therapeutic approaches are required to eliminate bacteria using different and novel mechanisms. Among these, the silver nanoparticles have been proposed as a substance with antibacterial properties against gram-positive and gram-negative bacteria. The present study aimed to investigate the effects of silver nanoparticles with a size of less than 20 nm on the genome of Staphylococcus aureus (S. aureus) as a model for gram-positive bacteria.Material and methods: For this purpose, the bacteria were treated at concentrations of 100 and 150 µg/ml nanoparticles and antimicrobial properties of the nanoparticles were investigated in intervals of 2, 4 and 24 hours, then DNA was extracted. RAPD molecular marker was used to investigate the effects of nanoparticles on the genome. In addition, the results of electrophoresis for polymerase chain reaction (PCR) products on agarose gel were analyzed.Results: The present findings demonstrated that silver nanoparticles not only have an inhibitory effect on bacteria but also affect the genomic DNA sequence of this bacterium and change it in different sites.Conclusion: The nanoparticles are antibacterial compounds and can be an appropriate alternative to antibiotics.
Bal Yadav; Ritesh Kumar; Ravindra Kumar; Subhasis Chaudhuri; Panchanan Pramanik
Abstract
This paper presents the synthesis, characterization of the nanocomposite of silver and chitosan polymer composite reinforced by cellulose fibre and its electrical behaviour in presence of water vapour. The coated paper has been characterized by XRD, IR, SEM and EDX techniques. The size of silver nanoparticles ...
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This paper presents the synthesis, characterization of the nanocomposite of silver and chitosan polymer composite reinforced by cellulose fibre and its electrical behaviour in presence of water vapour. The coated paper has been characterized by XRD, IR, SEM and EDX techniques. The size of silver nanoparticles is found to be around 9 nm and deposited uniformly. Chitosan, as well as cellulose, contain a hydrogen attached to electronegative nitrogen and oxygen. This gives a favourable environment for the formation of hydrogen bonds. IR peaks of the composite infer the intermolecular hydrogen bonding between the two constituents. The SEM pictures show that the coating of the fibres with nanoparticles is quite uniform. EDX analysis shows that the coated filter paper has sufficient amount of silver along with carbon and oxygen. The coated paper shows good sensitivity towards humidity. It gives excellent linearity in response with a concentration of water vapour after heat treatment of composite at 130 °C. The sensitivity of the sensor is 0.8 MΩ per unit of relative humidity. Sensing properties originate from protonic conductivity from adsorbed water molecule.
Mustafa Nadhim Owaid; Sajid Salahuddin Saleem Al-Saeedi; Idham Ali Abed
Abstract
Twelve extracts belong to four species of edible oyster mushrooms were screened for their chemical value (viz. proteins, carbohydrates and phenols were assessed) and their capability to biosynthesize silver nanoparticles (AgNPs). In limitative conditions, dark incubation and temperature 25 °C, three ...
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Twelve extracts belong to four species of edible oyster mushrooms were screened for their chemical value (viz. proteins, carbohydrates and phenols were assessed) and their capability to biosynthesize silver nanoparticles (AgNPs). In limitative conditions, dark incubation and temperature 25 °C, three modes of extracts preparation were developed. Properties of silver nanoparticles creation from extracts solution with 1 mM AgNO3 were investigated by color and UV-Visible spectroscopy to confirm silver nanoparticles formation. The bright yellow oyster mushroom (Pleurotus cornucopiae var. citrinopileatus) was finding as a potential candidate for the synthesis of AgNPs. Brown color of aqueous solution was given indication for AgNPs formation. Results showed that AgNPs absorption band was located at a peak of 440 nm for P. cornucopiae var. citrinopileatus. Although others P. ostreatus (grey & white) and P. salmoneostramineus (pink) were not form AgNPs due to no change in color of extracts with Ag ions when incubated under the same conditions, which indicative for no silver nanoparticles synthesis. Thus, AgNPs formation depended on species of oyster mushroom, method of extracting, concentration of extract and the conditions of incubation (of light and temp.), but no on content of proteins, carbohydrates and phenol in crude extract leastwise in this study
Koilparambil Divya; Liya C. Kurian; Smitha Vijayan; Jisha Manakulam Shaikmoideen
Abstract
The emerging infectious diseases and the development of drug resistance in the pathogenic microorganism is a matter of serious concern. Despite the increased knowledge of microbial pathogenesis and application of modern therapeutics, the morbidity and mortality associated with the microbial infections ...
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The emerging infectious diseases and the development of drug resistance in the pathogenic microorganism is a matter of serious concern. Despite the increased knowledge of microbial pathogenesis and application of modern therapeutics, the morbidity and mortality associated with the microbial infections still remains high. Therefore, there is a pressing demand to discover novel strategies and identify new antimicrobial agents to develop the next generation of drugs or agents to control microbial infections. The use of nanoparticles is gaining impetus in the present century as they possess defined chemical, optical and mechanical properties. In the present study green synthesis of silver nanoparticles by Escherichia coli has been done. Various parameters such as mixing ratio of culture supernatant and silver nitrate, media, temperature and pH for production of silver nanoparticles were optimised. The nanoparticles synthesised was characterized using SEM, FTIR and XRD. The antibacterial activity of silver nanoparticles synthesised using both pellet and supernatant against human pathogens Salmonella typhi, Vibrio cholerae, Bacillus subtilis and Klebsiella pneumoniae was analysed and MIC was calculated as 20µg and 50µg respectively.