The size, shape and controlled dispersity of nanoparticles play a vital role in determining the physical, chemical, optical and electronic properties attributing its applications in environmental, biotechnological and biomedical fields. Various physical and chemical processes have been exploited in the synthesis of several inorganic metal nanoparticles by wet and dry approaches viz., ultraviolet irradiation, aerosol technologies, lithography, laser ablation, ultrasonic fields, and photochemical reduction techniques. However, these methodologies remain expensive and involve the use of hazardous chemicals. Therefore, there is a growing concern for the development of alternative environment friendly and sustainable methods. Increasing awareness towards green chemistry and biological processes has led to a necessity to develop simple, cost-effective and eco-friendly procedures. Phototrophic eukaryotes such as plants, algae, and diatoms and heterotrophic human cell lines and some biocompatible agents have been reported to synthesize greener nanoparticles like cobalt, copper, silver, gold, bimetallic alloys, silica, palladium, platinum, iridium, magnetite and quantum dots. Owing to the diversity and sustainability, the use of phototrophic and heterotrophic eukaryotes and biocompatible agents for the synthesis of nanomaterials is yet to be fully explored. This review describes the recent advancements in the green synthesis and applications of metal nanoparticles by plants, aquatic autotrophs, human cell lines, biocompatible agents and biomolecules.
"In the wet chemical process, metal nanoparticle is generally synthesized by reducing metal ion (solution phase) using a reducing agent in presence of a stabilizer. To make such synthesis environment friendly, scientists have attempted to use reducing agent as well as stabilizer of biological origin and also to use aqueous phase as a reaction medium (Narayanan and Sakthivel 2011; Kumar et al. 2014; Merin et al. 2010; Kumari and Philip 2013; MubarakAli et al. 2011; Rao and Paria 2013; Jha and Prasad 2010). These green synthesis protocols are not only cost effective but also produce nanocolloid which are very much acceptable for subsequent biological applications. "
[Show abstract][Hide abstract] ABSTRACT: Aqueous silver nanocolloid was synthesized in a single step by a biogenic approach using aqueous leaf extract of Lippia javanica plant which acts as both reducing as well as capping agent. The as-synthesized silver nanoparticles were characterized by UV–visible absorption spectroscopy, high-resolution transmission electron microscopy and Fourier transform infrared spectroscopy (FTIR). The UV–Vis absorption spectra of colloidal silver nanoparticles showed characteristic surface plasmon resonance peak centered at a wavelength of 415 nm. The kinetic study showed that the reduction process was complete within 2 h of time. The TEM analysis showed that most of the particles were spherical in shape and their average diameter was about 17.5 nm. FTIR study confirmed the presence of some organic functional groups in leaf extract and their participation during the reduction as well as stabilization process. In addition, the as-synthesized silver nanoparticles showed antimicrobial activity against clinically isolated pathogenic strain of E. coli and B. subtilis.
"The former two methods are expensive and are associated with the use of toxic substances for reduction and/or stabilization of the metal NPs. Biological methods become an attractive alternative , because it exploits the natural resources such as plant, fungi and microbes, and are believed to be biocompatible  . Among other biological methods for synthesizing NPs, plant extract based synthesis has been recognized to be more advantageous over the other environmentally benign biological process, since it eliminates the elaborate process of maintenance . "
"However, the industrial synthesis of nanoobjects , as for chemical synthesis, is a source of environmental pollution via the numerous chemicals used in their synthesis. Development of new and clean nanotechnology manufacturing approaches which minimize potential environmental and human health risks is a challenge which motivates the scientific community (Guowu et al. 2011; Narayanan and Sakthivel 2011; Korbekandi et al. 2009). "
[Show abstract][Hide abstract] ABSTRACT: Testing biotransformation capacities of living aquatic microalgae diatoms to naturally synthetize gold nano-particles (AuNP) from gold salts and assessing aftereffects on their viability by microscope observations is a great challenge. In this work, a laboratory experiment was conducted, which aimed to observe (i) directly by transmission electronic and light microscopy and (ii) through indirect measurements (UV-visible spectroscopy) the periphytic freshwater diatom Eolimna minima exposed to gold salts. This work revealed the capacity of E. minima to intracellularly biosynthetize AuNP and to tolerate it. AuNP synthesis appears as a mecha-nism of detoxification to protect diatom from gold salt con-tamination. We also pointed out the risks associated with the spread of diatoms full of AuNP, through the trophic web of freshwater ecosystems. The preponderant part of the diatoms in natural biofilms associated with their position at the basis of the trophic webs in rivers could then make them responsible for the contamination of their consumers (grazer animals) and consequently for the potential release of AuNP through the entire food web.
Environmental Science and Pollution Research 01/2015; DOI:10.1007/s11356-015-4139-x · 2.83 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.