Abstract
Biological silver nanoparticles were successfully synthesized from a simple green and natural route using the extract of Allium cepa (onion) with the use of silver nitrate as precursor and chemically synthesized using silver nitrate and tri sodium citrate. Nanoparticle synthesis was proven under UV-Visible absorption spectroscopy. Toxicity of sliver nanoparticles was tested using ToxTrak test, in which, fresh overnight broths of Bacillus subtilis and resazurin dye were used to calculate percentage inhibition (PI). PI is only a relative measure and since there is toxic substances that increase respiration, to give result to a negative number. The PI of both chemically and biologically synthesized silver nanoparticles was compared in order to evaluate toxic effect value. The toxic effect value, PI of chemically synthesized silver nanoparticles is much greater (85.45%) than the biologically synthesized sliver nanoparticles from onion (51.39%). These observation shows that the bacteria B. subtilis killed by chemically synthesized silver nanoparticles are more as compare to biologically synthesized sliver nanoparticle. Key words: Silver nanoparticles, Allium cepa, ToxTrak toxicity test, resazurin dye, ultraviolet spectroscopy, Bacillus subtilis and percentage inhibition (PI).
Highlights
Nanoparticles are generally classified based on their dimensionality, morphology, composition, uniformity, and agglomeration
An important lesson we can learn from nanoscience is that simple classifications of physical behavior are overly limiting and that toxicology of each material and morphology must be studied, in addition to particle ageing, to obtain accurate information to inform policy and regulatory processes
Onion (Allium cepa) was used for the biological synthesis of silver nanoparticles collected from local market of Meerut in the month of April, 2012
Summary
Nanoparticles are generally classified based on their dimensionality, morphology, composition, uniformity, and agglomeration. An important additional distinction should be made between nanostructured thin films or other fixed nanometer-scale objects (such as the circuits within computer microprocessors) and free nanoparticles. Are the many objects containing nanostructured elements that are firmly attached to a larger object, where the fixed nanoparticles should pose no health risk when properly handled? An example of this important distinction is the material asbestos, which is perfectly safe in its primary state (basically a type of solid rock), but is a significant health hazard when mined or worked in such a way as to produce the carcinogenic nanometer-scale fibrous particles that become airborne (aerosol) and are readily absorbed in the lungs. It is very important to recognize that not all nanoparticles are toxic; toxicity depends on at least chemical composition and shape in addition to size and particle ageing. An important lesson we can learn from nanoscience is that simple classifications of physical behavior (and toxicity) are overly limiting and that toxicology of each material and morphology must be studied, in addition to particle ageing, to obtain accurate information to inform policy and regulatory processes
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